Failed slab heat

[Ryanhueston]

I am purchasing a home. The home was built in 2007. It has heat in the slab floor. There are 2 zones. One of the 2 has failed according to the seller. I have 2 questions:

1. How would I find the failure? Thermal imaging?

2. What is likely to be the cause of the failure? A leak in the piping?

 

[Ryanhueston]

By the way, the failed zone is in the garage, so there is no floor coverings to deal with.

 

[Former Farmer]

Leaking pipe is most likely the culprit. Are there any major cracks in the garage floor? Thermal imaging would be tough to see a couple of degree difference. It takes a while for concrete to change temperature. I would start by looking for major issues in the floor. How many loops are in the garage? If you close all of the loops and open one at a time and watch for a water pressure drop, you may be able to isolate it to a specific loop leaking.

 

[Ryanhueston]

There are no places that are visibly a problem in the concrete. I don't know how many loops are in the garage.

 

[tom in maine]

You might be able to locate a leak with a thermal imaging camera. At least get it down to an area.
You might just do a pressure test first to understand which loop it is.
Then only heat the leaky loop and thermal image the floor.

And check on jackhammer rentals.

 

[Ryanhueston]

My father in law is a concrete finisher. He has all the tools necessary to cut a section out of the floor. I'm just trying to narrow it down to as small an area as possible.

 

[cityboy172]

There is more then likely more then 1 tube on that zone. I would pressure test the tubes individually, find the culprit (s), abandon them, and hook the rest of them up. That's just me though.

 

[tom in maine]

If there are enough loops and you are not trying to heat to 70F all the time, a single loop could be abandoned.
How many loops are there in the garage?

 

[Ryanhueston]

I don't know how many loops are in the garage. We are still involved in the loan process. Our appraisal has been ordered and should happen soon. I am expecting to close in late February or March. I won't really be able to investigate it until that time.

 

[Ryanhueston]

Currently the heat is supplied by a designated water heater. My plan is to install a wood boiler prior to next winter.

 

[Bob Rohr]

Or it could be something as simple as a failed zone valve, relay or pump? Two zones or two loops? in the garage.

With Infrared cameras you can pinpoint a leak in the tubing if that is the problem. Search around your area for home inspectors and building efficiency contractors, most have cameras now, or rent one from Flir. If it is a one piece pex loop it's rare for a tube to go bad unless the slab shifts.

 

[heaterman]

I am purchasing a home. The home was built in 2007. It has heat in the slab floor. There are 2 zones. One of the 2 has failed according to the seller. I have 2 questions:

1. How would I find the failure? Thermal imaging?

2. What is likely to be the cause of the failure? A leak in the piping?

Question........

When you refer to "2 zones" are you talking about total number of zones in the house or are you referring to the number of loops in the floor of the garage?

 

[Ryanhueston]

Question........

When you refer to "2 zones" are you talking about total number of zones in the house or are you referring to the number of loops in the floor of the garage?

By 2 zones, I mean one for the living space, and one for the garage. The seller has shut the garage zone down and just uses the heat in the living space now. I don't know how many loops are in the garage yet. I'm worried that it is just one.

 

[heaterman]

By 2 zones, I mean one for the living space, and one for the garage. The seller has shut the garage zone down and just uses the heat in the living space now. I don't know how many loops are in the garage yet. I'm worried that it is just one.

What is the garage dimension roughly? A basic guideline would be 1 loop of 1/2" per 300 sq ft of floor in that type of an application.

 

[Ryanhueston]

The garage is 26 x 42 (1092 sq ft)

The living space is 30 x 42 (1,260 sq ft)

 

[Bob Rohr]

The garage is 26 x 42 (1092 sq ft)

The living space is 30 x 42 (1,260 sq ft)

Should be at least 3 loops, maybe 4 if it is 3/8 or 1/2" tube 12" on center. Unless you need to heat the shop to 70 degrees, you will be able to get some heat even with a loop disconnected.

But then again I've seen some wild radiant installs out there like 1000 foot single loops, or 24" on center spacing, hard to say without finding the original installer. Some installers take pics of their tube layout before a pour, any chance?

Sounds like a good bargaining chip for the selling price

 

[BoilerMan]

Worst case you can install a modine heater in the garage or if your boiler will be in that space you won't need heat in the floor. Garage slabs can freeze too. Typically the owner turns it down to 45 and the tubing near the base of the garage doors freeze from the extra heat loss there and a cold room.

I always keep radiant tubing 18-24" from the edge of a slab where an overhead door will be.


TS

 

[Buzz Saw]

The home inspection should allow you to investigate the loops situation. I would find out before you close, or at least negotiate the price down to offset for a complete tear out, replacement and new concrete. Good luck

 

[john11756]

did you see the manifold? this is a 7 loop manifold

 

[slowzuki]

lol I have no idea what you're talking about. We threw in tubing in my shop in a rush before pouring without calcing pressure drop. 1800 ft2 with 2000 ft of tubing in two loops, of course!

I've since jackhammered the floor and broken the loops in half to get 4 x 500 ft loops. Haven't put water too them yet as I have to buy a high head circulator just to put a minimal amount of heat into the floor with a high delta T. I'll always be punished with high electrical costs to circulate the loops and possibly a reversing valve on timer to alternate circulation direction.

But then again I've seen some wild radiant installs out there like 1000 foot single loops, or 24" on center spacing, hard to say without finding the original installer.