OK, here are the heater tips I promised.
As a side note, looking at my records my heater was overhauled at the same shop in Redding that others have recommended, and it's has been trouble free and flawless for the past 500 hours. When it's minus 20 C at altitude it will keep the cockpit toasty warm.
There are other options, including an STC'd heater from C&D (
http://www.aircraftheater.com) that is an improvement on the Janitrol design. There are no recurring AD's on the C&D heaters, but I note on their website that they do have a Service Bulletin requiring inspection on their heaters for Piper PA-31 Chieftains, so they are not immune.
Again, my advice would be to have your heater overhauled by a good shop. A failure of the combustion chamber can lead to really bad things.
Good luck,
Jay