leak in slab

bk9

Pics below. I've got a leak in the slab in an attached garage. I suspect the leak is from a hydronic 3/4" copper pipe that I'm guessing runs from under the room just behind the garage (behind the wall in the pic), under the garage and to the hallway where it connects to the next baseboard in the circuit. I turned off the thermostat to this zone last night, thinking with no more calls for heat, the pump for this zone would stop running, and thus no more pressure pushing water out of the hole in the pipe. As of right now, the wet spot is still there, but while before I could touch the ground and my fingers had droplets of water, now no visible water on my fingers. So I think it must be the hydronic pipe as I suspected, and not a water supply pipe or waste pipe.

Assuming it is hydronic pipe, my near term concern is we are getting overnight temps down to the low 20s *F in my area. If I leave this heating zone on overnight, I'm thinking the water leaking out may freeze as it gets farther away from the warm pipe. If the water in the slab freezes, will that start breaking up the slab?

If so, I'm thinking the better option is to leave this heating zone off, and to prevent the water in the pipe from freezing, drain this zone (which heats ground floor and basement). Draining would get most of the water out of the ground floor baseboard piping. There would still be water in the basement piping, but that's not getting anywhere close to freezing, so seems this would be a satisfactory solution to dealing with freeze risk.

Thoughts on how to handle near-term freeze risk? Or is water freezing in the slab not a problem - in which case, I'd be able to heat this zone which would be more comfortable since the room adjacent to the garage does get used during the day.

As far as fixing the leak, I'm guessing breaking up the slab to repair the leak may solve this leak, but other leaks may develop in the same pipe either under the garage, or under the adjacent room. As far as I know, there are other spots in the pipe that are close to leaking, so this kind of repair could be for naught. Do pros prefer to reroute the pipe in slab leak situations?

Jamie Hall

First things first: unless you can valve off both ends of that loop -- if it is a loop -- it will continue to lose water from the pressure in the rest of the system. You will see this as a loss of pressure overall, and you need to keep a close eye on it to ensure that the rest of the system has enough pressure. If you have a pressure reducing valve sort of automatic feeder, that should do it -- but watch it.

If the loop isn't valved off and the pressure in the rest of the system is not dropping (turn off any automatic feed to check this), it's not a leak in a heating loop. It's something else. What other pipes run under or in the slab?

As to freezing, it will take a day or two -- at least -- for the slab to reach freezing. In fact, if the garage isn't well insulated from the rest of the house, it probably won't.

bk9

Jamie Hall said:

First things first: unless you can valve off both ends of that loop -- if it is a loop -- it will continue to lose water from the pressure in the rest of the system. You will see this as a loss of pressure overall, and you need to keep a close eye on it to ensure that the rest of the system has enough pressure. If you have a pressure reducing valve sort of automatic feeder, that should do it -- but watch it.

Well there are two zones. All I've done so far is turned off the thermostat for this zone. I could isolate this zone and drain the water from it, if necessary.

Jamie Hall said:

If the loop isn't valved off and the pressure in the rest of the system is not dropping (turn off any automatic feed to check this), it's not a leak in a heating loop. It's something else. What other pipes run under or in the slab?

There must be a waste pipe that runs under the slab in the garage given where the main sewer pipe exits the house. I don't think any water supply pipes run under the garage. But I don't think it's the waste pipe. That wet spot is noticeably less wet and slightly smaller since turning off the thermostat last night.

Jamie Hall said:

As to freezing, it will take a day or two -- at least -- for the slab to reach freezing. In fact, if the garage isn't well insulated from the rest of the house, it probably won't.

If the water in the slab does freeze, will that damage the slab?

hot_rod

No the slab will not be damaged by the copper tube freezing. But the tube itself may not be salvageable after a freeze. Either disconnect both ends and blow out with a compressor, or pump some rv antifreeze into the disconnected loop.
How old is the copper radiant tube?

bk9

hot_rod said:

No the slab will not be damaged by the copper tube freezing. But the tube itself may not be salvageable after a freeze. Either disconnect both ends and blow out with a compressor, or pump some rv antifreeze into the disconnected loop.
How old is the copper radiant tube?

