In slab Radiant Heat

I was talked out of it by two different people in the industry when I built my shop. Their reasoning was the temp swings we see here in NC. Basically they said you'll get the floor nice and warm when it's cold out and then It'll warm up to 70 like yesterday and the slab will have bad sweating problems. I've seen lots of shop floors with sweeting problems without radiant heat but think that's a problem with % humidity such as leaving doors open or pulling in dripping wet vehicles when it's raining. Maybe bad slab prep would play a part too.
 
I put it in my shop 30x50 when I built it 15 years ago. Ran a small 5kw tankless water heater on it for a couple years. Only ran it on days where it didnt get above freezing or real close to it. Never had sweating issues from the heat. Cold is what makes something sweat, have you ever seen a warm cup of coffee sweat? The biggest thing is insulation and vapor barrier under the concrete. I used 2" closed cell foam and a heavy mil plastic under that also insulated around perimeter of slab. Water heater crapped out abot 5 years ago and havent replaced it, I can tell a diffrence on really cold days but thats about it.
If I built a shop again here in Sanford NC no I wouldnt do it. If I built one in a colder climate I would def. do it. Family member in Todd NC has a large shop 60X150 and it makes a world of diffrence when the floor heats running and not running. No sweating issues on his either.
 
Recently stayed in a cabin in Wyoming with it. That was the only heat source for the cabin and it would keep it at 70-72* all the time with it in the teens as the high outside. In the case of it out there, it qualifies for energy credits as the concrete stores the heat so they essentially get 50% off their per kwh rate after 5pm. We are going to do it when we build our barndo here in VA since most of the space will be polished and sealed concrete floors. I know of a couple people with it and never having the sweating issues. I'll run it off a wood boiler with provisions in the manifold for tankless water heater to be plumbed in when we get old and don't want to deal with the wood boiler.
 
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I have a 28x40 shop with radiant heat and would not consider another without it. Built about 6 years ago, installed myself for about 2.5k for everything. I did a hybrid insulation with a heat sink in the center. Keeps shop nice and comfortable. Building itself is insulated well. Happy to share any info.
 

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StretchASU said:
Recently stayed in a cabin in Wyoming with it. That was the only heat source for the cabin and it would keep it at 70-72* all the time with it in the teens as the high outside. In the case of it out there, it qualifies for energy credits as the concrete stores the heat so they essentially get 50% off their per kwh rate after 5pm. We are going to do it when we build our barndo here in VA since most of the space will be polished and sealed concrete floors. I know of a couple people with it and never having the sweating issues. I'll run it off a wood boiler with provisions in the manifold for tankless water heater to be plumbed in when we get old and don't want to deal with the wood boiler.
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I looked into it for my shop that didn’t get built when I sold the farm.
I was told not to do it with epoxy floors because it could cause the epoxy to de stick…didn’t make sense to me, but again changed plans and never built the building. Just soemhting that’s worth investigating I guess
 
Ron said:
I looked into it for my shop that didn’t get built when I sold the farm.
I was told not to do it with epoxy floors because it could cause the epoxy to de stick…didn’t make sense to me, but again changed plans and never built the building. Just soemhting that’s worth investigating I guess
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Thats really odd. I know guys that use it in their car washes and have epoxy floors in some bays. I'm sure there is some special prep/primer and epoxy combo that needs to be used for the heat to not weaken the bond, but the floors never get THAT hot I wouldnt think. Like the place we stayed it was just a concrete stain and clearcoat sealer basically is all they had on the floor.
 
Concrete with a densifier and sealer from ghostshield has worked well. Easy to clean and concrete dust has not been any problem.
 
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