Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Pump Control Based on OA

Matt_49 Member Posts: 4
I have a hot water heating system with two constant speed pumps set up in a lead lag control fashion. No DDC, all stand-alone controls. During very cold days, when all the control valves open, I get a very large supply and return water delta T and not enough heating capacity. I would like to use a controller that will bring on the second pump to run in parallel based on outdoor air temp.

Does anyone know of a controller that will work?


  • Uni R_4
    Uni R_4 Member Posts: 6
    Johnson A419

    What about a simple setpoint controller like the A419?
  • Brad White
    Brad White Member Posts: 2,398
    That or a Ranco ETC

    Anything simple as these will work. I prefer external thermistor sensors. The Ranco ETC also has a two-stage model so you can set it up in a variety of ways.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
This discussion has been closed.