7 wires to a 6 wire thermostat - http://www.hvacmechanic.com/ Forums
Original message
| Nate
 |  "7 wires to a 6 wire thermostat"
, posted Tue 26 Oct 12:29:  
I'm trying to install a Carrier TSTATCCPS101 thermostat for multi-stage systems to replace my old Amana Thermostat.
The old terminals are X1 E W2 R W1/Y1 G B
The new terminals are C ? W2 R Y1 G W1
The installation manual shows that O should go to W1 but the new thermostat has a programmable configuration for B/O so that should be okay.
There is no E terminal on the new thermostat even though the thermostat has an emergency heat mode. My guess is that it just turns on the W2(2nd heat) and G(fan) in Emergency Heat mode.
Sooo the question is, do I just shut down the breaker cut the E wire and electrical tape it safe, turn on the breaker and see if the old thermo still works before installing the new?
Logically this should be okay but having zero experience in hvac I'm hesitant to test.
I have read that some systems only use the E when in emergency heat mode and others use it at all times.
Any help would be appreciated. Thanks.
[this message was edited by Nate on Tue 26 Oct 12:31] |
| Replies:
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| Freon
| "Re(1):7 wires to a 6 wire thermostat" , posted Tue 26 Oct 13:11
Judging from the new thermostat having a C terminal, it may require 24 volts from the transformer. Did your old 'stat have a C terminal? You may need that extra lead to connect C from the 'stat to C at the air handler. Verify that the new 'stat requires 24 volts power and is not a "power stealing" stat.
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| | Nate
| "Re(2):7 wires to a 6 wire thermostat" , posted Tue 26 Oct 15:10:
Supposedly, X1 is the same as C in old electromechanical thermostatsts according to the heat pump and thermostat wiring diagrams in the Honeywell Thermostat Cross Selection Guide http://hbctechlit.honeywell.com/request.cfm?form=70-6627 .
I don't know if my thermostat Carrier (TSTATCCPS101) is a "power stealing tstat." Both R and X1(C)are larger wires so my guess is that those are the power and common and the E is used for power only in emergency power overide mode on the old tstat.
The old terminals are:
X1 = I believe this is the same as C (large purple wire)
E = should be emergency heat (large blue wire)
W2 = should be 2nd heat /auxilary (small white)
R = should be 24VAC (large blue)
W1/Y1 = wired toghether, should be heat pump on (large purple)
G = should be fan (small green)
B = should be heat pump Reversing Valve(small blue)
The new terminals are:
C = X1 is supposedly how C is designated on electromechanical thermostats
W2 = W2
R = R
Y1 = W1/Y1 from old
G = G
W1 = B from old (according to manual with b/o & hp configuration)
***No E on new thermostat
Do you think the old thermostat pulls power from E during normal operation or is it only used for the emergency heat overide?
Would it damage the system if I tested it with the E unhooked from the old thermostat?
Thanks again for your help.
[this message was edited by Nate on Tue 26 Oct 15:17] |
| | Freon
| "Re(3):7 wires to a 6 wire thermostat" , posted Tue 26 Oct 15:16
Check at the air handler(Furnace) connection box and see which 'stat wire connects to the C terminal. I'd also verify the other 'stat wires by color and terminal connections at the air handler.
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| | Nate
| "Re(4):7 wires to a 6 wire thermostat" , posted Tue 26 Oct 17:29:
I apologize for the complexity of the post but it is necessary to describe the situation.
The wires at the heat pump are well marked. The wires at the furnace are not marked at all. Most troubling of all is the fact that the 3 large wires at the thermostat are a higher guage than any of wires at the furnace or heat pump.
HEAT PUMP WIRES (seem to correspond to FURNACE WIRE2)
r red
y yellow
b blue
e black
w1 white
c orange
he1 brown
FURNACE WIRING
WIRE1
green Xnot connected
white connected to WIRE2orange, ?transformer, humidifier
red connected to WIRE2black
WIRE2
white connected to WIRE3white
yellow connected to WIRE3yellow
green Xnot connected
brown connects to furance relay
blue connects to WIRE3darkblue
orange connects to WIRE1white, ?transformer, humidifier
black connects to WIRE1red
red connects to WIRE3orange
WIRE3
orange connects to WIRE2red
white connects to WIRE2white
yellow connects to WIRE2yellow
green connects to ?fan control
darkblue connects to WIRE2blue
THERMOSTAT WIRING
LargePurple1 connects to X1 ?WIRE1white
LargePurple2 connects to Y ?WIRE3yellow
LargeBlue1 connects to E ?WIRE1red
LargeBlue2 connects to R ?WIRE3orange
white connects to W2 ?WIRE3white
blue connects to B ?WIRE3blue
green connects to G ?WIRE3green
The schematic on the heat pump lid shows E coming into the heat pump with an A(em heat)B before merging with C and going further into the heat pump inerts. Like this
C-------------------------|
E---A(em heat)B---|
........................|
........................|
The furnace is a an Amana Air Command BHAA36T002B.
The heat pump is an Amana ZRHF36U01B.
I hope that helps. Thanks.
[this message was edited by Nate on Tue 26 Oct 17:32] |
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