I'm asking about the water that has leaked out of the pipe and is soaking the slab (and will continue to soak the slab if I turn the thermostat back on). If that water freezes, will it damage the slab?

As for the pipe, I can easily prevent freezing of the water inside the pipe by draining it. But that means no heat for ground floor and basement. I'd rather have heat until the problem is fixed.

It's not radiant tube. It's hydronic/baseboard 1/2" copper pipe running from baseboard in adjacent room, then under slab in that room, under slab in garage and connecting to baseboard in hallway. It's as old as the house, so ~60 years.

hot_rod

That is hard to answer, depends on how much is under the slab and how much freezes. Also what type of drainage below. Sidewalks and driveways fail from frost heave on a regular basis 

As Jamie mentioned, you possibly have a day or two, water near the outer edge would be most at risk

bk9

hot_rod said:

That is hard to answer, depends on how much is under the slab and how much freezes. Also what type of drainage below. Sidewalks and driveways fail from frost heave on a regular basis 

As Jamie mentioned, you possibly have a day or two, water near the outer edge would be most at risk

OK, sounds like the safer bet is to drain most of the water out of this zone. And maybe most of the water already in the slab will evaporate by the time slab gets cold enough to freeze the water.

hot_rod

Unless you are on clay hard pan the water should soak away, the less you add the faster the perc.

EBEBRATT-Ed

@bk9

That's too bad.

I only see two choices

Keep running it and monitor the leak and make sure to keep water in the boiler.

Drain the loop and blow it out with air as @hot_rod mentioned. If it is baseboard only the maybe a new pipe or pex and be run exposed somehow (it may not be pretty) but could get your through until summer.

As you said if it leaks in one spot other leaks will follow

bk9

So I isolate the zone for ground floor and basement, opened one of the bleeder valves at one of the ground floor baseboards, then opened spigot to drain this zone until the water stopped flowing.

Something I noticed that I don't quite understand that you guys might be familiar with. This is the return pipe for zone 1 (basement and ground floor) after it leaves the last ground floor baseboard and enters the utility room in basement. This section is at ground floor height. Note the little threaded plug.


Then it turns up 90* and runs ~3ft up to this:


Then it turns 90* several inches below basement ceiling (so now it's *above* ground floor height - split level house) and runs horizontal toward the boiler, where it turns down 90* and runs down to the pump for this zone. Since the return pipe is higher, at least for several feet, than the ground floor piping, how does it drain? I'm guessing it's the siphon effect - the falling column of water pulls water behind it.

Assuming that's correct, it won't get all the water out of the ground floor piping since the siphon will be broken before all the water gets out. So I go to that little threaded plug, thinking I drain more water out since that plug/hole in the elbow is at ground floor height. I remove the plug and not a drop of water comes out. I tried taking a pic of the opening, but couldn't get the camera to focus. What is the purpose of this? Is there a tool you use to open this to drain water?

hot_rod

Try poking a Phillips screwdriver in there, looks like a sludge build up. 

EBEBRATT-Ed

That fitting is called a "baseboard elbow" although some call it a tee. It's just a 1/8" threaded pipe plug someone left there for a drain. I would poke a wire in it it looks like it is full of sludge

bk9

hot_rod said:

Try poking a Phillips screwdriver in there, looks like a sludge build up. 

EBEBRATT-Ed said:

That fitting is called a "baseboard elbow" although some call it a tee. It's just a 1/8" threaded pipe plug someone left there for a drain. I would poke a wire in it it looks like it is full of sludge

Probed up there with a piece of 12g wire. Feels like a hard stop, and I'm only able to get in about as far as that little plug threads in, so definitely not getting deep enough into the elbow where the water would be.

bk9

hot_rod said:

Unless you are on clay hard pan the water should soak away, the less you add the faster the perc.

Soil is fairly sandy once you go ~8-9" down, so soil does drain well here.

bk9

EBEBRATT-Ed said:

Drain the loop and blow it out with air as @hot_rod mentioned.

I do have an air compressor, but not sure how to blow out - I guess I can attach my sprinkler blowout adapter to this spigot (that sits between the one-way valve and the closed zone 1 valve - all of this is downstream of the boiler), then open up that closed zone 1 valve, and the drain spigot on the return side. Would air pressure of, say 40psi, damage the one-way valve? I guess not since water pressure when zone is active/heating must be at least that high?



