what size of a hot water heater or boiler(btu) do i need to heat a radiant concrete floor in a 32x58 workshop to a room temp. of 65-68 degrees. the following is a list of my building specs.:
wood framed/vinyl sided/4"conc.
1600' 1/2 pex tubing on 1' on centers
6 loop manifold
1 1/2" styrofoam insulation around foundation
1 1/2"x 4' styrofoam insulation around floor perimeter
double bubble insulation in center
16x9 insulated garage door
building is located in east central ohio
Re: radiant heat
You would definitly have to do a heat loss calculation to come to a sound estimate of the total btu's/hour you would need.
A heat loss calculation would take into account all the factors you listed & crunch the numbers for your total btu need---there's an excellent free HLC by Slant/Fin (below).
I think the rough estimate is approx. 25 btu/square foot---but this could be way off from what you get.