Thermal Regulator Replacement on Pentair Mastertemp 400 Pool/Spa Heater

[@ystebadvonschlegel3295]

Great video - just paid hundreds to have this fixed - but next time I'm gonna do it myself! Very much appreciated.

[@pmanification]

Can’t trust no pool guy lol

[@zuhalterei4090]

Awesome video. I have same problem. But instead of removing the regulator I lowered the temp on the heater to 65 and let it run for a few minutes. Then cranked it up to 104. Fired up and had heat. Now it is doing it again next day so I think we have the problem solved. You are the man.

[@yvesgagnon58]

Thanks...that fixed mine ......I leave in Toronto and pool is on all the time heater is a must

[@peterczurak]

Thank You very much. The heater was making a very annoying noise, because of your video I was able to check the thermal regulator, although there was nothing wrong with it, after I put it back the noise was gone - what a relief! And just before the Memorial Day weekend, thank you, thank you.

[@brand0nb4rn3s]

Love the videos you have helped me fix my HLS light problem, thermistor and thermal regulator. Appreciate the videos and thank you!

[@kenscott1082]

Cool video

[@chuckroelen7341]

My 400 unit would heat up to about 88º then it began cycling on & off. I bought the new thermal regulator from Amazon & installed per this video. Took longer to drain the water then instal the parts. Everything works like new. Thanks for the video.

[@paulabrilla5531]

My thermal regulator cap is too tight. It won't easily come off like on the video. I'm afraid to break it. Not sure, if I'm supposed to do something first before unscrewing the cap (counter clockwise).

[@zohrabgrajyan3250]

Hi and thank you for all your videos. I looked through all of them including the comments to find a solution but didn't find it. I have a pool and no spa. Heater is a Mastertemp 400. I turn it on the blower motor turns on then there is a clicking sound and I can smell gas through the exhaust pipe but the ignition never happens. It cycles through this process for 3 times before the service heater light comes on. I have no error lights on the back of the control board. I tested the Thermal Regulator and that works. I bought my house about 4 years ago and back then it would turn on for few seconds and I could also feel the ignition because of burst of hot air coming from the exhaust pipe but then it would turn of after that. Also back then the heating light would blink for few seconds. Now the heating light never comes on. Since I don't have a spa it was never an emergency to find a fix for it. Now that I found your channel I want to get to bottom of this :). Any help would be much appreciated. Thank you.

[@pvt-pilot]

Hi there, I will try to make suggestions based on my experiences with mine. The clicking you hear is the gas valve opening as seen in my videos. My suspicion is that you have a faulty igniter just because you say you can smell the gas but have no ignition. Try unplugging the igniter and put an ohm meter on the side going down into the combustion chamber where the igniter is located. If you get an open (infinite ohms reading) then it is likely that your igniter is cracked or broken inside the tub. 2 screws is all that hold it in there. There is no diagnostic LED on the control board that point you to the igniter. From what I have seen, the igniters are understandably very fragile (they have a rough life you know), so be careful with handling them if you need to remove/replace it. If you find that there is a solid resistance reading to the igniter, check the feeder side of the connector. See if you get an open in that direction. Make sure to check for a break in the wiring if you get an open. Make sure the connector is clean on the incoming and outgoing side. If all checks out there, open the box that is about 5"Wx6"Hx4"D. This is called the Ignition Control Module (ICM). Look at the red LEDs inside that box. I think if it blinks 3 times repeatedly, it means that it is in "ignition lockout". If this is the case, search KZbin for "ignition lockout" and see if you can find a reset for that. I know there is a video about it but I haven't had that problem yet so I don't know a lot about it and don't want to steer you in the wrong direction. Lastly, another thing that will surely allow gas valves to turn on and no ignition would be if there is water in your combustion chamber. Take out 1 of the 2 bottom bolts of the manifold before you do anything else and see if water comes out. If so, your heating coils are leaking, filling the tub up to the level of the igniter and preventing it from firing. That would be a rather involved repair to replace the coils as you may have seen from my other videos. Hope this helps for now. Write back with what you find and we'll go from there.

[@jeff2385]

@@pvt-pilot This was exactly my problem Zohrab! I installed a new igniter and the bad boy started up again. However, one issue fixed leads to another issue. The heater turns on and blower but only lasts for about 1 min to 2 min and service light comes on. After about a min or two, the heather re-ignites and cycles and service light comes on and its the HLS light. After about another 1 to 2 min, it reignites. Not sure if the thermoregulator can attribute to this?

[@pvt-pilot]

@@jeff2385 I think you have either a corroded nonfunctioning thermal regulator or you have a broken manifold bypass valve. Do you hear crackling like ice cubes bouncing around in your manifold when the water is running? If so, you have a broken manifold bypass valve. I posted a video for that easy repair a couple of years ago on this channel. kzbin.info/www/bejne/q57ZdZWYnsx3nqM

[@jeff2385]

@@pvt-pilot You are the man!!!! Thank you so much, it turned out it was the thermal regulator. I picked a new one today and the heater no longer "cycles" through on/off. I can't help but say THANK YOU! From my family to yours, I am grateful for the videos you posted. Much gratitude especially during these weird quarantine times. It was tough getting someone to fix the heather let alone trust someone to come! My friend, you helped resolve this issue and the pool is now being enjoyed by my family! You also gained a subscriber haha!

[@geoffap]

Hey there. Would be handy if you showed how to mount the thermal regulator on the spring. Thanks for the vid!

[@dotd76248]

Thank you. You save my day.

[@christivel8464]

Thank you for this video - this really helped me out.

[@selfmademadness]

Great video!

[@jamescerneka5452]

that's a relief. I will try it later today.

[@mr.d7776]

Thanks so much!!!

[@rleader1]

Hey. My Heater runs fine for a while but then shuts off and I get a service heater light. No error codes. I checked the backside of the panel and no lights were lit. I believe it cycles back on again eventually, but I'm not sure. If I shut it down though it will fire back up and heat again but eventually stops. Any suggestions? Is it likely the part in this video? Thanks!

[@jimmykhuc3288]

Good job

[@irmaperez6327]

Hello do you have to add lubricant to the plug

[@Hoffyrevhead]

Mine is stuck in that hole behind a black tab on the upper part. What solution to get that out

[@irmaperez6327]

So i changed mine out and now its leaking water can the manifold be damaged

[@adnanshaben8889]

Very informative and thank you. I have a MT250 and replaced the AGS as per the code under the circuit board and still got a service light so I checked the thermal regulator and it was corroded so I replaced that. The heater worked great for a few days and the service light is back on and not showing any error codes. I did notice a leak where I put the new thermal regulator and perhaps that is my issue, even though I taped it. Glad I kept the original cap perhaps it fit better. When I turn the heater off then on it does run for about a day before the light comes back on. Any help is appreciated.

