Running radiant floor heat above an unconditioned garage

PeterOrion

Hello All,

Energy Auditor hoping to retrofit exposed hydronic distribution within an unheated garage. The distribution is currently running below the floor joists. Would it be acceptable to convert to radiant floor heat between the floor joists along the underside of the floor making it possible to sheath and insulate the cavities afterwards? Upper flooring is linoleum. Many, many thanks in advance!!

Larry Weingarten

Hello and welcome! First impression is that you will want to use plates that the PEX can be pressed into. Fasten these plates securely to the subfloor so there is good heat transfer, then you can insulate underneath them. This method works much better than trying to warm the air above your insulation with bare PEX tube, and hoping the heat will get through. Others will have a lot and more intelligent stuff to say.
Yours, Larry

hot_rod

Like this?
You want all the tube above an insulation batt. So drilling the ends of the joists is part of the plan.
No harm in doing a heat load analysis for the rooms above to see if retrofit radiant will cover the heat loads.

EBEBRATT-Ed

If the garage is unheated I would consider constant circulation below 40 degrees and a 3 way valve to control the temp. Don't know if you should consider glycol and a heat exchanger