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-   -   A few cool register - why ? (http://www.diychatroom.com/f17/few-cool-register-why-33534/)

adamk 12-10-2008 04:25 PM

A few cool register - why ?
 
Hello;

I'm trying to figure out why I have some registers that are cooler than others.
I was at the air handler looking for leaks on the ducts but didn't find any. I also didn't
find any leaks where the register connects to the duct.

Can there be mixing problems in the plenums that would make one side hot and the other side cool? I've tried to seal the plenums so there are no leaks. The ducts are rigid metal and wyes or 90's. The hot register is connected to a longer duct on the other side of the plenum compared to the shorter ducts with the cool registers.

What else should I look at ?

Thanks.

beenthere 12-10-2008 05:38 PM

Is it a gas furnace.
An oil furnace.
A heat pump.
Or an electric only furnace.

adamk 12-10-2008 05:47 PM

Electric air handler (goodman ar36)

DangerMouse 12-10-2008 05:57 PM

Quote:

Originally Posted by adamk (Post 196393)
I'm trying to figure out why I have some registers that are cooler than others.


1: they hung out in the right crowds in high school.
2: it's the sunglasses, they make anyone look cool.
3: i know, i know, 300,00 comedians out of a job..... sheesh....

DM

DangerMouse 12-10-2008 06:03 PM

ok, sorry, couldn't resist.... that is odd as it would seem the shorter length would be warmer, yes? closer to the source and all. perhaps someone stuck some foam or even an old pillow to partially block them at some point? don't laugh, i've removed them BOTH from ducts before..... worth checking.

DM

SKIP4661 12-10-2008 06:38 PM

Are the ducts both from the same plenum?

adamk 12-10-2008 06:49 PM

Yes, the ducts are from the same plenum, opposite sides.
The ducts are about the same size too (didn't measure.)

It is strange. One duct is good, hot (with 2nd stage.) Others are cooler.

Thanks.

sammy37 12-10-2008 06:52 PM

I think it's just velocity. The furthest vents from my unit are large and free flowing and always seem to blow very warm. The smaller vents near the unit, bathrooms, small bedrooms etc, are at a much higher velocity and only feel lukewarm most of the time.

biggles 12-10-2008 07:43 PM

the discharge will only drop off the plenium as it splits to the zones......all metal :whistling2:how about some insulation,and is the cold problem going thru a crawl or unheated space?

Winchester 12-10-2008 07:56 PM

Just to cover all the bases, are you sure this isn't a cold air return?

beenthere 12-10-2008 08:11 PM

Common to some electric furnaces.
Its teh way the electric heat kit is made.
The air on that side isn't going through the coils as much as it is on the opposite side.

adamk 12-11-2008 08:27 AM

Checked the cfm through the vents. The hot one is around 470 cfm. The cool one is around 240 cfm. The ducts were sealed as well as the return air ducts. The ducts are all covered with insulation as are the plenums.

I had a feeling that the air wasn't mixing well after moving through the light bulbs (ahh heating coils) and getting heated differently. Is there anything that can be done to mix the air more effectively ? Or does this not work due to the pressure of the plenum ?

Thanks.

sammy37 12-11-2008 11:35 AM

Quote:

Originally Posted by adamk (Post 196663)
Checked the cfm through the vents. The hot one is around 470 cfm. The cool one is around 240 cfm. The ducts were sealed as well as the return air ducts. The ducts are all covered with insulation as are the plenums.

I had a feeling that the air wasn't mixing well after moving through the light bulbs (ahh heating coils) and getting heated differently. Is there anything that can be done to mix the air more effectively ? Or does this not work due to the pressure of the plenum ?

Thanks.

I was not happy with the hot and cold spots in my house, my thermostat has a circulation mode that kicks the fan on to redistribute the air in between heating cycles. This has helped alot with comfort.
I also added a switching relay in the unit so when it is not calling for high speed heat or cool, circ mode runs the fan at low speed.

beenthere 12-11-2008 02:42 PM

There is no simple fix for it.

Dampers installed in the plenum to through the 2 airs into each other may work.


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