I noticed this just downstream of the one-way valve and closed zone valve. What is this for?

EBEBRATT-Ed

@bk9

Your in luck.

That is an air bleeder on the supply. With your valve closed as it is in the picture open that bleeder to get rid of water pressure in that zone. Remove the bleeder and put a 1/8" inch fitting in there to attach your compressor to.

Remove the 1/8" plug from the other tee and clean out that gunk and you should be able to blow that zone out. You should have a ball valve between the gunked up tee and the boiler return. Make sure that is shut off

Jamie Hall

I might add -- if that copper pipe below or in the slab has a leak after 50 years or so, I'm not too surprised. And there will be more. Start thinking about ways to bypass that line!

bk9

EBEBRATT-Ed said:

@bk9

Your in luck.

That is an air bleeder on the supply. With your valve closed as it is in the picture open that bleeder to get rid of water pressure in that zone. Remove the bleeder and put a 1/8" inch fitting in there to attach your compressor to.

Remove the 1/8" plug from the other tee and clean out that gunk and you should be able to blow that zone out. You should have a ball valve between the gunked up tee and the boiler return. Make sure that is shut off

I don't have the necessary fitting on hand, I guess I'd need a 1/8" NPT male industrial plug? Not seeing this on Home Depot site (so that I can buy locally instead of waiting for shipping), but I suppose I can get 1/8" male NPT to 1/4" female NPT adapter, and then connect air hose to that.

As an alternative, can I use that spigot on the supply side? I have a sprinkler line blowout adapter that will fit the spigot. Or would this damage the one-way valve in the pic?

hot_rod

With care you can use a cordless drill to penetrate that sludge, you need a free flow there to move forward with the blow down. If you remove that air vent an 1/8" tire stem Schrader valve will fit to connect your compressor to.

bk9

hot_rod said:

With care you can use a cordless drill to penetrate that sludge, you need a free flow there to move forward with the blow down. If you remove that air vent an 1/8" tire stem Schrader valve will fit to connect your compressor to.

I don't think that's sludge, I tried sticking 12g wire in there, feels like something solid. Unless sludge can get so hard it feels solid?

I don't have a 1/8" schrader valve on hand, so that, like the 1/8" NPT adapter, would require a trip to the store. Can I not just use the spigot as an access point? As mentioned, I already have a blowout adapter that will fit that.

hot_rod

your drain valve seems to be on the wrong side of the ball valve for what you are trying to do. Maybe a wider camera shot would shed some light on how best to purge with what you have.

sometimes when you flow backwards thru a bib like that you can push the washer off the stem and it will not shut off. The like to flow in one direction. Worse case you put a hose cap on it.

bk9

hot_rod said:

your drain valve seems to be on the wrong side of the ball valve for what you are trying to do. Maybe a wider camera shot would shed some light on how best to purge with what you have.

sometimes when you flow backwards thru a bib like that you can push the washer off the stem and it will not shut off. The like to flow in one direction. Worse case you put a hose cap on it.

I see. Ok, well I certainly don't want to screw things up.

Here's a wider shot of what I'm working with:


Downstream of this pic, there are no more valves, just pipes for the two zones running off to their respective parts of the house.

Worst case I can get the parts tomorrow and go in through the opening for the bleeder valve as suggested.

hot_rod

The two copper pipes on the left run out to manifolds somewhere? Where is the return piping from those manifolds. A bigger pic yet to show where pipes come back to the boiler would help.

Basically you need to push into the system, valved off from going the opposite direction, then a valve or connection on the opposite end of the loop to purge out of.

Here is an example with an all in one purge valve to show you the concept.

bk9

hot_rod said:

The two copper pipes on the left run out to manifolds somewhere? Where is the return piping from those manifolds. A bigger pic yet to show where pipes come back to the boiler would help.

Basically you need to push into the system, valved off from going the opposite direction, then a valve or connection on the opposite end of the loop to purge out of.

Here is an example with an all in one purge valve to show you the concept.

No, those 2 pipes run out to the first baseboard in their respective zones, and then they each continue to run in series to other baseboards in the circuit, then return back to the boiler.

