Is this the transformer for my doorbell? It is located in the furnace room, but it looks like it is connected to the furnace. I am just wondering because I have been searching for the transformer and a lot of posts say it should be near the furnace area. Thanks for any help.


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  • 2
    simple test .... disconnect one wire .... does the doorbell stop working? – jsotola Nov 29 '18 at 23:35
  • looks kind of big for a doorbell transformer. – Jasen Nov 30 '18 at 2:19
  • @jsotola OP doesn't say why they are looking for the transformer. If it is "doorbell isn't working and I tested the switch and I'm not getting any power" then "disconnect one wire" won't help at all. – manassehkatz-Moving 2 Codidact Nov 30 '18 at 3:52

Anything is possible, but my bet is on a thermostat transformer. Typical (US) thermostats run on 24V AC. Typical doorbells (though there seems to be less consistency than with thermostats) use 16V AC.

Get a multimeter. Test the voltage:

  • 24V - Thermostat
  • 16V - Doorbell

Something else? Post it here and we can try and figure it out.

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