Changing the Blower Speed on a Furnace

In this video, we are changing the blower speed on a Trane XR 95 furnace so that the forced air furnace circulates more air on heat mode. This will increase the number of air changes per hour (ACH) in the house and also help compensate for a more restrictive whole home air filter like a MERV 16 being installed. A MERV 16 filters particles at a level near that or a HEPA. This furnace features the common White-Rodgers Intell-Ignition circuit board. The blower fan on this blower has four speeds.

[@walterw8310]

Thanks for the video. Dallas tx here, blower speed seemed too fast in the summer, followed video, turned down fan speed, wife noticed immediately, I left detailed directions/instructions/this video link taped to the unit for next owner. Makes sense. Slower more "conditioned air" in the summer here, is the way to go. Turn that central blower fan speed down in the summer. Crank it up for heat in the winter. It really works. Anyone thinking about changing your speed, Don't be afraid to try. You can always put it back. Label your wires, and take pictures. I only switched 2 wires. GOD SPEED!

[@Puffalupagus360]

Blower speed you always be set for the application in question. Those settings should always be done based on superheat and temp drop across the coil and cooling, and heat rise across whatever your heat exchanger is in heating mode IE heat strips or a coil for a heat pump or a tube and fin heat exchanger for a furnace or boiler.

[@Pnwhvacman]

You helped me a lot! Thanks man! I never even though of changing blower speed.

[@tracybaker1062]

Great video. Very informative, and just what I needed to see to look for the blower speed on my furnance.

[@92camaro100]

Thanks for the information on the wires of what speed they are, it really help me out

[@dekoomers]

That was just the clafrication needed for my DIY project for reducing motor speed, Thanks!!

[@CoolStuffGuysLike]

Thank you! Glad it was helpful for your furnace project!

[@DawitTafere]

Hi there can you guys give me some information i am looking to lower the furnace speed its so strong and we can't sleep at night and do I have to switch the blue and black wires? Thanks!

[@rickcrawford7307]

@@DawitTaferelowering your motor speed could damage your furnace. Higher not so much. I'm sure somebody here can explain why better that me.

[@DawitTafere]

@@rickcrawford7307 thank you so much!

[@glendurant911]

Nice video and i was wanting to know this info,so this is great,thank you.

[@clintlester]

Thank you for this video. Recently had an HVAC specialist tell me it would be more energy efficient to lower the blower speed in the winter because the air moving too fast "cools it off" and doesn't heat as well. Thankfully he told me, because after he left we got an error code pointing to "Bad airflow" which I was able to remedy thanks to these instructions and helpful information

[@youngeshmoney]

That is true, Bernoulli's principle. Flow and temperature are inversely proportional. Fast air=cooler air and vice versa.

[@SerenoOunce]

The HVAC tech was correct. Using high for heat is inefficient. The heat exchanger won't reach optimal temperature and the fast air will also cool it down further. You end up using both more electricity and gas. Of course if it's too air movement is too slow the exchanger will overheat causing a lockout. It's a balancing act that needs to be tuned to every system. But using HIGH for HEAT is NEVER the correct option.

[@hectorgarza228]

@@SerenoOuncewhat if i changed from using regular fiberglass filter to a high Merv filter should i increase the speed because of the more restrictive filter?

[@joeruder]

would slowing it down not make it run longer thereby increasing the amount of overall air exchange?

[@mgomez5606]

They replaced my motor and does not run as fast as old one. Motor has connectors going to it. If he crossed the connectors when he hooked them up to motor would it cause this problem? I told the tech that I did not think it was running at speed it was suppose to. Apparently not because temp went up in house and lines on outside unit were frozen.

[@frankoreka2900]

Thank you a lot good explanation keep it up 👍

[@mikearnie1]

Awesome video. Thanks!

[@maddoe7189]

Set to heat blower fast speed set to cool blower slow speed ...I switched as you said and it works ..thank you

[@Sesamestreet9080]

Awhhh man you gonna end up with some problems lol

[@lancekoller5284]

You have that backwards

[@Datacorrupter234]

damn imagine being able to change fan speed soo high tech

[@tedzone5544]

Very good video :)

[@joeythefoxxo]

I discovered this when cleaning my flame sensor today. Figured out that my furnace was set to low cool and med low heat. No wonder heat never made it to the far parts of the house! Set it to med high cool and high heat. Works so so so much better now!

[@MegaDnw]

Does this increase or decrease your bill by it running faster?

[@ktefccre]

Thank you 🐱 👍

[@ezzghanem]

Great and informative video. Instead of changing the black wire from cool to heat in the winter, then moving it back to cool in the summer, can I splice the black wire and keep it connected to "both" cool and heat all the time?

