Wow — thanks so much for such a thoughtful reply! I’m sorry for being M.I.A., but I’ve had a sick baby to attend to for the past few days.
Anyway, I guess my husband assumed that any propane fumes from the furnace were vented outside so there’d be no real danger in installing a hybrid near it. (Good thing his wife likes to ask for directions!) But are you saying there’s a risk that the propane fumes would ignite? If that’s the case, thanks so much in advance for keeping us from taking a deadly chance! A neighbor two doors down actually had his house explode because of propane problems, so I take that risk extremely seriously.
And does all this lead us back to the best choice being a regular electric water heater?