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Can't adjust low limit on Honeywell AQ2000

ChrisF80ChrisF80 Posts: 14Member
edited April 2018 in Oil Heating
Hello, I recently installed a Honewell AQ25A42B Zone controller on my hot water boiler. I like the fact that it has up to a 40 degree high limit differential. However the control isn't operating the way i expected. The instructions state that it will split the differential around the hight limit. So 40 degree diff. with a high limit of 160, I would expect to operate between 140 and 180. But the control is completely ignoring the differential setting. The burner kicks on at 150 and off at 160. The 150 degree setting is the low limit setting default, which is suppose to be adjustable, but it does not come up in the menu. Can anyone familiar with this control tell me if I'm missing something. Thank you


  • newagedawnnewagedawn Posts: 549Member
    ya, read the directions, every adjustment is in there
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"
  • ChrisF80ChrisF80 Posts: 14Member
    I've read the directions many times. The low limit adjustment is in the directions, but does not show up on my control menu. That is why I am here. I attached a picture to illustrate, low limit should be right between high limit and boiler diff...
  • ChrisF80ChrisF80 Posts: 14Member
  • rwhtgrwhtg Posts: 21Member
    we have installed a lot of these controls and always leave the boiler diff set to the factory auto setting
  • rwhtgrwhtg Posts: 21Member
    if the high limit is set to 190 and a 10deg diff high limit operating range will be from 185-195
  • ChrisF80ChrisF80 Posts: 14Member
    Thanks for the response. I really wanted to take advantage of the controls high differential. The problem I am having is that the control is completely ignoring the differential setting. No matter what I set the boiler differential or the high limit to, it always uses 150 as the low setting. So high at 160 with a 40 degree differential, 150-160
    High at 170 with a 40 degree differential, 150-170. It just does make sense to me.
    So I am actually experiencing 2 problems.
    Ignoring the differential, and I can't change the low setting. Beginning to think it's defective.
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