The upstairs loop is independent of the basement loop. Unfortunatley,
there is no good place to put a zone valve on the downstairs loop
without redoing a lot of the plumbing. (All of the plumbing is less
than 3 years old, but the downstairs was done afterwards by a
contractor finishing the basement, and they did not do a very tidy
plumbing job). But there is a good spot to put the zone valve on the
upstairs loop. There are two scenarios that I want the circulator on:
1. Upstairs and downstairs need heat so the upstairs zone valve is open
and the circulator is on.
2. Only downstairs needs heat (it's always cooler in the basement and
we use it very much, so we would never just want the upstairs heated)
so the upstairs zone valve is closed and the circulator is on.
The third scenario is the circulator is off.
So can I hook two thermostats up to the Aquastat? If my understanding
of a thermostat is correct, all it does is close a circuit, so it would
be like hooking up two regular light switches to the same light.