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General => Temperature Monitoring & HVAC Control => Topic started by: mbairhead on March 01, 2011, 10:44:08 pm

Title: WDC-20 Thermostat issues, possibly dead
Post by: mbairhead on March 01, 2011, 10:44:08 pm
I came home from work a few days ago and both of my WDC-20's were "off", meaning the screens were blank and the house was cold. I pulled them both off, replaced the batteries, stuck them back on the wall and everything seemed fine except Vera lost them both. I wasn't surprised by this nearly as much as having both of them go the same day. I spent an hour tonight trying to exclude/include them, reading the directions, searching this forum and I'm not able to get Vera to recognize either of them.

I'm willing to accept that they could be dead but before I pull out my pistol and put them totally out of their misery (and mine) and buying a couple Trains I wanted to make sure I'm not missing something.
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: yovinman on March 02, 2011, 02:24:32 am
It sure sounds like they both lost their 24v power. Have you checked the wiring and the transformer on the furnace to make sure it is outputting the correct voltage?
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: mbairhead on March 02, 2011, 05:50:11 am
I have not but have lost power a few times recently. I should add that these have both been installed and working flawlessly for over a year now. In fact, they seem to be working fine now other than seemingly to have lost z-wave capability.

I'll pull them off tonight and test voltage to be sure though
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: oTi@ on March 02, 2011, 06:41:25 am
I have not but have lost power a few times recently.[...]
I'll pull them off tonight and test voltage to be sure though
You mentioned the screens were blank and after changing the batteries everything was fine, except you can't get Z-Wave to work.

That sure sounds like there is no 24VAC to the units, as yovinman stated.

You should be able to operate the tstats without batteries. The batteries are only there as a holdover to maintain target temperature during a power outage, they don't power the Z-Wave radio.

So see if stuff works without batteries. If it doesn't, check the wiring/power to the tstats. There should be 24VAC between RH and C.
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: mbairhead on March 02, 2011, 07:30:49 am
I have not but have lost power a few times recently.[...]
I'll pull them off tonight and test voltage to be sure though
You mentioned the screens were blank and after changing the batteries everything was fine, except you can't get Z-Wave to work.

That sure sounds like there is no 24VAC to the units, as yovinman stated.

You should be able to operate the tstats without batteries. The batteries are only there as a holdover to maintain target temperature during a power outage, they don't power the Z-Wave radio.

So see if stuff works without batteries. If it doesn't, check the wiring/power to the tstats. There should be 24VAC between RH and C.

I'll check it out when I get home tonight but it seems equally as unlikely that both furnace/air handlers suddenly broke as it does that both thermostats did.
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: oTi@ on March 02, 2011, 07:44:03 am
I'll check it out when I get home tonight but it seems equally as unlikely that both furnace/air handlers suddenly broke as it does that both thermostats did.
True. I had assumed it was going to the same furnace. Even then, it sounds like the house is warm. Could be on the same external transformer though (depending on your setup).
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: mbairhead on March 02, 2011, 07:50:40 am
I'll check it out when I get home tonight but it seems equally as unlikely that both furnace/air handlers suddenly broke as it does that both thermostats did.
True. I had assumed it was going to the same furnace. Even then, it sounds like the house is warm. Could be on the same external transformer though (depending on your setup).
Honestly, I don't know but the house is two years old and one furnace is in the attic and one in the basement (three stories plus and attic) so it's likely they don't share anything but an address. Anything is possible (especially with z-wave) so I'll get my tester out and see what I'm getting at the wall. They are still doing construction on my street and I've gotten hit by a couple bad power surges that nuked a few electronics that weren't on surge suppressors (I'll miss that Keureg and powered hdmi cable) so it's very possible that the furnaces and/or the thermostats got hit one time too many.
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: oTi@ on March 02, 2011, 08:40:41 am
[...] it's likely they don't share anything but an address. [...] and I've gotten hit by a couple bad power surges that nuked a few electronics [...]
I think you're on to something there. If your heat works fine right now (it sounds that way), except Z-Wave, then it could be the 24VAC input circuitry inside the thermostats that got fried / protection kicked in. May or may not be repairable.
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: aa6vh on March 02, 2011, 10:16:53 am
The batteries are only there as a holdover to maintain target temperature during a power outage, they don't power the Z-Wave radio.

That is not quite true. When I first connected my WDC-20, I miswired it such that the 24 volts was not reaching the WDC-20. The batteries ran the WDC-20 and its ZWave just fine. However, the batteries did go dead after just 2 days.
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: oTi@ on March 02, 2011, 10:54:23 am
The batteries are only there as a holdover to maintain target temperature during a power outage, they don't power the Z-Wave radio.
That is not quite true. When I first connected my WDC-20, I miswired it such that the 24 volts was not reaching the WDC-20. The batteries ran the WDC-20 and its ZWave just fine. However, the batteries did go dead after just 2 days.
OK, thanks for those facts. The manual left that open to interpretation (I don't own the actual thermostat). I guess the implication is that the problem may be bigger than just the AC input circuitry.
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: sjolshagen on March 02, 2011, 11:09:07 am
I had 3 WDC-20's installed in my house and approximately one year after installing them, two of the WDC-20's stopped drawing from the 24V source and drained the battery (in 48 hours - replaced the battery and the same happened again).

One of the WDC-20's are still working, the other two got replaced by Thrane's with _zero_ wiring modifications (obviously, the back of the thermostat wiring changed as I changed the thermostats, but the source hasn't) and I checked the voltage with a multimeter (it was at ~24V).

The Thrane's are functioning great and if (when?) the last WDC-20 dies I'll replace it too with a Thrane. Heating problems always seem to happen while I'm not at home and the wife gets to deal with the fall-out (never pretty and a "major" HA vs Wife relationship trial ;-))
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: mbairhead on March 02, 2011, 01:05:37 pm
I decided to go home at lunch and test them (well one anyway) and I have plenty of juice behind them (it). So, I just ordered two of the $98 Trane's on Amazon. Next step will be to break in my new .380 on the WD's  ;D
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: oTi@ on March 02, 2011, 01:21:01 pm
I decided to go home at lunch and test them (well one anyway) and I have plenty of juice behind them (it). So, I just ordered two of the $98 Trane's on Amazon. Next step will be to break in my new .380 on the WD's  ;D
I had a feeling this is where that was going with your tstats after the last few posts. Apparently not bulletproof in more than one way.

The Trane's are nice. No battery backup at all though.
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: mitch672 on March 02, 2011, 02:31:33 pm
Yes, but even with no battery backup, the tranes still maintain their time of day, and programming.....  How well does your heating system work with no AC power/24VAC anyway?  At least the Tranes maintain their settings without battery backup :)
Title: Re: WDC-20 Thermostat issues, possibly dead
Post by: mikemsd on March 02, 2011, 02:53:45 pm
I had one of my WDC-20's die on me too. Mine was drawing from the 24v and the ZWave radio was operating however it wouldn't update the ambient temperature. I had to press the reset switch to have it update the room temp which basically turned my thermostat into an on/off switch for my heater.

I talked to someone at Wayne Dalton and they blamed it on static discharge. The person I talked to made it sound like that was a common occurrence. I replaced my two WDC-20's with the Trane's and have been fine since. The Trane's are a lot nicer anyways. The setup is way easier as it is all in the menus and you don't have to mess with dip switches.