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

Everything You Need to Know About Relays

HeatingHelp Posts: 437
edited September 23 in THE MAIN WALL
Everything You Need to Know About Relays

A relay is just a switch. The purpose of any switch is to turn something on and off. A relay turns HVAC equipment on or off. It’s that easy.

Read the full story here


  • geno907
    geno907 Member Posts: 7
    In a situation for an oil boiler. Would you wire a relay and an aquastat together? If so, would line voltage go the the boiler's kill switch, then to the aquastat, then to a relay switch, then to the primary/zone controls/pumps? thanks.
  • Jamie Hall
    Jamie Hall Member Posts: 16,618
    Why do you need a relay at all, @geno907 ? What would be powering it on or off? And what, in turn, would it be turning on or off? Is there a reason the two circuits need to be separate (there sometimes are very good reasons, but you need to know why you are doing it).
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England