Check out some similar questions!

ColdFeet · Mar 18, 2008, 06:49 AM

I have a 90% efficient WeatherKing furnace that I bought last January. We live in a bi-level house that heats the upstairs fine. My problem is that the downstairs is always very cold. My thermostat is in our upstair hallway about 5 feet away from the heater vent in the bathroom across the hall. I have tried closing vents upstairs to force more downstairs, but that doesn't help. I was told that I could change the fan configuration in the furnace to get higher speed, but nobody seems to know what wires go where. I have 3 wires, a red, black, and blue one in that order and have no idea which way to put them. Does anyone know how to optimize this furnace fan wiring? I called WeatherKing/Rheem and they gave me a number to a useless distributer that wouldn't help and WeatherKing has no online or phone help. I figure if the fan blows harder it would force more air to the downstairs and convection would take over like my wood burning stove.
:rolleyes:

hvac1000 · Mar 18, 2008, 07:30 AM

Higher fan speed will not cure your problem. You have a duct work air distribution problem from the way the ducts were installed during the building process. The cure is in the duct work not the fan speed.

ColdFeet · Mar 18, 2008, 08:02 AM

I had a furnace that was less efficient in place before this furnace without this problem. That indicates to me that it is the furnace over existing vent work. I can easily check cold air returns and vents, but I had my vents cleaned when I had the furnace installed. I think having the fan blow harder would push the hot air further down from the ceiling vent into the rooms and that would then migrate upward. The only other option I can come up with is to plug the vent in the main hall bathroom and restrict the heat that hits the thermostat.

hvac1000 · Mar 18, 2008, 09:03 AM

Hot air goes up that is for sure Look on the blower door on your furnace. There is a legend /drawing there. You can change your speed if you wish just read and change the wires.

I have no idea what you had before but in all my years of experience air flow problems on the heat side have always been duct or duct damper problems.

Your furnace is also turning off to soon because of the placement of the thermostat.

ColdFeet · Mar 18, 2008, 10:23 AM

It seems I had a bigger blower on my older furnace is all that makes sense to me. That's why I thought blowing harder would push more hot air around. Another thought is to keep my blower on continuously and see if that pushes more air around too. I thought someone might know what colors to what posts would give me the highest fan setting possible. I have a schematic on the filter, blower door, but it shows nothing about those 3 wires that control the blower fan.

hvac1000 · Mar 18, 2008, 10:41 AM

Here is a picture for you.

http://apps.motorboss.com/Dimensions/FHP/V01727098.pdf

Not all motors are wired the same. The color code in this drawing are standard color codes used in the HVAC biz BUT it could be different. If you really want to be absolutely correct remove the motor in your unit and there will be a diagram on the motor for you to wire from.
Here is the entire catalogue

Emerson Motor Technologies - Products