Does more wood between heating element and space only mean longer initial heat up?

MacDee

I have a cabin on posts. From bottom up I have 2" foam board tacked across 2x6 joists on 24" centers then empty space till 1" subfloor boards and final 3/4" plywood floors. Deciding weather to pull down foam boards and tack up Aluminum Heat Transfer Plates on 1/2 tubing or cut channels into plywood floors and cover the tubing with new with vinyl floor planking. I realize having the tubing right under a new floor wood heatup faster. But does more wood between heating element and space only mean longer initial heat up? From then on wouldn't the more heated mass be advantageous? Or would there be more heat loss to the outside faster than up into the living space?

hot_rod

Also a higher supply temperature required as you add any wood or material over the tube

Yes a bit more mass is involved 

Robomoo

MacDee said:

I have a cabin on posts. From bottom up I have 2" foam board tacked across 2x6 joists on 24" centers then empty space till 1" subfloor boards and final 3/4" plywood floors. Deciding weather to pull down foam boards and tack up Aluminum Heat Transfer Plates on 1/2 tubing or cut channels into plywood floors and cover the tubing with new with vinyl floor planking. I realize having the tubing right under a new floor wood heatup faster. But does more wood between heating element and space only mean longer initial heat up? From then on wouldn't the more heated mass be advantageous? Or would there be more heat loss to the outside faster than up into the living space?

Does work under 2" solid wood. Our house (26yrs old) has concrete main floor w/1/2" tube, 2nd floor 1/2" strand board with 1 1/2" t&g western red cedar on top with metal plates under with 1/2" tube fiberglass bats below. Have been very happy with the radiant floors since we built. I would never heat a building any other way. Transfer through the 2" solid wood is slower than the concrete (water at 120f) but still makes a nice warm floor. In your sock feet you can find the rows of tubing. Two lines of pipe per 16" bay. The insulation underneath is critical. I would double up what you have. Put 24" bats in the bays then the foam board back underneath. Spray foam the joist bay ends, greatest heat loss to the outside. You will still have another layer of plywood over the grooved boards, if you don't your vinyl floor will collapse into the grooves. You would also have no metal plates to spread the heat out. You should price out both ways. That may make the decision for you.