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[CooterD.]

I'm looking to put in an owb in the next couple of years, but right now I'm finishing up a 5x24 addition on a 24x34 garage. Only 5 feet of the addition is at grade, the rest is a few feet above. My question is, is it going to be worth my time, effort, and money to put radiant heat in the 5x24 slab? I realize this won't heat the entire garage, I'll also need a heat exchanger. My goal is to keep my shop well above freezing all the time, and a comfortable temperature when I'm working. Should I spend the money on the pex now, so I have it for later, or save it for another heat exchanger later?

[slimjim]

I would not put concrete in my garage floor ever again without radiant lines in it as there are some very good benefits to radiant heating, here are a couple of thoughts. Radiant consumes far less power to operate than a modine style heater, it is far quiter  and it also adds thermal mass much like an added water storage tank and lastly it heats from the floor so you are not trying to heat the top of your garage space but instead you are heating the floor keeping your feet warm, if my feet are warm, my whole body is warm.

[CooterD.]

I've been in a few shops that have had radiant heat in the floor, and I agree it's pretty much the best way to heat a shop in my opinion. The addition is where my workbench will be, so it would be nice to have a warm floor where most work will be done. But since it's such a narrow strip and it's well above grade i wouldn't think it would keep the entire shop comfortable, so I figured I'd have to put in a heat exchanger as well. What I was hoping was the floor might be enough to keep it above freezing, and the heat exchanger would heat it up the rest of the way when I'm working? But since it's so long and narrow and I'm not going to bust up the rest of the concrete to do the whole shop, would it be worthwhile to put it in this part?

[slimjim]

Yes it would, even if it does not heat the entire shop it will certainly help and anything that you can do to keep those noisy power consuming rad fans from coming on helps, it is money well spent.

[LittleJohn]

Its is far cheaper to insulate and put pex in now; then to have 2nd thought and put it in a couple of years.   

I have to agree with SlimJim, you will not be disappointed, unless designed and installed poorly

[Sprinter]

I've been in a few shops that have had radiant heat in the floor, and I agree it's pretty much the best way to heat a shop in my opinion. The addition is where my workbench will be, so it would be nice to have a warm floor where most work will be done. But since it's such a narrow strip and it's well above grade i wouldn't think it would keep the entire shop comfortable, so I figured I'd have to put in a heat exchanger as well. What I was hoping was the floor might be enough to keep it above freezing, and the heat exchanger would heat it up the rest of the way when I'm working? But since it's so long and narrow and I'm not going to bust up the rest of the concrete to do the whole shop, would it be worthwhile to put it in this part?

Yes it would, and inslab will do much more than you think. On a IR camera it's like walking into an invisible bath or upside down shower of heat. But you have to protect all edges in order to prevent the rest from acting like a heat sink. With a simple stat and slab control, you can make it heat or just maintain a min set point temp.

[CooterD.]

Thanks for the replies.  That's what I figured, I just wanted an opinion from someone who knows more than me.  After using a woodstove as my primary heat source for over 15 years I think it's time to keep the dust, dirt and bugs in the out of doors. Not to mention the MUCH longer burtimes.   However, I've never installed or helped to install a boiler so I'm sure I'll be back with more questions

[cantoo]

cooter, I built a 24x56' shop last year and was planning to run pex in the floor. I had everything ready to go just needed to pick up the insulation and pex. My concrete guy screwed up some dates and called me at night saying they were coming the next morning to pour the floor. Winter time and concrete had already been ordered and put inside to warm up. I decided to just do it. I've been kicking my azz ever since. Floor is perfect but it's always damp from melting snow. I put in an exchanger but now I'm paying for hydro too and it doesn't work near as nice. The air in the shop is too hot to work and the concrete floor is freezing cold. Put the pex in now.

[agriffinjd]

How's the cost compare though?  Do you just run 180 degree water through it nonstop or do you need to install something that regulates it somehow?  So you are paying for the pex, insulation, and some other thing?

[CooterD.]

It's going to have to be on a thermostat.  I don't want the floor so hot it's uncomfortable to stand on for any length of time.  I figured for right now though, I'd just need insulation, pex and manifolds.

[yoderheating]

Please don't run 180 degree water though concrete. You need a mixing valve and a thermostat.

[Scott7m]

Please don't run 180 degree water though concrete. You need a mixing valve and a thermostat.

 

Shewwww...   radiant is something if done wrong it can turn into a disaster.

Better put some good insulation under your concrete as well

[farmboythegreat]

Please don't run 180 degree water though concrete. You need a mixing valve and a thermostat.

what is a good temp ??

[Scott7m]

In concrete?   110-120

[mlappin]

In concrete?   110-120

I've seen a few sites claim as high as 150 and 130 for snow melt, I have my sidewalk set for 120 and it does just fine.