I have a ceiling mounted 240V 30A heater that is currently controlled by its built-in thermostat. The heater is in a workshop (in an out building). The heater is wired using three wires (two hot and a ground).

I'd like to be able to add a countdown timer so that I won't have to worry about forgetting to turn the heater off when I leave the workshop. Maybe, one that could be set for up to an hour.

Thanks in advance for any help you might offer.

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    It's not quite clear to me what you are asking. Are you looking to find out if it's possible (yes it is), how to do it (need details on your timer etc), of a recommendation? If product recommendation, that would be considered off topic.You may also want to edit your question too add the above info and let us know about where you are located (to address local codes). – PhilippNagel Oct 15 '20 at 15:59
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    One question for the electric gurus on this site is whether you need to switch both hots on this type of heater? (DPST vs SPST switch) – Jon Oct 15 '20 at 16:16
  • Another question for the gurus is what types of timer switches are even able to switch such a high current. I'm looking at Wall-Mount timer switches and most of them can only switch 10amps at such 240volts. – Jon Oct 15 '20 at 16:18
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    could you share the brand & model of the installed heater- perhaps it could be controlled by a low voltage thermostat circuit – Jon Oct 15 '20 at 16:25
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    I use a relay for that, but it probably has one. Hold on. Does this thing have an internal 24V thermostat? Does it have provision for an external thermostat of any kind? – Harper - Reinstate Monica Oct 15 '20 at 18:35

Just to answer your question, you could always use a common Intermatic double pole single throw timer. You'd have to have a fixed "off" pin and just rotate the time wheel to an hour before the "off" pin each time you used the shop.These timers are relatively inexpensive and available everywhere. It would also give you the ability to set the heater to go on at a certain time so it's warm when you get there. enter image description here

Another alternative would be to get count down timer from a heating supply company. They're good for up to a 6000 watt heater. They are over twice the price of the Intermatic

enter image description here

Providing more information on your heater will help us to help you further.

  • The heater is a Comfort Zone CZ220. It has an internal thermostat, but no provision that I can see for adding an external 24V control. The manual is very brief - here's a link to it on Amazon: images-na.ssl-images-amazon.com/images/I/91KBbn27xCL.pdf I'm located in Colorado in case that matters. Thanks all. – Lee Oct 16 '20 at 16:22
  • @Lee the Intermatic timer runs on 240V and the other one is a spring wind down timer. – JACK Oct 16 '20 at 16:42
  • Thanks Jack. I think I'll go with the Intermatic timer. Looks like all I'd need to do is to remove the "on" tripper if I want to use it for countdown. Stay well! – Lee Oct 17 '20 at 17:50

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