Blower motor died on a 18 year old Furnace: Update 2

[vferdman]

Well, it's been over 24 hours and my home is quiet and warm with the new furnace motor. I have replaced it yesterday and everything is well so far. I hope it stays that way.

Now another question. How does one adjust the dampers in a 2 story house. I understand that in the winter I need to favor downstairs with the air flow and in the summer the upstairs. I have two dampers to control the left and right side of the house downstairs and a third damper to control up/down distribution. I have set the bottom two to be almost all open and the up/down one to be almost closed, which would divert most of the air flow downstairs. After 24 hours with the new motor and these settings the temperature is within 1 degree between upstairs and downstairs. I am happy, but what do I do in the summer? Just the opposite? I noticed when installing the motor that the heating wire went to the high speed and the cooling wire went to the slow speed on the old motor. I wired the new motor the same way, but am wondering why is the cooling slower?

Thanks as usual, love the forum! Vladimir

[CJT]

That sounds backwards to me. I think cooling is normally the higher speed. See, e.g.:

(I'm not endorsing this site in particular, it's just one of the first I found via Google which addressed the issue)

[RP]

It may have come from the factory that way. It's also possible that somebody was home remedying it and put them back on the wrong terminals. Another possibility is that a tech switched them as a Band-Aid solution to high temp limit trips. The list is endless.

hvacrmedic

[Mikepier]

You will not know until you actually try the A/C. Perhaps it does turn at high speed. Maybe the wiring changed with the new motor.

[m Ransley]

Heat is set to lower speed cooling higher speed, more even winter heat and more efficient cooling and less chance of freezing the coil. ducts cant be closed off if temp rise is higher than unit recommendations. These are a few thing for you now to spend a week learning about.

[Oscar_Lives]

What a dumb f*ck...

[scott21230]

High speed for cooling, low speed for heating is the norm. You can use high speed for both if you want to. You need to fix this.

[scott21230]

You never did say how easy it was to get a new motor or where you got it from.

[Stormin Mormon]

Cooling is typically a faster speed, cause the cold air is heavier.

YOu're right about air ducted up in the summer. Cause the codl air will settle and keep the first floor cold.

[m Ransley]

Stormin, so cold air is heavier , does my car take more HP to run in cold air from wind resistance.

[CJT]

It probably does, if that's all you consider. Happily, engines are more efficient when their intake is cold (plus, you're less likely to be running the A/C).

[vferdman]

I did post in the original thread, but I'll repeat. I got the motor from Gainger, it cost $69 and change including the cap and taxes. The replacement is made by Dayton and made in China (what isn't these days), the original was a GE and assembled in Mexico. Both are 1/2 hp

1075rpm, but the Dayton is 3 speed and the GE was 4. I wired the replacement the same, I thought only using low for the wire that used the medium low on the old motor. I will double-check the speed again. The way I did it originally was to go upstairs and turn the thermostat's fan control to "on" instead of "auto" I think that may cause the motor to run at a different speed than when the thermostat actually calls for heat. I will re-check and make sure I am on low speed for heating and high for cooling.

How would I make the cooling and heating use the same speed? Wire both wires to the same winding?

Thanks Vladimir

[CJT]

That's probably true.

I will re-check and make sure I am on low

[vferdman]

The heat was wired correctly. I did originally test using fan on function instead of heat setting. When I tested using thermostat to call for heat (set the thermo for 80 degrees), I got the low speed winding to energize. I tested it by disconnecting the connections until the fan stopped. When I broke the one that stopped the fan it was the slow one.

[CBHVAC]

On modern vehicles, when you go to WOT, the AC is kicked out...even then, at highway speeds, less than 2HP is used to run it.

The reason that a car likes cold air is that cold air is more dense. Helps to slightly increase volumetric efficiency.

The reason that with HVAC issues you have a faster speed on cool than you do low, is two fold, and if Stormy had a clue, (he does not) he would know why.

[RP]

Great. Now you can stop f****ng with it :)

hvacrmedic

[CBHVAC]

No...of course not, but in the case of a furnace say..the slower of the two speeds NORMALLY will be your heat fan speed.

[RP]

There is no *requirement* that heating speed be lower than cooling speed. What is important is that you have the proper cfm per ton set up for cooling, and that your temp rise in heating falls within the specs (temp drop range) listed on the data plate or label in/on the furnace. Factory default isn't necessarily what's going to be required.

hvacrmedic

[RP]

I didn't doubt you for a moment, I was just clarifying because your statement could have easily been misinterpreted as meaning that there was some requirement for heating speed to be lower. :)

NORMALLY, the heating speed is lower, simply because the engineers arranged for it to be. Lower face velocity and higher temp means less draft and thus more comfort for the occupants. It is however less efficient.

hvacrmedic

[maradcliff]

Try your heat on the middle speed and see if you like it that way. Thats the way I like mine....... If you got to xwap a few wires in the summer, it's no biggie.

Mark