Unable to turn knob on Rheem hot water heater to pilot
Below is a picture of the lighting instructions for your water heater taken from Rheem's website. Make sure to follow the lighting instructions carefully and do not skip any steps. This same instruction set should be available as a sticker on your unit.
It looks like you do in fact have to depress the knob in order to turn it so avoid using force.
If you are unsuccessful with the instructions then it is a good idea to call a professional.
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