Thermostat just 'died?!' Honeywell CT3611

Old 11-19-05, 10:35 PM
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Question Thermostat just 'died?!' Honeywell CT3611


[don't you hate it when you type your whole post & then it tells you you're not logged in?!]

I installed a Honeywell CT3611 electronic programmable thermostat in my condo about 4 years ago, and it worked fine (with my 20 year+ old Carrier heat pump) until this morning. Screen dead, no red light indicating heat pump failure. I fiddled w/the unit, unmounted it, checked/tightened wiring connections, re-seated it & it powered up. Phew!! Only for a few minutes, though, as it went dead again as I started reprogramming the clock. Came back on again for a minute, then went dead completely. No amount of nudging got it to come on again. No circuit breaker issues, but I don't know if there's a fuse in the thermostat itself (I couldn't find one.)

As it's gotten really cold here in the mid-atlantic, I was lucky I'd saved the original (carrier) mercury-style thermostat. I reinstalled that & it's working fine now. Heat pump seems to be doing its usual job.

My concern, prior to rushing out & buying the latest programmable thermostat to replace the 3611, is that maybe there's something deeper here, given the age of the wiring in my condo and age of my heat pump. Does anyone think either of these could 'fry' an electronic thermostat which has worked flawlessly for 4 years, or do you think the 'stat just died? I did open the thermostat & do visual inspection/blow out any dust I saw (the extent of my electronics repair/diagnostic capabilities). Only thing I noticed is that one of the pins/prongs on the wall plate seems darker than the rest, and its female receptacle on the thermostat box itself also seems darker, maybe even wider. As if some kind of short happened and something overheated. But not enough to really look bad.

So, has anyone heard of these programmable thermostats just dying after a couple years of normal operation? I searched the forum & googled, but the only issues I've found are people's wiring questions. Before I invest another $100+ in a programmable unit and lose even more precious millemeters of already-short wires while installing it), I wanted to check w/the folks who seem to know about these things! Thanks in advance for any advice!
Old 11-20-05, 04:19 AM
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You might inspect the circuit board very closely for anything tha catches your eye. My thermostat failed a couple of years ago in a similar fashion and when you looked real closely at the circuit board you could see where one of the little components on the board had failed - some discoloration and a contact wire broken/corroded/melted.
Old 12-21-05, 07:06 PM
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Same Here

I have the CT3611 as well. I've had it less than a year and now it is completely blank like it doesn't have power. Any luck with any solutions besides purchasing a new one?
Old 12-23-05, 06:31 PM
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I am not familiar with this tstat but there are 3 possible causes. No power to the thermostat, bad batteries in the thermostat, or a blown fuse in the thermostat or on the control board in the air handler. In the latter there will be no power to the thermostat. I guess there is one more possible cause. A bad thermostat!
Old 12-26-05, 11:56 AM
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Well, it's been awhile. I've been operating with no problems using the old mercury-type thermostat with no problems. Of course, i tend to forget to adjust it down when I'm away/sleeping, and my heating bill has gone up up up (whose hasn't, this year?!)

My mom was kind enough to get me a new Honeywell touch-screen programmable unit for Christmas, and I'm thinking about tackling that project today, but still haven't figured out what's wrong with the 3611. As it doesn't seem the 3611 had a fuse (or if it did, I checked it and it looked ok; it's been awhile), and there's no battery in it, I'm still somewhat concerned about my line voltage. The lights on the 3611 always seemed lower than what they should've been, though the unit worked for a couple of years. Is there a chance the voltage could be an issue, yet the old-style thermostat works fine with that?

Mom also gave me a multimeter for xmas. About all I know how to do with this thing is check the voltage on a household battery. Stepdad is an engineer but isn't here to show me how to measure line voltage on the hvac wiring - anyone care to enlighten me?


PS - From what I've read, the touch-screen Honeywell unit will provide me with hours of fun and confusion!
Old 12-28-05, 04:09 PM
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technology, you gotta love it


take the 3611 and place it with any amount of force that will make
you feel like you have got back at the tech gods that be, in to the nearest
trash container, it has died, met it's maker, seen better times, you get the message. the electronics in these HIGH tech devices are very sensitive to
any type of power surges, brownouts (low voltage). thats why i recommend to my customers to cutoff their heating/cooling at the main service (breaker box etc.) as well as they do thier computers when a bad storm, or when a power-
outage has already happened, and wait for an hour at least until the power grid has had a chance to stabilized. i hope the thermo that mom got you for
christmas has an option that allows manual control to turn the unit back
on once power has been restored to the home if you are away. also note, that most heatpumps
and air handlers also have very delicate electronic, they can be fried in the same way. ........ sorry for the delay but i was re-reading your latest post.
with the old thermo. working well i would'nt be so concerned about the
voltage they basically work or they don't (as long as they are properly wired).
i'm not about to tell you how to check voltages on this subject because
i don't think it is a problem, and i don't want you to blow your transformer.
ps, if you ask most hvac guys out here they leave their systems on at a set temp. thru-out the year and dare anyone to touch the thermo. it's a control thing. i hope some of this helps, and happy new year!
Old 12-28-05, 06:05 PM
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Yep, I get so sick of adjusting, programming and fine tuning thermostats for customers that I have a very simple non programmable and i NEVER touch it.
Old 10-17-06, 06:51 PM
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Problem with Programmable T-Stat

I have a Honeywell ct3611 which has been stored since I got it a couple years ago since it had a problem not turning off my "emergency heat" when the stat "clicked off"
Today, I decided to give it a shot by bypassing the external circuitry between the stat and the furnace to see if that was the problem.
It seems to be working turning on and off now.
Now, my problem is that it only seems to handle the up / down heat and the main settings, but wont let me program the time/day, etc. It only flashes the screen when I try to hit the button.
I am going to try to call honey well tomorrow.
What do you think? there is no battery in this model that I know of. the back light seems to work ok, and the temporary temp settings work.

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