Need programmable stat for dual stage heat pump and A/C
#1
09-26-07, 09:37 PM
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Need programmable stat for dual stage heat pump and A/C
Looking for a recommendation for a thermostat that can be programmed separate for each day and will handle a 2 stage heat pump where the A/C is also a two stage system. I had one at a previous house for a 2 stage heat pump but the air was only a single stage system. On this house the Lennox system also has a 2 stage (speed) mode for the A/C. Thanks. John of Memphis
#2
09-27-07, 09:32 PM
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I'd go with a Honeywell VisionPro TH8320 if your air handler isn't variable speed, or humidity control isn't an issue.
Or go with the Honeywell IAQ t-stat if your handler is variable speed, and you want huimdity control.
Or go with the Honeywell IAQ t-stat if your handler is variable speed, and you want huimdity control.
#3
09-27-07, 10:21 PM
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The air handler and compressor appear to just be two speed units. The current unit has 2 mercury bulbs for both heat and cool. In the cool mode when the first one trips, the air handler and compressor run on low speed, when the second bulb trips both advance to high speed. I have seen a variable speed unit some time ago and it had some type of mini computer to go with it. This does not appear to have such. This is a 97 unit but I had a York from about 1982 that had the same type stat but the second mercury bulb on the A/c side was hooked to nothing. Thanks for the advice and the quick response..
John
John
#4
10-10-07, 10:30 AM
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Honeywell says NO!
Honeywell says NO!
Jay;
I e-mailed them and they asked for list of all terminals on current stat. They said that them have no consumer installable stats for a 3 stage heat pump. They answered each email within 24 hours. I did find some pdf files for the top of the line stats and I can see where there could be a wiring problem. (i.e. they never reference a "T" terminal) and they do reference problems in the install pdf ( http://customer.honeywell.com/techlit/pdf/69-0000s/69-1900ES.pdf ) if you have 2 wires from different terminals on the old stat that would wind up on just one on the Honeywell stat.
Here is the info they wanted if anyone has any ideas.
This is a Lenox 51H4301 mechanical stat. (1996 or 1997 model)
Terminals...Color Wire
C Black
L Brown
G Green
O Orange
Y2 Blue
E not used
Y1 Yellow
W1 White
T Purple or Violet
R Red
( Gray wire from wall to stat not used)
No jumpers are used.
Jay;
I e-mailed them and they asked for list of all terminals on current stat. They said that them have no consumer installable stats for a 3 stage heat pump. They answered each email within 24 hours. I did find some pdf files for the top of the line stats and I can see where there could be a wiring problem. (i.e. they never reference a "T" terminal) and they do reference problems in the install pdf ( http://customer.honeywell.com/techlit/pdf/69-0000s/69-1900ES.pdf ) if you have 2 wires from different terminals on the old stat that would wind up on just one on the Honeywell stat.
Here is the info they wanted if anyone has any ideas.
This is a Lenox 51H4301 mechanical stat. (1996 or 1997 model)
Terminals...Color Wire
C Black
L Brown
G Green
O Orange
Y2 Blue
E not used
Y1 Yellow
W1 White
T Purple or Violet
R Red
( Gray wire from wall to stat not used)
No jumpers are used.
#5
10-10-07, 05:59 PM
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Spend a few more $$$ and look around on line for a TH8320 t-stat, and it will have a lot more choices to set up to your system than the t-stat from most retailers.
Also, get the outdoor sensor. What is your back up heat, gas or electric?
Also, get the outdoor sensor. What is your back up heat, gas or electric?
#6
10-14-07, 02:22 PM
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8320
My backup heat is electric. I also looked the installation manual for the 8320.
It appears to be limited to a dual stage heat pump. Honeywell said that they have no consumer installable stats for a 3 stage heat pump. From the info I sent them, they did conclude I had a 3 stage heat pump. I did find some information on their site that shows the installation of additional relays or other things would make these stats work with a 3 stage system. When cold weather hits I am going to see exactly what the heat pump does. I know that the heat pump side of the factory Lennox stat only has 2 mercury bulbs but it has more wires to them and one other part on that side of the stat than an old York 2 stage heat pump I once had. When it gets cold I need to see exactly what sequence everything is going through in the heat mode. THANKS
It appears to be limited to a dual stage heat pump. Honeywell said that they have no consumer installable stats for a 3 stage heat pump. From the info I sent them, they did conclude I had a 3 stage heat pump. I did find some information on their site that shows the installation of additional relays or other things would make these stats work with a 3 stage system. When cold weather hits I am going to see exactly what the heat pump does. I know that the heat pump side of the factory Lennox stat only has 2 mercury bulbs but it has more wires to them and one other part on that side of the stat than an old York 2 stage heat pump I once had. When it gets cold I need to see exactly what sequence everything is going through in the heat mode. THANKS
#8
10-15-07, 10:16 AM
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Thanks Jay
Thanks.
I tried the heat this A.M. and it appears that as far as the stat is concerned, it is a 2 stage system. Stage 1 is high speed compresser and blower. Stage two adds the electric heat strips. I didn't let it run long enough to see if it would ever drop to low speed. I have studied the wiring diagram I found for the stat and conclude that if the system goes to low speed it will be controlled by something other than the stat. The only problem now is with the Honneywell stat, unless the IAQ has a place, would be the lack of a place to hook the wire for Lennox Terminal "T". Per Lennox manual: :The ambient compensating thermistor must be used to assure proper operation. It improves control characteristics of the thermostat by reducing droop. Thermostat will not control properly with out" Per schematic, this thermistor is located outside the stat in the condensing unit between terminal "T" and ground. Inside the stat, "T" goed through a resistor to the 24 volt source "R". I am assuming this is the outdoor sensor you refer to. I have a new problem (or question) and will start a new thread for it. Jay, Thanks very much for your input. John
I tried the heat this A.M. and it appears that as far as the stat is concerned, it is a 2 stage system. Stage 1 is high speed compresser and blower. Stage two adds the electric heat strips. I didn't let it run long enough to see if it would ever drop to low speed. I have studied the wiring diagram I found for the stat and conclude that if the system goes to low speed it will be controlled by something other than the stat. The only problem now is with the Honneywell stat, unless the IAQ has a place, would be the lack of a place to hook the wire for Lennox Terminal "T". Per Lennox manual: :The ambient compensating thermistor must be used to assure proper operation. It improves control characteristics of the thermostat by reducing droop. Thermostat will not control properly with out" Per schematic, this thermistor is located outside the stat in the condensing unit between terminal "T" and ground. Inside the stat, "T" goed through a resistor to the 24 volt source "R". I am assuming this is the outdoor sensor you refer to. I have a new problem (or question) and will start a new thread for it. Jay, Thanks very much for your input. John
