Triple Aquastat Basics

Learn what a triple aquastat is, what a cold and warm start boiler is, how hi, low and diff settings work, and what ZC and ZR terminals are used for.
00:00 Warm Start / Cold Start Boilers
01:18 Hi Limit Control
02:21 Lo Limit Control
02:47 Differential Control (Burners)
03:57 Differential Control (Circulator Pumps)
05:25 Aquastat Wiring Schematic & Sequences
08:53 ZR & ZC Terminals

[@steve-real]

Great video explaining a very arcane controller box that was originally made when gas was still 50 cents a gallon. Well done.

[@jeffcaron9819]

Thanks for the quick reply Mike, I will pick up a high limit only aquastat. Thanks for your time.

[@superbroolyy]

thank you very much very helpfull

[@JamesBrown-db9pk]

u do a good job show us stuff

[@sirhc07]

Such an underrated channel

[@JerseyMikeHVAC]

Thank you.

[@oodeeps]

Great video, thank you

[@NROhvac]

Zr + zc is good for indirect water heaters too

[@oilandfireguy1739]

I literally took one of those apart last week while looking at the schematics to figure it all out. This video definitely helps. Zc and zr have always been a little confusing

[@JerseyMikeHVAC]

I do the same thing with just about everything. Drives the wife a little crazy sometimes. Ha.

[@carllinton]

Great informative video Mike 👍🏾👍🏾

[@JerseyMikeHVAC]

Thank you

[@williamsimmendinger817]

You are very knowledgeable on these topics! I really appreciate you sharing! I have a New Yorker residential boiler with a weil-mclain gold 40 hydronic hot water tank. Water temp has been feast or luke warm. Changed the thermostat and taco valve control. Still having issue, turn the thermo up on hot water, check the taco voltage after 45 seconds, seems to be functioning, but the circulator works when calling for heat, but not for hot water. I got a new resideo L8124 from a friend , retired plumber. Watched your video to get educated on the way it works, took pics, installed the new one, double checked all conns, ok. Fired it up and all seemed ok. left the house for a few hour, came home and found the water boiling! I would appreciate your thoughts! I figure a bad hi-limit in the control. I'm going to get another control, this time a honeywell, like before. Thanks for any help, really appreciate you! Keep up the great work!

[@fdcap9835]

Outstanding explanation! Thank you!

[@JerseyMikeHVAC]

You're very welcome!

[@acrservicesmathewr7565]

Thanks Mike, this was a great informative video.

[@JerseyMikeHVAC]

Thank you

[@danl4892]

Thank you Mike!

[@JerseyMikeHVAC]

You are most welcome, brother.

[@JohnDoe-ej1lw]

Great video Mike..made it simple to understand.. now my question is how do we determine what will be our High limit temp, Low limit and differential on a boiler?

[@JerseyMikeHVAC]

Good question. In general, a higher Hi-Limit setting will make the boiler more efficient, but you have to be careful not to create excessive pressure on the safety relief. Also obviously don't want to make steam. A lot of people just set it to 180 but 190 or 195 can be a little more efficient. With the Lo-Limit, you always want to be at least 20 degrees below the high limit. Getting the 2 too close together can cause circulator problems. Too low and you risk flirting with condensation problems. About 130 degrees and lower flue gases can begin to condense into an acidic coating that can eat away at the block and flue system. With the diff, if you're tankless on a domestic water loop, a higher diff setting provides more available hot water than a lower one. It can also prevent short cycles. It will also depend on whether you have a mixing valve installed to prevent scalding. Many guys will suggest going all the way to 25, but that is going to depend on your LO and HI settings. Going 25 on a Lo setting of 160 and a Hi of 180 will cause overfiring to 185+, and your shower will end up in a ride to the hospital without a mixing valve to temper that hot water.

[@brianmcdermott1718]

Great info. to know. Thank you.👍👍👍👍👍👍👍👍👍.

[@JerseyMikeHVAC]

No problem.