[@markhannigan8510]

I was able to replace my thermal regulator without using the clip (I noticed it in the box after I installed it). Is it absolutely necessary to have the clip installed or does just hold onto the spring? Thanks

[@michaelmiller6843]

Thank you for your video! If I set my water to say 95, my heater will turn on, heat the water from 70 to about 84 or 85, then cycle off for a few minutes, then cycle back on for a few minutes and then back off. It won’t heat the water any higher than that. I tested the thermal regulator as you showed and it appears to be working, although it does appear to be very corroded. However I can’t get the water out of my faucet very hot, so I put the regulator in a pot of almost boiling waters. Is it possible the regulator is working but only at temperatures higher than what it supposed to? Therefore when I put it back in the heater it is not actually working as intended? Is it worth replacing it to see if that will fix the issue?

[@pvt-pilot]

I would replace it. It should only take scalding temp (120 degrees) to open it, not boiling temp (212 degrees)

[@michaelmiller6843]

@@pvt-pilot Thank you very much! Your explanations are fantastic.

[@michaelmiller6843]

@@pvt-pilot I have not yet replaced the thermal regulator yet, but have discovered the heater only cycles on and off when the water reaches 93-95 degrees. Anything lower than that, the heater works normally. Could that still be the thermal regulator not fully opening? Thanks again, I really appreciate your help.

[@pvt-pilot]

@@michaelmiller6843 Yes, perhaps. Here is why... Thermal regulators have a relationship with the HLS and control board. If the heater heats water too quickly to the point of scalding, the thermal regulator must open to let some cold water bypass the heat coils and go straight through to the output side and dilute the hot water with cold water. If this does not happen, the HLS that is located on the output side of the manifold will open which in turn gives an electrical open which is seen by the control board. The control board will immediately turn the heater off and throw a service heater light until the water in the output side cools down enough to close the HLS and provide the control board with a 0 ohm short (electrically closed). If you are getting cycling at 95 degrees, check to see if it is throwing a service heater light during the cool down part of the cycling. If it is, then yes, the water is simply too hot in the output side detected by the HLS and the thermal regulator is not doing it's job. Good thing is the HLS and contol board will have proven to you that they are doing their jobs. You could temporarily strap a wire across the HLS leads to trick the contol board into thinking the water is not super heated and is still safe. This will help prove the point of failure but it is EXTREMELY dangerous. DO NOT LEAVE IT LIKE THAT. This can melt plastic pipes, cause a fire hazard, and scald those kiddos. How about forget I wrote that and just replace the thermal regulator and we go from there.

[@michaelmiller6843]

@@pvt-pilot Thank you very much. We are all lucky to have your expertise.

[@lynnenoel4075]

This is helpful. My heater on a Pentair Mastertemp 400 is not working but shows an EO5 error code. What does that mean??

[@pvt-pilot]

Wiring to stack flue sensor wiring could be corroded causing open, but more commonly, the problem would be that the electrical open is inside the sensor itself. Replace the sensor on the exhaust pipe.

[@lirpa_j]

Hi, we were mostly successful at replacing this but the spring came apart and the regulator dropped into the pipe below, which leads to the return. Please help! We may need to be able to get it out with a hanger, but how do we get the the spring to not unscrew when we screw the cap on?

[@twotone9987]

Well crap, wish I saw this video earlier. Super informative. Learned a bunch thank you. Having the same exact issue you were describing at 4:15

[@bernardoorellana540]

Why would it display on my topside (too hot) after igniting and running?

[@Salbritt]

Thanks, I believe this is exactly whats wrong with my unit. Except I have the 250 instead of 400. Do you know if my unit has a complete different spring and thermal reg?

[@pvt-pilot]

I know for certain the STA-RITE 400,000 BTU heaters are the same as the Pentair Mastertemp 400, but I am not certain if the 250 is different than the 400. I would imagine they are all the same because if you search the thermal regulator model for your unit on eBay and Amazon, they same part # comes up as shown in my video. I would check with a local pool supply company first before buying it though.

[@Poologix]

Yes it is the same ! For both heaters ( sta rite & pentair )

[@russellschonmeier9437]

Great video. Thank you. Question: I have a Pentair 200. What I am experiencing is that my service light will come on a few times a day for my spa and the temp will be around 85 (set point is 103) when I check on it. I power off the unit and then press "on" and it will start up and heat the water again to 103ish. It can take a couple of hours to reach full temp. Then at some point it will shut down and the service heater light will illuminate. Then when I notice the service heater light back on, I will hit "off" and wait 5 seconds and then press "on" and it will fire up again. I am not sure but it appears that once it makes temp and shuts off, then it will get a service heater light (no codes). Is this possibly the Thermal Regulator"?

[@pvt-pilot]

No codes on the display, understood. Did you check for any illuminated error lights on the back side of the control board?

[@ryandohrwardt1258]

Do you know how to change heater form Celsius to Fahrenheit?

[@pvt-pilot]

I do not, sorry. Hopefully someone else on here knows how and can respond.

[@officerkrupke4966]

Your spa button should be programmed to turn on your filter pump, rather than you manually having to press both. Mine is set up that way, valves change over, pump starts, than heater kicks in.That way, if you get a remote control later on, it will operate system.

[@officerkrupke4966]

Also, you can set your pump speed to automatically increase to a speed that will keep spa heater from tripping on high temp due to low flow if you have a variable speed pump set too low for spa mode.

[@pvt-pilot]

Very cool input. Thank you!

[@jamescerneka5452]

Is it possible to push the thermal regulator in too far. Yesterday, I took it out and tested it. It opened but not enough. I put it back in because it would work up to 92 degrees before cycling on and off and my family wanted to use the spa. When I received the new part, I tried to pull it back out and it was "stuck". The spring came out with a lot of force, but the regulator never came out??? When I look into the tubing it is not there. I am pretty sure that the opening will not let it enter the main tubing, but am I missing something??? Unfortunately, these low-probability complications always happen to me, so I am willing to believe anything at this point.

