My very own thermostat thread

[jacdx]

Hey all,

One of my thermostats (only a few months old) has begun acting strange. It's in my master. One night while up late, I noticed that the backlight was flickering/flashing (like the lights in Super 8). I figured there was a loose connection, so I pulled it off the wall, checked the pins, checked all the wires, everything was tight. Put it back on, everything was fine for a few days. Last night the backlight came on again, then went off. It seemed to click off then on twice. I noticed this double clicking a couple of times more this morning. Later this morning, I noticed that the screen was blank and the heat was on. I nudged it a little to see if it was seated properly, no effect. Unresponsive to button presses. Pulled it off, put it back on, all better again. I have no idea if the heat would have been on runaway if I hadn't caught it. Is there any safety mechanism to stop the furnace if the thermostat craps out?

Power stealing is turned off, common wire in place from Day 1, running 2.11.

Is this thermostat on it's way out? Is it a safety hazard as-is?

Thanks,

-J

[TexasBill]

I had a very similar issue over the Thanksgiving holiday. In my master as well - if you take the battery out does it go completely blank? Mine was eating a battery every 24 hours. It was a bad thermostat and had to be replaced. It was not indicating that it was on battery.

Hope this helps.

Bill

[jacdx]

I tried taking the battery out. It acted fine at first. Later, I came in and it was dead/blank. Then I left it for a few minutes and it came back on...

[TexasBill]

I tried taking the battery out. It acted fine at first. Later, I came in and it was dead/blank. Then I left it for a few minutes and it came back on...

I worked on this with my dealer for several weeks - the upshot of it was that the thermostat was dead/doa/defective and I got a new one free. I suggest that you try the same route.

Bill

[jacdx]

Resurrected!

So I did as you suggested TexasBill and went for the RMA. Tech Support came to the same conclusion after a few basic tests (that I'd already done). I installed the new one and it has been working perfectly...until this week!!!!!!!!!!! The other morning, I woke up and it was cold, thermostat set to "Off". This is odd, since it's fully programmed, I don't mess with it. In fact, I have buttons locked so it can only be set via Navigator (which only I use).

Another night, I noticed the furnace was having a really hard time heating up the room to the target temp (7 degrees). It would kick on, heat a degree...then shut off. Rinse repeat. That sounded like a furnace issue, so I checked/cleaned the burn sensor on the furnace (pretty clean already). I triple checked the thermostat wiring at the furnace, too.

Fast forward to today. I come home, it's cold again. This time is was still on "heat" but set to the lowest programmed temperature in the schedule. And the date display says May 2000. So it either missed a scheduled event or it's defaulting somehow.

In Network Manager, I see that it's Boot Count is 461, Reboots 89. This has been installed a month. Obviously this is a problem. My other thermostat is working fine...and has a typically low Boot Count. And FYI, Low Power is false and it shows 'Externally Powered'. T-stat wire was re-run just for C4.

Both furnaces are Bryant Plus 90's, 5 years old. Any ideas?

...getting frustrated.

-J

[TexasBill]

Resurrected!

So I did as you suggested TexasBill and went for the RMA. Tech Support came to the same conclusion after a few basic tests (that I'd already done). I installed the new one and it has been working perfectly...until this week!!!!!!!!!!! The other morning, I woke up and it was cold, thermostat set to "Off". This is odd, since it's fully programmed, I don't mess with it. In fact, I have buttons locked so it can only be set via Navigator (which only I use).

Another night, I noticed the furnace was having a really hard time heating up the room to the target temp (7 degrees). It would kick on, heat a degree...then shut off. Rinse repeat. That sounded like a furnace issue, so I checked/cleaned the burn sensor on the furnace (pretty clean already). I triple checked the thermostat wiring at the furnace, too.

Fast forward to today. I come home, it's cold again. This time is was still on "heat" but set to the lowest programmed temperature in the schedule. And the date display says May 2000. So it either missed a scheduled event or it's defaulting somehow.

In Network Manager, I see that it's Boot Count is 461, Reboots 89. This has been installed a month. Obviously this is a problem. My other thermostat is working fine...and has a typically low Boot Count. And FYI, Low Power is false and it shows 'Externally Powered'. T-stat wire was re-run just for C4.

Both furnaces are Bryant Plus 90's, 5 years old. Any ideas?

...getting frustrated.

-J

My understanding is that these thermostats has a high initial failure rate - I would again contact technical support and get a new thermostat - what my dealer did on mine was to trade thermostats and see if the problem followed the tstat. It did. It was easy to get a new one. It sounds like you are having simply a bad run of luck (IMHO). Now - iyou do TWO MORE and they all fail on THIS furnace - then possibly you have a bad power supplying it? Or something is CAUSING the TSTATS to go bad?

Once my bad one was replaced I have had no issues with it - Now My JANDY controllers and drivers - are simply driving me to drink... <grin>

Bill