volts = 120, Amps = 13.5, Watts = 1620 according to the label on the back of the hot plate.
With the temperature control at 4.75 (out of 10), the resistance is 9.0 ohms.
Given a couple of percent of variation in the manufacturing process, this all checks out.
Apparently, the temperature control works by switching the heating element on and off. When it’s on, the hot plate uses 13.5 Watts and when it’s off, it uses 0 Watts.
I guess the safe way to go is to use a timer rated for 120 v and (13.5 Amps or 1620 Watts).
Is this correct?
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There are some points to be noted. If you are using timer then the statement ” with temp control at 4.75 the resistance is 9 ohm ” is wrong.
Temperature control (if it is based on on/off timer) then the resistance is constant.
To implement this control you need timer alright, but switching of heater element cannot be done by timer. You need relays (or contactors) capable of carrying about 20 amp current (minimum) and rated for 120 v (min). The timer will control this relay. These are ratings of the relay not of timer.
i guess your question is how to control a hot plate temperature
you can buy this device in any electrical store. the device is called “infinite switch”, just ask for 120v infinite switch for range surface element
infinite switch is work like a timer using bimetallic strip, when current pass through the strip it bended and cut off the power on and off, the on time must be less than steady state time say 2min. the relationship between the duration of on-off time and temperature is a curve, it is done experimentally. i have difficulty getting a formula out of my experiments. on range surface element, a 50% setting, the temperature is around 9F dull heat (no visible light)