Help! New thermostats, old home


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Old 12-01-18, 09:07 AM
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Help! New thermostats, old home

Hello all and thanks in advance for any guidance you can offer.

i have an older home I purchased this year and want to install new smart thermostats. Was looking at the nest E and Ecobee 3 lite. Problem is my wireing is not straightforward and Iím a novice at home ownership and HVAC systems.

i have a two story home, two thermostatss up and down. I have two big units outside, a big HVAC downstairs and then a unit in the attic. Both units are tranes and so are the thermostats.

The downstairs thermostat is more complicated, twires oN the left side: F, X2, W1, S1, S2...the W1 has two wires in but the control board downstairs seems to not have only one of them running to it. Right side: R, O, Y, G, B.

the upstairs thermostat is simpler: straight across the top there is E, Aux, Y, G, O, R, C.

My questions are on what is critical and what I shouldnít mess up.
1. Iíve gotten answers from Nest and Ecobee that some wires are ok to tape off: S1/s2 (thermostats get temp over wife), F on downstairs (already have a fan through g?). Is this ok?
2. But some debate as to if I need x2 downstairs (does emergency matter and so I have coverage through the W1 wire) and same on E upstairs. Would it be ok to not plug in this wire?
3. Maybe related, but I live in Georgia so the temperature rarely gets too bad (<20 only a few days out of the year). Does this matter for the emergency heat issue?

any thoughts on this and and the install would be SO helpful. Thanks!

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Last edited by PJmax; 12-01-18 at 11:49 AM. Reason: cropped/resized/enhanced pics
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Old 12-01-18, 09:14 AM
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Welcome to the forums.

It is very helpful to post pictures of the thermostats and wiring. How-to-insert-pictures
 
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Old 12-01-18, 09:43 AM
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Thanks Pete, sorry I didn’t before, I uploaded pictures of my downstairs thermostat wiring, my upstairs thermostat wireing, my downstairs HVAC control panel and my upstairs HVAC unit (not sure where the control panel is). Hopefully this is helpful
 
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Old 12-01-18, 12:25 PM
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Picture 1 - downstairs stat.
F - brown
W1 - white (jumpered to X2)
S1 and S2 - red and white - needs further use confirmation
R/Rc - red
O - orange
Y - yellow
G - green
B - blue - C (common)

Picture 2 - upstairs stat.
E - black
AUX - white
Y - yellow
G - green
O - orange
R - red
C - blue

Please confirm I have the colors addressed correctly.
It looks like the stat in picture 2 belongs to the system in picture 3.
Picture 4 doesn't help us much.

The Ecobee 3 lite is fine for the upstairs system. It will control your heat pump with aux electric heating coils. Your current stats probably have an E (emergency) heat position. I don't think the E3 lite or the nest E has E heat. That means you cannot select just the electric heat only.

I see two S connections.... S1 and S2 in picture 1. That could mean a humidifier is connected. Confirm that.
 
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Old 12-02-18, 09:28 AM
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Would need to get the thermostat models and information about system to give specific instructions on wiring and setup.

The S1 and S2 terminals are likely for an outdoor sensor.

It appears you have heatpumps and the outdoor temp sensor on the main floor unit can be used by the stat to lock out the aux heat in mild weather and heatpump in extreme cold.

It can have other functions too.

You can lose a lot of functionality replacing the stats.

Plus, heatpumps are best left at a constant temperature due to not having the capacity to recover and these smart thermostats are designed so you can raise or lower the temp remotely to "save energy".

You'll be better off not switching to nest.

You should know, it's a low quality consumer product sold at a premium price. It has a horrible reputation. If you insist on using smart thermostat, you should get a professional grade honeywell or ecobee for your application.
 
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Old 12-02-18, 10:21 AM
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Since you have a heat pump, any thermostat should be one that has the ability to lock out auxiliary heat.
Otherwise your best to leave the thermostat set at a constant temperature. Otherwise you’ll raise your electric bill.
 

Last edited by PJmax; 12-02-18 at 03:55 PM. Reason: Removed opinion of nest
 

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