My old 4 wire 240V mechanical line voltage thermostat stopped working. I want to replace it with a digital thermostat. Problem is I don't know the amp rating of the old thermostat. I checked with maker and they have no info...too old. Is there a way to check amp rating of old thermostat? A very good electrician installed the two 8 foot baseboard heaters, thermostat, 2-pole 20 amp circuit breaker and all wiring about 25 years but he is nolonger around.

  • Your options of smart stat will be limited. How do you feel about a significantly more complex install, but that will open you up to pretty much all the popular smart 'stats such as Nest? Sep 26, 2018 at 19:21
  • I found the label on the heaters. 2000/1504 amps 240/208V. Based on amp calcs I found online they showed watts/volts=amps. I have two heaters so total watts = 4,000. So 4,000 /240=16.6667. So wouldn't a 16.7 amp stat work?
    – henrylr
    Sep 26, 2018 at 19:59
  • Can you post photos of the labeling on the old 'stat? Sep 26, 2018 at 23:34
  • That is the problem...the only markings on the old Berko stat are on the bi-metal tab (H00D 36-10) and the manufacturer told me they have no info...to old.
    – henrylr
    Sep 27, 2018 at 0:12
  • The two heaters - watts 4,000. So 4,000 /240=16.6667. So would a 16.7 amp stat work?
    – henrylr
    Sep 27, 2018 at 16:02

1 Answer 1


20 amp circuit, so 20 amps (or more, but not less) for the thermostat.

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