Is in-floor going to be too HOT!

[overkill 19]

Planning my garage build for the spring, it will be a "L" shaped shop, basically a 24x24 beside a 20x32. My ? is in floor heat going to be too hot? I don't like working in a hot shop. I don't plan on doing very much work "laying on the floor" I will have a car lift. but I will be welding on the floor somewhat.

I was debating putting a radiant over the 24X24 as that will be were the cars are parked the put a Reznor heater in the 20X32 section.

Does anyone have in-floor and disappointed with their decision?

 

[jmh21586]

I have in-floor in my house. It's no diferent than any other heat. Can be however hot you want it. But it is a very even heat. No cold floors and hot ceilings. I think you'd love it. Wish I put it in my garage. Is this shop going to be someplace you'll be everyday?? Or just once in a while?

 

[Schrodingers Cat]

just make sure you have a good control system...
I assume you'll have a boiler (Munchkin or similar)
make sure it's modulating
make sure it can be reset based on OA temp
make sure you have 2 pump loops, 1 thru the boiler, the other sharing that loop thru the slab (think a figure 8, pump in each round section, one is the boiler, the other the floor)
ie, primary and secondary loop

 

[chevelle64]

No, the floor will not be too hot. And no, I am not disappointed with my radiant floor decision. Sorry to ramble on....

 

[tdkkart]

Depending on your heat load the floor temp will only be 5-10 degrees above the desired air temp. 60* air temp only requires 65-68* floor temp.

The other thing to remember is that you will find that your air temp requirements will be somewhat lower than with forced air. The heat is coming up from the floor so your feet will be warm which means your whole body is warmer.

My old shop space required 65-70* or more air temp to be reasonably comfortable in a T-shirt and flannel. Now I set the T-stat at 56-58 degrees and am plenty comfortable if I'm moving around at all.

 

[overkill 19]

The part I worry about is when the door opens, how long it takes to recover. I was concidering putting in a fan coil to help. Our winters get farly cold. 0c to -35c.

 

[sneezer41]

You are thinking about it wrong. Usually you are cold after you shut the door because you have a 40 degree floor under you. You will have a 75 degree floor [for example] and will not care that the door was open.

The real recovery time issue is if you turn the heat off and try to heat the slab up from 40 degrees to 75, it may take days.

It really depends on how you will use the garage. If you keep the thermostat at 50, but make sure you run the floor for an hour a day[turn the heat to 70 for one hour] I think it will be comfortable for most things. You could use a fan coil to get the air temp up in short order. If you are working their a lot, set the temp warmer and don't worry about the fan coil. If you work their rarely set the temp low[or off] but run the slab daily to keep it from being an ice cube.

the opening the door issue is not such a big deal with radiant.

 

[Stuart in MN]

Yes, the recovery time from opening the door will actually be pretty fast. The floor slab temp will barely change, assuming you don't leave the door open for hours, so once the door is closed you should feel comfortable again very quickly. On the other hand, with a forced air system opening the door will let all the warm air out, and then all the air inside the garage will have to be heated up again.

I sure wish I'd put infloor heat in my garage when I built it. A friend of mine has it in his garage, and it's great.

 

[Schrodingers Cat]

each has advantages, forced air vs radiant slab
forced air, fast response and ventilation
blowing air out can be mitigated by balancing for slightly positive pressure
all the hot air can't rush out, replaced by cold...what happens is some escapes but is made up by the AHU as it does...even with unit heaters for the space a small OA fan can be used to pressurize the space to prevent infiltration...or door interlocks, go neutral when the door opens, no air should move

slab, large thermal mass, large lag time...but it does not radiate very well, you can still (and will) have a chill in the air at times...but if it's done right, good insulation beneath, it can be very economical...if not, the earth becomes a big heat sink...

I have a friend who did his whole house with infloor (he owns a HVAC company) but he still added forced air, the combo is the best of both and with good control integration works amazingly...

maintenance is a factor...access can be a problem with in floor slab if you have an issue
manifold the runs with iso valves so you can take a leaking section out of service