Add radiant floor loop to existing baseboard loop, with tempering valve?

[Joe acquiost]

Always wanted to add radiant floor heat in bath.

While salvaging piping from an old tankless heater loop on a boiler, I cut out a relatively new tempering valve and was struck with the idea that I might use that in a mad scheme to add the radiant heat I have always wanted by simply plumbing the valve into the existing baseboard loop?

Genius, or Madness?

 

[Dana]

Always wanted to add radiant floor heat in bath.

While salvaging piping from an old tankless heater loop on a boiler, I cut out a relatively new tempering valve and was struck with the idea that I might use that in a mad scheme to add the radiant heat I have always wanted by simply plumbing the valve into the existing baseboard loop?

Genius, or Madness?

I'ts neither Genius nor Madness- try "Hackery".

What temperature are you running the baseboard?

Have you verified that it even needs to be that high?

A fuel use based heat load calc and the total amount of baseboard would give you a rough idea of the water temp, once you have the rough BTU/hr per foot of baseboard. There are many systems being run at 180F that could still cover the load with 140F, which would be fine to run even on a staple-up radiant floor. If it needs to be a high temp system, suspended tube radiant (with or without finned convectors) can add that luxury by just running it in series (or in parallel using flow balancers) with the baseboard, without installing the tempering valve.

What is the max flow of the tempering valve, and the pressure drop at that flow? Were you planning to add a pump to drive the radiant loop?

What is boiler's DOE output (and range, if modulating) , and the total amount of baseboard, zone by zone?