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[justinb]

I finished  insulating my 20x44 garage, and am ready to hook up the radiant floor. Naturally, I have a few questions along with a plan.  My plan is to T off my return line and install a 30 plate fphe.  From there, Ill run into a thermostatic mixing valve-->pump (not sure on size)-->to manifolds.

Im going to put antifreeze in lines.  Is RV antifreeze what I want?  How do I guesstimate needed volume?  I want to keep a thermostat in the garage, but dont know how to tie that into my system.

Appreciate any and all input.  Im on my 3rd year with my OWB, and,have done all install myself.  None of which would be possible without this site.

[juddspaintballs]

If you're using a heat exchanger to bring heat from the return line into the garage lines, you'll obviously need a pump to move the water in the garage lines.  You can hook up the thermostat to that pump so it's only moving water/antifreeze when your garage is calling for heat.  They make 120v thermostats that can be used in that fashion. 

[slimjim]

Justin, you are about to embark on a journey, first, skip the 30 plate and go bigger,I would suggest a 50 plate, you will also need an auto fill for make up water and pressure as well as an expansion tank and pressure relief valve and mixing valve. Do yourself a favor, don't skimp on doing it right the first time, I'll be happy to guide you but Please don't skimp or it could cost you your floor.

[willieG]

1/2 in pex  = .92 gallons per 100 feet of pipe
5/8 = 1.34 per 100 feet
3/4 = 1.83 per 100 feet

[mlappin]

Do NOT use RV antifreeze, get the proper glycol to use, is expensive but worth it.

[justinb]

Thanks everyone.  Looks like this will be more involved than I thought.  I dont know what an expansion tank even is...I also dont know how much line was installed in the floor.  I do know that its 1/2 wirsbo pex A.  I would love some guidance on this Slimjim.

[justinb]

Any idea what size pump I would need to feed the floor?

[slimjim]

A small circ like a 15-58 Grundfos or Taco 007 will be fine.