[@pvt-pilot]

Can you push it in too far? No. It mates to a circle cut out on a plastic wall and the thermal regulator is larger than the circle so that only the thermally reactive material extends past the circle in the wall inside the manifold. If you pulled the spring and the thermal regulator fell off the end of the spring, it will remain in a cavity just inside the exterior threaded hole that you pulled the spring out of. So, at this point, do not recap it and turn the pool pump back on because you will blow the thermal regulator out of the output port and it will take a long ride toward your pool. So, stop for a second...let's get it out one of two ways. Either fish it out with a wire coat hanger, possibly a magnet, or what I would do is disconnect the bottom white pipe (output) from your manifold and move it to the side a bit out of the way but leave the top white pipe connected (input). Then turn the pool pump on and let it blow you pool water out onto the ground. Your thermal regulator should come out in the wash. Then, reassemble the thermal regulator in the spring and give it a go. For a good look at the inside of the manifold including the thermal regulator, plastic wall with circle and output cavity where your thermal regulator landed, scroll to 4:05 of my other video here: kzbin.info/www/bejne/q57ZdZWYnsx3nqM Hope this helps. Cheers!

[@samuelriebel5535]

Is it the LEDS that run along the bottom that are used for T/S or is it the ones on the left-hand side? I replaced my thermal regulator after a constant SERVICE HEATER lamp. If I was lucky, I could secure the breaker reset the fault and the heater would start-up for a min or so and shut off. My thermal regulator was really corroded. The SFS led is lit.

[@pvt-pilot]

Diagnostic LEDs are on the left side of the control board (not visible from the touch pad). The status LEDs are on the bottom and they just line up with the little transparent LED windows in the membrane pad (so they are visible from the touch pad which include HEATING, SERVICE HEATER, POOL, SPA, etc.

[@samuelriebel5535]

@@pvt-pilot Thank you. I attempted some T/S of the issue using the owners manual flowchart for an SFS LED. Upon inspection, I found a very corroded thermal regulator. I've replaced it but when I re-energize I still get the SFS led, a SERVICE Heater led on the pad. Any suggestions?

[@pvt-pilot]

@@samuelriebel5535 I'm sorry. I failed to mention what SFS means. That is your Stack Flue Sensor. It is likely metalically open to throw a SFS light. Check for corrosion or break in the SFS wires/spade contacts. It is nothing more than a thermistor mounted on the side of your exhaust pipe. If you need an explanation of what each diagnostic light means, please view this video on my channel: kzbin.info/www/bejne/rX_Hc3V-pqpkrNE

[@samuelriebel5535]

@@pvt-pilot Thanks. I did watch your video and found it very informative.

[@pvt-pilot]

@@samuelriebel5535 Thank you for your service!

[@willlandrum9514]

My Regulator seems to be stuck. I'm afraid to use too much pull pressure to dislodge it. Any suggestions? Thanks.

[@pvt-pilot]

Don't be afraid to pull harder. Worse case scenario, the spring comes off without the thermal regulator. If that happens, you will have to take the manifold off and remove the thermal regulator from the other side. Nothing should make it stick in there, so it is likely something else is wrong and you need to put your eyes on it. I would take off the manifold and take a look around inside.

[@turelillegraven4528]

Hi, thanks for the video. I have a Mastertemp 300...it turns on, no codes or anything but it's not heating the water in the pool. I replaced the thermistor but still no luck. Could it be the regulator if it's stuck open?

[@pvt-pilot]

Possibly, because the thermal regulator will open when the water exiting the coils gets over 135 degrees just to prevent scalding and pvc pipe damage. Is the air at the exhaust hot? If so, is the water entering the pool hotter at the outlets on the wall of the pool than the temperature of the water in the pool? If not, your thermal regulator if stuck open could be the path of least resistance from the input of your manifold to the output of your manifold which makes a vast majority of your water actually bypass the journey through the heating coils. A clog in the output chamber of the manifold or one of the coils could cause this, but you would have to take the manifold off to check for that. Another similar scenario of the water having the ability to skip the journey through the heating coils will occur if the manifold bypass valve breaks. This threw an HLS light on my control board when mine broke. You might check out my Manifold Bypass Valve replacement video to see what I am talking about on that scenario. Hope this helps you.

[@JohnHastie]

I have a MasterTemp 250, which seems to work fine. It heats the tub to 104 F then turns off and comes back on again when the temperature drops. However, when my Jet Pump is turned on, the water temp (as reported on the panel inside the house) slowly increases to around 109F. The temperature in the tub slowly drops while the Jet pump is running until it is turned off and the temperature again reports correctly and the heater turns on. Any ideas on what bits need to be replaced?

[@pvt-pilot]

Well, let's see, you kinda lost me at Jet Pump. I don't have a separate pump of any kind aside from the one main pool pump to run my pool and spa. I just have 2 actuators sitting on top of my 2 valves that simultaneously turn when I change from pool mode to spa mode. These valves dictate which drains to draw water from (either pool only drains or spa only drains) on one valve and which outputs are used to drive water back into the pool or spa on the other valve. If I activate the air blower for about 10 seconds while in spa mode, it primes the output line with air and this keeps bubbles flowing down the line to all 6 spa outlets even when the air blower is turned off. Please clarify what you mean by "jet pump" and I will try my best to answer again if I am off base here. With what you have said so far, it sounds like you are talking about a failing actuator that is not moving and thus you are pulling cold pool water from your pool drains into your spa at a moment when it is actually supposed to be pulling warm spa water from spa drains. Actuators are about $100-$110 on Ebay and Amazon. Test your existing actuators by moving the toggle switch on the back of each one repeated to see if each one moves correctly. Return the switches back to their original positions when you are done testing them. Sorry if this isn't what you mean. Perhaps I may not be understanding your question/problem correctly.

[@JohnHastie]

@@pvt-pilot I figured it out. I'd turned the speed down on the filtration pump and when I reset it back the temp was being reported correctly.

[@louieorozco960]

Hi, your videos are very useful and informative but not sure if my issue is caused by the thermal regulator. The issue is that the water heater runs without problems but it doesn't appear to put out hot water as it used to do about 3 years ago. Just 2 weeks ago, it ran for hours and it only heated the pool approx. 10 degrees to about 82 degrees. That was the intake temp showing on the panel . My hot tub heated to about 90 degrees. I would have let it run longer but it probably would have cost me a fortune. BTW, the exhaust is super hot so I know there is heat being made somewhere inside. Thanks, any suggestions will be greatly appreciated. I also have a Mastertemp 400 heater.

