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gdickson
In-slab duct repair
gdickson

I have a single floor house build in the 50's. The house is on a slab and the duct work was build into the slab. I has noticed that when it rains alot we get water in our vents. This is causing multiple issues. When we run the heater or AC it gets real humid in the house and smells like meldew. I was wondering how I would go about repairing the old ducts with out busting up my foundation. I have a down force gas furnace so running new ducts in the attic is not an option either (as far a I know).

Sten
Re: In-slab duct repair
Sten

I doubt that your going to be able to fix the present duct system without tearing up the floor, is it ground water that seeps in as the water table rises or is it coming in from the chimney through the furnace. If it's ground water I would remove the furnace, fill the hole in the floor with cement and replace your downflow with an upflow, rerun your ductwork into the attic with supplies to each room, rework your return out the closest wall by the furnace. If the water is coming in through the chimney fix the leak. If you have a high enough pitch on your roof you may be able to put a horizontal furnace in the attic and run your ductwork accordingly. Good Luck!:)

gdickson
Re: In-slab duct repair
gdickson

Thank you for your reply.
The water is coming from the ground water. I ran my shop-vac in the ducts to try to clean out as much water as I could and sucked up alot of mud. I would love to just replace this furnace with an up-flow one but can't afford to make that purchase at this time. Too bad I just can convert the one I currently have. I do need to do something, the air quality in my house is aweful.

dj1
Re: In-slab duct repair
dj1

Some furnaces can be used with up flow or horizontal ducting, so it might be worth it for you to check if your specific unit could be converted. Contact a reliable HVAC guy.

gdickson
Re: In-slab duct repair
gdickson

Thank you for your reply,
I will do that, I was not aware that some units could be converted, I was told it one way or the other.

Sten
Re: In-slab duct repair
Sten

I don't think they can be converted as that would also mean changing the burner assy, and heat exchanger but I may be wrong. As dj1 says check with a reputable HVAC Co. Good Luck:)

Clarence
Re: In-slab duct repair
Clarence

Check with company that do sewer pipe repair they insert a dry sleve looks like a sock inject hot water or steam this causes the duct to be lined with a plastic like material than a robit is placed in the dout to cut the openings where required.
Final product is a one piece duct no joints.

perchinonlakeerie
Re: In-slab duct repair
perchinonlakeerie
Clarence wrote:

Check with company that do sewer pipe repair they insert a dry sleve looks like a sock inject hot water or steam this causes the duct to be lined with a plastic like material than a robit is placed in the dout to cut the openings where required.
Final product is a one piece duct no joints.

this would be the best way, but its very expensive

museumgirl1
Re: In-slab duct repair
museumgirl1

The previous owners of our home had thee same issue, and put a furnace in the attic and ran duct work from there. They never filled the ducts or put in cold air returns, so make sure you or a contractor to the complete job! It actually works quite well, and having the furnace in the attic freed up some main floor space in the house. Good luck!

Theresa
Re: In-slab duct repair
Theresa

Hi

I live in a slab home. The heating ducts are run through the attic. The cold air return is a system of what looks like clay pipes that run in the cement slab. I have noticed when it rains, I hear water in my bedroom duct. I recently took off the vent and looked inside. The house is brick and I see brick and then I look down and see the vent pipe. I can see water running into the pipe from the bottom of the brick and it looks like it has been occurring for years due to a lot of mortar corroded away. 

I have read a bit and most suggest abandoning them and having the cold air returns run in the attic, which may be an option in the near future, but what can I do now? It has been raining so much in my area that the water built up a bit and I could hear gurgling when the air kicked on. I used a shop vac to suck as much water out as I could, but I am weary of turning the air back on, I am not sure if it is dangerous. the furnace is in the laundry room and I did notice some moisture on the floor around it.

What type of company do I call? Any advice will be welcomed. 

Thanks, 

Theresa

Keith
Re: In-slab duct repair
Keith

The answer might be to put in a French Drain around the perimeter of your foundation to keep water from getting into the ducts in the first place.  If you are at all handy and physically fit, you could do this yourself for not much money.  Once the ducts dry out, have them cleaned.  That will cost a little as it takes specialized equipment but it will be worth it.

If you still have any budget left over after this, there is a product that is mixed with air and run through the ducts that leaves a rubber like film over any openings in the ductwork.  It's been featured on TOH a couple of times.  That would have a payback as it saves heat lost through air leaks.

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