Hey All. Our house was rebuilt after it burned down a couple years ago. The new house has Demilec foam insulation, hydronic radiant in-floor heat, an Amtrol indirect hot water tank, and a 100amp Electro-boiler. The boiler heats water for the in-floor heat, domestic water, and a few baseboards in the basement. The house is about 2000sqft. The insulation works great. The problem is I'm not convinced the radiant is doing it's job. Currently I have the tstats set to come on at 5AM to 69deg. When I get up at 7AM, the tstats in the rooms still read 65-67deg and the boiler is working away. The temp gauge on the boiler says 185deg, but the temp gauge at the radiant manifold says 140deg. PSI on the boiler says 18. The water in the radiant pipes looks gray and at the return leg it looks like some sediment is in the pex. We live in a smallish town in Alaska and the local plumber we used didn't quite get an A+ for service in my book. So I'm asking here - anything I can do / should look at to tweak our system to optimal performance?

I'd wonder why you're dropping 40 degrees on the way to the manifold. or is that supply out to manifold return?

I would also wonder why you have 180 degrees in a radiant system... plateless staple up in a joist bay?

If so, that's a slow response system. give up on setbacks.

I am on the same page as NRT.Rob.Besides the temperatures, it sounds as if your tubing was never flushed before putting into service.Do you know what your flowrates are. Post some pictures, it could be helpful.

Thank you for the replies.

The 40deg drop between boiler and manifold was due to the mixing valve. I've since opened up the valve a bit and now the gauges both read about 180. I plan to check it again tomorrow morning and see what difference 180 vs 140 in the pex makes. I don't know if 180 is too hot? The tstat in the main room reached temperature about 3.5 hours after the boiler came on.

The pex is stapled to the underside of 1" plywood with another 1/2" layer of engineered flooring on top of that. Beneath the pex there's a cardboard baffle and then open cell spray foam.

Any advice: appreciated!

Here are some pics:

return manifold, sediment?:

send and return manifold:

boiler temps and valve:

180 is too hot. If you don't have plates on that pipe it will never be fast response. Pick a room temp you like and leave it. If it won't maintain that temp, turn up the water temp in 5 degree increments from the base of 140 you were starting from.

I have had a bare tube stapleup radiant floor running 180F since 1991:-).
But other than that, Rob is right!

DIY radiant design; always the first mistake.

OK thanks all for the advice. So if it takes 4 hours for the room to come to temp using 140F water, then your recommend is to just live with that?

What about the sediment in the pipes... should I be worried about it?

Set it and forget it and the dark water as well. Don't worry, be happy.

Set it and forget it means that the room is always up to temp. give up on the setback unless you plan to retrofit plates in that application.

Even with heavy extrusion plates the response time is going to be pretty long through 1.5" of subfloor & wood flooring unless you keep the water temps up. A constant room temp strategy would cut 15-20F or more below what would deliver a fast response (and probable overshoot), and by keeping the water temps as low the distribution losses to the semi-conditioned spaces drops, saving on total power. (You don't really care if the boiler room runs cold, and you're probably using to much power if the boiler room is the warmest place in the house.) Only if the conditioned space is pretty lossy and you'd be setting back for 12-15 hours at a time would you reap any real savings with a setback strategy.

Dont treat radiant heat like forced air and don't think yo need to set back you will use more energy with the higher water temp than night set back. And you will be more comfortable. If you installed a good outdoor reset it would compensate and provide a boost in water temp in the recovery period and then drop back after satisfying room temp. You pay for it weather you get it or not.