In Okla finding radiant floor heat is like finding teeth in a chicken. In my 20 years in inspecting I have had three but one of those was in Kansas. Just not popular here. The one today was on a 2006 home and google stated the MFG of that brand was no longer being MFG go tell. A 140,000 BTU boiler and a 3 thousand one hundred SQ FT home. I suppose Most HI’s in this state have never operated one. The boiler was off when I arrived and it took almost 2 hours before the thermal camera was able to detect a pattern and not a very good one at that, but good enough to determine the distance between the tubes.
I guess they don’t have a TPR valve, only a pressure relief valve.
Yeah, they do take a longgg time to show its heating when in concrete flooring, especially when covered with carpet.
That, Charley, is a big home!! :shock:
I love in floor heat. 
Whoops I left out the Coma the SQ FT was 3 thousand 0ne hundred
The flooring was wood over concrete except the utility and the bathroom floor and it was very slow to start with.
Concrete is a big heat sink and slow to heat up, especially if they did not install a thermal barrier under the concrete slab.
I agree and the one I did in Kansas we learned during the law suit that no thermal barrier was installed plus the tubes as per MFG should be no more than 12 inches apart. There is no visible way to know if a thermal barrier is installed after the fact at least to my knowledge.
I do thermal imaging for a guy who installs hoists in auto repair shops. Many if not most larger shops like newer car and truck dealerships have underfloor heating. He needs to know where the water lines are to place his drilled anchor bolts between them. The hot water lines are about 6 inches deep because the slabs are designed for heavy equipment, so the images are really fuzzy compared to what you might find in a home. If they forget to turn on the heat before I arrive its a half hour wait at least before we can find them.
Charlie,
In floor heat is tricky in even beginning to determine if its functional.
Some of it here in Northern Michigan and often done incorrectly with inadequate insulation, Rfoil bubble wrap under the concrete and some times no insulation with excessive downward heating into the ground or basement.
I make sure the boiler is up to temp and by the way if a cast iron sectional was used a mising valve or injection station will be present, and like indicated above an IR camera can help with detecting heat.
Beyond that I use the following and go no further:
In floor radiant tubing not visible to inspect. Inspector cannot verify adequate heat output from this system. Although boiler may appear functional, this is not an indication of a properly installed radiant in-floor heating system. Have a heating contractor review after the heating system has been in heating mode for a minimum of 24 hours.
In addition, many systems are zoned with pumps and you would need to verify each are working.
Too many areas to get tripped up…
Major drawback with in-floor systems is the time it takes to raise the temperature. Back when I was in the HVAC trade we had a couple of large commercial clients that would wait until returning back from the first cold weekend to turn the system on. Even after telling them year after year, they would then be surprised that it took 1 hour per degree to raise the temperature. Great system once they are started up though.
Good post Scott.
I hope you’re staying warm.
Jeff, that sounds like a ground water heat pump we had 25 years ago. It worked great at keeping the house within a couple of degrees once it was up to temperature but we needed a commercial grade water heater as backup to bring it up to temp quickly.
Also it would keep the house as cold as a meat locker for $5/month back then.
It was great! 
Yes Larry , keeping warm here in Gaylord!
However, some in floor radiant heating would feel good on my toes:D
This was run by a Lochinvar boiler. Not sure if they still do it, but they would design the loops and system for you, if you bought their equipment.