Originally posted by: HappyPuppy
Pneumatic thermostats only make a hissing noise when they are leaking. You can fix it with duct tape quite easily.
I dumped my pneumatic thermostat for a hydraulic thermostat that requires no electricity. It is fed by a five gallon bucket in the attic that I only have to refill once a year.
If you have an old fashioned low voltage DC thermostat that is making noise you can repair it by removing the cover and licking the internal circuitry while grounding yourself to a waterpipe in the kitchen or bathroom.
I would appreciate it if you would name me as beneficiary on your life insurance policy before repairing your thermostat. I need the money.