Water Pooling Under Furnace When Outside Temp <0°

heshootshescores

If I do find water coming up through the hole, any idea what I can do about it? Do you think it's safe to simply seal the concrete pad to prevent water from seeping through?

heshootshescores

I have a strange problem when the outside temp gets below zero. My furnace sits on about a 3" concrete pad that appears to have been poured after the basement floor was in. When the outside temperature gets really cold, water will seep THROUGH the porous sections of the concrete pad and onto my basement floor. So far, nobody can explain this and I'm not sure if I can simply seal the pad or if sealing will just cause water pressure build-up and heaving somewhere. Trust me, there are absolutely no leaks from my furnace or ductwork. It is bone dry everywhere except where the pad and floor meet. Any ideas what the heck is going on?

mark schofield

ground water

it could be ground water/water table and some frozen footing drains at very low temps. why don't you cut/drill a hole in the floor- probably 2 to 4 inches thick - right next to the pad and dig some dirt out, and see if and when water rises in the hole.

Brad White_9

Too coincidental...

You say that there are no system leaks. Naturally, I suspect condensation from the furnace coincident to cold weather, perhaps within the footprint where it cannot be seen...especially if it is a high efficiency/condensing appliance.

I mean, this is heatinghelp.com so at some deep level you must suspect the appliance is at fault somehow.

Does the heating appliance have photographs of you in a compromising position or some other form of blackmail which prevents you from making a direct accusation?

heshootshescores

Not that I know of! Seriously though, there is not one water molecule coming from under the furnace or the ductwork. I can actually see under the duct and nothing but dust, I removed all the outside sheetmetal possible on the furnace and the inside is dry as a bone. I can actually see the water kind of "weep" through the concrete pad. Any ideas of other sites like "foundationhelp.com" that you are aware of that could help?

Jamie Hall

got to admit

I think I might go with Mark on this one -- some frozen footing drains or some such. If you're up north or anywhere east, the weather we've been having...

And, if so, you're not going to stop it. If you plug it up at point A somehow, it's going to show up at point B, which might be less appreciated. Ground water is amazing stuff that way.

A general rule for foundations and ground water (and I made my living looking at this sort of thing for years, as a civil engineer) is that you should never attempt to seal off ground water from the 'air side' -- of a foundation wall or floor, for instance, or the free face of a retaining wall, etc. Always, always the only safe and reliable way to handle it is to provide drainage on the soil side. If you can't (for instance, my own basement), provide a way for the water to flow back out of the basement without damaging stuff, and learn to live with it.

Dave Yates (GrandPAH)_1

sounds like

the condensate drain (and A/C too) was simply dumped via a hole drilled through the slab into the stones below? If so, you're at peak condensate production and may well have exceeded the ability of snot-laden stones to accept condensate for drainage. Best cure - install a condensate pump, add a trap to the A/C line (if one isn't there now), and send that condensate to a neutralizer prior to it draining to the sewer via a safe waste connection.

mark schofield

sump pump

If there are no condensate drains from AC or a condensing boiler dumping into ypur footings or floor drain, and no washing machine dumping into a clogged or full drywell, and you find water under the slab when you drill a hole, then you might enlarge the hole enough for a 5 gallon sheetrock pail with holes punched in it and surrounded with 3/4 stone and put a sump pump in it. does the house have gutters. has it been raining. water comming down the chimney. good luck

heshootshescores

Forgive my ignorance, but the condensate drain is the tube that comes out of the duct work directly above the actual furnace unit, right (about

Dave Yates (GrandPAH)_1

that's

most likely the A/C condensate drain. If your furnace is vented with plastic pipe, it's a high efficiency unit that will have its own condensate line & often the two are joined together. If one runs to a floor drain, most likely both would. If it's vented into a chimney or metal pipe, then it's an 80+ model that doesn't condense & in that case, you'd have just an A/C drain to deal with.

A remote possibility is that yours is an 80+ model seeing sustained flue gas condensation that's running down through the furnace and appearing around its base.

Can you post some pics?

heshootshescores

The furnace is vented with PVC pipe and there is a T in the 1/2 line. One comes from above the furnace, the other from the AprilAire, then that runs to a floor drain. I'll try to post some pics tomorrow if it would help. Thanks!

Mike T., Swampeast MO

Is this an older home? If so, I'd verify that the floor drain is actually connected to the sewer. Not particularly uncommon for floor drains in old home basements to lead to nothing more than a gravel-filled pit under the floor. Eventually these loose their drainage ability. You should be able to run a hose full "on" indefinitely into the drain.

Dave Yates (GrandPAH)_1

missing in action!

There's a third line you're missing. Sounds like a 90+ model, so there is a condensate line that should appear about 20" off of the floor - coming out the side of the furnace itself. Could be they ran it internally, in which caee you'll need to remove the front access panels. Live voltage present, so it's best to turn off the power before touching any internal components - especially if pets and/or youngsters will be present.

heshootshescores

The house is about 60 years old and I'm almost positive its all connected to sewer.

There is a 3rd line coming out of the side (the top one connects to it via pvc T). If the side drain tube is dry (maybe clogged), where would I see the condenstae draining to? Maybe thats the real problem....draining somwhere out the bottom in lieu of the condensate drain. The inside of the furnace is dry and there's no runoff that I can see. Thats what bugs the heck out of me.

Dave Yates (GrandPAH)_1

That's the ticket!

With a 90+ model and a dry condensate drain at the termination (floor drain), you're leaking somewhere internally. You'll need to determine if it's clogged or broken. Where it leaves the furnace, there is often a rubber coupling, or connection, that can be removed. That'll isolate both sides & if the drainage line is clogged, that's a relatively easy fix.

heshootshescores

I'll check it tonight! I'm hoping this is the problem rather than some crazy groundwater/drainage issue....
I guess if that's not it it would have to be some crazy drainage/water table thing that I'll be content to live with for now!
Thanks!

heshootshescores

Problem Solved!

I found the problem last night! As I was sitting there staring at everything through a couple heating cycles and muttering to myself, I caught something out of the corner of my eye. A small drip of water was running down the AprilAire drain tube and onto the floor. That explains why there was no water on TOP of the slab and it met the floor near where the slab and floor meet. The drips then wept around the crack making it look like it was coming from the crack! Hallelujah! Easy fix!

Thanks for your help!