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Simple boiler aquastat with wider differential

D107 Member Posts: 1,814
Currently has a high limit that connects with 3 Honeywell R845A1030 relays. Does honeywell have a simple aquastat/hi limit (not necessarily as involved as the L8148 relay series, since I want to keep current relays.)??

Current hi limit has only about 3-4 degree differential which brings burner on too much. looking for maybe 0-30 degree adjustable differential unit.

I had previously been advised to get AQ475 or Aquatrols but I'm not looking for outdoor reset on this old boiler, just a greater differential.




  • Tom Hopkins
    Tom Hopkins Member Posts: 552

    about a Beckett Heatmanager? If it doesn't save you 10% Beckett refunds your money.Hard to beat that deal.If you don't like that use a L4006 with an adjustable diff. I don't know the suffix off the top of my head
    I would use the AQ2000 with it's post purge feature you can basically eliminate standby loss between that and the ODR the payback wouldn't be long at all.

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  • D107
    D107 Member Posts: 1,814
    thanks, that's what I was looking for

    I'm sure once the function of the L4006 can be defined, the particular suffix can be gotten. Basically with this old way oversized boiler--which I hope to replace in five years--I'm looking for simplicity, not even ODR. The L4006 and 4007, 6006 comparisons are a little hard to follow for me, some break, some make on temp rise.

    Function would be:

    I believe the existing hi-limit would remain, and the new L4006 would, on a t-stat call for heat, fire the burner and start the circs, then cut the burner at hi limit (say 170) but if there was still call for heat in any/all zones, permit circ operation until water temp dropped to lowest differential setting, say 150, at which point, if any/all of three t-stats still called for heat, burner would fire again. There should be no need to add relays, as I already have 3 Honeywell R845A1030.


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