radiant heat: keep it hot or ??

[andis65]

So i know you guys with radiant heat floors have tried both. I live in upstate NY where it gets in the teens at night and currently have my shop at 50 degrees. I had a guy tell me that it will cost me less money to keep it at 60 -65 because the floor will stay warmer and require less use.Did any of you find that your system worked better keeping the temperature warmer? what about the bill? my system runs on natural gas.

 

[Gary S]

Try it both ways for a month and decide for yourself. Your loss or gain will depend on outside temperatures, insulation, and a number of other factors.

 

[custom1]

Depends on what you are asking. If you mean turning it up and down each day then maybe it would be cheaper to just leave it at one temp. But if you are saying it would be cheaper to set it at a constant 65 than it would be at a constant 50, there is no way. All other things being equal, you are looking at a higher delta to the outside temp and it will take more btus to maintain the higher temp.

 

[mooseeater19]

I have radiant in- slab with a condensing boiler and my Veissmann boiler rep suggested not to do a night setback or an outdoor reset.
Part of this logic was the slow recovery time of in-slab and the boiler is more efficient when condensing.

 

[anthony666]

I have radiant in- slab with a condensing boiler and my Veissmann boiler rep suggested not to do a night setback or an outdoor reset.
Part of this logic was the slow recovery time of in-slab and the boiler is more efficient when condensing.

i got called in to sort out a boiler system last spring .. it was an nti tft, i think a 250, can't recall .. the bones of the system were good, i cleaned up the sloppy wiring, and added an outdoor reset sensor .. the customer called me and said his bill from september til december was less by a third .. if your machine is capable of matching the buildings hear loss to the requirements based on the outdoor ambient temp it is never a bad thing

 

[AmickRacing]

No matter if it's in floor heat, or radiant heat along walls, a fan blowing air across a coil, and outdoor reset will almost always save you money.

The problem with them though, is they take some fiddling to get them adjusted right. That's much easier to do when you're in control of it, and it's just your shop, vs a school full of kids, and every custodian wants to monkey with the dials.

Error on the high side of water temp and keep going down until it can't quite keep up. Then turn it back up a few notches, you'll be fine. The cooler you can run the boiler the better it is (for condensing boilers especially).

 

[GYPSY400]

In floor heat has a low reaction time for temperature swing.. it is better to keep it warm, unlike a forced air system. If your not planning on using the shop for 3 or 4 days, then by all means, turn it down a few degrees. . But be warned, its going to take 1 hour per degree to heat it back up.

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[the_saint]

In floor heat has a low reaction time for temperature swing.. it is better to keep it warm, unlike a forced air system. If your not planning on using the shop for 3 or 4 days, then by all means, turn it down a few degrees. . But be warned, its going to take 1 hour per degree to heat it back up.

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How warm is warm? 45F 50F 60F?

 

[GYPSY400]

How warm is warm? 45F 50F 60F?

Now bear with me as I'm just learning about radiant heating myself. . I have yet to have my own system installed.
You won't need it to be 70* like a forced air system. . I bet if it was set at 60*F the garage would feel pretty warm.
From what I understand it takes about an hour for temperature to climb 1* and if you shut it off it takes about 24 hours to fall to outside ambient temperature.

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[Rookie2]

You'll be working in your skivies with a shop at 60-65 deg.

 

[tdkkart]

Now bear with me as I'm just learning about radiant heating myself. . I have yet to have my own system installed.
You won't need it to be 70* like a forced air system. . I bet if it was set at 60*F the garage would feel pretty warm.
From what I understand it takes about an hour for temperature to climb 1* and if you shut it off it takes about 24 hours to fall to outside ambient temperature.

You're learning quickly. My dad and I were just talking about this over Christmas, we both run our floor heated shops at 52* and work in shirt sleeves. Dress any heavier and you sweat if you actually do anything. Primarily because your feet are warm, the warmth is at the floor rather than at the ceiling, and everything in the building is the same temp all the time.
It takes a LONG time to lose much more than a few degrees with the heat shut off.

 

[Burl]

In my experience, it all depends on how tight your building is, how well it would adjust to outside temp changes. I keep my 30X32X12 garage at 63deg., no problems. I work all winter in a light sweatshirt.

 

[endmill]

Keep mine about 54-56 might have to have a light jacket on big deal MY FEET ARE WARM.

 

[the_saint]

I keep mine at 45F and have no problems working in it. I was out in the garage for 3 hours this afternoon and the boiler didn't cycle on at all. The outdoor temps are -25C / -13 F. Very happy with the temps. I was only wearing a light workout jacket as anything heavier I was sweating too much.

I wonder how much more it would cost to run at 50F.

The garage is almost 1500 sq/ft, R20 walls, R50 ceiling, R18 doors (for what that is worth, they need to be sealed better).

 

[jlckmj]

Good info above on turning the slab heat up and down. Set it and leave it.

NOW, if that person means it will be cheaper to run it at 60-65 rather than 45-50, that's just plain silly. The warmer it is, the more fuel you will use.

Jim

 

[andis65]

I think that was what he meant, whatever the case this is all great information. I have mine set at 55 and its perfect, I hate being cold. This was the best idea ever to install this system. It barely runs now that its up to temp, and i find that all the neighborhood gear heads are over checking in on things alot more. haha Thank you for the help on my install!!

 

[Randy in Maine]

Also keep in mind that most thermostats are mounted on the wall and measure the temperature about 4' above the radiant heated floor.

That being said, I keep the garage zone at 55º and the house zone at 67º. I told my wife to put the house zone anywhere she wants it and she has dropped it from 72º down to the current 67º as otherwise it was just too warm.