Welcome! Here are the website rules, as well as some tips for using this forum.
I have a coal boiler with 5 automag zone valves and 5 thermostats. I have a gas boiler for backup which uses the same zone valves but has a separate thermostat controlling it's own circulator pump. Presently to use the gas boiler I switch off the coal boiler which opens the zone valves and switch on the gas boiler. So when using the gas boiler I have no control of the zone valves. When the gas thermo calls for heat, gas circulator pump turns on and pumps to all 5 zones.
I would like to be able to control the gas boiler independently, either by using the existing thermostats or installing 5 new separate thermostats. I am able to run new wire for the additional thermostats.
I can direct the heated water through either boiler or both boilers by closing or opening various valves.
Any advice would be appreciated.