I have a propane boiler and a fuel oil boiler. The propane is the primary and the oil is the secondary.
When there is a call for heat, the propane boiler energizes the primary 120V heat pump. When there is a call for Domestic Hot Water, the propane boiler energizes the 120V DHW pump. Only one pump is energized at a time. The boiler cannot call for both pumps simultaneously. The system works great.
I am placing my oil boiler in a series with the propane boiler. Basically I want the oil boiler to preheat the water before it goes into the propane boiler. So, I have a third 120V pump hooked up to that boiler to inject the preheated water. If I only wanted the oil boiler pump to come on with the heat pump, that would be a simple as all I would need to do is splice in the oil boiler pump to the heat pump of the propane boiler. That way, when there was a heat call, both pumps would run.
However, I want the oil pump to run when there is a call for Heat and/or DHW. I dont think I can simply wire the oil boiler pump to the post in the gas boiler for DHW and heat. If I did, then when the heat pump was energized, there is a potential that the electricity would back feed into the DHW pump.
So, how can I wire the oil pump to come on when the heat pump is energized and how can I wire the oil pump to come on when the DHW pump is energized without back feeding? I assume a relay, but what kind? Im thinking a Single Pole Double Throw, but not sure.
Thanks
When there is a call for heat, the propane boiler energizes the primary 120V heat pump. When there is a call for Domestic Hot Water, the propane boiler energizes the 120V DHW pump. Only one pump is energized at a time. The boiler cannot call for both pumps simultaneously. The system works great.
I am placing my oil boiler in a series with the propane boiler. Basically I want the oil boiler to preheat the water before it goes into the propane boiler. So, I have a third 120V pump hooked up to that boiler to inject the preheated water. If I only wanted the oil boiler pump to come on with the heat pump, that would be a simple as all I would need to do is splice in the oil boiler pump to the heat pump of the propane boiler. That way, when there was a heat call, both pumps would run.
However, I want the oil pump to run when there is a call for Heat and/or DHW. I dont think I can simply wire the oil boiler pump to the post in the gas boiler for DHW and heat. If I did, then when the heat pump was energized, there is a potential that the electricity would back feed into the DHW pump.
So, how can I wire the oil pump to come on when the heat pump is energized and how can I wire the oil pump to come on when the DHW pump is energized without back feeding? I assume a relay, but what kind? Im thinking a Single Pole Double Throw, but not sure.
Thanks