How do know if I have a gas leak ? It's a ventless heater
...gas leak. I can't help you with how to go about it, its a matter of personal safety. Gas leaks will smell like rotten eggs, which comes from an additive put into gas simply to alert occupants to a leak. We have no option but to suggest you err on the side of caution, I just can't help you with how.
As for the heater -...