Furry wrote:
Folks,

We have a 1200 sq ft full basement that we're heating via radiant heat.
There are 4 runs of Pex. We're very happy with it but I'm worried that
there is something wrong with the system. When the basement calls for
heat the pump turns on and I can see the temperature gauge go up to
around 100-110 degrees. There's no gauge on the return but feeling the
Pex it's obvious that the water coming back is pretty cool. The
problem: It takes at least an hour, sometimes 2, for the basement to
warm up enough that the thermostat stops calling for heat. 1200 sq ft
is a lot of concrete to heat up but isn't that a long time?

Any thoughts much appreciated.

I don't have a radiant system so I'm writing not from personal
experience, but solely from what I've read. Slow response is one of the
drawbacks of radiant systems. I'd say that what you are seeing is
completely normal. Heating up a 1200 square foot slab of concrete that
is probably 4" or so thick is going to take a fair bit of time. This is
nearly 15 yards of concrete which is a lot of mass to heat up!

Matt