Which thermostat is primary.

Hi guys,

I have 2 zones ( first floor, and second floor). the first floor thermostat wires are hooked directly to aquastat on EFM. the second floor thermostat wires are hooked into the R845 relay. When both thermostats call for heat, the second floor takes precedence. I would like that reversed..Should i just hook second floor thermostat wires to aquastat and hook first floor thermostat wires to R845 relay? Thanks for your help.

The only call for heat that ever should stop other pumping would be a call for Domestic Hot Water Production --- IF the appliance we so undersized that it could not produce both call for heat and DHW simultaneously.

Now -- where did I leave that party hat????

Hi, Still can't get first floor circulator to come on if both ( first and second floor) Thermostats call for heat. Second floor circulator takes precedence. Any help?

Does each circulator have its own relay as on page 4?

http://customer.honeywell.com/techlit/p ... 5-6571.pdf

Each circulator does have its own relay. First floor circulator comes directly from EFM 520 aquastat. Second floor circulator comes from R845 relay. Is that what you mean? Should I connect both zones thermostat wires to the R 845 relay?

Well -- It depends!

I wouldn't have a zone connected to the coal boiler aquastat. I would connect the T1 and T2 on the coal boiler aquastat with a jumper and let the boiler idle fire as it needs --- and react (hi fire) to energy draw as the building requires.

I would wire each t-stat to its zone pump via the relay of course to control energy flow out to the zones as its called for.

But I am simply a figment of the public internet - Your mileage may vary.

I would also have an outdoor reset wired in place of the jumper I describe above to command the boiler temperature to degree day load.

Then there is that pesky Balancing of the flow out to the zones - but lets get the house heating wiring corrected first.

Sting, thanks for your help. I will wire both thermostats as you said and go from there. Thanks again. Happy New Year.

Lets not forget -- By re-commanding the pumps as I suggest -- You gain control but you have lost your "heat dump"

May I suggest you address that before the heating season moderates.