Are there any fumes that are released from the heater? I'm wondering as
I too need a back up plan.


No, it is very clean burning and has a device to turn off the heater in the
event that the oxygen is depleted. It lights with a pizio electric device and
has a pilot.

It puts out a maximum of 9000 BTU's which is enough to keep my 8x10 greenhouse
from freezing.

I thought about a generator, we had a 5KW propane unit when I had a commercial
orchid business. At the time I think it cost us about $4000 including the
automatic switching panel and installation. We had a 24x48 lexan covered
greenhouse plus a 18x20 work room at the time. The generator was in the
basement of the house and even though the exhaust pipe was outside it still
made enough noise to wake the dead. Modern units are much quieter.