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BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22115
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have a wire on the panel to w1 and a black wire on the

Customer Question

I have a white wire on the panel to w1 and a black wire on the panel to w2. Then on the thermosrat, those wires are jumped into a "W" plug. Why? I'm installimg an ecobee3 and theres not enough room to plug both into the w2 slot.
Submitted: 10 months ago.
Category: HVAC
Customer: replied 10 months ago.
Its an old electric heat pump system... from 1986. Cant read make or model. The compressor was just replaced on the outside oart, thats a trane from 2002. Its on its way out, just need to get through the next few months
Expert:  BillyHvac replied 10 months ago.

Hello,

it is because you have 2 stages heat.

If you want a single wire...just wire nut a single wire in with the 2 ends. Then attach the single end into thermostat.

The thermostat you had existing nor the ecobee are really exactly what you want for your system...so they combined the 2 stages

Customer: replied 10 months ago.
i should plug them into the w1 and w2 slots as they were wired, respectively, on the ecobee3 thermostat?
Customer: replied 10 months ago.
Is there an advantage to not using both stages? I thought two was more efficient...
Expert:  BillyHvac replied 10 months ago.

yes you can.

The black wire for you is actually electric back up heat. Which usually uses a thermostat with a emergency heat selection..this turns off heat pump and uses electric backup in case of heat pump fail.

Expert:  BillyHvac replied 10 months ago.

when previous thermostat was installed the emergency heat became auxiliary heat (second stage only).

Being a 1986 unit...the efficiency you gain will be minimal.

Expert:  BillyHvac replied 10 months ago.

basically the w1, first stage heat is heat pump...the black wire "emergency" heat was used as a second stage.

This is coming from description...but the only time we see white and black tied together is when a thermostat was installed without emergency heat option.

When you are all set just rate service at top of page and then you have 30 days of follow up available.

Expert:  BillyHvac replied 10 months ago.

The question is still open, Did you need further information?