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Honeywell AQ475

zjfish78 Member Posts: 1
1st post and hopefully it makes some kinda scene. Just had the service guy here which seamed to be very knowledgeable. Says the AQ475 needs to be replaced. When we go through the test cycles buy hitting the red test button it makes domestic hot water. That was the reason for the service call, Ice cold shower before work! With out hitting the test button it will not tell the boiler to turn on to create the hot water. The AQ475 has the call for heat led on at all times. If I hit the test button 3 times it fires the boiler. from my understanding all test cycles are working as from what I'm understanding from the manual. The AQ is Also wired through a Argo Industries AZ-4P zone valve control that the tech said is not the problem. Just trying to figure out what it could possible be before going to try and locate a new AQ475 tomorrow. The only trouble shooting the book gives you is out door sensor or supply sensor fail.Which says to replace the sensors.Or self test sequence error, which is replacing the control. Now it says that the control attempts to operate normally, But both the Call for heat and Boiler LED's will flash.I have no flashing LED's at all. My power test, WWSD & Call for heat LED's are constantly lit. So Im lost but and a little confused! Any Ideas or clues are greatly appreciated!


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Did the service guy explain/show you why the control needs to be replaced. IOW, if the control is calling for heat, there should be power coming off the proper terminals to the zone controls and/or boiler. If not, then yes the control would need to be replaced. If so, more investigation is needed.

    There was an error rendering this rich post.

  • Ironman
    Ironman Member Posts: 7,399
    Do you have an indirect water heater or a tankless coil in the boiler? If you have an indirect, was its aquastat calling for the boiler to heat it.

    More info is needed. You can't simply diagnose the control without looking at everything connected to it and without knowing how it's setup.

    Here's a link to the instructions:
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.