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yani · Aug 22, 2009, 09:37 AM

Hi,
Started noticing these issues with our 7 years old Honeywell chronotherm IV plus thermostat recently - it works fine for a while and then starts making these continuous clicking noises - and then the thermostat display fades and thermostat turns off. Our repairman replaced the thermostat and now the new one with the same model and now the new one has started doing the same stuff. The only way I have figured out to stop this cliking noise it turn off the system, wait for a while and restart it. However, the clicking noise reappears :confused: BTW, Our heating cooling unit is at least 7 years old now.

Any suggestions/ideas is very much appreciated.

Thanks in advance.

hvac1000 · Aug 22, 2009, 09:57 AM

Our repairman replaced the thermostat

Did the repairman check for any low voltage condition problems before replacing the thermostat? If not that should have been done before replacing the old thermostat since I believe a low voltage problem is causing what is going on with your system.

That is not to say that the old thermostat has not seen better days but as you can see for yourself even with a new thermostat your problems are still there.

It would also be nice if you would supply the Complete model number for the thermostat and subbase if so equipped.

yani · Aug 22, 2009, 10:08 AM

Thank you for replying. I did not see the repairman check for low voltage conditions - he replaced the transformer - told me that transformer (near the unit in attic) was busted and hence no power at the thermostat.

The details on thermostat are T8611 Honeywell Chronotherm Plus IV. I do not see any numbers quoted on the unit as model number - however there are some number imprinted on both thermostat and subbase. They are T8601D2019 0249 and 32207415-024 0249 respectively.

Thanks again for your help.

Originally Posted by hvac1000

Our repairman replaced the thermostat

Did the repairman check for any low voltage condition problems before replacing the thermostat? If not that should have been done before replacing the old thermostat since I believe a low voltage problem is causing what is going on with your system.

That is not to say that the old thermostat has not seen better days but as you can see for yourself even with a new thermostat your problems are still there.

It would also be nice if you would supply the Complete model number for the thermostat and subbase if so equiped.

hvac1000 · Aug 22, 2009, 11:30 AM

Here is a link to your stst. Down at the bottom are DL's for manuals etc.

Product

If he told you the transformer in the attic was busted as you say then I guess he replaced it.

The VA (volt amp) rate of the new transformer could be to small allowing low voltage to cause the problem OR my real opinion of your problem is that some device that uses the 24 volt circuit is drawing too much current causing the thermostat to experience problems.

BTW the thermostat you said you just replaced is obsolete. Just thought I would let you know that fact. As long as it was new when installed it should be OK.

Are the batterys in the new thermostat new if your model uses them?

You might have to call another repair person to

Check the current draw on the 24 volt circuits of the HVAC system.

Check all the wiring for good connections and possible damage that could be causing your problem.

With your problem showing up so soon after being fixed there is a definite problem with the low voltage supply somewhere along the line. Since I am not there I can do not testing and that is your next step. Good luck.

yani · Aug 22, 2009, 05:45 PM

You are definitely right about this. About a month ago, we replaced one of our a/c unit with a higher seer a/c unit (we have two - one for each floor). With that I wonder if the power requirements have changed enough that it needs me to get the wiring checked out if it is sufficient. We do have some power issues in the house - we cannot use microwave and another high amp appliance at the same time without tripping the breaker.

The thermostat does not require any additional battery power other than what it pulls from its hookup.

Thanks again for your input.

Originally Posted by hvac1000

Here is a link to your stst. Down at the bottom are DL's for manuals etc.

Product

If he told you the transformer in the attic was busted as you say then I guess he replaced it.

The VA (volt amp) rate of the new transformer could be to small allowing low voltage to cause the problem OR my real opinion of your problem is that some device that uses the 24 volt circuit is drawing to much current causing the thermostat to experience problems.

BTW the thermostat you said you just replaced is obsolete. Just thought i would let you know that fact. As long as it was new when installed it should be OK.

Are the batterys in the new thermostat new if your model uses them?

You might have to call another repair person to

Check the current draw on the 24 volt circuits of the HVAC system.

Check all the wiring for good connections and possible damage that could be causing your problem.

With your problem showing up so soon after being fixed there is a definate problem with the low voltage supply somewhere along the line. Since I am not there I can do not testing and that is your next step. Good luck.

hvac1000 · Aug 22, 2009, 06:15 PM

The thermostat may not require a battery but put some in and try it if the thermostat takes batterys.

yani · Aug 30, 2009, 04:28 PM

Looks like this issue is resolved - the circuit board up in at attic (near the transformer) was busted - it was replaced and system seems to be working now - been working for last 4 days. Voltage checked out OK too.

Originally Posted by hvac1000

The thermostat may not require a battery but put some in and try it if the thermostat takes batterys.

hvac1000 · Aug 30, 2009, 05:16 PM

Good deal. It seems from your post that the circuit board was causing the low voltage problem so your old thermostat that the repairman replaced is probably still good. I would keep it around as a spare.

thesomani · Jan 1, 2013, 07:06 PM

How to bypass the thermostat?