Originally Posted by loschi
Thanks for all the replies. It is a single 20lb tank and it was filled by the dealer so I suppose it may have been underfilled.
I'm going to fill it and take it out once more and troubleshoot it. If I smell propane, then I'll hit the dealer. My father in law was camping near us and sprayed the tank/hose with Windex and claimed it would "bubble" if there was a leak and there was no bubbling. But I'm not sure how scientific that all is.
I never thought of bringing along an electric heater. Good tip.
Now that I totally hijacked the OP's thread, let me try to bring it back to his problems. I would do as you already stated, and have the cylinder REFILLED, not exchanged with a cylinder that is only 75% full, which may be what the dealer did originally too. Who knows.
Furnaces do use a lot of propane, and are the #1 hog of propane in your RV. Depending on how much you used the furnace, then yes it could just be as simple as that.
Since you are new as you stated, I'm not trying to hijack your thread further, but provide more links to read up on as you learn the nuances of your RV. Hope you don't mind. When using a space heater in your camper, it can be a power hog in it's own right, especially on 30 amp power supplies. These links may help you understand that aspect too, so you don't trip circuit breakers.
Basic RV Electricity - RV Information (RV Maintenance)
RV Converters and Amp Draw - RV Information (RV Maintenance)
Suburban's electric switch and much more