DIYbanter - View Single Post - Adding underfloor radiant heating with PEX?

Pete C.

Freud wrote:

In article m,
says...
Freud wrote:
Hi:
We're remodeling the bathroom in our small 1930s house. I'd like to
put radiant heating in to replace the radiator that's there now. From
my reading, I'm thinking of adding loops of oxygen-barrier PEX under
the floor (easily accessible from the unfinished basement) and tying
it into our existing natural gas hot water boiler radiator system.
The system is closed loop with iron pipes and radiators. I was
thinking of using heat spreaders & then insulating below the tubing.
Does anyone have any advice on this? Am I likely to need a tempering
valve to reduce the temperature of the water in the system? Are heat
spreaders unnecessary? Any problems with tying into the iron pipes?
Thanks in advance,
Freud

If its closed loop system how can you add a tempering valve to lower the
temp to the loop? You would have to dump water out of the system to put cold
water (that has disolved oxygen in it) back in and then get the air out of
that? Am I missing something?

I like idea of radiant heat but not in your case.

Rich

That's a good point - as you can see I don't really know what I'm doing,
I had just read about people adding tempering valves so I threw it out
there. I'm not sure how hot the current system runs, and I'm also not
sure what's optimal for radiant heat, though I've read that 100-110
degrees F is a good range.
Thanks for your help!
Freud

You don't need a separate cold water supply to temper the water in a
closed loop, the valves designed for this purpose simply recirculate the
"sub loop" water mixing in heated water from the "main loop" side as
necessary to control the temp. You typically need an additional
circulator pump. The radiant heating system manufacturers have all the
necessary components and expertise for this type of setup and typically
can provide a design service and complete installation package for what
you want. Pickup a copy of Fine Home Building and you'll find ads for
many of the manufacturers and can review the info on their web sites.

Pete C.