Help wiring new Heat Pump thermostat (Hunter 44760)

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Old 12-05-15, 03:44 PM
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Help wiring new Heat Pump thermostat (Hunter 44760)

I am trying to connect a new thermostat to replace an ancient mercury switch thermostat. I have a Day and Night, 4 ton heat pump, model# 542D048HP, product number 542DBX048000AAAF with electric auxiliary heat strip. The new thermostat that I have is a Hunter model 44760.

The existing thermostat wiring is:

Y- Yellow
RH jumpered to RC - Red
G - Green
W1 - White
W2 - Blue

Connections at the heat pump low voltage terminal are:
Y- Yellow
R - Red
W1 - White
W2 - Blue
G - Green

The terminals on the new thermostat (Hunter 44760) are:
G - Fan Relay
C - common?
L - System Monitor
O - Reversing Valve Cool
W2 - Auxiliary Heat
B - Reversing Valve Heat
E- Emergency Heat
R - 24V supply
Y1 - Compressor Stage 1

I have tried to contact Hunter for help and didnít get any answers that helped out. If anyone can let me know how I should wire the new thermostat or if I need to get a different type of thermostat Iíd greatly appreciate it.
 
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Old 12-05-15, 04:03 PM
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I don't see a O/B terminal on your existing stat. Are you sure about the model # you gave?

Just to clarify the furnace/air handler is the inside unit and the heat pump is the outside unit.
 

Last edited by skaggsje; 12-05-15 at 04:09 PM. Reason: added
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Old 12-05-15, 04:16 PM
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The heat pump is a full package mounted outside. It has the compressor, coil, blower and condenser in the same package.
 
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Old 12-05-15, 04:22 PM
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OK, Yes that's a packaged unit. Do you see a O/B terminal in the unit? With no O/B it's not a heat pump.
 
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Old 12-05-15, 04:41 PM
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I don't see an O/B terminal. Here are the terminals that are in the unit:
R
P1
Y
W2
C
P
W1
G

I'm trying to post pictures of inside as well as the schematics that are glued to the covers.
 
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Old 12-05-15, 04:54 PM
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The only two I don't recognize are P1 and P. I think what you have is a standard package unit with either natural gas or electric heat strips. That being said, you need to return that stat. I would recommend a Honeywell 6000 series or better. Hope this helps.
 
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Old 12-05-15, 05:04 PM
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They probably used W1 as the reversing valve connection and W2 as backup electric.

This looks to be the manual for your unit....
hvac partners/docs/1009/Public/00/40542DP2-A.pdf
 
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Old 12-05-15, 05:07 PM
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Here are some images of the schematics on the heat pump as well as a shot of the low voltage wiring on the unit.
 
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Old 12-05-15, 05:23 PM
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In looking over the schematic quickly..... your stat should work however the stat requires a C connection to the unit.

Are there any spare wires in the thermostat cable ?
 
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Old 12-05-15, 05:33 PM
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Connections at the heat pump low voltage terminal are:
Y- Yellow
R - Red
W1 - White
W2 - Blue
G - Green

The terminals on the new thermostat (Hunter 44760) are:
G - Fan Relay - GREEN
C - common? - ????? - NEEDED
L - System Monitor
O - Reversing Valve Cool
W2 - Auxiliary Heat - BLUE
B - Reversing Valve Heat - WHITE
E- Emergency Heat - JUMPERED TO W2
R - 24V supply - RED
Y1 - Compressor Stage 1 - YELLOW

These are my tentative connections.
 
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Old 12-05-15, 05:37 PM
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Wow, page 11 paragraph B states that a conventional thermostat will control this heat pump.

Energizing G and W1 runs the compressor, blower, and puts the reversing valve in the heat position.
 
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Old 12-05-15, 05:42 PM
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PJmax
I don't think there is an extra conductor in the bundle. I will tear it apart tomorrow and check. I know it will not be easy pulling in another cable if there isn't a spare conductor. If I did pull in another wire and connected everything like you have mentioned. What risks do I run if it isn't correct?
 
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Old 12-05-15, 05:53 PM
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Yes PJ is right, They are using W1 to energize the reversing valve. I have not seen this before. Just for my information could you post the serial # so I can see how old this unit is?
 
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Old 12-05-15, 05:58 PM
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skaggsje
E961856 is the serial number. I believe that the unit was built between '79 and '82.
 
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Old 12-05-15, 06:04 PM
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If you don't have an extra wire than you'll need to switch to a battery operated thermostat that doesn't require a C connection. Unfortunately..... all those cool looking blue ones that are always lit require the C connection.


The service manual carries a date of 1978 on it so that unit is fairly old.
 
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Old 12-06-15, 09:54 AM
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Your right, May 1979. That's one tough machine.
 
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Old 12-07-15, 12:06 PM
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The B terminal is energized the entire time the thermostat is in heat mode. The heat would never cycle off. A 2 stage conventional thermostat is required for this unit.
 
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Old 12-07-15, 04:53 PM
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Thanks Carlos... that was the thing that was bothering me. That's why I labeled my wiring tentative. You're right..... B is powered when in heat mode.... not just when calling for heat.
 
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Old 12-07-15, 05:08 PM
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Yea, I've been meaning to look that word up .
 
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Old 12-07-15, 05:11 PM
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Tentative..... preliminary.
 
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Old 12-09-15, 05:12 AM
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Thanks Pete,
I have learned a lot from this site.
 
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Old 12-14-15, 02:01 PM
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What would be an example (recommendation ) of a 2 stage conventional thermostat?
After looking at the wiring path for my thermostat wires it isn't going to be pretty. Have you heard of (and will it work) add-a-wire for thermostats?
 
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Old 12-15-15, 08:37 PM
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The Honeywell FocusPro TH6220D, The VisionPro TH8321R, The VisionPro TH8320R, Can be configured for conventional or heat pump so any of these would work. (I like the 8000 series and higher).

The are Honeywell WiFi thermostats that will also support your application.
RTH6580WF, RTH8580WF, RTH9580WF.

Search Results for honeywell wifi at The Home Depot
 
 

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