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ThermoFin U Install Question

jb9 Member Posts: 104

I have been looking at the ThermoFin U product for a radiant floor application and was wondering if folks here have experience installing it in the field under a floating engineered wood floor. I like the fact that I can install this product at 8" or 6" OC which will help me keep my water temperatures lower. I plan on using an air source heat pump (been looking at the SpacePac products). The house will be SIP enclosed and super-tight (1500 sqft).

It seems that folks are encouraged to install this product with the slot down to provide the flattest possible surface for the flooring. I would think the performance might be better with more of the aluminum facing up. It seems that the manufacturer does sell "recessed" sleepers to achieve the flattest surface for the finish floor. Does anyone here have any experience with ThermoFin U installed this way over an engineered wood floor? Do folks use an underlayment on top of the ThermoFin?

Any thoughts are appreciated.

Thanks in advance,



  • hot_rod
    hot_rod Member Posts: 22,157
    U fin is slot up, how else would you install the tube?

    With some engineered flooring you can float right over the fin, thinner glue down flooring, I like to put that thin underlayment wood. It is a metric size, just under 1/4" plywood.

    For tile, put the cement backer board over the fins first.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Tim Potter
    Tim Potter Member Posts: 273
    I have found Thermofin's tech line very helpful, They were more than happy to share their knowledge.

    Winter Park, CO & Arvada, CO
  • ripHST
    ripHST Member Posts: 1
    jb9....did you end up using this product? I'm looking at this too in a very similar situation. I'm planning to use SpacePak's air-to-water heatpump and need to keep the water temperatures low. This or warmboard (or similar) seem to be the best options. I get what you're saying about the slot up or down.....IIRC, slot up would be fins up and then you put the sleepers below and keep the aluminum against the bottom of the finished floor. I'd like to do this as well. If you went this direction...I'd love to hear how you made out.