Replacing basement baseboards

Snowturtle

I just bought an old house that was remodeled in 2005. They converted heat to staple up radiant throughout except for a couple of hydronic baseboards in the basement. Those units are shot and I want to replace them. My question is this: there are two 6' baseboards on that basement zone. They are 3/4" but are fed by 1/2" Pex (or something similar, it's grey). Do I replace the baseboards with 3/4" or buy 1/2" this time? Also, there is no mixing valve in the system - do baseboards and staple up tubes (not embedded in gypcrete or concrete) run the same temps or should I have a mixing valve somewhere?

Jamie Hall

Those two six foot baseboards won't provide that much heat, so they don't need that much flow — so 1/2 inch PEX should be fine — but be sure to use oxygen barrier PEX. Not the cheap stuff…

However, they should be fed with much hotter water than the radiant system should take — to produce any significant heat, probably at least 140 and maybe more like 160. The radiant system should not have water over 120 or so. So yes, you need some sort of mixing valve arrangement, and there are a number of ways to do it. The radiant circuit will need its own pump taking suction from whatever mixing valve arrangement you come up with.

Snowturtle

The pex is already in place, I'm wondering if I should use 1/2" or 3/4" baseboards or if it matters at all. I'll look into the mixing setup. Thanks

Jamie Hall

Either will work —but you should check the output rating of the units.

EdTheHeaterMan

3/4" baseboard is more readily avaiulable…. You may need to pay a premium for 1/2" or at least extra fro shipping a non-stock item to your supplier. the output of 1/2" and 3/4" will be very similar. So I would go with what ever you find at the best price point.

hot_rod

check into panel radiators also. They can run on lower SWT, 1/2" tube generally.