[@pvt-pilot]

Could be a stuck thermal regulator letting cold water into side of the manifold that is supposed to be the hot output. This often will not throw a code because it is not an electronic part and no sensors are tied to the problem on the diagnostic LEDs on the contol board. Mine didnt throw a code when my thermal regulator quit working. The heater would just cycle off within a few minutes, show service heater light and takes forever for another heat cycle to start, but never show error code or LED lights on control board. Another thing to try, pull out one of the 2 bottom bolts in your manifold. Make sure no water comes out. If you have any water in there, this is a leaking coil assembly and you could be heating only 5, 4, or even 3 of the 6 tubes depending on how high the alleged water level could be. This could cause slow heating caused by a leak, but usually tub filling won't stop until it teaches the top and then wont fire at all. If all is ok and tub is dry like is supposed to be, another possiblity that causes slow heating might be calcium or scale build up on the inside of your heat coils. You would need to take things apart and visually inspect the coils. Calcium and scale lining the insides of the heat coils can act like an insulator between the copper tubes and the water rushing inside them. You would probably notice flakes of scale spitting into the pool on a daily basis if things got bad. These are a few things to take a look at. Hope it helps.

[@louieorozco960]

@@pvt-pilot just saw your reply. It makes sense. I will check it out. Thanks for your help.

[@mcquiddybragg9431]

Thank you for the information and video on replacing a thermal regulator. I have a Sta-rite Max E Therm 400 heater on my pool and spa. Initially it would only heat up to 85 degrees, start cycling on and off, and not get any hotter. I replaced the thermal regulator and tested the heater. It reached the set temperature of 104 but started cycling on and off when the temperature was around 97 degrees. The cycle would be about 1 minute to 1 minute and 30 seconds on and about 45 seconds off. During the re-ignition process the service light would briefly come on then off just before the heater would light. Is this normal or if not any suggestions?

[@pvt-pilot]

Is you fan turning off during each cycle? If so, please understand that there is an immediate SERVICE HEATER light at any given moment that you AFS is not closed, meaning any time there is not full power air flow being blown by the fan. So, during the boot up process, it is absolutely normal for the SERVICE HEATER light to illuminate each and every time for a quick moment between the second you turn the heater on to second that your fan spools up. As for not reaching 104 before cycling, that might be a false temp reading by the HLS (High Limit Switch - which does not have a temp display) shutting the heater down before reaching your true desired temp. Pull out your HLS using a 7/8" wrench to check for green/blue oxidation caked up on it. If your thermal regulator had that garbage on it, chances are that your HLS and thermistor will likely have some pooky on them too. Thermal Regulator is responsible for preventing you from scalding yourself or melting your pipes. HLS is an electrical way of making sure your thermal regulator and various other parts are doing their job. It is the last water temp safety check sensor before water leaves the manifold. So for safety reasons, keep your sensors happy and healthy.

[@mcquiddybragg9431]

Sorry for the long time for a reply but I had a massive tile project take precedence. Anyway, I replaced the HLS and everything is working great. Thank you very much for your assistance.

[@officerkrupke4966]

@@pvt-pilot During start up, pool water flowing thru heater will cause condensation on outside of heater pipes. To combat this, they put a thermal regulator to keep heater water flow shut off until water temp inside reaches 120 degrees, than opens to allow flow thru heater, much like your cars tstat works. If it sticks closed, heater overheats and the high limit switch will shut heater down. If it sticks open, heater pipes will rust due to the condensation forming on outside of pipes. Newer models now have capability to add an automatic bypass around heater when it is off.

[@christianmayhew2617]

I have a Mastertemp 250. Cycles off and on until desired temperature in either pool/spa mode; however, it does it 30 seconds at a time, takes forever to heat the spa.......Thermal regulator?

[@pvt-pilot]

Maybe thermal regulator is the problem. Pull it out and test it.

[@liquidmojo1439]

My Mastertemp 400 was cutting out after beginning the process of calling for heat and attempting to ignite, then it would shut off and start over. I pulled my thermal regulator and it was definitely stuck closed, corroded and green. I swapped it for a new one and thought I'd be set, but it is continuing to cycle and then ends with a Service Heater light. There is no error code on the back of the controller board. As it cycles, the Heating light blinks, then goes solid, then I hear a puff sound from inside, then it starts blinking again. It seems as if it is attempting to light, but can't for some reason. Could the faulty thermal regulator have allowed water into the combustion chamber? Are these potential separate issues? How can I check to see if the combustion chamber is dry, preferably without tearing the entire unit down. Another thought is could it be clogged in some way? Prior to this issue, we had torrential rains that caused the patio to flood and a bunch of soil and sediment got into the pool. It is all filtered out and looking clear now, but I wonder if it somehow got through the system and gummed up the heater.

[@pvt-pilot]

You asked can a stuck thermal regulator allow water into the combustion chamber? Answer: No, the manifold and all of its internal parts are sealed and separate from the inside of the combustion chamber. A stuck thermal regulator will prevent opening a path for cold water to dilute hot water at the manifold output that is too hot to contact human skin (120 degrees). To prevent scalding, pentair put a HLS (high limit switch) at the output side of the manifold that will provide an electrical "open" circuit that the control board will see and react by shutting down the heater and throwing an HLS light on the back side and SERVICE HEATER on the front side. This chain reaction of safety devices and switches is how a faulty stuck thermal regulator results in a SERVICE HEATER light. You asked what is a quick way to see if your combustion chamber is full of water without tearing it down? Answer: Unscrew one of the 2 bottom bolts (13mm) that holds the manifold on the side of the combustion chamber. Since each bolt hole is essentially an unobstructed threaded tunnel directly to the inside of the combustion chamber, when you remove one on a flooded combustion chamber, water will come out. I stated to unscrew the bottom bolt on either side so that you will "remove the drain plug" at the lowest elevation and have the maximum effect to get it drained as far down as possible. This should clear the cavity enough to get it to fire. That said, if you have any water in your combustion chamber, your heat coils are leaking, no mistake about it. See my channel for another video on how to replace the coils if your tub has water in it. You asked can there be mud clogging up the inside if the heater tubes? Answer: theoretically possible to clog one or two, but not all of them and not likely at all to clog any of them. The reason is because every drop of water that your main filter pump pushes runs through your heater coils day after day regarding of whether or not you are using your heater. If the heater's coils were clogged inside each tube, none of the water that your pump is moving would make it back to the pool. You are moving water fine so this is not the case. Also, your filter is in line before your heater and would not allow dirt through it anyway. If a little dirt passed through the filter, it would be so small that it would pass through the heater tubes too and spit out in the pool. Hopefully the filter would catch that dirt on the second pass. Hope this helps!

[@liquidmojo1439]

@@pvt-pilot Thank you for the detailed reply. I pulled the bottom bolt and it was dry. I have now ruled out the following: thermal regulator, leaking heat pipes, water in combustion chamber, controller board, gas supply. Since I can smell the gas and hear a puff sound, but it doesn't seem to ignite, in wondering if it may be the ignitor. It's three any other component I should be looking into?

