I have a Taco 006-BC4 hot water circulator pump installed on a mechanical timer and its been working fine. However, I would like to install a Honeywell L6006C Aquastat to drive the pump so I could eliminate the timmer. The aquastat will only be working with the hot water circulator pump. It appears that I would only use 2 of the 3 terminal screws of the aquastat. I am looking for some help with the wiring of the aquastat to turn the pump on/off? Also, what would be considered typical high, low and differential temperature settings to start with? I greatly appreciate any help. Thanks!

1 Answer 1


I looked at the instruction manual for the switch, and it says:

Switching action is as follows: Upon a drop in boiler water temperature (to dial setting, less differential), makes R to B burner contact; breaks R to W contact, preventing circulator operation. Upon a rise in boiler water temperature (to dial setting), breaks R to B burner contact, makes R to W circulator contact.

Manual link

That said, I don't know much about how the circulator should work, and what temperatures to set, but if you want the pump to come on when the temperature drops, you would wire it to terminals R and B and if you need it to come on when the temp goes up, it would be terminals R and W. One is typically meany for heat (B) and the other for a circulator (W), but your installation might be different.

  • Perfect, you clarified it. Yes, I would want the pump to come on if the temperature drops so I will use terminals R and B. I will initially set it at 120 with a differential of 20 and see how that works out. If I understand it correctly, at these settings, this would turn the pump on when the water temp drops down to 100 and shut it off when the water temp get 120. Thank you for the assist!
    – Nickrnm
    Mar 27, 2020 at 19:48
  • @Nickrnm, glad to help, and welcome to the site. Upvote answers that help you and after a day or so, accept the answer (check mark) that helped the most. We typically don't accept answers immediately because someone else could come along and give a better answer.
    – JPhi1618
    Mar 27, 2020 at 19:54

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