Chevsky
Member
EDIT2 -- It's apparently confusing. Reworded.
I'd like to setup a HEAT PUMP LOCKOUT. This is for a dual fuel system -- combo Heat Pump and Gas Furnace/2-stage.
Could be creative thermostat wiring, or simple Johnson Controls A421 / other temp sensor and relay.
For two purposes:
• Generator operation -- only run heat stages 2 and up, no heat pump
• Outdoor temp below 30°F
So the question is about how to control (force) heating stage to Aux heat.
I believe there are thermostats that do this natively -- e.g. Honeywell Vision8000pro, Venstar --- not sure, I know they do the temperature lockout (when outside temp gets below set-point, only engage furnace, no heat pump -- typically referred to as "balance point"), but not sure if they do automatic emergency heat.
First generator. How woud that work with a thermostat that does have support automatic emergency heat? When generator is running, send 24vac to E terminal?
What about an external Relay. If first stage of heating is Y, then relay contact set-A breaks Y between air-handler (furnace) and heat pump; Relay contact set-B connects W to W2. Since this furnace is 2-stage, W2 is low-heat, so this tells the furnace to run on low. When thermostat calls for 2nd stage heat, this will already be running. When thermostat calls for 3rd stage heat, it will close W3 and furnace will run on high.
Is it that simple?? Now I can lockout heat pump for whatever purpose. I can energize the relay either/both by connecting to my generator load switch lockouts (SSM module) and via any standalone temperature controller, say Johnson Controls.
What about G -- the heat pump is a MrCool Universal MDUO18 which want's G connected (I think). I may need to leave G disconnected, or break it, requiring a relay with >2 contact sets. Furnace is Goodman 804BN.
I know that in some markets the Utility provides a wire off the meter that goes hot when the temp dips below n°F their electric rate jumps up, and that can be attached to the thermostat or furnace in some way to auto-switchover from heat pump to furnace. It's a disincentive to use electricity. They also put a light somewhere to inform the customer of the rate switch so they refrain from doing laundry and other high-electric-use tasks. So how is that wired up?
Re thermostat -- I wish to use a specific t-stat, RadioThermostat CT80. It does some unrelated things that are important to me, that no other thermostat does, so I'm very egar to make this work, and it supports multistage heat/cool, and multistage Aux.
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I'd like to setup a HEAT PUMP LOCKOUT. This is for a dual fuel system -- combo Heat Pump and Gas Furnace/2-stage.
Could be creative thermostat wiring, or simple Johnson Controls A421 / other temp sensor and relay.
For two purposes:
• Generator operation -- only run heat stages 2 and up, no heat pump
• Outdoor temp below 30°F
So the question is about how to control (force) heating stage to Aux heat.
I believe there are thermostats that do this natively -- e.g. Honeywell Vision8000pro, Venstar --- not sure, I know they do the temperature lockout (when outside temp gets below set-point, only engage furnace, no heat pump -- typically referred to as "balance point"), but not sure if they do automatic emergency heat.
First generator. How woud that work with a thermostat that does have support automatic emergency heat? When generator is running, send 24vac to E terminal?
What about an external Relay. If first stage of heating is Y, then relay contact set-A breaks Y between air-handler (furnace) and heat pump; Relay contact set-B connects W to W2. Since this furnace is 2-stage, W2 is low-heat, so this tells the furnace to run on low. When thermostat calls for 2nd stage heat, this will already be running. When thermostat calls for 3rd stage heat, it will close W3 and furnace will run on high.
Is it that simple?? Now I can lockout heat pump for whatever purpose. I can energize the relay either/both by connecting to my generator load switch lockouts (SSM module) and via any standalone temperature controller, say Johnson Controls.
What about G -- the heat pump is a MrCool Universal MDUO18 which want's G connected (I think). I may need to leave G disconnected, or break it, requiring a relay with >2 contact sets. Furnace is Goodman 804BN.
I know that in some markets the Utility provides a wire off the meter that goes hot when the temp dips below n°F their electric rate jumps up, and that can be attached to the thermostat or furnace in some way to auto-switchover from heat pump to furnace. It's a disincentive to use electricity. They also put a light somewhere to inform the customer of the rate switch so they refrain from doing laundry and other high-electric-use tasks. So how is that wired up?
Re thermostat -- I wish to use a specific t-stat, RadioThermostat CT80. It does some unrelated things that are important to me, that no other thermostat does, so I'm very egar to make this work, and it supports multistage heat/cool, and multistage Aux.
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