# Goodman heat pump - W2 wire to thermostat



## gregzoll (Dec 25, 2006)

W2 lands on the thermostat as it states, if you are using a heat pump. The manual that comes with the thermostat, furnace, heat pump has te wiring diagrams in them.

They are your best friend, and are better than a Internet forum, that none of us are physically there.

Really it is pretty straightforward, just make sure no power is on on the furnace or heat pump while you are connecting the thermostat, otherwise you will fry stuff.


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## taxmantoo (Jun 11, 2013)

Manuals:
Heat Pump (there's more detail in the wiring chart on the access panel)
Furnace
Thermostat
Alpine's web site has a handy little diagram for controlling dual fuel with a Vision Pro, but they don't use the W2 on the heat pump or jump AUX and E on the thermostat. 
The thermostat doesn't have a W2 in the 'heat pump' column of terminal labels, but the thermostat's heat pump AUX is the same terminal as the conventional furnace W2. 

According to the thermostat manual, I'm supposed to hook the furnace's white wire to the thermostat's AUX, and apparently jumper it to E.
* 
Should I just go by the Alpine diagram and ignore W2 and Honeywell's E-AUX jumper comment?*

*My main problem is the heat pump documentation just says the white wire is W2 without explaining what W2 does. If I don't need it, what's it there for? *


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## beenthere (Oct 11, 2008)

The W2 from the heat pump can land on either the W terminal of the furnace, or the W2 of the stat.

Yes, jumper aux and E.

Yes, aux and E are what runs the furnace for heat, when it is needed.

Did you install the outdoor temp sensor.


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## taxmantoo (Jun 11, 2013)

*So HP(W2)=T-Stat(AUX+E)=Furnace(W)?*

Yes, I've got the outdoor sensor on S1 and S2 of the 8320. Found out that when the sun hits the west glass of my sunroom late in the evening the outdoor temp goes into the mid-90s when it's only 88 outside, so just west of the sun room in the shade on the north of the house isn't the greatest place for it. Thinking of putting the temp sensor in the shade under the heat pump, or I can leave it on the north side of the house and try moving it 15' further from the sun room.


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## beenthere (Oct 11, 2008)

> So HP(W2)=T-Stat(AUX+E)=Furnace(W)?


Thats it.


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## gregzoll (Dec 25, 2006)

Yes, always place the sensor where there is shade all day if you can. Placing it where Heat gain or direct sun will skew the sensor readings, will do nothing for you. Same goes where during Winter if you are in an area that gets below zero temps with high winds, you want it where it will not wind blowing past it, that can also skew the results.


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## beenthere (Oct 11, 2008)

gregzoll said:


> Same goes where during Winter if you are in an area that gets below zero temps with high winds, you want it where it will not wind blowing past it, that can also skew the results.



Wind will have no effect on it.


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## taxmantoo (Jun 11, 2013)

It's in a zero sun area on the north side of a house, but apparently there's a serious radiant heat factor when the sun gets low enough in the evening to hit a glass room addition that's 3' away from it. 

*I can relocate it so it's still on the north side of the house but 18' away from the sun room, or I can put it in the shade under the heat pump, where it might pick up radiant heat from the ground. Or maybe leave it where it is and put a reflective barrier between it and the sun room?*


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## beenthere (Oct 11, 2008)

Any one of those options should work.


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## gregzoll (Dec 25, 2006)

beenthere said:


> Wind will have no effect on it.


Actually Cold Wind during Winter does affect Thermometers if the wind speed is high enough.

http://physics.stackexchange.com/qu...show-a-lower-temperature-than-one-shielded-fr


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## taxmantoo (Jun 11, 2013)

Greg, your link seems to indicate what beenthere said.

"Why, given two temperature sensors or thermometers in the same environment, do both report the same temperature if one is exposed to wind when the other is shielded from it?"

"Its really pretty simple, the thermometer measures temperature, wind chill measures heat loss for a body warmer than the air. Wind makes more unheated air available to conduct heat away from a hot body, but with a body at air temperature no heat is being condicted away from the thermometer."

"The thermometer in wind will (at equilibrium) show a lower temperature than one in still air, *if and only if it is a wet-bulb thermometer.*"

The only conflicting answer was the one that said if you have radiant heat sources the still air sensor will be warmer and the windy sensor will be closer to air temperature. Therefore wind isn't something to be avoided, it's something to be sought after, but only if there's a major radiant source (like my sun room) or you're looking for more precision than is required to set the 5°F range in which the thermostat switches from heat pump to furnace and back.


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## beenthere (Oct 11, 2008)

Wind chill only effects objects that contain and or generate heat. So a thermometer isn't effected by wind/wind speed. It can only show display the actual air temp, within its accuracy range. The same as it would if no wind was blowing.


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