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After reading another thread here about digital/mechanic thermostats, I'm now planning to upgrade to wifi thermostats to replace my Builder's grade LuxPro's. Below the model I plan to get because it retails at $99.xx and there is a $100 rebate from my gas company in MA which means the cost ends up close to free.
I've read the instructions, watched the manufacturer's instruction videos and several Youtube videos on thermostat wiring. Thus I went from knowing NADA about wiring a thermostat to elementary skill level. However, a little knowledge is a dangerous thing and I need help from the wonderful people here to clarify some things before I dive in.
Background: HVAC unit a gas furnace / AC combo (single stage, I think). System is definitely not a heat pump. Current thermostats run on batteries.
I understand that the new thermostat requires a C wire which my current system does not have. So I'll need to take the existing G wire and put it into the C position at the thermostat. Plus, I'll need to open up the furnace and do the same thing as well as jump 2 of the connections together with an extra piece of wire (I need to re-watch the video to remember which 2 ). Anyway, I'm getting it so far (not bad for a newbie).
Here is where I start to get confused: According to most videos, I should have 4 wires ( W, Y, G, R/Rc ). OK, check. However, the current wiring (attached pic for you guys) has other wires beside those 4. In particular, I see B and O wires and all the videos say that B /O are used for heat pumps.... Wait-a-minute, I know it's NOT a heat pump
Question: Am I supposed to put the B and O wires back into the new thermostat even though the system is not a heat pump?
According to most videos, I (need to) have (no fewer than) 4 wires ( W, Y, G, R/Rc ).
the current wiring has other wires beside those 4.
In particular, I see B and O wires ...
Are these other wires ATTACHED at both ends now?
Not just the t-stat end but down at the furnace too?
If so, what are they connected to?
Hi Mr R - I trust you always so I'm intrigued that you recommend Not Wifi. What's the reason?
I'm a bit afraid fancy features like wifi may turn my furnace/ac on or off inadvertently. I only plan to use the wifi feature when I'm home or away for a few hours. If I'm not home for a long time on trips, I don't keep my modem/router powered anyway.
Wouldn't the T-stat work like a normal non-wifi version if it detects no wifi signal?
Quote:
Originally Posted by MrRational
Are these other wires ATTACHED at both ends now?
Not just the t-stat end but down at the furnace too?
If so, what are they connected to?
I'll go to the furnace and see how the wiring looks. Will take pics when I get there...
Just a heads up, the wifi function probably won't work as you don't have a C wire going to your thermostat. I had the same issue with mine and ended up plugging in a 24v transformer in my attic and dropping the wire down to the thermostat.
The wifi comes in handy for me as my wife tends to mess with the thermostat and then leave. Popping on the AC right before I leave work in the summer also comes in handy.
O and B are for heat pumps ONLY. Use either of the 2 for the "C" conductor and terminate at both the stat and furnace circuit board. Leave the remaining wire unused.
Taking the "G" wire and using for "C" will back fire once cooling season comes around as the stat commands the fan on with the "G" wire. The furnace board commands the fan control during heating and therefore, you wouldn't realize the problem you've created until cooling season.
According to most videos, I (need to) have (no fewer than) 4 wires ( W, Y, G, R/Rc ).
OK, here is a pic from my upper level Tstat .... notice the G is NOT CONNECTED I do see a green wire tucked into the wall hole... Is there a reason this wire was purposely left un-connected?
BTW, when I first moved into the house (2 yrs ago), I turned on the heat to the 2nd flr and nothing happened. Scared me for a few minutes but I figured out that my system works this way:
1st F Tstat is 'off': No heat or AC entirely. Even if 2nd F Tstat calls for heat/AC
1st F Tstat on 'heat' (but room temp is already warmer than setpoint) / 2nd F Tstat on 'heat' (room temp cooler than setpoint): Heat goes to the 2nd F & dampers block heat from entering 1st F.
2nd F Tstat is 'off' / 1st F Tstat on 'heat' (room temp cooler than setpoint): Heat goes to 1st F & heat goes to 2nd F (no dampers blocking 2nd F heat).
Is it a typical arrangement?
1 other thing I just learned is adjusting the 'swing' on my current Tstat. I've now set it to a higher # (default was 1) to reduce the # of cycles. However, the new Honeywell Tstats (wifi or no wifi) do not have the swing adjustment option. So I may to go with another brand that allow swing adjustment - Lux has that feature but then it's the same brand as the one I'm using that's occasionally not kicking the furnace on or off, so don't know if I want to get another Lux.
Unnecessary complication (hiding as convenience) and the added expense.
The uses you've described don't warrant either.
ok... I was only considering the wifi unit because the rebate makes it almost free. So it's actually less costly than non-wifi units. I understand that complication is not a good thing most of the time
Quote:
Originally Posted by btuhack
O and B are for heat pumps ONLY. Use either of the 2 for the "C" conductor and terminate at both the stat and furnace circuit board. Leave the remaining wire unused.
Taking the "G" wire and using for "C" will back fire once cooling season comes around as the stat commands the fan on with the "G" wire. The furnace board commands the fan control during heating and therefore, you wouldn't realize the problem you've created until cooling season.
Thank the lord you told me this Love and kisses to you. So don't mess with that G wire. I can't believe Honeywell made the video telling people to do something that's completely wrong.
Unnecessary complication (hiding as convenience) and the added expense.
The uses you've described don't warrant either.
Its only unnecessary if you think you won't use the WIFI features. I use my iPhone to control my Nest thermostats quite frequently. In addition, I hated programming my old Honeywells. Its so much easier to program a thermostat via a smartphone or PC.
Hi Fellow CDer's, I'm back with pics from the furnace (see below). I'm able to match the furnace wiring up with the T-stat wiring... but not completely. Hope you guys can help decipher what the installer did.
I gathered that the B (blue) and O (orange) wires inside the 1st Floor Tstat are not connected at the furnace. So one of these can be re-purposed as C. That means I can take the blue coiled up wire currently free at the furnace and put it on C, and also move the Blue wire in the 1st Floor Tstat from B (current position) to C (currently empty). The orange wire seems to have disappeared at the furnace. Is this correct??
What puzzles me is why there is a 2nd bundle of wires (Red and White wires indicated by the blue boxes). They don't seem to correspond to the Tstat wiring. These connect to the 'C' and 'Y' at the furnace. However, it doesn't make sense since the C isn't even connected to any wire at both Tstat's. Any clue as to what these Bundle #2 wires are for??
BTW, this is a for a 1-stage Gas Heat / AC unit. Other Related Questions:
1) When I add the Blue wire into C at the furnace, should the white wire (from Bundle #2) that's currently there stay or be removed?
2) Notice the Y at the furnace have 2 wires feeding it (one from each wire bundle). Is that legit?
3) The 2nd Floor Tstat has no G wiring. Is that legit (Both heat and AC work properly as far as I can tell)? Thanks in advance... you guys have been really helpful.
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I do see a green wire tucked into the wall hole... Is there a reason this wire was purposely left un-connected?
Love and kisses to you. So don't mess with that G wire. I can't believe Honeywell made the video telling people to do something that's completely wrong.
