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Phil
Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I'm replacing a Rite Temp 8050 with a Honeywell rth3100c

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I'm replacing a Rite Temp 8050 with a Honeywell rth3100c thermostat. I labeled the wires as I took them off the old it but the Honeywell terminals don't match. My wire colors are White, Yellow, Red, Green . The red was jumped between RH and RC.
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: The homeowner doesn't want to deal with a programmable T-stat anymore so I got this simpler one.
JA: Do you plan on doing the work yourself?
Customer: Yes.
JA: Anything else we should know to help you best?
Customer: Not that I can think of.

Hello, tell me please which color wire you attached to each lettered terminal on the new thermostat. Have you fit a jumper between Rc and Rh on the new thermostat,

We can go from there

Customer: replied 27 days ago.
I attached the White wire to the Aux and jumped that to the E terminal (per the instruction manual). Yellow to "Y", Green to "G", Red to "R". No jumper between Rc and Rh as these are not terminals on the Honeywell. There is only an R terminal.
Customer: replied 27 days ago.
Did I lose you?

Hello again, I have to come and go to handle a lot of different questions, I am back with your question now.

Customer: replied 27 days ago.
I think I may need to get a different T-stat with terminals for Rc and Rh to run heat and cooling. Does this sound right?

Click here please, wire as shown, no jumpers. let me know how it goes

I used grey to represent the white wire

Customer: replied 27 days ago.
Okay I'll give it a try without the jumper. I'll let you know tomorrow. Thanks.

Incidental background notes:

Honeywell unfortunately shows all the right wiring for a HEAT PUMP... you do not have a heat pump, you have a conventional system, and nowhere does honeywell define that thermostat as a heat pump only thermostat. These are errors of omission, that is unusual for Honeywell.

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Furthermore they do not tell you anywhere how to wire the system for a CONVENTIONAL SYSTEM, as you have.

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They DO have the W terminal that is only used in a conventional system though. So we can give it a try.... heat pumps do not use the W terminal, but do use the E, Aux and O/B terminals (your system uses none of those heat pump application terminals).

( The packaging does not limit the thermostat to either heat pump or conventional systems or both as virtually all of their other thermostats and all other manufacturers do.)

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The only clue aside from Honeywell not mentioning that is might be a heat pump only thermostat is that they have only one R terminals, virtually all other thermostats for conventional systems have both an Rh and Rc terminal that need to be jumpered together for 98% of HVAC systems built.

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