[Indyoaks]

I need to connect a portable generator to my gas furnace blower. It seems that I can put male and female plugs between the manual on/off switch and when I need to use generator power just unplug the house feed and plug in the generator.
I don't have the bucks to hook up the whole house which would be the best way.

[medic-dan]

Are you in the US? Using a cord is a violation of the NEC 422.16.

They make a single circuit transfer switch for just such a purpose. It can mount anywhere in the line. When the power goes out you plug your extension cord into the switch and flip a switch. All NEC approved for about $80.

Amazon.com: Reliance Controls TF151W Easy/Tran Single-Circuit 15 Amp Furnace Generator Transfer Switch For Up To 1875 Watt Generators: Patio, Lawn & Garden

[T-Top]

If your furnace has a wire that plugs into a receptacle. Just use a extintion cord to make the switch. If your system does not have a receptacle it plugs in to you will need to add it for the quick and easy change over.

[billpowers]

The easiest way to get power to your furnace is to put power to your electrical panel. You can use transfer switches but they take a lot of wiring. Look up interlock kit on Google. Their website is pretty good. For $150 you can do it with a little afternoon work. The kit makes it legal and safe.