Honeywell Programable Thermostat filter reset

CT3600, CT3611, CT3500, CT3595, CT8602 Thermostat Filter reset addendum

I purchased and installed a Honeywell CT3500 programmable thermostat last year. It works very well and I am satisfied with it, however, after a few months an annoying “Filter” message began to blink at me. Since I have a baseboard hot water system (hydronic), I do not have an air filter, so I don’t need a reminder to change it. The owner’s manual does not say how to reset or defeat this function. I dug through the box and found an addendum to the owners manual that gives all the information needed.

Reset the filter timer by pressing the “i” key until the expired timer is displayed, then press the “Time up” key to reset it. After you are done, press the Run Program key.

To defeat the filter timers, see picture of addendum below.

Honeywell CT3500 manual addendum

Honeywell CT3500 manual addendum

Click on image to get a larger, readable .jpg.


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24 comments to Honeywell Programable Thermostat filter reset

  • Stewart

    Thanks for posting this — no info at Honeywell’s site that I could see!

  • No trouble at all, Stewart. I had to dig through my pile of manuals to find the addendum, fortunately, I did not throw it out.

  • Ed


    Another “thank you!” for posting this. My wife and I bought a house that had one of these installed. The Honeywell site is very poorly constructed, and as far as I can tell, still does not have this info. It was great to finally get rid of that flashing light. :)

  • mkk

    Thank you for the information on resetting the flashing filter message, this was very helpful information.

  • jody

    thanks for this post…my husband and i bought a house too with thi and honeywells wedsite and customer service line isnt good at all.

  • Danny

    Thank you for posting this information. That flashing filter message was bugging me!

  • Steve

    Thank God for the web. So many times good people care enough to post how to fix annoying things companies do or (don’t do) in this case.

    Thank you very much for this thread.

  • denise

    Thank you soooooooooooooo much!!!!

  • Bruce

    Wow, I’m glad you posted this. I bought a house 2 months ago with the flashing filter reminder. I had the manual, but no addendum. THANKS

  • [...] What make and model is your thermostat? Here’s one reset solution for a Honeywell Thermostat. I don’t know if yours has an "i". This is how I reset mine. Honeywell Programable Thermostat filter reset | Homeowner’s Blog [...]

  • Elizabeth

    Thank you for posting this – The informaiton was still not available on Honeywells website.

  • A big thanks for posting this, mine has been flashing for 3 years and I finally got tired of seeing it and decided to Google a fix. This was the first hit and fixed it right away. Thanks for taking the time to post this.

  • Jack Goodspeed

    Thank you for this information, Paul. Like Bullfrog I’ve been watching my “filter” indicator flashing at me for about three years and it finally drove me crazy enough to email Honeywell for instructions after nearly memorizing the manual that came with the unit. So far they haven’t answered back. You’re a lifesaver!

  • Sal

    I bought this thermostat 5 years ago and while I have the original owner’s manual, I couldn’t find the addendum. I remembered there was one, just couldn’t find it as it wasn’t with the owner’s manual. Anyway, I had to make a slight change and I didn’t know what feature number 43 was. Thank you so much for taking the time to post this; I saved a copy on my hard drive for future use. Thanks again!

  • Previously Frustrated Now Happy

    I couldn’t change the number of days on my filter timer, but this information allowed me to reset it and get rid of the flashing “filter”. Thanks to you, Paul!

  • Jim

    does anyone know how to reset the filter on honeywell model
    32207501-002 rev.c I do not have the manual and would appreciate any help offered, Thanks

  • Ted

    Thanks this was so helpful; fixed the problem with the blinking filter reminder right away. You’d think this information would be on the Honeywell website, but I couldn’t find it.

  • Alan

    Thanks once again. Honeywell site has manuals but you have to get model number off the back of the unit. I just finished reprogramming the times and temps after replacing the batteries, and I didn’t want to do it yet again. I have two suggestions to honeywell and other vendors. (1) put model number where it can be seen (e.g. on the fold down panel), and (2) add Reset Filter operation to the hints on that fold down panel.

    Thanks again!

  • Irene

    Thanks very much for posting this info, Paul! I couldn’t find anything in the booklet but saw your post and found the addendum… Flashing “Filter” all gone :)

  • Thanks for the Post, I own the ct 3600 Model and this Problem has been bugging me for a long time. Thanks for the link to the Pdf File. It was rather simple to fix.

    thanks Again for the tip.

  • MLB

    Greetings, Paul,

    Thanks so much for your kindness in posting this useful information for those of us who found the need for it. I truly appreciate persons like you, Paul, who give of themselves and who take the time and who make the effort to share their knowledge and expertise to allow others to benefit. Thank you!

    You can find and save the following two “Guides”:

    The Honeywell CT3600, CT3611, CT3500, CT3595,CT8602 Thermostats User’s Guide Addendum

    Honewell Document 69-1583-1 G.H. Rev. 05-02, is now posted at:

    The Honeywell Document 69-1081—3 J.H. Rev. 11-01, which is the
    Honeywell CT3611 PROGRAMMABLE THERMOSTAT User’s Guide, is now posted at:

    With Very Best Wishes,
    Thanks again,

  • FrankO

    Paul, you rock! Finally got rid of that annoying blinking warning.
    Thank you, thank you, thank you.

  • Kayla

    Thank you very much for posting this! I had an A/C guy come out and he didn’t know how to do it either.

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