Drastic variance in tempature

[shoothebunnies]

I have a Coleman Model G9T06010UPB13C Furnace, installed 2007.

We just purchased the house and I noticed that one side of the house is drastically warmer then the other.

Air temp coming out of the east side vents are at least 15 degrees cooler than the west side vents.

The duct works come straight off of the top of the furnace, plenum is large enough for an A-coil but doesn't have one (no central a/c) then tees off going east and west. If you place your hands on each side one is really hot the other cool.

No damper (just in the take offs), there is a humidifier that is no longer working but still attached.

Any idea what the problem is and how to fix it?
The rooms that are receiving the cooler air are the living room, library, etc... most often used.

Thanks in advance for your knowledge.
Willis

[HayZee518]

one stack off the plenum has shut off devices in the round ducts and it looks like the others just have dampers at the registers.

[paul52446m]

I have a Coleman Model G9T06010UPB13C Furnace, installed 2007.

We just purchased the house and I noticed that one side of the house is drastically warmer then the other.

Air temp coming out of the east side vents are at least 15 degrees cooler than the west side vents.

The duct works come straight off of the top of the furnace, plenum is large enough for an A-coil but doesn't have one (no central a/c) then tees off going east and west. If you place your hands on each side one is really hot the other cool.

No damper (just in the take offs), there is a humidifier that is no longer working but still attached.

Any idea what the problem is and how to fix it?
The rooms that are receiving the cooler air are the living room, library, etc... most often used.

Thanks in advance for your knowledge.
Willis

A plenum is a mixing chamber, the air going through the furnace has hot and cold spots so when the air goes up into the plenum it need to bounce off the top and this action mixes the air up so when it leaves the plenum it is the same temp. So what i am saying is, the ducts should come off the side of the plenum and at the same height. No ducts should come off the top of the plenum. Make sure the humidifier is not by passing air.. Paul

[shoothebunnies]

Here is a picture of the plenum coming out of the top of the furnace, attached is the humidifier that is not connected to the return and has been capped and sealed awaiting removal.

There is a tee attached to the top of the plenum as I mentioned before. There is no damper in either side of the plenum.

All of the rounds coming off for both sides of the house have dampers and all the registers have dampers also.

Temp out of the left side (marked with X tape) taken at first take (disconnected at spin in and used digital thermometer) off 3' from the x is 61 degrees.

Temp out or right side (plain tape) taken 41" from the tape is 88 degrees temp taken with the same method.

Any ideas?

[shoothebunnies]

removed the humidifier and there are no dampers or deflectors that would be sending different temp are one way or the other.

Anyone else have any ideas?

[mdm1005]

Did you ever figure this out?

I'm having the same problem in my house and the temperature difference is ever more dramatic: 140F on one side and 110F on the other side.

-Mike

[shoothebunnies]

Still have not remedy the situation here, just dealing with it.

[paul52446m]

Drastic variance in tempature

Still have not remedy the situation here, just dealing with it.

If you want to get deeper into this problem we can start in again.
Model and ser. no. of furnace?
Size of duct going east and how many hot air opening?
" " " " West " " " " " " ?
More pic. showing Return air opening. How many return air opening?
Size of air filter?
How many wires coming out of the blower motor and what color?
Look at you electronic board and find the heat post and tell me what color wire
is on that post?
Is you filter clean?
Has anyone checked the gas pressure going into the burners?
What is the size of the return duct going into the furnace.
Check the insulation in the blower compartment to make sure it is not up
against the blower.
Make sure there is nothing in the blower to restrict air flow.


I lot of times when i give people a list this long, they don't get back with me.
The only way i can help is for you to check out and try to answer the questions. Paul

[mdm1005]

I spent some more time trying to diagnose the problem here. It turns out that there are three ducts coming off the plenum. The lowest (closest to the blower) is a huge trunk line and then above it are two other smaller ducts coming off in opposite directions. In my case, it looks like the trunk line is getting all the hot air; if I close it off with a damper, the other smaller ducts get hotter. It's a sub-optimal solution since it makes my living room colder while the bedroom gets warmer. But I guess I could do that and just turn up the thermostat, but at $3.50/gallon of oil, I'm disinclined.

[paul52446m]

Drastic variance in tempature

I spent some more time trying to diagnose the problem here. It turns out that there are three ducts coming off the plenum. The lowest (closest to the blower) is a huge trunk line and then above it are two other smaller ducts coming off in opposite directions. In my case, it looks like the trunk line is getting all the hot air; if I close it off with a damper, the other smaller ducts get hotter. It's a sub-optimal solution since it makes my living room colder while the bedroom gets warmer. But I guess I could do that and just turn up the thermostat, but at $3.50/gallon of oil, I'm disinclined.

You can stop where you are at or you can answer the question i asked you in the last post. It is possible we can fix your problem by getting more return air or upping the blower speed. I have been engineering out heating systems for over 40 years, but i can't see your system so with out you answering my question, i can not help you. Paul