[@TomCorcoran-og2di]

You are Jersey John's (from American Pickers) brother right?

[@jeffcaron9819]

Hi Mike, great channel, hoping you can offer some direction. Recently installed a hybrid hot water heater and no longer use the boiler for domestic tap water. I know my boiler has to run periodically to Maintain a set water temperature that circulates for home heating, but does the boiler need to heat to provide domestic tap separately if so is there a way to turn the temperature setting off or down so that it's not running for nothing? It has a triple aquaStat installed. It seems like it runs a lot without the circulator coming on so I know it's not running to heat the home. Thanks for your input.

[@JerseyMikeHVAC]

You can bypass the low limit by taking the red wire off of the R and the white wire off of W near the low limit controls and just wire nut them directly together. Just make sure to test everything and make sure the boiler turns on and shuts off during heating cycles as it should. Just be aware this is highly frowned upon by manufacturers, and you are taking on a liability for doing this in the event something ever goes wrong, even if unrelated I would guess. A better option would be to just replace it with a standard high limit only aquastat.

[@NegAyiti]

Great Video. Very Informative. What if I wanna install a stand alone tank water heater and not use the tankless feature of the boiler for domestic hot water. What would be my settings then? Should I also cap off the water lines? Thank you

[@JerseyMikeHVAC]

A stand alone tank can be put on a zone valve and set up like any other heating zone. On the tank there will be a very simple aquastat that would tie into the zone valve just like you would a thermostat. The temp is set with a dial on the aquastat and usually put to about 120. The boiler itself can be set to 180-195. If you have a triple stat on there now you won't need to set a minimum. You can set it all up as a "cold start" boiler since the storage tank will retain hot water and the boiler doesn't need to meet that demand quickly. Steven Lavenmonier (spelling?) has a video on aquastats where he shows you how to bypass the minimal setting if you wanted to. Yes, cap off the unused coil.

[@NegAyiti]

@@JerseyMikeHVAC Thank you much

[@user-db1xp4gs1b]

Mike- The aquastat on my boiler is also set at 180-160. However, when the boiler shuts off the temperature on the gauge typically reads 10-20 degrees higher, then gradually drops. Is this normal? Thank you.

[@JerseyMikeHVAC]

Gauge temps are often off a little compared to the sensors used that the boiler runs on, and it usually gets worse as the boiler ages. So long as the boiler isn't exceeding 200 degrees it should be fine. If the boiler is actually getting to 200 (which it likely isn't) then its actually running more efficient. I wouldn't adjust the Hi limit above 180 just to play it safe.

[@superbroolyy]

i would like to know what would happen if both rb and 1k1 are closed because of call for heat and low temperature ??

[@JerseyMikeHVAC]

Great question. Nothing will happen until the low limit satisfies. R to B will open, R to W will then close providing power to 1K2, the circ pump(s) come on and the boiler will continue firing to high limit. This basically prevents the circ pumps from activating when the boiler is at a low temp condition so cold water in the plumbing isn't pushed back into the boiler to drop the boiler temp even further down below low limit. It acts like a time delay, basically. Until then, 1k1 just provides alternate power to the burner so there is no interruption to firing when R to B switches over to R to W.

[@superbroolyy]

@@JerseyMikeHVAC Thank you for the answer, if low limit satisfied and both zone 1 and zone 1 call for heat wouldnt be two currents cross one from 1k1 and the other from 4?

[@brandoncoffee8044]

Are you familiar with steam systems? Oil and Natural gas fired??

[@JerseyMikeHVAC]

What's your issue?

[@brandoncoffee8044]

@@JerseyMikeHVAC Thank you for responding!! I just wondering if you could do a video explaining how to wire in an auto fill with low water cut off. Primarily the McDonnell Miller style set ups and the delay switches on the auto fill. Thanks!!

[@JerseyMikeHVAC]

@@brandoncoffee8044 kzbin.info/www/bejne/mITIi6SpbdOSbq8 About 6 minutes in, but the whole video is good to watch.