Radiant plan?

[Ict57]

Built a 1000 sq ft garage (approx 28x36) with 10’ walls and vaulted ceilings (14’ at peak). R15 in 2x4 walls and insulated garage door, etc. The 6” slab has 4 loops of about 200’ each of 1/2” pex.

My question...planning to buy an electric tankless unit (ecosmart 24/27) along with a small pump and possibly a expansion tank, then use a small Timer to heat the floor a few times daily, running in closed loop.

Live in Kansas, it gets to about +15* most nights in winter.

This is an hobby garage, I get out there most evenings for a few hours but happy with 50-55*, don’t care about 75* temps.

So, any huge red flags with my plan?
PS—plan B is to do a simple 20 gallon electric tank, seems this may simplify the pressure related challenges in a tankless system. Thoughts??

 

[fitter30]

Expansion tank needs to be used. What is the spacing of the pex tubing? The ecosmart heater 24/27 looks like it either 24kw or 27kw both are oversized. 3.4 btu's per watt.

 

[Ict57]

Spacing is about 12”.

And debating tankless vs tank. I read that most tankless have major flow limitations. But hoping for input...

 

[Chris705]

What’s the point of using a timer vs. a thermostat? Or were you thinking of using both?

 

[PWC Repair]

Very similar to mine. Mine is 30x48 with 12ft sidewalls, 17ft high in the center. Insulated, 6" floor, insulated overheads. I'm going to try and use a 50 gallon electric water heater and keep mine at about 55*. I guess we'll see. The recovery time is the downfall of the standard electric water heater. I might wire mine up so both elements kick on at the same time. Actually worked on it most of today and will work on it tomorrow too. You will need an expansion tank, and you can get a line voltage thermostat to control your pump, and you will need some form of air purging device.