PEX heat transfer plate – extruded or aluminum sheet?
We are retrofitting an existing house with radiant heat under the floor. From my research, it seems clear that we should install aluminum heat transfer plates, but I haven’t been able to determine if it’s worth investing in an extruded aluminum C-shaped heat transfer plate (omega o or U-shaped) on top of a metal plate. Even if bought in bulk, extruded sheet is about 3 times more expensive than sheet metal.
A useful study was carried out in 2013 comparing the temperature distribution of extruded aluminium and U-shaped plates. The biggest takeaway I took from that article was that the extruded plate had uneven heat distribution but a lower return water temperature (good for efficiency). I guess the main question is whether the increase in efficiency is enough to compensate for the extra cost upfront.
I realize that there are many factors that can affect the energy performance of a particular home, and we will work with the local heating company to determine the setup of the system. I’m hoping someone with experience with both boards can give us a feel for how much different extruded boards are compared to aluminum boards.
If we were using sheet metal, my hunch would be to use the omega shape, considering there is more contact between the metal and the pipe. However, I’ve also heard that the sheet metal makes noise when the pipe expands as it heats up, and I’m wondering if there is more room in the U-shaped channel for the pipe to expand without affecting the surrounding metal. Any thoughts on this?
For extra background, we plan on 1/2″ PEX, two lines between the joists (16C), insulated from below. Hardwood (oak) floors above, small rugs. We haven’t decided on the water heater.
PEX heat transfer plate installation video