Water damage from crack in concrete slab with radiant heat.

Nitroman58

Hello, this is my first posting here. I reside in a 1950's constructed home with radiant heat in the slab. There are two zones on the first floor, and two zones on the second floor.
About 9 years ago, I had the heating system replaced with a Dunkirk 95M-200 gas fired direct vent boiler. Back in the fall we realized the the heater element had a crack, and was replaced under warranty. I will say that Dunkirk was wonderful with their help on this. A couple of the heating professionals commented that my home should have been set up with either a mixing valve or a dual zone system to adjust for the temperature in the slab.

My problem is that the floating engineered hardwood floor in the kitchen was ruined by moisture damage. I did not realized this until just recently and when I took up a section of this floor and exposed the slab, I found a crack about 3 foot in length. A flooring professional suggested taping plastic wrap over the crack, and after an hour's time there was evidence of moisture on the plastic wrap. At this point, the kitchen floor is ruined, and we are planning to replace it.
A few months back I had a plumber do a pressure test on my two radiant heating zones. They stated that you would see a drop in pressure pretty quickly if they were leaking, but both zones did hold pressure for about 1/2 hour's time.

At this point, I do not want to replace the kitchen floor until I can determine where the moisture is coming from. The ground floor of my home has 4 other rooms without any evidence of water damage.
Also of note is that the cracked area is away from exterior walls.

Is there a test to look for the origin of the moisture? Could this be from excessive heat in the slab?
Thanks.

kcopp

A thermal imaging camera will show you where this is. Then you will need to open up the floor.

Gordy

Does the system continual need make up water? If no water is being lost then it is not leaking.

The plumber who did the pressure test. What psi did he use, and why only 1/2 hour?

Nitroman58

The plumber felt that you would see the problem in the first 1/2 hour. I realized after the fact that this plumbing company was mostly in plumbing, and not heating.
I have a radiant heat guy coming out tomorrow. How does the thermal imaging camera appear with the leak? Would it be a big red area? Is that something that I can rent? The prices on Amazon were high, but I could get one, and sell after also.

Nitroman58

I believe the plumber set the pressure to 25 PSI.

Gordy

Yes thermal imaging would show up as a large red area rather than a defined pipe image.

25 psi is not much.

If there was never water before. The piping is suspect. An option could be to wait until your out of heating season, and see if area drys up with system off, and drained.

With an area as small as 3' long with a crack, and water. I would be inclined to carefully chip the concrete away down to the pipe to examine exposed while under operation. If there is a leak it can then be fixed. If not simply re cement the area.

Most times the leak is not noticed coming up through the slab, but going down under the slab. With no evidence from above.

BobC

There are a lot of homes like yours south of me and the slab radiant heat has failed in a lot of them. People have repaired them by exposing the pipe and repairing it only to have it fail somewhere else a year or two later. Copper pipe buried in cement will fail, it's just a matter of when.

That system was installed almost 70 years ago, if it is a heating pipe that has failed i would consider abandoning it and installing baseboard heat.

Bob

Zman

You are getting some solid advise here.

I would suggest buying a Flir One IR attachment for your smart phone. They are not very expensive and would work well for your needs. They are also nice if decide to start looking for Sasquatch or just want to see if that noise you heard in the yard at night is a person or squirrel.

The trick is to let the slab cool down completely, then turn the heat on and watch until the radiant piping appears. If you have a leak, it will appear as a blob where the pipes will be just a line.
Once the slab gets hot, it is harder to distinguish.

For Sasquatch, it is best to just walk around in the woods with a friend video recording you.

Nitroman58

It looks like I could get the FLIR TG130 for about $200, or the FLIG one for iPhone for about $220.
I will await advice from the heating pro tomorrow. There are 3 areas in the kitchen that I have uncovered, which have leaked. These may be in the same loop.
What are the best options for replacing the radiant heat? If I were to put another floor down, I would not want it be damaged.
We were planning to replace the kitchen and living room floors. There is also a family room floor which is over 20 years old.
I have been in this home over 20 years, There was a little moisture stain under the kitchen table when we moved in. Part of me wants to try a repair, since it is less invasive, and we love the radiant heat.

Zman

The TG130 has a 80x60 sensor. The One is 160x120. That 4x better. They can do this because the use your phones processor.

Nitroman58

Thanks Zman. I assume it is compatible with an iPhone 7?

Gordy

If there are multiple leaks, and the floor is already tore up. Give a hard look at an over the top installation. Options are warm board r, sunboard, Rehau panel, Roth panel, quick track, or a DIY sleeper profile.


We can go into that once you nail down the issue 100%. There is options.

Nitroman58

I was looking at the Warmboard a while back. It is a bit too thick, and expensive. The quick track seems okay. What is the thickness of sun board?

Gordy

What build up thickness are you able to do? Were you looking at warmboard s, or,R?

Zman

Nitroman58 said:

Thanks Zman. I assume it is compatible with an iPhone 7?

I would think it is. I have the android version and it works great

Nitroman58

Okay, to give you guys an update, the heating guy was at my place this morning. He said the first thing we should do is turn off the automatic fill valve off, and watch it over the next few days. Apparently, you have to allow for the expansion tank to decompress too?
He does not think it is worth my buying a thermal imaging camera since they have one, and he said that the concrete slab would have to be cold, which can take a few days. Also we would have to turn down the first floor thermostats for a few days.
So far, the shut off has only been closed for 6 hours, and the pressure has held at 16 PSI's.
He did think that the heat going into the slab was too high also, and feels a mixing valve would be of benefit in my system.
He also thought that it is possible that the 1000's of gallons that leaked under the slab when the domestic hot water line cracked, could be one cause for humidity coming up through cracks in the slab.
I will let you know more as I find out more, which he stated would be a few days.
Thanks for the help.