mjc87

I have a similar age nuheat system. I'm using a system boiler which has an internal pump (and thermo stat). It works ok with an extra relay external to the nu-heat controller board arranged so that the boiler gets a call for heat and runs the pump when the flow switch is triggered (also over-riding the cylinder stat and relying on the boiler stat). It works, but is far from ideal so my long term plan is to drop the energy master thermal store, replace with an unvented cylinder and switch to a heat pump directly running the UHF at low flow temp.