My hot water for the shower doesn't work. It in the guest bathroom so its hardly ever used. What could be the problem?

My hot water for the shower doesn't work. It in the guest bathroom so its hardly ever used. What could be the problem?

Hi Loretta,
Before I can help I have to know the brand name of the shower valve and its approximate age. Cheers, Tom

It is a Simon shower valve and it is 10 years old. I barely use this bathroom. So I don't understand how it can break.
Thanks

Hi Loretta,
You will have to shut the water off, open up the valve and flush out the supply lines. Some crud got into the inlet ports of the valve and must be cleaned out. If you wish to do this yourself here is a exploded view of a Symmons valve. http://www.plumbingpartsdepot.com/symmonstemptrol.html

Good luck, Tom