Slab Heat Leak

Jeff_Hanaway

I have a split level home built in the mid 70’s that has both, radiant heat in the basement slab; finished living area and garage, and also radiant heat in the 2nd floor living area ceilings. I myself had never heard of plastered in heating circuits before, maybe some of you have, but what a comfortable heat we feel in this house when working properly. In the spring of ‘21 I started developing air in the upstairs, this was evident with cool rooms at first, then when I heard water noise in the vertical supply runs, I knew I had an issue. I finished out the heating season constantly bleeding the system in the attic. During this it time I purchased a thermal video camera so I could see where I had airlocks on the second floor, which aided in purging the air from the 4 upstairs zones, but I was also hoping I could see a sideways plume with the camera in areas in the downstairs slab. Unfortunately this wasn’t to be, if there was a leak it wasn’t a gusher. When early summer hit and we had a week or so of very dry weather, I noticed a crack in the garage that refused to dry up as I would’ve expected. Eureka! When I excavated the local area I found the leak at a soldered joint. Good and bad; I was able to fix the leak, but I now know the copper was soldered and not soldered/brazed with an approved material to hold up to being buried in concrete. So it’s fixed for now I thought and I go on to other summer projects! Long winded I know, but the following winter, last winter, was a constant air purge fest and I’ve determined throughout the year that I have leaks in all three basement zones. So here’s my question… is there a product or additive that will fix my leaks without abandoning the slab heat? It’s my belief that I have no gaping ruptures in the copper, just that the solder has been compromised from years in the cement creating small area leaks as the concrete is still holding all the fittings in place. I have verified that it is the proper copper that they used when installed. 

My worry is that switching to baseboard radiators will leave me with a very cold basement considering the basement isn’t covered by ground on all sides; ground level at the slab at the rear of the house, full of floor to ceiling windows and french doors, and also the two garage doors on the end. I can feel the cold creeping into the slab as I write this. Looking for a hail-mary I guess to continue our comfort level in the basement. It’s not about the cost of installing baseboard heat in a finished living area, although I’m not excited about the prospect of that either, but I’m just looking for advice before I abandon the slab heat. Thanks in advance and sorry about word salad! Lmk if any of you feel a product is available and worth a shot. Jeff~

mattmia2

I would do a heat loss and size panel radiators to heat the basement spaces. They won't be quite as comfortable as the radiant slab but they will produce some radiant heat. Baseboard has essentially no mass and little radiant heat. I think you will be chasing the slab leaks forever and sealant products cause other problems.

Jeff_Hanaway

Appreciate your input!

PC7060

50 year run on that system is pretty good! But I have admit that 50 years life always sound better on year 1 then it does on the year 48. 

  

hot_rod

That looks to be beyond a sealer fix.
There are a number of thin over the top panels for retro fit. Viega, Uponor, Roth.

Ceiling radiant is a close second to floor radiant. Radiant energy travels in all direction, line of sight.
Ceilings are sometimes easiest to retro fit, no wall trim /stair riser issues.

kcopp

Still yet a 3rd option would be to pipe in some cast iron radiation, baseboard or even some old radiators. Lots of mass there. slow even heat. Could find them used that someone is going to scrap.

mattmia2

Cast iron baseboard might be an easier retrofit and would still give you radiant heat.

Dave Carpentier

Just throwing this out there, as I have no idea if it's feasible. Does anyone "trench" slabs ? If there is a machine that can trench out a 1" slit down to 2" depth, and you could drop in some 3/4" wirsbo and fill it back in with some kind of thinned concrete ? It would have to be more like a router so you could do curves as opposed to a concrete saw which would be all right angle corners. It sounds expensive (or non existent lol ?) and would be a mess , but you could get some semblance of in-floor back.

hot_rod

Dave Carpentier said:

Just throwing this out there, as I have no idea if it's feasible. Does anyone "trench" slabs ? If there is a machine that can trench out a 1" slit down to 2" depth, and you could drop in some 3/4" wirsbo and fill it back in with some kind of thinned concrete ? It would have to be more like a router so you could do curves as opposed to a concrete saw which would be all right angle corners. It sounds expensive (or non existent lol ?) and would be a mess , but you could get some semblance of in-floor back.

One of the saw blade companies made a saw and router for grooving in radiant slabs years ago. A very slow, messy job. Properly easier to have a pro demo and remove the old slab, labor wise