[@pvt-pilot]

@@liquidmojo1439 You may try testing the igniter next. It has a modular plug to disconnect it next to the blower so you dont have to remove it to test it. Put an ohm meter on it. If it is open (infinite ohms of resistance), it is defective. If it has low resistance reading at the plug, it is not likely that the igniter is defective. Test both directions while you are there to confirm no opens. Let's go from there.

[@liquidmojo1439]

Fixed. Thank you very much for your help. The new ignitor did the trick.

[@officerkrupke4966]

@@pvt-pilot If the heater coils were clogged , the pool water would circulate thru the internal bypass valve, which it does normally when the heater is off and the thermal regulator seals the heater output to prevent condensation on heating coils, and rusting them out. Review the manifold flow diagram. The thermal regulators purpose is to prevent condensation on the heating coils, not to prevent scalding water to attack swimmers. Low water flow would cause scalding water to attack swimmers near the jets. To protect them, they installed the high limit switch. The ags switch is set to shut off the heater at about the same temp as the hls, so that is the backup. Enjoy your videos, keep up the good work.

[@kndlvon]

I have the same heater-- I tried heating the spa this week and the unit comes on, ignites and then immediately shuts off. I have no error codes and there are no lights on the back side of control board. I've messed around with it several times and only once did the SFS light come on--- I haven't seen it on since. I was able to feel the hot water coming out of the jets briefly until the unit went back off. Do you know what that could possibly be?

[@pvt-pilot]

I don't think you are giving me quite enough information but I'll try my best to help. It really sounds to me like you have a defective thermal regulator, but I will assume you have already tested your thermal regulator since you watched the video and will assume all is well with your thermal regulator. So... How about a service heater light? If you have a service heater light, then your control board is receiving readings from at least one sensor that is out of limitation. For example, you could have an SFS (Stack Flue Sensor) reporting 400° to the control board when it is actually only 310° or less. This would not produce an SFS error light because the SFS is not shorted nor open...just giving erroneous readings that the control board thinks are legit. So, for obvious safety reasons, the control board will shut everything down and illuminate the service heater light. To check your SFS temp reading, turn on the heater and heat the spa. While heater is running, the spa light on the keypad will be illuminated. Hold the spa button down for 5 seconds to view the temp reading of the SFS. If you ever get temp over 310°-320°, you might have a blockage in the blower fan or combustion chamber tub (like water, dirt or lime/scale buildup) causing overheating. You will likely have discoloration of the stack flue (exhaust pipe) and burned off black paint. How about NO service heater light? For example, you could have a high temp reading from your thermistor (any temp higher than ambient temp when the heater hasn't been running). So, your contol board will accept an erroneous high thermistor reading as legit and shut down. This isn't because the control board thinks something is wrong, it is because the control board thinks the water is already hot. This will also result in no error codes and no diagnostic lights and also NO SERVICE HEATER light. Cool huh? In this scenario, just check your pool water temp displayed on your phone app, pentair remote, pentair easytouch control panel or the red number display on the heater itself. These are only guesses, with and without service heater light, based on your stated symptoms, but if you need further help, just reply here. I still feel it is your thermal regulator causing the problem, so start there if you haven't checked it already. If the thermal regulator is stuck closed, scalding hot water will be all that will be able to pass to the output and on toward your hot tub. This could melt your plumbing (especially joints), ruin equipment and worse case even scald hot tub users. The thermal regulator should open up when exposed to temps over 120° in order to let some cold water mix with the output and dilute the scalding hot water a bit. So that's why there is a HLS in place as a secondary safety for a failing thermal regulator. If the HLS reports 135° or more, the control board will shut the heater down. This is what it sounds like is wrong with yours. Cheers!

[@kndlvon]

@@pvt-pilot WOW thank you so much for your detailed answer and taking the time to explain. After watching your video I immediately went online and bought a new thermal regulator and stack flue sensor (since I saw the light on the control panel once)... once I got both in, I tested the old thermal regulator under the sink water and it barely opened up. I decided to go ahead and replace it-- tried turning it on, same thing happened. Then I wondered if maybe my faucet water wasn't hot enough, tried the old one in hot water from the stove and it did open completely up just as your new one did in the video--- so I guess I didn't need to buy a new one anyway, now I can't get the darn thing unscrewed to take out the new one and put back in the old one. As of right now I do not have a service heater light--- it was on a couple days ago but the last two days it has not been on. I did get the ad1/sf1 ad0/sf0 screen and I did read that those are supposed to match in order for it to work. As far as I could tell I had them both on the 1. I do not know what's causing that to come up or what that is for but the last time it did come on the screen it appeared they both said ad1 and sf1. I will try and see if it will stay on long enough to test the SFS temp reading once I get home this afternoon. Again I appreciate your time. I was also wondering if this could be a problem w/ the rest of my pool equipment or water flow and not the heater itself. As of right now when I turn on the pool pump/cleaner it seems fine but when I change to spa on the control panel the Jandy Actuator Valve never moves from pool to spa. I have to turn the valve manually over to spa. The valve on the "pool/spa return" turns automatically to spa when I turn the spa on but not the valve by the pump for "pool/spa intake." Wasnt sure if this was just a coincidence or not.. everything was fine at the end of the season last year but I don't believe we got in the hot tub all winter and just now gearing everything up and now I'm having both issues.

[@pvt-pilot]

@@kndlvonSorry, I am not familiar with the ad1/sf1 ad0/sf0 codes. As for the valve actuators, swap their wiring at the control panel to help isolate if you have a bad actuator or if the one that is not moving is just not receiving the command to move. Shame, those aren't cheap...I think over $100 each.

[@officerkrupke4966]

@@pvt-pilot The actuators usually can be fixed by replacing the limit switchs. There is a video out on that, and where to buy the switchs, they are pretty cheap.

[@arielv2sing78]

I am having trouble opening the pipe with a screw driver, it seems like it is stuck. I tried pouring hot water on the pipe and it did not work.

[@pvt-pilot]

Try using a long screwdriver so you can turn with 2 hands...one pushing, one pulling. It is just plastic so it will not be corroded shut.

[@arielv2sing78]

Thank you that helped me open it!!

[@stevengraham6842]

Why did you remove the thermal regulator in the first place? What was the heater issue?

[@pvt-pilot]

My heater would start and run for 1-2 minutes, then cycle off, sometimes cycle back on again for another 1-2 minutes, then cycle back off and then it would throw a SERVICE HEATER light but not have any diagnostic error lights illuminated on the back side of the control board while my SERVICE HEATER light was illuminated. It is a 100% mechanical component, not an electrical component, so there is no error light tied directly to a faulty thermal regulator.