[@CoolStuffGuysLike]

I think you may fry your circuit board if you do that. You will basically be back feeding into the board as if you connected the cool and heat pins together. You could connect a switch so that you could easily toggle between the two but not actually be connected to both.

[@infotechyeti]

New home owner here. On low speed the blower motor or something there seems like there is a very small rattle. At the end of the heat,once it reaches the temperature, it then goes to high speed and the sound goes away. Appreciate the video and help.

[@jonathonvince561]

Bearing goin

[@infotechyeti]

@jonathonvince561 for the blower motor? Think it's worth to replace that and the blower wheel at same time?

[@jonathonvince561]

@@infotechyeti the wheels u normally can clean but check the motor for leaks. There will be a build up on the case if it that attracts dirt if the bearings leaking and whiping grease everywhere

[@thelonerangermtb]

Thanks! But my furnace automatically started blowing on high after a windstorm that made all the power in the neighborhood flicker about 3 times in less than 2 seconds... any suggestions?

[@superkhal94]

I switched my heat wire from blue (medium high) to red (low). And it doesnt seem to change the fan speed. Any ideas? My furnace blows air too fast and loudly i wanted to lower it for the sound.

[@philfarias-qh1rw]

Question what if the blower motor has 1-4 per your video. But the blower motor has an option 5 but no wire is connected? Would this be a higher speed than 4 for the cool side? Also the plug next to it black plug doesn’t have a wire for 5 either.

[@todds5956]

I just installed a Goodman furnace everything working good but not very warm at the outlets. Sounds like the blower is running way too fast. Huge air movement but not very warm. Maybe i need to slow it down? Thanks

[@dardaniaal7299]

I have same problem with mine Goodman, brand new , did you do anything?

[@micahrandolph4397]

I have a question I have a wood furnace hooked up to my furnace and I turn my fan only on to circulate the heat but the outer parts of my house don’t have the greatest airflow is there a way to switch the fan only to high instead of it just barely trickling out the air which I assume it’s set at low? Hopefully this makes sense

[@micahrandolph4397]

@CoolStuffGuysLike

[@lancekoller5284]

High speed is ALWAYS on cool; it never leaves that terminal! Heat speed should be on low to medium low so you don't get hot spots on your exchanger. There are temp differences that should fall within spec of the furnace, but that's for the pros.

[@marcknab7456]

Now we're all pros thanks.

[@Puffalupagus360]

Most furnaces allow for running the same blower speed in heat and cool. The application is what determines the blower speed necessary in each mode as you have to match blower speed, total external static pressure and heat rise/temperature drop to the equipment specifications. What he said about changing blower speeds to overcome high static pressure on the return side is incorrect though as you would need to add more returns or add another filter slot altogether to negate the added static from a high merv filter. An air bear setup shouldn't add more than about .01 static pressure (if that much) but people think more pleats=better filter.

[@todds5956]

My blower was running too fast not offering enough heat. Slowing it down increased the outlet temp

[@richf761]

What do the park pins do? I can switch them around without affecting anything?

[@rickcrawford7307]

There the different speeds that are not being used. Just parked there to keep them from just dangling in air

[@jason.arthur.taylor]

You want max air flow, so each season you swap the wires. Why not short the cool and heat and connecting the black wire to either cool or heat. This should give you max blower speed in both seasons, right?

[@CoolStuffGuysLike]

That seems like it would work but I can't say for sure if it is safe for the circuit board. You would be sending power to the output pin of the one that you are not using. If it is just a relay turning that is sending power to the pin it is probably fine but I would be afraid that backfeeding it might burn something up. Would really have to stare at the diagram for a while before trying that.

[@ajisup]

Pulled this straight out of my Goodman furnace manual: To adjust the circulator blower speed, proceed as follows: 1. Turn OFF power to the furnace. 2. Select the heating and cooling blower speeds that match the installation requirements from the airflow table in the Product Data Book applicable to your model. 3. Relocate desired motor leads to the circulator blower heat and cool speed terminals on the integrated control module. (Terminals are identified as HEAT and COOL (hot)). If heating and cooling blower speeds are the same, a jumper wire must be used between the heat and cool terminals. This wire is provided in the literature package. 4. Connect all unused blower motor leads to the “PARK” terminals on the integrated control module. Any leads not connected to the “PARK” terminals must be taped.

[@joeythefoxxo]

@@ajisup So supposedly a jumper wire exists. Must find mine lol.

[@JTMONEY2247]

I have this same furnace i had a new ac unit an coil installed what should i put wires on for best ac performance?

