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Weil Mclain aqua plus and cold start

Peteys Member Posts: 62

I installed an aqua plus indirect hot water heater last week to replace an amtrol and the wiring diagram for the aquaplus heater said to install a r845 relay and connect 5 and 6 to the aquastat, which I did. Now the boiler only goes on when the hwh calls. Is this cold start? The boiler is a 25 year old WM 868 steam boiler.

Before this , the boiler was wired straight from the aquastat to the relay and used to come on when the aquastat in the boiler said to and maintained a temperature of 170 degrees.

Which wiring do you guys recommend? Maintain boiler water temperature all the time or only come on when the r845 and indirect calls?

Much appreciated


  • Peteys
    Peteys Member Posts: 62

    Am thinking as it's in a 5 family house, there would be hot water usage every day and it wouldn't truly be cold start. Would like to get a few more years out of the boiler and not sure if this would be rocking the boat.