[@stevengraham6842]

@@pvt-pilot My heater is starting and running until the stack flue reaches 475 degrees, then shuts off. I have read that it is probably a water flow issue where the water is not getting the heat. It could be as bad as plugged heat exchanger coils. I was hoping it was a thermal regulator fix, but I guess not. I do get a SFS light on the circuit board. I am just learning this heater, so I appreciate your video and your response.

[@pvt-pilot]

@Steven Graham The air temp leaving the stack flue should be low 300s at the most. You should be able to put your bare hand above the exhaust baffle and reasonably tolerate the heat under normal 300 degree SFS reading. If you can tolerate the heat with your hand while the SFS is reporting 475 degrees, then the exhaust air is not 475 (impossible to tolerate) and the SFS should be replaced for reporting false temperature readings (different resistances from the SFS are translated by the control board into different digital temperature readings). If you can't tolerate the extreme heat with your bare hand, then your SFS is likely correct, and you may have a blockage of air flow, not a blockage of water flow. The only problem with a diagnosis of blockage of air flow is that it would normally be accompanied by an AFS light too. It takes good air flow to close the AFS (air flow switch) in order to ever fire up the heater in the first place. So, my gut tells me to check the SFS and replace it if necessary. Let's try this: check the temp reading that the stack flue is reporting before the heater ever fires. It should be very close to the actual ambient air temperature. If it says something crazy, like 200+ degrees before the heater ever fires, then you have an SFS that has fallen out of specs and must be replaced.

[@stevengraham6842]

@@pvt-pilot Thanks! I will go test it now.

[@stevengraham6842]

@@pvt-pilot Ambient temp: 54 SF temp: 91 Fired up and quickly the stack flue was extremely hot in a very short amount of time. The outgoing water pipe was not getting warm. I will try to find the records of the last filter sand replacement.

[@timmytfpv7316]

Smae heater my regulator wont come out its stuck any ideas ? Thanks in advance

[@pvt-pilot]

Absolutely, just take the manifold off and find why it is stuck. Push it out from the inside if necessary. Bolts are 13mm. There are about 10 of them, so it will take a few minutes, but easy to do.

[@timmytfpv7316]

@@pvt-pilot thank you so much for the fast reply when i take it off is there anything i have to worry about falling off or gaskets coming out etc

[@pvt-pilot]

@@timmytfpv7316 It will have 12 O-rings (1 on each heat exchanger tube) that will remain on the heater. The larger O-ring that goes around the manifold will come off of the heater but likely remain seated on the removed manifold.

[@timmytfpv7316]

@@pvt-pilot cant thank you enough

[@megmarc70]

What was the issue with your heater before you figured out that part was bad? I have a Master temp 400 that will start up. Heats up for approximately 3-4 minutes and then shuts down with the service heater light on. When I shut it off and then turn the heater back on there's a 128 r=8 that displays.

[@pvt-pilot]

128 followed by R-8 is normal bootup sequence for you control board. You and I have software revision-8. I have seen revision-12 and they display R-12. You can't update the software revision number, so always expect that number to be R-8. As for your heater shutting down, you should first turn the top panel of the heater upside down so you can see the diagnostic LEDs on the control board. Do you have any of those LEDs illuminated? If so, watch my video to help you understand what electronic component if faulty: kzbin.info/www/bejne/rX_Hc3V-pqpkrNE If you don't have any diagnostic LEDs on the control board illuminated when the heater goes shuts down with the service heater light on, you could have a faulty stack flue sensor (not quite fully internally open SFS) or a faulty thermal regulator. Hold down your "pool" or "spa" button (whichever one has the green light when you are heating) on the membrane pad as I showed in the video to see if you are getting a legitimate temperature reading from the stack flue sensor. If you get an erroneous reading, it is an easy replacement. If it is good, then test your thermal regulator with scalding hot water in a sink and replace if it is locked open or locked closed. Before I replacing this faulty thermal regulator, my heater would ignite for about 20-30 seconds and then the electronic gas valve would close and the heater would shut down and it would display "service heater" without any diagnostic LEDs illuminated on the back side of the control board. I could turn the heater off and immediately back on and it would run for another frustratingly short cycle. This is due to the High Limit Switch (HLS) doing its job correctly. The hot water was getting too hot and since the thermal regulator was stuck, but wouldn't open up and let any cold water in to dilute the very hot water down to a 120-135 degree output range. The HLS is a safety designed to detect the output temperature and shut down the heater if the water output exceeds 135 degrees. You don't want to melt a hole in your underground PVC pipes with boiling water so this is a good safety. I'm all good after the thermal regulator replacement. Hope this helps.

[@megmarc70]

@@pvt-pilot thank you for your time and in depth how to diagnosis! I will get to the bottom of the issue with my heater and let you know. Hopefully I will not have any issues. One more thing. My unit is about 11 years old. Do you have any idea what the life expectancy is?

[@pvt-pilot]

@@megmarc70 Life expectancy is directly related to how you keep you water chemistry. If you always keep too much acid, too much chlorine and PH imbalance, you will tear your equipment up prematurely. Mine only lasted 8 years before I ultimately ended up replacing just about every sensor in the unit, heat exchange coils and plastic manifold bypass valve. I would say you are on the tail end of life expectancy at 11 years. But keep in mind, you can buy a sensor replacement pack for $99 on Amazon and run through all of them. Heat exchange coils are around $600-$700 and manifold bypass valve is around $40. All of this stuff is replaced on mine now and I am not even close to the cost of replacing the whole unit which is about $2200-$2400.

[@megmarc70]

@@pvt-pilot oh man, I'll be seeing what is up with it shortly. I think we live in the same area as each other. I live by the lake..

[@megmarc70]

Hello, I removed my access panels and found a mess. There is heavy rust on the top of the manifold chamber and around the exhaust stack. There is a rust hole on the top cover. I also have a AFS light on. I'm thinking it is the hole that is triggering the AFS light on.

[@alexgannon801]

Thanks for the video. I have a master temp 300 that i set to 92 but actual water temp reaches 100 + and it constantly turns on and off every 10 minutes around 100. Is this a faulty thermal regulator symptom?

[@pvt-pilot]

Well, surely test the thermal regulator like you see in the video first before buying one, but I am thinking more along the lines of HLS or thermistor are likely not reporting correctly. I dont think it would burn that long without giving "service heater" light if you had a defective thermal regulator. You are on the right track though.