[@lancekoller5284]

Blower for AC is always highest speed.

[@mildredwilcox3618]

Hello , I'm wondering putting a boost to blower is it good for a/c as well as heat ? Does it harm unit at all ?

[@CoolStuffGuysLike]

Normally the blower speed will be set to high for cooling and medium or med-hi for heat. You can increase it for cooling if it is not. It is nice right now to have the higher flow and higher air exchanges per hour in the house with the pandemic.

[@ralphroberts8930]

Mine has black to AC at the moment but not enough air flow into the house. Brand new unit. 59 degree air coming out of vents but low air flow. No holes or leaks in supply run. Filters changed. 410 charge good. Any ideas!?

[@defaultusername2371]

Undersized return duct work or undersized furnace

[@mildredwilcox3618]

Does it use more energy?

[@egeniojaramillo9048]

Does having good faster, use more energy? What do you think? ;)

[@josearreola3629]

Thanks for creating jobs for us HVAC technicians… not enough information to insure proper adjustments are being made, but enough information to make it easy for any one cause some serious damage…

[@lancekoller5284]

LOL you are exactly right.

[@mantyshub90]

My landlord just put a new blower motor but it seems to high or fast ..I hear a hummm front vents in my room thats driving me nuts it's on med high ..I want to put it on med

[@beetlejes]

I just had all new HVAC installed, and my blower is set WAY too high, as well. For me, the intake is in the hallway, right by the living room. It's LOUD. Sounds like a wind tunnel, or something, and the air flow itself is intense. Feels like it's industrial strength...totally unnecessary for my house. I live in a cottage. The AC guy couldn't even hear me when we were only about 10 feet apart. Someone knocked on the door, and I heard nothing. That's how loud it is.

[@Mr.Adolvera]

Same thing with me Did y'all ever get it to be less loud?

[@mantyshub90]

@mr freeze the motor was to big they put a smaller one.. it still made noise but we got used to it

[@alcleverdon1414]

Make sure that when you change blower speeds, the temperature differential between the supply air and return air falls within the recommended range of the furnace.

[@razlink]

Can you please explain how to check that?

[@alcleverdon1414]

@@razlink You drill a hole in both the return and supply air ducts and insert a stem type thermometer in each hole while the furnace is running.Subtract the 2 readings and make sure the resulting number falls within the range on the sticker on the furnace.This should be where the model and serial #s are. Take your readings close to the furnace. I don't bother but you can put small pieces of duct tape over the holes in the ductwork afterward.

[@blackericdenice]

Upload a video showing how to do that.

[@ShailendraSingh-ue2gt]

Useful video, I am thinking about tinkering with furnace blower speed, because here is my problem. We just got a new AC as our old one went out just when it got really hot and we hurriedly got couple of estimates and went with this company who offered to throw in an air purifier. We had 2.5 ton Bryant AC which was about 20 years old and the company installed a Rheem 2.0 ton unit. Now the problem is that this AC takes a very long day to cool down, for example we were out of town one weekend and we have Nest thermostat which puts itself on Eco mode detecting that we are away and sets the temperature to 78, when we got back it took around 8 hours for it to come down to 71 degrees. Its been over a month and this is consistent, it will take over 3 hours for it to cool from 75 to 72 and then it will run for couple of hours before it can get to 71. We called the company and they sent a guy out, he said that our furnace blower is overpowered and it does not match with our AC, he said back in the days people would do that, and that the blower is meant for 3.0-4.0 ton AC, he turned the blower speed down to bring it close to AC power and that did not make any difference, infact I am pretty sure it now cools down the place even slower. What they are saying is they can't do anything about this and that we were explained of this problem before installing(which I do not remember) and that our only option is to replace the furnace too. I don't buy this for couple of reasons, and maybe I'm wrong and thats where I need your inputs. Our old AC was 2.5 ton and it worked great for an old unit with the same furnace blower. When the technician turns the blower speed down it worsened the situation so that means higher the furnace blower speed the better airflow i.e more power is better? What are your thoughts?

[@Ross-kt3nd]

Rheem is not even close to a Bryant unit

[@willisfrey6343]

I am an HVAC technician and it sounds like they put the wrong size condensor unit on. If your air handler is sized for a 2.5ton unit then the outdoor condensor unit needs to be 2.5tons if it's a straight ac unit. If you have a heat pump then it needs to be the same size and brand.

[@jakejeffrey13]

What’s your square footage that’ll tell you the tonnage your AC should be. How’d they determine you need a smaller ac without a load calc? I would hope your house is smaller than 1,400 sq ft, and 350 cfm per ton of cooling is what I was taught. So they could be right about the blower. But idk. Lol sorry was in a mood good luck 😅

[@lancekoller5284]

Do not slow the fan speed down on the AC. The unit is actually more efficient the longer it runs as it draws out humidity. A unit that cools down quickly and shuts off makes a humid home.

