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

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.

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?

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.

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

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.

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

Quote:

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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.

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

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

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

Quote:

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Originally Posted by Missouri Bound

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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Thanks for your input. Deedee can quickly check that out by laying a piece of papper over the vent. Either it will blow away, or Be sucked flat.

Hi Missouri Bound,

Sorry for the taking so long to reply. The return vents are not near the supply registers.

I believe I have found a solution to the problem. I disconnected the ducting intake near the top of the furnace that was attached the intake ducts under the house. I replaced the ducting by redirecting the intake ducting flow near the top of the furnace before the filter as well as closing off and sealing all ducting that went to the dusts below the house. It seems to be working well.

What I noticed is that the original intake registers were, cold air was still blowing. I now believe that there is a hole(s) in the duct work under the house. I tried to find it but due to the way the intake duct were constructed, I was unable to. In any case I have closed off the registers and everything seems to be working fine.

Thanks for everyone's help.


Dee Dee

That sounds like the duct work was poorly installed. If there is a hole in the duct work under the house, you are losing warm air and at today's prices, big money. The price you paid for the house entitles you to a proper working furnace. Whoever installed the duct work is obligated to come back and make it right at their expense. You may have to work through whoever you bought the house from. You have been ripped off, scream.

I am sure it was accidental. Everybody makes mistakes. Good trades men make fewer ones, and correct them as soon as they find out about them. Don't make the mistake of living with your fix. If you do, you may end up paying to have it fixed right if you ever sell the house.

Furnace Blows Hot Air But Cold Air Return Blows Cold Air Instead Of Sucking Out Cold Air Why!!

Blower running wrong way/backwards.

Warm air is blowing in the ducts however VERY COLD AIR (as if direct from outside) is forcefully blowing in from air supply register... what would be causing this? Thanks for any help.

Quote:

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Originally Posted by deedee1

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

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I can only imagine the plenums reversed and you have a package unit? Or the furnace was replaced with an upflow when it required a downflow or vica versa, which is hilarious sorry! Lol!