thermostat replacement

Reply

  #1  
Old 06-15-03, 01:15 AM
kaybyrd's Avatar
Member
Thread Starter
Join Date: Feb 2002
Location: N.W. MS.
Posts: 1,774
Received 0 Votes on 0 Posts
thermostat replacement

I just replaced the thermostat for my heat pump/aux heat (gas)/a-c and was curious as how I'm suppose to dispose of the old thermostat since it has mercury in it.

Also, I had one wire that didn't match the replacement diagram and after reading the wiring diagram for the thermostat (control box for heatpump) I think I did it correctly BUT would like to make sure before I burn down the house LOL.

The unit is a York, Model: P4UGD12N08001A, serial: ECXM116964

Thermostat is a Honeywell CT70, replacing a York (Honeywell stamped on inside) 2TH11702224A -date stamp P9009

All the wires matched up except for the gray wire. The gray was originally on 'X' but I don't have a system monitor which the install diagram said it should go to. If I did that (hook to sys monitor), then I would be one wire short since I don't have the 'H' for c/o valve.

Here's the details:

funtion - existing tstat(color)- new tstat:

common - B (black) - X
power - R (red) - R
compressor - Y (yellow) - Y
aux. heat - W (white) - W2
fan - G (green) - G
c/o valve heat - H (no H on old) - B
c/o valve cool - O (orange) - O
sys monitor - X or L (X, gray) - L
(the funtion is what the new tstat instructions stated it was for)

So... I hooked the unknown gray wire to the B terminal. However, I'm curious as to the note of E for emergency heat, but it isn't required unless the old thermostat had an E wire, which mine didn't.

The gas isn't even run to the house right now since I have it shut off in April because we won't need it again until late October, early November and they charge $15 per month just for the honor of it going to your house whether or not you use it. Saves me about $50 after reconnect fees.

The heat pump came on, but I couldn't determine if it was actually heating or not. It was 90 degrees in the house when I did this. Now the house is cool, thank goodness! Not freezing up like it did before. I thought it was the coils (although a good cleaning is in order) so I can wait until I can actually afford it to have it done.

Thanks for any information guys. I will hang on to the old thermostat until I know what to do with it.

Kay
 
Sponsored Links
  #2  
Old 06-15-03, 09:14 AM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,147
Received 0 Votes on 0 Posts
typically

you would not use both B and O both. the reversing (c/o) is either energized in heat or cool, and if it is cooling now, you have it right.(some units need power to O in heat, others, cool). remove that wire from blue, because during heating there will be power sent down that wire and we are not exactly sure where it goes, therefore a short will very possibly occur during call for heat. the emergency heat wire is energized when switch is set in that position, flipping a relay turning off the outside unit and energizing the backup heat. sounds as you have dual fuel? you mentioned gas.....take the old tstat to the local DIY store or an a/c supply house.
 
  #3  
Old 06-15-03, 10:50 AM
kaybyrd's Avatar
Member
Thread Starter
Join Date: Feb 2002
Location: N.W. MS.
Posts: 1,774
Received 0 Votes on 0 Posts
I'm not sure what its called because I've never had a heat pump and gas heat and an a/c. Its always just been heat and a/c. I manually flip to swip to em. heat for the gas heat to kick in.

I don't want to mess with it too much since there is a very real possibility that I may have to call someone into fix what I've done, fix the unit or replace the a/c. I believe its dated back to 1979. What little information I have is from research, from you guys here online and a few (very few) documents the previous owner left for us when we purchased the home.

I do have everything written down. I may store the old thermostat until I'm sure that I don't need it to show the hvac pro along with my notes of what I've done.

Kay
 
  #4  
Old 06-15-03, 01:23 PM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,147
Received 0 Votes on 0 Posts
you may need

a dual fuel tstat for this reason....when heat pump is running in heat, and indoor temp is @ 3 or more degrees cooler, the backup, in your case, gas, kicks in. you do not want both to run at the same time as the hot discharge air from the gas furnace will be too hot to pick up heat from the heat pump coil, playing hell with the refrigerant pressures. in a straight heat pump, the auxiliary heat is AFTER the coil, allowing both to run at the same time.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: