Oil furnace and a/c wiring + ecobee3


Old 11-25-16, 02:34 PM
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Oil furnace and a/c wiring + ecobee3

Hello, i'm new here and i don't find any answer regarding my Hvac setup.

My system is 1 stage heat (oil furnace), 1 stage cool (a/c pump) and a fan. I want to install a ecobee 3 thermostat and my wires setup look some kind weird to me.

Here is my actual setup:
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I have a few questions on my basic setup:
1) Is it OK that some wire are connected in the same port (screw) ? Whats the max ?
3) Is it normal that the furnace is connected directly to the thermostat ?
4) I have a cable running from the 24vac R port to the Rc port of my thermostat. Is that good ? What is it's used for ?

Can I do this:
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Or I need to do a cleanup of this kind ?
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Do you have any other suggestions ?

Sorry for all questions. But I need to figure this out and I can find precise answer to those questions.

Thank you!
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Old 11-26-16, 06:41 PM
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A photo of the source of what you have labeled as "24 VAC" would be helpful.

If the A/C system uses a blower separate from the one on the furnace, you need to run its "R" to terminal RC on the stat & the red from the furnace to R or Rh. Do not run the "furnace" wiring to the air handler's 24 vac terminals. To do so would likely cause one transformer or the other to fry (most likely, the one on the furnace).

Does the thermostat require a C (common) wire?

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