How Wire Heat Pump to H/Well Thermostat ?


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Old 10-28-06, 02:47 PM
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How Wire Heat Pump to H/Well Thermostat ?

I'm considering wiring a Honeywell programmable thermostat to my ~18 year old Lennox Air-to-Air Heatpump (it has auxilary electric-furnace heat).

The Wiring on the old Thermo doesn't match the Letter-coding on the new programmable (of course !)

Can anyone help out here ? The OLD Honeywell Thermostat wires are listed as follows:

Top-left: R,Y

Left-to-Right: X, F, V/VR, E, L (V/VR jumped together)

Top-right: M,A


New Honeywell Programmable Thermostat:

RC / R, O/B, Y, G, C, L, E, Aux


I know a programmable won't save me much money on a Heat Pump type system, but I want to upgrade the old slider system (and have the unit allow for cooler temps when sleeping at night).

Any advice -- greatly appreciated !

Thanks,
Matthew
 
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Old 10-28-06, 03:04 PM
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On a heat pump we try to tell people to set it and let it alone. You dont say how old it is can be HP6 on up to a HP 19
On the lennox X is common V/VR is power That F is fan. We have had some honeywell tstats that we have called them on and they cant say how to wire them.

ED
 
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Old 10-29-06, 05:14 AM
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Unhappy

Thank you Ed,

The Heat Pump is either a HP10 or HP11 (5-Ton) on an EC-10 forced-air electric furnace... the T-Stat is a T874 (Honeywell).

The new Honeywell instructions indicate terminal connections as follows:

New T-Stat Possible Wire (Old system)
-----------------------------------------------
RC --> Rc or R
R --> R or V or VR (RC/R are jumped)
O/B --> O or H or B (no wires on H-Pump !)
Y --> Y or Y1 or M
G --> G or F
C --> C or X or B
L --> L or F
E --> E or X or X2
Aux --> Aux or W or W1 or W2

There are no O, H, or B wires on my old system so its a bit of a mystery which wire should go to O/B on the new T-stat.

I have a feeling this may not be a do-able project but will give it one more try if anyone has info !

Thanks,
Matthew
 
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Old 10-30-06, 04:13 PM
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Id say ring this out for sure Cause I dont recall on this unit. My paper work on the HP10
X is common Hot is V/VR Now R is the switch over to cool that is O or B L is malfunction
 
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Old 10-30-06, 07:59 PM
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talked to an oldtimer at work today about this HP10.

He said, old new
M - Y
X - C
R - O
VR - R
E - W1
F - G
L - L

Not sure about A, and Y




Top-left: R,Y

Left-to-Right: X, F, V/VR, E, L (V/VR jumped together)

Top-right: M,A

RC / R, O/B, Y, G, C, L, E, Aux
 
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Old 10-30-06, 08:29 PM
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Still at a loss here
There are no O, H, or B wires on my old system so its a bit of a mystery which wire should go to O/B on the new T-stat
you say lennox HP10 heatpump.You had to have a wire on O/B
O/B --> O or H or B (no wires on H-Pump !)

The heatpump has been runing in the winter ok???? Does the electric heat come on some and in defrost?

ED
 
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Old 10-31-06, 07:18 AM
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Many Thanks Guys:

See if this makes sense to you:

I'm told that "R" is the Reversing Valve and connects to O/B on the new T-Stat

Was also told that "Y" is Aux-Heat on the old and should be connected to the new T-Stat, "Aux"

Lastly, was also told the "A" on the old T-stat is for "Anticipator" and that this is no longer used.

This information came from an HVAC Board similar to this one (though not as good !), so I don't know how reliable it is.

We just bought the house this summer (I'm in Canada) and its working great in the cool temps - I expect we may need Aux-heat support in December / January but will wait to see. We budgeted to replace the HP with a natural gas system when we purchased the home, however, the old homeowner had the system rebuilt last year, so we'll use it as long as she lasts.

Thanks,
Matthew
 
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Old 11-01-06, 10:25 AM
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Go to http://warmair.net You can compare fuel cost for where you live.

ED
 
 

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