Yep, I understand the concept in terms of isolating the zone from boiler and other zones, and then using air to expel water from the zone. Both zones on the return side come into their respective pumps next to the boiler. Here's a pic. The blue valve above the green pump is currently closed. Earlier pic shows the valve I closed off on supply side. So the zone is isolated. The spigot above the pump is where I drain the zone.

hot_rod

Yes you have good ball valves and ball type bibs to do a good purge.


Close the blue valve above pump.
Connect air pressure to bib above the blue valve

On the other side of the boiler see the green flow check valves, close the ball valve to the right of that.
Now you can purge air from the bib on the left side of that green flow check valve.

You will be flowing air backwards, not a problem, gunk should flow out.

One question, on the first post you mentioned a 1/2 copper line in the garage being the heating tube?
At the boiler you have a 3/4 and a 1" loop, it's rare they would reduce to 1/2 anywhere in the loop between heat emitters.

bk9

hot_rod said:

Yes you have good ball valves and ball type bibs to do a good purge. Close the blue valve above pump. Connect air pressure to bib above the blue valve On the other side of the boiler see the green flow check valves, close the ball valve to the right of that. Now you can purge air from the bib on the left side of that green flow check valve. You will be flowing air backwards, not a problem, gunk should flow out. One question, on the first post you mentioned a 1/2 copper line in the garage being the heating tube? At the boiler you have a 3/4 and a 1" loop, it's rare they would reduce to 1/2 anywhere in the loop between heat emitters.

Doesn't this method present the same risk to the flow check valve as what I described earlier (attaching air compressor at spigot downstream of flow check valve)? Either way, seems there will be air pressure against the flow check valve.

Apologies, I misspoke - all the piping at baseboards and between baseboards are 3/4", not 1/2".

bk9

Got it done. I went to HD and picked up a 1/8" schrader valve as @hot_rod suggested (for anyone who runs into this needing the same part, HD calls this a 1/8" NPT tank valve). So I was able to blow out the way you initially suggested, with the ball valve downstream of the flow check valve closed and air blown in through that bleeder port just downstream of the closed ball valve.




Thanks for all the help!

Now I need to start thinking about how I'm going to reroute this line, so I can abandon this section of pipe in the slab. And hope that none of the other baseboard piping in the slab leaks anytime soon.

Solid_Fuel_Man

If the buried copper is 3/4" soft copper, then you can slide 1/2" oxygen barrier PEX through it and reconnect the baseboard on either end. If that is the case, I'd do it to all the buried copper at the same time. 

Jon_blaney

These leaks may be covered by your homeowners insurance.

lkstdl

If the space above is finished and you can't simply reroute above the slab in a way that you like, it is possible to hydro-drill a hole underneath it. Not the easiest option, but it's an option. I've done this to add drainage under a below grade slab. The model I used is the Earthworm 7800 from Wheeler-Rex.

Goes very easily through clay & sand, less so through rocks. Just keep adding sections of 3/4" black pipe as you get farther into the hole. When you are done you can either pull the pipe out, or just leave it there & use it for your run. You'd need to make a hole in the wall first, and depending on your layout, a hole down through the slab where it comes out. Hopefully you have a friend with a core drill...



Luke

bk9

Solid_Fuel_Man said:

If the buried copper is 3/4" soft copper, then you can slide 1/2" oxygen barrier PEX through it and reconnect the baseboard on either end. If that is the case, I'd do it to all the buried copper at the same time. 

It's 3/4" copper, straight pipe with fittings every time the pipe has to go in a different direction. Not coiled pipe such as the type used in radiant heat applications. But apart from 90* turns up through the floor, I'd guess the underground line is a straight run. Can't imagine they'd be making turns in pipe that is going to be buried in concrete.

Can 1/2" oxy barrier PEX be pushed through that? Can it make it through what I assume are 90* turns (though may not be 90*s - I guess it depends on what practice was 60yrs ago - would they have put a copper pipe elbow in the slab, or would have have put a gentle bends into either end of long run of copper pipe)?

100% agreed that if I went this route, I'd sleeve all the in-slab pipe in this heating zone at the same time. In fact, I'm reluctant to reroute just this section through walls and ceilings because other sections may be on the verge of springing a leak.