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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a Weil Mclain hot water boiler, natural gas about

Customer Question

I have a Weil Mclain hot water boiler, natural gas about 75,000 btu. and would like to know how the pump control wiring is configured. The pump stops when the high limit is reached. I think the pump should be controlled by the thermostat and the burner by the high and low limits.
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: My question is how does Weil Mclain wire the controls on a hot water boiler.
JA: Do you plan on doing the work yourself?
Customer: Yes
JA: Anything else we should know to help you best?
Customer: Sorry i do not have the model number
Submitted: 9 months ago.
Category: HVAC
Expert:  Rick replied 9 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

You're correct the pump should run as long as the thermostat is calling for heat. The only exception is if your boiler has a tankless DHW coil. In that case the pump wouldn't run until the lo limit setting is reached (prioritizes DHW). I need the model number of your boiler and if you have multiple zones what do you have for zone control? a pumps for each zone? zone valves?