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Chad Fabry

Radiant slab circa 1956

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I inspected a huge ranch today- nearly 3,000 square feet of hydronic radiant slab. Floor temps @ 82 degrees, air temps @ 72 degrees and water temps pushing 125 when the boiler was on. Interestingly, net btu's for a lightly insulated 3,000 sq ft home were just 80K and the whole house has just 6 loops.

I checked the copper.org website and they say copper in concrete is OK pretty much forever and ever as long as water temps aren't above 120 F. Does anyone have experience with speed limit, AARP aged copper in concrete radiant systems?

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Yes. There's a large development here that was constructed in the early and mid 50s with copper tubing for in-slab radiant heating. Every single one failed by the late 1980s.

I always found termite damage in those homes too. The bugs thought the radiant heat was there for them.

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Inspected two;One built in the late 40's (English Cottage) on a slab. System had failed and owner had baseboard installed. The other was a split built in the 60's. Most of the house had baseboard except for the family room which was on a slab.

Found the boiler taking on water when thermostat was turned up. Closed slab loop and boiler needed no more water. Buyer was a HVAC contractor and planned to install Furnace and A/C.

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After 30 years in my area, cap it and forget it. Most failed around that age. As a p.s. it was always easy to find if it leaked, and yes, the termites loved it.

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The copper.org site is wrong.

I've seen a few hundred; it was very popular in post WWII housing in Chicago. Large developments in Des Plaines, Northbrook, and other ring suburbs all had it. Every one has failed and been replaced with various forced air or baseboard radiator systems.

There's a bunch of Usonian homes all around the country that have failed systems. All the FLW homes that have it have failed. In every FLW restoration I've read about, replacing the copper floor heat was tops on the list.

Some of them have so many leaks, you can put your hand on the water makeup pipe and the pipe is cold because of the constant flow of fresh water into the system.

Have confidence in shit canning the thing.

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Yes. There's a large development here that was constructed in the early and mid 50s with copper tubing for in-slab radiant heating. Every single one failed by the late 1980s.

I always found termite damage in those homes too. The bugs thought the radiant heat was there for them.

Ditto. Try finding a leak in a system like that. Nearly impossible. They all get replaced with baseboard systems sooner or later.

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Try finding a leak in a system like that. Nearly impossible. They all get replaced with baseboard systems sooner or later.

I wonder if one of 'dem 'dare infared thigamajigs would be able to find the leaker.

You have one Kurt, would it work? Not saying you should repair the leak, just wondering...

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Yes, I've found leaks in a modern PEX system, so I suppose it would work in a copper system.

Mine is accurate down to .05 of a degree. Yes, that's 5/100's. It will find teeny tiny almost nonexistent anomalies.

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My bcam could but the timing would have to be pretty phenomenal. I can only see tubing in a slab when the slab is cool and the system fires. There is only a brief period when the tubes are hot enough and the slab is cool enough to find them. If it's full on heating season, forget it.

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Yeah, I guess I never thought of usin' them thangs. Excellent point. Only trouble is: once you dig 'em up, repair 'em, and patch the floor; the next leak is still just around the corner.

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If there's one thing that IR is really useful for, it's radiant system analysis.

There's a lot of older electric systems in condo ceilings in Chicago. I've found several that don't work. Same thing with electric radiant bathroom floors.

It's really good for any radiant floor system; you can track tubing, see layout, and determine function in a few minutes. Without IR, you're basically turning the thing on and hoping.

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