Cold Air Duct Return Blows Instead of Sucks

deedee1 · #1 Nov 26, 2005, 07:43 AM

HI,

I need your help. I have purchased a home that has a new Hi-Effency forced air furnace. The house has a 2 1/2 ft crawl space - no basement. The heating and return ducts are below under the floor boards of the house in the crawl space. The crawl space is insulated as are the ducts.

My question is; When the furnace comes on, the return cold air ducts are BLOWING NOT SUCKING COLD air into the house. Is this normal and if not how can I fix this.....? I have checked the duct work and there does not appear to be any leaks....... The cold air gets somewhat less cold as the house begins to heat up BUT the RETURN ducts still blows and not suck....

I have tried to partially cover the return air vents - not sure if this is a good idea -

The furnace is inverted so that the hot air blows from the bottom and the intake (cold air) from the top. I have thought of detaching the cold air duct return from beneath the house to adapting a new duct return where the filter is at the top of the furnace inside the house. Do you think this will improve the situation?

Any help and advice is welcome and appreciated.

Dee Dee

labman · Nov 26, 2005, 09:41 AM

Down flow furnaces are fairly common, maybe the dominate type. It sounds like yours has a major flaw in the duct work. The blower usually is at the top, and forces air down through the heat exchanger and ''A'' coil into the supply ducts below. It is them distributed to vents on the outside walls of the house. There are return vents near the center ducted under the floor to the furnace and up one side of it through the filters and into the blower housing. Sounds like the main duct that collects the returns is somehow also connected to the supply duct. Whoever installed the furnace should come back, figure out what is wrong, fix it, apologize, and skip any bill. The best of workman make mistakes. The difference between them and the shady ones, is that they make fewer mistakes and when they do, they come back and make it right. Next question, where was the building inspector?

Study your furnace and post back with any questions. The furnace is a simple, logical thing. You should have no trouble seeing how it works. Don't be flimflammed.

deedee1 · Nov 26, 2005, 01:10 PM

Thank you so much Labman,

Unfortunately whe I purchased the house the Furnace and duct work were installed..... I do not know who did the work.... and I cannot find where the main duct that collects the returns is connected to the supply duct.....

What do you think of the idea of me detaching the cold air duct return from beneath the house to adapting a new duct return where the filter is - at the top of the furnace inside the house?. There is a lot of room and area where the furnace is situated and it is possible to put in ducting to receive house air....

Can this work and improve the situation?

labman · Nov 26, 2005, 07:42 PM

The return duct should come up through the floor to the top of the furnace, not be connected to the supply beneath it.

However, the seller of a house is responsible to have the major systems including the furnace in good working order or so disclose it at the time of the sale. Seek legal council. I think you can hire anybody to come fix it and sent the seller the bill. Be nice and give the seller a chance to go back on the installer.

deedee1 · Nov 27, 2005, 11:13 AM

Hi,

I guess I am not explaining myself...... sorry.

The return duct does come up through the floor to the TOP of the furnace just before the filter. What I am wondering would it be safe and O.K. for me to DISCONNECT the return duct that comes up from the floor and INSTALL a NEW vent before the filter NEAR the TOP of the furnace. As stated previously there is a lot of room and area where the furnace is situated. This way I would be able to suck the air in from a relatively heated place from the main floor.

Dee Dee

labman · Nov 27, 2005, 12:38 PM

It should work, but no reason to cobble up what you have paid to have done right. Not only that, if you ever sell the place, you may be forced at that time to fix it right. Buyers have a right to a furnace that works like it should.

Check with who you bought it from, the realtor, your lender, or any lawyer you had at the closing. Document you notified the seller.

labman · Nov 28, 2005, 06:00 AM

Quote:

Originally Posted by hvac1000

Is the blower motor running in reverse? Backwards? This would have the same effect and I have seen it happen before.

You didn't say anything about air going in the supply vents. If it is, this is the answer.

deedee1 · Nov 30, 2005, 08:00 AM

Hi and thanks to everyone....

I do not think that the blower is running in reverse because after the furnace warms the air in its chamber it blows warm air from the forced air heating vents into the house. As well, ONLY at this time does the cold air return vents BLOWING (NOT SUCKING as shoud be doing) dissipates to a degree......

Dee Dee

Missouri Bound · Dec 8, 2005, 09:36 PM

HI...
Just a quick observation....when I place my hand over my cold air return it feels as if it's blowing cool air. But it's just the air passing over my hand that feels cool.

You say it diminishes after a while? What diminishes, the cool temperature or the feeling of air blowing? Is it possible you have a supply register close enough to the return that you are feeling that blowing?
Just curious



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