I’ve just moved in to a house with a gas furnace and heat pump that has 3 wires going to the thermostat - Y, W, and R. I’ve replaced the thermostat with a T2000 but when I go to configure it on alarm.com it says the configuration is not valid - “Y cannot be connected without G.”
Any ideas?
Thanks,
Alan
P.S. with the T2000 installed I can manuakky put it in heat mode or cool mode and it works correctly and the fan comes on.
It doesn’t seem to do anything in auto mode, and as explained above I can’t configure it with alarm.com.
Thanks,
Alan
Correction… auto mode seems to work too. It’s just that alarm.com won’t let me configure it. Should I configure it to have a G wire even though there isn’t one?
That’s some old wiring! The G wire is your fan control wire, industry standard is to use this separate fan control wire. A number of features on ADC-T2000/Alarm.com require it.
What your current setup means is that the fan is tied to the system kicking on. It cannot turn on independently.
I do not believe the ADC-T2000 is going to be compatible in this circumstance, but we will verify with ADC.
Commonly thermostat wire runs are pretty simple to follow. Does the current cloth-sheathed wiring run straight down into a basement to connect to the hvac? It may be the best idea to replace the wiring with a five-conductor new cable in this circumstance.
Hi Warren, I don’t think I’d be able to replace the wiring without ripping into drywall. I understand I won’t be able to control the fan independent of the furnace or heat pump turning on, but can I just have ADC automated what I can already do manually?
Is there any way to override the requirement for a G wire? Or, what would happen if I configured ADC to think there was a G wire even though there isn’t? Or, is it possible to jump one of the existing wires onto the G terminal?
Thanks
Alan
ADC indicated that while fan-specific controls would of course not work, you shouldn’t run into further issues beyond that. Logically I’d say the same. Your fan just physically cannot turn on without a call for heat/cool.
Is there any way to override the requirement for a G wire? Or, what would happen if I configured ADC to think there was a G wire even though there isn’t? Or, is it possible to jump one of the existing wires onto the G terminal?
You should be able to just indicate that a G wire exists during setup. Do Not jump a wire to G.
Let us know if you see any further errors.
Thanks Jason. I was able to configure the thermostat by indicating that the G-wire was connected, but now it does not seem to work. When I set the heat or cool setpoints outside the current range I can hear the relay click on the thermostat, but neither the furnace nor heat pump turn on.
Also, although the website and android app seem to be in sync with the physical thermostat, when I try to view the thermostat on the GC3 I just get a spinning wheel. After a bit the wheel goes away but nothing else appears on the screen. I tried removing and re-adding the device by bringing the GC3 a few inches from the thermostat but it’s still happening.
Thanks,
Alan
Hmm, well that is interesting. That error message may in fact indicate true incompatibility. I wouldn’t recommend continuing to try if there is an issue. Let’s troubleshoot the basics first:
Did you remove power from the system before removing and rewiring the T-stat?
Did you power the system back on after? (by circuit breaker or switch on the circuit if there is one)
You say you have a furnace and a heat pump. If you have a heat pump, that should be selected in configuration, and you would also have a changeover wire. A 3-wire config would not be correct for that. Can you confirm what model of heating and cooling devices you have?
Oops, no, I did not turn off the power before rewiring the stat, but it did work fine manually with the T2000 until I configured it through alarm.com. It seems the thermostat itself is compatible with my system since it worked before, but after configuring it through alarm.com it somehow is now mis-configured.
The furnace is a Trane model TUX080C942D3 and the AC is a Trane model 4TTR3036G1000N.
Thanks for all the help,
Alan
Always make sure to cut power to the HVAC prior to making physical changes or rewiring. Blown fuses and system damage can result.
Also, one last thing before we move on, how long did you wait to determine whether or not the system turned heat or air on or off?
We can try to resend defaults to the tstat and see if that returns local function. Would you like us to send that now?
If that does not work, I would strongly recommend returning to the previous Tstat for now. We can discuss with ADC and figure out what is inhibiting function, but the ADCT2000 will be set up through Alarm.com and a number of fan settings cannot be disabled and may be interfering. Logically the Tstat would just fail to kick on the fan, but there may be a check which inhibits running the Tstat if the blower isn’t running.
Thanks Jason, yes please try to resend the default if that might help. I was waiting at least 5 minutes after changing the setpoint to see if the system turned on.
Thanks,
Alan
Actually there is another issue here to resolve before we can troubleshoot further (and may resolve this). I just checked again and your panel is on 3.0.0 launch firmware. It needs to be 3.0.1 for the ADC-T2000 to function properly.
GC3 firmware is applied via usb drive. You can find firmware links and info here.
Thanks, just to confirm, I also see 3.0.2 posted. Should I install that or 3.0.1?
3.0.2 would be fine and includes updates from 3.0.1
OK, updated and system info confirms 3.0.2. Might it be worth removing and re-adding the tstat now?
Yes. You will need to remove and re-add.
Once that is complete, let us know if you see any setup questions again on Alarm.com. You can then test through Alarm.com. The panel firmware should no longer play any factor.
I removed and re-added the tstat, and then configured it on alarm.com. Afterwards, it still did not control the furnace or AC, and when I viewed the tstat screen on the GC3 it was empty. I could see and control the tstat from alarm.com and my android app though.
I cut the power and re-installed the old tstat, and now the furnace and AC are working.
I’d really like to get the T2000 working. Any other ideas?
Thanks,
Alan
I cut the power and re-installed the old tstat, and now the furnace and AC are working.
I haven’t heard confirmation yet, but I would bet that there is a check going on for fan functionality prohibiting further usage. It is likely preventative to ensure the system does not continue running with a malfunctioning blower.
We’ll discuss with ADC and see if there are any other options. It may come down to requiring updated wiring.
Thank you for looking into this. Also if it helps, I noticed when I reconnected the old Tstat that it had R and RC jumpered together.
Alan
Hi, have you had a chance to find out from ADC if there any other options? I need to decide whether or not to return the T2000.
If I do, would a Nest thermostat work instead? According to https://nest.com/widget/compatibility/ it says it will work with the 3 wires I have, but would it work with ADC or would I have the same problem?
Thanks,
Alan
