Thermostat or Furnace
I recently had a company (Sears) install central AC in my home. They retrofit the coils to my existing furnace. They also installed a new thermostat.
The air works great, but the heat no longer comes on. I have looked at all the wires in the back of the thermostat and inside the furnace itself. According to the manual for the thermostat - E/W1 is supposed to be used for controlling Emer/Stage 1 heating. I have no wire on this lead. Could this be the cause of my furnace not kicking on? I am fairly clever when it comes to electronics, but I don't know how it could possibly turn on if there is no control wire for the furnace.
The wires that are hooked up are the
(R) Red -red wire (24 V for powering the thermostat)
(C) Common - white wire (actually it is hooked up to my furnace W post - I would think this is the control wire, but they are using it as a ground)
(Y1) blue wire - Compressor control wire
(G) green wire - fan control
There is not another wire in the wall. I feel that they hooked the air up and did not have enough wires to hook up both air and heat, and rather than run a new cable that has 5 wires - they figured "It will be another 2 months before he finds out. Hehehehe (sinister laugh).
Is there any way that the system could be connected properly using only 4 wires? From my calculations, I think that they would need a minimum of 5 to control my single stage heat and single stage air.
I have them coming out tomorrow and would like some ammo for them. If it is a problem with the furnace, it is my dime - if it is an issue with the installation, it is on Sear's dime.
Any help is appreciated.
Last edited by ualr_jmjones; 10-05-2009 at 04:45 PM.
There are stats that can control both heat and cooling with only 4 wires. Some can do it with less.
I have never had any issue with my furnace. I believe it to be 7 years old (Carrier natural gas furnace), I have lived in the house for two years.
I am quite confident that this thermostat is not a fancy one that can do it with less wires.
I knew nothing about HVAC until I found this issue and their tech support wasn't very helpful, so I started digging around for something obvious - like a wire not connected properly, etc. When I found that all the wires were in their correct spaces, I started to trace them out. Every letter on the furnace mates up to a wire on the thermostat. The stat has other capabilities as it can be used on dual stage heating and cooling - so I expected there to be some empty terminals on it.
But, without the E/W1 terminal being connected to anything, and the manual clearly states that it is the "Emer / Stage 1 Heating" terminal - I saw no possibility of ever getting the furnace to kick on. Is that assumption correct.
Oh, and thanks for all the HVAC people out there that do a good job at what they do. When you find someone that doesn't it really pisses you off - so cheers to all that do a good job.
They need to either use a different stat, or pull another wire bundle for it to work.
I would give them a chance to fix it. It may have just been an honest mistake. I've put wires where they didn't belong before myself.
old mercury type Heat pump stat may be 4 wire. but most likely they need to pull a new 8 wire to the stat or at least 5.New stats can just have 2 wires. if pulling a wire is a problem you can goolge 2 wire visonpro thermostat it will work fine.
Originally Posted by ualr_jmjones
Well, I'm not a pro, but I know W controls the furnace so I think it's unlikely to work with 4 wires if your tstat needs a a common. If you don't need the common on your stat I'll take a guess that they will probably just move the white wire from C to W on the tstat.
If pulling another wire is going to cost you, I'd recommend looking at the Honeywell VisonPro IAQ thermostat instead. I think it can run on 3 wires (though I'm not sure just how they manage that).
Oh, and if they make the furnace work, I'd check it to make sure the AC still works before they leave.
The IAQ uses a control board at the indoor unit, where all wired are terminated for the indoor and outdoor units. The three wires to the stat are basically communication wires. The stat sends information to the IAQ board, and the board decides what to do with the unit.
Originally Posted by garya505
I figured it was something like that. The IAQ was my second choice, and would have been my first choice if I couldn't pull new wire. This might be the best solution in this case, and it's a nice thermostat anyway.
Originally Posted by CommtechinVA
Ha ha ha! You called Sears...
Not as lean, not as mean, but I'm still a hardcore, ass-kicking, hard charging Marine! Oohrah!
I just got off the phone with the service guy that is on his way. He agrees that there really should be a wire coming out of the E/W1 on the stat. BUT, he says he is going to move the white wire from (C) on the stat to the (E/W1) terminal. His logic is that my stat has batteries and therefor does not need the Common.
My question is....
Is this a half ass solution? Does this mean that my stat will run solely on batteries? When the common is connected, is it running off of the power from the furnace (DC) that is powered by my house (AC), thus only running off of batteries when the power is out? If my batteries go dead, does that mean I have no heat or air? When I replace my batteries, do I lose all my programming?
Ultimately, should I insist that another wire is run, so I can have 5 wires instead of 4 and power the stat via the house wiring and not the batteries? He will be here in two hours (supposedly)
Hindsight being 20/20 - probably wouldn't do it again, but they had no interest no payments for a year, and the unit has a 10 year warranty. I am hoping that Sears can make it though this economy. I was leary of some of the local shops that came out to give an estimate as I wasn't sure they would be around to do any warranty repairs.
Ha ha ha! You called Sears...
Now, had I known that this warranty == headaches - I would have gone with someone else.
Thank you for suggesting the option of changing out the stat and board, but I doubt they will do this since it is a warranty repair, but I will suggest it to the repairman.
What thermostat do you have? If it does "power stealing" to conserve battery life, then yes, your stat will be running on batts and they will go dead much sooner. Of course, with C-stat wired to W-furn, the power stealing may not have worked anyway. BTW, my stat does not require C to work propoerly, but needs it for power stealing to conserve battery life and enable the continuous backlight.
Originally Posted by ualr_jmjones
I suggest you read your contract to see if upgrading your wiring was part of the deal, but I doubt it. I mean, if you were in the business, would you include home wiring upgrades as part of the deal, not knowing what the wiring upgrade would cost to do? I wouldn't. On the other hand, they should have told you up front that they needed to check your wiring to see if it will support the installtion, and if it didn't, tell you what it would cost to upgrade it. If it turns out you need new wire, and they never talked to you about that, I think it would be reasonable to negotiate some sort of deal with Sears to remedy the situation. I mean really, if you needed new wiring they should have told you that BEFORE you accepted the contract.
I really doubt if they would throw in a new programmable stat as part of the deal. Personally (if it was me doing it), if the wiring change doesn't work, and they don't offer to do anything else, I would get a new stat that will run on 4 wires or less. There are other advantages to a stat like the VisionPro IAQ. For example, you can program it to circulate your air when heat/cool are not required, which can help eliminate hot and cold spots in your house. You could also run a humidifier from it.
Oh, and I would negotiate with Sears. The repair guy is probably just a contractor with little authority to give you anything much.