[@alexgannon801]

@@pvt-pilot Thanks for the reply. So i just replaced the thermistor last weekend and still same 8-9 temperature difference where it runs hotter than what the board is reporting

[@pvt-pilot]

@@alexgannon801 Where are you reading this 8-9 degree difference? A stand alone thermometer detecting this or are you reading the main breaker box panel/remote control? If you are reading the breaker control panel display, consider the wired pentair thermometers. There are two identical thermometers for that panel (air vs water). One should be drilled into a water pipe and the other should be exposed to the air in a shaded area. Try swapping them. See if the air thermometer unit produces the same temperature reading as the one that is drilled into the water pipe. I don't think the heater knows about the breaker panel thermometers, I dont think they don't talk to each other about temperature. Just on/off status. If you are getting your readings of temperature difference by other means, then disregard the above troubleshooting.

[@alexgannon801]

@@pvt-pilot The temp master 300 pad will say 92 but the thermometer inside the spa/pool itself will be 100

[@telesean6231]

My 250 mastertemp keeps heating up to 110 to 115 and I be already changed my thermistor and control board but it’s still constantly over heating. Could the thermal regulator be causing it

[@pvt-pilot]

Please test the thermal regulator to verify. It is very easy to test it to see if it responds to scalding hot water. However, my guess leans towards a faulty High Limit Switch (HLS). When you first turn on the heater, it will display "128", then r-?(software revision number), then the next number is the temp of the water intake detected by the thermistor. What is that number? It should be very close to ambient temperature before the water heats up. Now, on to the next component, if the HLS is stuck on a given resistance, it is not doing its job. I don't know of a way to test the HLS using the control board display like you can with the thermistor, but if you test the thermal regulator and find it good, I think the HLS would be a very like next culprit. Good Luck!

[@pvt-pilot]

To answer your question, yes it could be the problem. The thermal regulator has thermally reactive material that is designed to move at 120 degrees. So 110-115 shouldn't open it at all. The purpose of the thermal regulator opening at 120 degrees (scalding threshold) is to create a bypass for incoming cool water (bypass - to skip going through the heat exchanger) to directly dilute the scalding water in the output chamber of the heater manifold before going out to the pool/spa. So if your thermal regulator seems to move under scalding hot water exposure, I would change the HLS.

[@paulabrilla5531]

Hi, @pvt-pilot this video is really helpful. I have the same Pentair MasterTemp 400. The Heating light blinks and then stays on for a minute or 2 and shuts off and starts up again. I feel hot water comes out of the returns when heating light is on for a minute or 2, but then it does the same thing again. No error codes. No lights on both of the service indicators. I was gonna replace the thermal regulator, but the cap is just too tight. Any advise will be appreciated. Also. Do you think it is definitely the thermal regulator.

[@pvt-pilot]

Shame about the tight cap. Try a longer screw driver for better leverage. Use one with a quality shaft like a Craftsman so there is less flex. Try putting the cap in the middle of a long shaft so you can push with one hand and pull with the other hand to help get double the tork pressure on it. If you still can't get it to turn, you can also use 13mm wrench or socket to remove all 10 of the bolts that hold the manifold onto the side of the combustion chamber. Then loosen the 2" inlet and outlet water pipe unions and remove the manifold. Take out the plastic wall inside the manifold and you will see the thermal regulator sitting there mounted on the spring. I'm 95% sure that the thermal regulator is your problem, but I recommend you test it like I did before ordering a new one. Hope this helps, Cheers!

[@paulabrilla5531]

Thank you for the very prompt reply. I was able to finally remove the cap following your instructions. I took out the thermal regulator and I don't see anything wrong with it except it's a bit corroded. I held it on a running hot water like you did and it did pop up. I also turned the cover upside down to see any LEDs and turned the heater on. No LEDs lit up. Also, the heating only turns on about 30 seconds before it restarts. I held down the pool button for 5 seconds and the reading I got is 201, 215 and goes up maybe to 235. Should I replace the thermal regulator anyway. It looks like the temperature reading is accurate though. It just doesn't go up because the heating keeps restarting.

[@pvt-pilot]

@@paulabrilla5531 If your thermal regulator moves to completely open position under hot water without delay, then I dont think this is your problem. If it is too slow or only moves only a little, we might be onto something. Try removing your thermal regulator and spring but screw the cap back on and turn the heater on. That will simulate an overwhelming full open and cold water will rush through and dilute the hot water before it flows past the HLS, so the HLS (High Limit Switch) will never get the chance to feel anything above normal pool water temperature. This should prevent the HLS from sending the control board a high temp reading that causes the control board to shut down the heater and restart. I have never tried this, just thinking out loud, but this is what I am thinking could allow your heater to burn longer without being told to stop for safety reasons. Let me know if it continues a long burn session without a thermal regulator and spring in it. If it burns longer, great, we found your fix. Then turn it off immediately and go buy a new thermal regulator. This is ultimately bypassing an extremely important safety, so dont run it beyond this little trial without replacing the thermal regulator.

[@paulabrilla5531]

I followed your instructions as soon as I got home today. As soon as I turned the heater on without the thermal regulator, the service heater lit for a second and then it started calling for heat. Heating light started blinking, and then it went steady for at least 1min & 45 secs this time before it cycles again, blinking, steady and then runs for less than 2mins. It seems to keep cycling every less than 2mins.

[@pvt-pilot]

@@paulabrilla5531 Hmmm, bummer, I don't think replacing the thermal regulator is going to do you any favors then. It's not an ignition lockout, it is not a Stack Flue Sensor, it's not an AFS issue, and it doesn't sound like a broken manifold bypass valve either because that produces a HFS light as a side effect. This is a tough one. Thermal regulator still falls in line as the #1 candidate for replacement, but I am just not very confident at this point. My recommendation is to try replacing it first before anything else. That is what I would still do at this point. If it doesn't fix it, then I don't know what else to try without some diagnostic lights illuminated that you say are all quiet right now, which is a bummer. Go ahead and replace it. That's a "$42 maybe" at this point. Check Ebay. Sorry mate, that's all I got. Your call.

[@richsouthall1937]

Hey PVT-Pilot, nice video, thanks for uploading. I have a Mastertemp 400 and it will fire-up initially; I can hear the blower start, the ignition goes click and then a little 'whoosh' as the gas ignites and smell a little gas from the exhaust. It seems to run fine for about 3-4 minutes with no error codes and then gas shuts off first, then the blower about 2-3 minutes afterward. Any ideas of what that might be?? I replaced the Flue (Themistor) about a year ago and solved that problem. Thank you! Rich

[@pvt-pilot]

When mine behaved exactly like that, it was the thermal regulator. No error codes, just service heater. Test your thermal regulator.

[@richsouthall1937]

@@pvt-pilot Hi PVT - I pulled out the Thermal Regulator yesterday and it worked fine under the sink with hot water and cold water; it opened and closed very easily. Thank you, Rich

[@pvt-pilot]

@@richsouthall1937 Ok, so you have no error codes displayed on your key pad. Have you checked for any diagnostic LEDs on the back side of the control board?

[@richsouthall1937]

@@pvt-pilot Hi, thanks for hanging in there with me. No, I have not looked at the back side of the control board yet. What would I be looking for exactly? Thanks again! Rich

[@pvt-pilot]

@@richsouthall1937 I would expect HLS to be illuminated. If so, replace the manifold bypass valve inside the manifold. It is made of thin plastic (terrible design) and will break over time since it is exposed to pool chemicals all the time. I posted a video on that too. The safety physics of it is pretty simple. When the valve is broken, water will almost completely bypass the journey through the heat coils and cold water will mix directly with the output side of the manifold via path of least resistance. Thus, the temp detected at the thermistor (manifold input) will be roughly the same as the temp detected at the HLS (manifold output) even when the fire is rockin'. This should never happen and the contol board is wired and programmed to detect this and to shut down heating if this occurs and throw the HLS light (High Limit Switch). This is not necessarily indicative of a faulty HLS, but the illuminated HLS could be the byproduct of a broken manifold bypass valve. Take a peek at the control board diagnostic LEDs and see what you got. We'll go from there.

[@meseahunt]

water DOES NOT SHOOT under pressure when all you have to do is open the air valve on the filter FIRST.... kinda simple logic????

[@pvt-pilot]

I didn't say water would shoot out. I was saying I had the expectation that the thermal regulator cap would shoot outward under the pressure of the spring tension. It really wasn't that powerful of a spring, so it didn't shoot out violently as expected.

[@StanleyASmith-im8bi]

Sorry I'm getting a r=5 code ? Thanks

[@pvt-pilot]

It is my understanding the r-?? is just the revision number for the software of the contol board which can't be updated. It does not indicate an error code. Mine is r-8. My heater is over 10 years old. I have heard others in comments say they have r-12. With you having r-5, perhaps your heater is old like mine? Do you have any error lights on the back side of the contol board? Do you have an orange service heater light on?

[@StanleyASmith-im8bi]

@@pvt-pilot Thanks! for getting back to me. After the R=5 code,display goes blank.I replaced the control membrane same results. Pentair cust. service guy thought it might be the transformer but the back side is hard to get to i'm working on getting the back cover off now. he said i need to check the voltage with a volt meter(make sense?) Thanks

[@StanleyASmith-im8bi]

My unit was mfr. in 2007

[@pvt-pilot]

@@StanleyASmith-im8bi Mine is 2009 with r-8 software. I would think it is the control board, not the transformer, otherwise how would it show r-5 to begin with? Check the power as the they said I guess, but if you have voltage, I would start with a control board swap. Do you have a friend that has a Pentair or Sta-rite heater you could do a test swap with? They are fairly expensive for a maybe.

[@StanleyASmith-im8bi]

@@pvt-pilot I will check around,I Iagree if the display comes on how could the transformer be faulty. Thanks! for your help

[@uponbase]

Hi. Just move into new home a few months ago. Kicked on heater last week and got E01 error...replaced the thermistor and still didn't kick on heat. Had service tech come out and he said get a new control board. Installed and it kicked on the heater (very hot by vent) for about 30 seconds and then short cycles a few times...then service heater light. Any thoughts?

[@pvt-pilot]

Did replacing the thermistor fix the E01? If yes, then you didn't waste your money. It needed to be replaced anyway. Some errors can be a byproduct of other faulty components. The E01 error is not one of those. E01 can only mean one thing...the control board's pins that are dedicated to the thermistor are detecting an open circuit. This could be due to a defective open thermistor or corroded/damaged wiring to the thermistor. That is all...no further testing beyond that. I have never replaced my control board. It is not a commonly defective component because it is not exposed to the corrosive chemicals found in pool water. I'm not so sure that the tech's suggestion to replace it was justified. It sounds to me like it was doing its job. Now for the service heater light...do you have any diagnostic LEDs illuminated on the control board when you get the service heater light? I will advise further pending your reply. I just can't shoot a valid suggestion to you without knowing what the contol board is crying about. I hope to be helpful to you soon but need more information. It is a very simple heater with multiple safety checks/stops which is very good by design, but unfortunately it is not made with very high quality parts. We can figure it out together. Talk to you soon.

[@uponbase]

@@pvt-pilot Thanks for the quick reply. Regarding the control board replacement. Before I replaced, the heater would not even kick on and once I swapped out it began to run immediately. That said, it would turn on, fire (20 seconds later) and then cycle off quickly. It would then fire back on after about 40 seconds and then began to rumble/bang/shake the unit...then service heater light. Therefore, I think both the Thermistor and Control Board were needed...hopefully just one more quick fix before it gets cold here in MD. Really appreciate your help and videos!!!

[@pvt-pilot]

@@uponbase I still would like to know what LED is illuminated on the control board (if any at all) when swrvice heater comes on. Shaking/banging...the only moving parts in the heater are the motor shaft and the fan. Shaking/banging may be due to an imbalance with the fan. Other than that, I don't know what would cause your heater to shake/bang. Check the fan housing as shown in my AFS video. It would not surprise me if you have AFS illuminated on your control board if you have a fan issue.

[@pvt-pilot]

@@uponbase I had another thought about the banging. The motor spools up to full speed before the gas valve ever opens and ignition happens. Is the shaking present before ignition when the motor is spinning or only after ignition? If it is present only after ignition, you might want to shut everything down and remove the top half of the heater as seen in my heat coil replacement video. Take a look at the big cylinder (flame arrestor) hanging down into the combustion chamber and see if you have any holes blown out of the sides of the cylinder. My mind has wandered into thinking about spontaneous ignition of unburned gas that has escaped the flame arrestor in a location that it is not supposed to escape. While still tucked away in the combustion chamber (the big tub), with it being a big fire bowl, it might not seem to some like that big of a deal to have misc bits of gases igniting, but to me it would be an obvious huge safety concern. So caution that possibly. Other than that tangent thought, I can't think of anything else without being there hearing it that would cause banging/shaking in your description.

[@uponbase]

@@pvt-pilot Hi - Thanks again for your insights, really appreciate the help. I just fired on the heater again, after the ignition happens (few seconds) it sounds like something is being rattled around inside the unit...the unit doesn't actually shake. Almost sounds like a piece of metal is flying around inside for about 5 seconds...then the unit cuts off...really odd. I am having a tech come out to inspect since my oldest is having a party this weekend and the pool is 72.