So the system that I have currently has two potential zones installed, but I am running them both off of one thermostat, so you can treat it as a single zone system. But be aware that eventually it will be split into two separate geothermal zones (upstairs/downstairs).
I have two circulators, on on each of the "zones". The thermostat in the living room currently actuates the circulators.
The boiler wants a thermostat circuit to actuate its own separate circulator and vent damper.
I have a tempering valve on the boiler output circuit. It is of course set below the boiler operating temperature (assume the boiler is 180 and the tempering valve 130), so the feed to the zone inputs should remain constant, and vary the draw from the boiler tank as needed.
So a topography question:
Should I run the zone circulators constantly and hook up the thermostat circuit to the boiler? Or should I leave the zone circulators on the thermostat control and trigger the boiler circulator from a separate aquastat on the return line from the zones (i.e. the cold side of the tempering valve)?
I suppose I should verify whether the thermostat actually fires the boiler, or whether it just triggers the circulator. If it just does the circulator, I'm gold. If it actually fires the boiler ignition, I probably need the aquastat.