[tomdashle]

If my power goes out how do I hook up a generator to run my natural gas furnace to keep heating the house but not backfeed power out of my house; which is dangerous & could kill someone.

[Deduke]

Shut off the main breaker, or pull the meter out.

[rats]

Originally Posted by Deduke

Shut off the main breaker, or pull the meter out.

Good advice
There are also "Automatic Switches" available for this.
Ask your local election

[ArmaLube]

A transfer switch is a necessity. It allows selected circuits to be connected to either the main power panel or the emergency generator. Use Google or other search tools to access references to 'transfer switches'. It is not necessary that the transfer be automatic, but it is necessary that the generator be absolutely isolated from the incoming power feed.

Bob

[Splatter]

Read and believe ArmaLube.

It's possible to just hit the main breaker, or to remove the meter (the removed meter is a bit harder to explain to your electricity supplier); but what happens the one time you forget? or when the power comes back and you flick the main breaker before disconnection the genny?

Nope, for a couple hundred bux, do it right.

[Deduke]

A transfer switch is only needed if you have a whole house generator. If I read the question correctly, he was asking about a portable generator to run the fan on his HVAC. The reason one would want to isolate from the grid is that when the power company gets around to repairing the downed lines, the linemen would prefer not to work hot. True, one portable generator won't make all that much difference, but if the whole neighborhood is feeding the grid, someone could get bit.

I've been a Master Electrician since 1982.

[RED]

Any gas powered generator used indoors can kill your entire family in a matter of minutes. In any event most of the small back-up generators out there are mostly a PITA to maintain and keep running for any length of time. Long term fuel storage is difficult at best and dangerous at that.

A good transfer switch, hard wired by a licensed electrician can be expensive, as is a quality generator capable of allowing you and your family not only to survive, but to live in relative comfort for weeks in any SHTF situation. A friend's Mother and Dad living in St. Louis were without electricity for 3 weeks just a couple of months ago.

There is a solution, it may look expensive, but what is your family's health and safety worth? Anyway, I opted to buy a propane powered 16KW Generac unit and connected it to my 500 gal. propane tank. It ain't perfect but it gives me (well) water and HVAC and can run for weeks.