Add Countdown Timer for Electric Heater
Just to answer your question, you could always use a common Intermatic double pole single throw timer. You'd have to have a fixed &quot;off&quot; pin and just rotate the time wheel to an hour before the &quot;off&quot; 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.

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

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