Ok so we've got the design pretty well done with joist trak, water temperatures around 110*F and an ASHP.

I have one bathroom that will run for a few hours a week sort of like a spa. The temperature at these times being 78*F whereas the rest of the house is always  68*F. The room is not that big and that loop is significantly less than the 300' limit. *The required water temperature for this room is 127*F.

My question is what options do I have to reduce the required water temperature?
a) A concrete topping is out.
b) Would reducing the tube spacing and thereby increasing the amount of tubing under that floor be the right solution or am I missing something?
c) Add radiant wall panel?
d) Add a towel warmer?

Am I looking for more panel area or better panels or will both work?

Thanks

John

The temperature was based on the btus needed to maintain the desired room temperature.A towel warmer will always add a finish touch to a bathroom . You may need to add the towel warmer if the flooring system can not deliver the heating output for the space.

A few hours per week - add electric radiant.

Electric towel warmer would work too. Just get a beefy one, that can provide the difference in output requirements (plus acceleration load, i.e. extra capacity to raise the temp rather than maintain). Plus side is you can get warm towels in the summer too, if you like, without fancy pants hacking at the hydronic system.

Wall radiant might do it too, but any radiant solution is going to be hit by the fact that you are starting from 78 degrees in room temp. Be aware that floors over 85 to 90 are uncomfortable to walk on, so even if you could get this from the floor you'd be limited to 14-24 BTUs/sq ft no matter how conductive the floor.

Good point - so consider electric forced air heater, heat lamps, etc.

Where can I get "fancy pants" ? hheheheee