[@johnmilus2889]

You may want to be careful messing with airflow this way. There are DiP switches on the board and a table for adjusting motor speed per temp rise over heat exchanger. If the airflow is too slow the exchanger can overheat and crack, spilling toxic gasses into your home. If it’s too high, you can get a dirty burn . I’m a do it yourselfer installing a 2 stage-multi speed and investigating this stuff. As it turns out, there really is more to all of this than a guy might think. Get a manual.

[@defaultusername2371]

He said that right at the beginning. Usually setting taps and dip switches adjust board measurements for gas as well

[@Duantuideguaiwu]

What's a dirty burn?

[@squidusn71]

Agreed, these units have specific input and output so to speak. As more of a car guy, you just can't change blower pulley without matching fuel requirements.

[@BongLogic757]

Just hire a pro hvac tech like me

[@SerenoOunce]

@@Duantuideguaiwu A restricted vent or cracked heat exchanger will allow for incomplete burn of the gas. This results in soot build-up which decreases the thermal exchange to the circulated air, along with just being a safety hazard in general.

[@bigdaddy4975]

You can also just make a jumper and have both wires on the cool speed and never have to mess with it again

[@CoolStuffGuysLike]

Yeah that may work but you would be back feeding power to the pin that isn't being used which may cause some trouble if there isn't a diode in the circuit.

[@bigdaddy4975]

@@CoolStuffGuysLike hey it worked on everything I’ve done it on so I don’t know. I see what your saying maybe this is on newer machines I work on mostly old shit.

[@bluesdirt6555]

Just had a new system installed and the furnace whistles the technician said my return was undersized. Talked to his boss he said they might try turning the speed down.

[@CoolStuffGuysLike]

That is probably fine for AC. For heat you run a little risk of the heat exchanger over heating and failing prematurely if you slow it down. If you can find a manual online for the furnace, you may be able to check if there is a minimum speed recommended for the heat setting. You may also be able to find where the whistle is coming from. It is probably a seam or sharp edge somewhere in one of the return lines. Could also be a vacuum leak in a return line that you may be able to tape off with aluminum tape. If any of your returns have adjustable baffles on them, try opening them all and see if it helps.

[@bluesdirt6555]

@@CoolStuffGuysLike The return collapses when it starts and stops . I was thinking about enlarging all the return openings right now they are 6 x 9 and are in between studs . I think that’s the problem same restriction going through the floor.

[@kathleenw3100]

The blower noise for heat and AC is so loud. My rental house is 70 years old. The vents are metal and they have door; flip it open/closed. Even closed, the noise is very loud. Any suggestions? Thx!

[@michaelfranks341]

@@bluesdirt6555 go to a cheap filter and see if that helps with the suction of the duct. merv 8 or less.

[@firstlast1732]

So many different configurations to a lot of these boards this is just the tip of the iceberg there’s so much more to this you shouldn’t touch any wires and let you know exactly what you’re doing. Some boards have dip switches some boards other ways of manipulating the speed this is just such a small part of it

[@beetlejes]

I watched the AC guy do this, to lower my blower speed, and all he did was switch two wires, so, I'm a bit confused as to why I'm seeing multiple comments about there being more to it. He did exactly what this guy did. Two wires switched, then he was done.

[@firstlast1732]

Because so many different systems Regis was easy many aren't

[@thechuckster1971]

You want slow for cool. If your too fast you will not be removing enough humidity. Longer run cycles in cooling are much better.

[@lancekoller5284]

Incorrect. You want the most amount of air hitting that coil as fast as possible.

[@logicalrat]

Hvac tech here. Need to measure static pressure with a manometer, refer to manufacturers literature regarding cfm, and adjust blower speed accordingly. If you want higher merv filters, typically you'll need to add another return, or install a media filter rack

[@willsu21]

Really? This is archaic.

[@bigstepper2235]

doing this will cause uneven heat, dropped efficiency, and unnecessary wear-and-tear on parts but to each their own

[@mslmmad]

Your furnace has cracks.. replace it.

[@Datacorrupter234]

Apparently my low rent piece a crap rheem unit cant run more than 24 hours constantly without ruining another motor who the hell designed these things

[@gocubsgo5055]

Guy in the video clearly has no business doing anything hvac related. Stick to changing your filter bud.

[@readynow12345]

Dude what the hell do you have stuffed in that air filter. is that one of those home made gizmos ??