Trouble with Honeywell RTH221B T'stat

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Old 04-13-14, 10:48 AM
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Trouble with Honeywell RTH221B T'stat

I have noticed several times that my Honeywell RTH221B thermostat loses the time of day. The time display flashes and the temperature setting defaults to the "Monday Wake" setting. The manual makes a note of this condition on page 6 and states that it will continue in that mode until time and day are reset. No potential causes are given anywhere in the manual including in the Troubleshooting section.

The first time this occurred I thought the batteries might be low even though the Lo-Batt was not flashing so I changed the batteries and reset the time. The condition occurred again about a month later for no apparent reason and I reset the time.

Yesterday I tried to make a temporary change to the temperature and when I pressed the Up button the display went blank. I pressed the Up, Down, Run, Hold and Set buttons to try and restore it but with no result. After several seconds (and no more button pushing) the display came on again with the time flashing and I was able to reset the time. The programming was not affected and all the correct times and temps were still there.

(Side note: There is no AM/PM indicator on this stat when it is in 12 hour clock mode, so when I reset it the time was 12 hours out of sync with the programming and last night I noticed it was in Wake mode when it should have been in Sleep mode. I thought the problem had re-occurred but it was too late to troubleshoot it so I just set a Hold temp for the night. This morning I realized the reason for the discrepancy and resolved it by setting the time 12 hours ahead.)

This thermostat is in a greenhouse and is subject to ambient conditions of 50-100 degrees, 30-98% RH. The manual does not list any specs for temp and humidity limits. Because the plants need different day-night temperatures the settings are 65 day and 52 night.

Has anyone else experienced such problems with programmable thermostats? Is anyone aware of a problem with this particular stat? It is past the 1-year limited warranty so unless there is a recognized issue with this model I will probably have to buy a new one.

Thanks for your feedback.
 

Last edited by NJT; 04-14-14 at 03:38 PM.
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Old 04-13-14, 10:03 PM
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It could be just caused by the high humidity in the greenhouse.

Try this first..... remove the batteries and clean the battery contacts with a pencil eraser.
 
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Old 04-14-14, 08:20 AM
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hi 2john-

I have the same exact problem with one of my RTH2218 thermostats (I have two). Sometimes the screen goes completely blank then comes back on if you play with the buttons or open it up. Lo-Batt is not flashing but I replaced the batteries anyway - and that had no effect. I donít think it loses any of the parameters, however a time reset is required.

I just leave the time flashing and donít bother to reset the time. (And I never use the programming mode anyway, but I had set up a program which Iím almost positive is NOT lost when the screen goes blank. But Iím not 100% sure.)

This stuff is junk.

p.s. I think I checked the battery contacts, I always do with problems on devices, but I'll double check.
 
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Old 04-14-14, 08:51 AM
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zoesdad: Thanks for telling me about your experience. How old are your t'stats? Mine is about 3 years old.

I have cleaned the battery contacts as PJmax suggested. We'll see if that makes a difference.

I have to rely on the programming in this thermostat to provide the daily warm-cool cycle that my wife's orchids need to bloom so I cannot ignore the time setting.

I hate to find in the morning that it has defaulted to the higher temperature overnight--both because of the plants and because of the gas usage! Now that the weather is warming up I will soon be able to turn the greenhouse heat off completely and monitor the time setting without burning gas.
 
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Old 04-14-14, 09:05 AM
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I'll just throw this out there as something to rule out. I had a similar problem with reset/no display and after some testing I found the thermostat was wired in series with the boiler high limit. When the limit was hit--which was every time I called for a large temperature increase--the thermostat power would be interrupted until the boiler temp fell.
 
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Old 04-14-14, 09:18 AM
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My thermostat is also the RTH221B (not the 2300 as I thought). If there are enough of us out there with the same problem maybe we can force an extended warranty replacement.

(Note to Moderator: Can you edit the title of the thread to reflect the correct model number?)

I called the 800 number listed in the manual and on the back of the thermostat. The call center lady could not find a reason or a solution to the problem even though she made several consultations. Since my latest occurrence was about a month after the previous, her suggestion was to check it again in a month and if it occurs again to consider that the thermostat is failing and replace it.

No suggestion that they would replace it. (It was worth a shot and only cost me 15 minutes of my time.)

In the meantime I think I will re-program the Wake time to the lower temperature and follow that with a Leave setting a few minutes later for the daytime temperature. That way if it loses the time setting overnight it will default to the lower temp and not be burning gas or screwing up the bloom cycle.

Good suggestion Guy and may be helpful to anyone that has a stat powered from the boiler. The RTH221B is battery powered so that is not the problem with mine.
 
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Old 04-14-14, 02:14 PM
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Oh crap on a cracker, I need new glasses Ėagaaain! My tístats are in fact RTH221B not RTH2218. Iíd like to junk that tístat. Makes me nervous. Every time I walk by I look for the blank screen. Afraid that a need for heat will go un-serviced. Canít tell what is going on when the screen is blank.
 
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Old 04-15-14, 09:25 AM
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How old are your t'stats? Mine is about 3 years old.
Sorry 2john. I missed that question. I usually keep good records but I can't find one for those t'stats. But I'm almost positive they are more than 3 years old. I think maybe more like 5? Not sure.
 
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Old 12-19-14, 11:07 AM
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I forgot that I had posted this. The problem has not recurred.
 
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