In my 12 year old 2700 square foot home in the high sierras, I have a ground source heat pump running a hydronic system in gypcrete (if it matters, I have soy foam insulation under the subfloor). We had a recent major plumbing problem in our master bedroom and bath and had to pull out all the hydronics in order to dry the floors and remediate any potential mold. When we remodel this area, my plumber is suggesting putting in the hydronics which fits in grooved subfloor (as we will most likely replace that too) rather than doing gypcrete again. I was wondering if there will be any difficulties with matching the hydronics in wood subfloor to the hydronics in the rest of the house which is gypcrete. The master bed and the master bath are both on separate loops. Also, any plusses vs minuses for the grooved subfloor? I would think that if the heat was turned down at night in the bedroom, the result would be instantaneous, vs not bothering with doing that with the gypcrete because of the long lag time of heating and cooling?

You're correct that a plus of the grooved subfloor + aluminum heat spreader under the finish floor solution is that it's far more responsive than gypcrete. A minus is that there is likely to be detectible striping, a less uniform floor temp.

Another more subtle plus is that the floor will now have bit of give- it doesn't feel as hard under foot as a gypcrete floor.

depends on the grooved subfloor. if it's a true subfloor... i.e. warmboard... we find the surface temps extremely even.

You are both right, but I think the finished floor has more to to with "striping" than any other factor, save AWT.

Aluminum is much better at distributing heat than gypcrete.

Thanks for the replies. We will be putting carpeting down so, any "striping" shouldn't be an issue. Glad to hear you guys think it will work. I like putting in a set back thermostat, so we can turn it down at night (and it will respond right away).

then you want a good emitter. the worse your finish floor the more your emitter matters to your water temps. don't use a cut rate panel unless your heat loads are very low.