My gas furnace was recently converted from natural gas to propane. It's an old Reem furnace that was originally used for a few years on propane. The H&A guy changed the orifices and the control valve. The new valve would make a terrible noise for about about a minute when it first open? I complained so he ordered another new valve. He first said it was air in the line. Well, the new valve makes the same noise? He now says he doesn't know anything else to do and blames it on the furnace being so old. I agree it is 30 years old but was working perfect until he tried to convert it back to propane?
Any ideas about the problem?
If you're wondering why it was first converted to natural gas was because we got free gas from a well on our property but now the well has stopped producing.

The conversion should not be the problem. High inlet gas pressure can be a noise maker, or low or high voltage on the gas valve when it calls for heat. If your transformer is not strong enough to carry the load you can get a fluctuation in your low voltage to start a chatter on the controls.

I had wondered about the pressure but a new 500 gal tank was installed with a new regulator. I will call the propane dealer and request he check the pressure.
THANK YOU T-Top!