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Old 03-15-2020, 02:10 PM   #16
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Re: My thermostat with separate O and B terminals


That's a heatpump.

B is energized in heating mode and O is energized in cooling mode - it signals the heatpump which mode.

Rheem uses B instead of O for the change-over but that fossil fuel kit is expecting O for input.

Since new stats can not use both, wiring modification will be required.

I don't know if the fossil fuel kit absolutely needs the O input but it's better to be safe.

Either a (normally closed_ relay will have to be added to apply power to O when B isn't energized or you'll have to bypass the fossil fuel kit and use the stat to control duel fuel.

I favour the latter.

The setup is a bit complicated -> have to go through the settings menu of the new stat.
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I am not in the business of any trade I give advice on. I have non-professional hvac experience + good knowledge of theory. Attempt repairs at your own risk. Never jump out safeties - especially pressure switches - on a furnace for testing with fuel supply on; use a meter. Do not troubleshoot with live line voltage present unless there's no alternative.
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Old 03-15-2020, 02:11 PM   #17
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Pics of outside AC unit
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Old 03-15-2020, 02:12 PM   #18
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What a mess - outside unit
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Old 03-15-2020, 02:12 PM   #19
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Re: My thermostat with separate O and B terminals


Do you see an outdoor thermostat anywhere?

Follow the wire from fossil fuel kit.

Is your furnace propane or natural gas?

What are your utility rates? (add up all delivery charges per kwh and cubic ft of gas)

Quote:
And why did my old one have a jumper, a wire from E to W2? Should I do that to the ecobee too?
Emergency heat mode automatically bypasses the heatpump and energizes E instead.

In most cases, emergency heat isn't a separate system -> so they get jumpered.

The ecobee doesn't come with an E terminal so there would be no jumper.
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Old 03-15-2020, 02:16 PM   #20
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Re: My thermostat with separate O and B terminals


Which version of the ecobee do you have?

I'll have to look up the setup manual to give step by step instructions.

Best thing to do is take the fossil fuel kit out of the circuit and use the ecobee for everything.

It's a great stat for dual fuel.
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I am not in the business of any trade I give advice on. I have non-professional hvac experience + good knowledge of theory. Attempt repairs at your own risk. Never jump out safeties - especially pressure switches - on a furnace for testing with fuel supply on; use a meter. Do not troubleshoot with live line voltage present unless there's no alternative.
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Old 03-15-2020, 02:21 PM   #21
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Its Ecobee4.
I feel like you're speaking another language. Is the "fossil fuel kit" a wiring harness?
I have no idea how much my rates are, and am not super concerned about the cost anyway, I just want to be able to turn my heat or air on from my phone or alexa.
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Old 03-15-2020, 02:23 PM   #22
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No thermostat outside ... at least nothing that looks like one?
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Old 03-15-2020, 02:29 PM   #23
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On this thermostat, the orange wire goes to the furnace and the blue one goes outside to the AC unit.
What do I do with them? Plug them bith into the same terminal on the ecobee4? The O/B?
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Old 03-15-2020, 02:34 PM   #24
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Re: My thermostat with separate O and B terminals


There should be an outdoor thermostat - it could be small and installed outside of the heatpump cabinet.

This is not a straight forward plug and play installation.

You'll need to bypass the fossil fuel kit before installing the ecobee or put a relay to energize O when there's no power on B.

I wouldn't bother with the relay, best to take the fossil fuel kit out of the picture.

For bypassing the fossil fuel kit, B wire will be used only, not O.

You'll need to go into the ecobee settings menu and change the defaults or it won't work right.

The new stat will get the outdoor temp off the internet instead of using an outdoor stat/sensor.
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I am not in the business of any trade I give advice on. I have non-professional hvac experience + good knowledge of theory. Attempt repairs at your own risk. Never jump out safeties - especially pressure switches - on a furnace for testing with fuel supply on; use a meter. Do not troubleshoot with live line voltage present unless there's no alternative.
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Old 03-15-2020, 03:15 PM   #25
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Re: My thermostat with separate O and B terminals


You may want to consider having a professional install the thermostat and set it up, if your not familiar with the equipment or comfortable with wiring.
This isn’t a plug and play type installation.
You could always have a spring maintenance done while the tech was on site, to check the equipment out.
When was the last time it was serviced and cleaned?
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