Hi zaborac,
Welcome to the Heartland Owners Forum. We have a great bunch of people here with lots of information and all willing to share their knowledge if needed.
A simple search with Google will take you to
Onan's site, where you will need model number to look at owners manual.
Do you have a Heartland product? If so please let us know which one. It will help the members a bunch to answer any questions you may have.
Jim M