There is no need to GFI protect the heater.

If you feel the need to there are two-pole GFI breakers. They are expensive, but are your only option.

Pushing what limits? If you are running a new circuit then what limit is there?

I'm not sure if you understand the tradeoffs between 120 and 240 volt heater. You buy watts, not amps so if both are available in the same wattage, it will cost the same to run them. You just may need a larger size of wire to feed the 120V heater. Unless you have a very small service you should be able to put a 120V load on whichever of the hot legs in the main panel is less loaded, so one side doesn't exceed your service capacity.

Guys, thanks for the feedback. I guess my concern was for future expansion. I am putting this in my basement which is served by a 100 amp subpanel. I am considering adding a full kitchen down the road, all electric, and figured if I had the cooktop and oven running I would be using half of my available amperage at 100 amps. I figured that at 240v I would be able to use fewer amps for the heateer.

Thanks

You have two hot legs coming to your panel, each one good for 100 amps, with 120 volts on each leg and 240 volts between the two legs. Lets say for discussion you have a 1440 watt heater. If it is a 240 volt heater it will draw 6 amps on each of the two hot legs. If it is a 120 volt heater it will draw 12 amps from one hot leg.

A cooktop and oven will undoubtedly be 240 volt units and draw current on both hot legs. Maybe on some settings the two currents won't be equal, but on the highest settings it will.

But there are still all those other 120V circuits that probably aren't drawing equal loads on both hot legs, so if you try to roughly balance the heavier loads between the two hot legs it isn't going to matter which heater you get.

1) I would like to install a small heat/fan to the ceiling of my bathroom where a small fan/only is now. It is turned on by a wall switch that has 3 switches. I saw a few heat/fans on the internet for about $75.00. What would be required to install? I am not handy. An electrician?

2) I have a 3 way switch in the kitchen. I turned it on and none of the under cabinet florescents that are in several unconnected place came on. Suggestions?

3) There is wiring for an AC at the NE corner of our 2 story house and a central heater directly above the kitchen. I would like to add 220 to my kitchen on the south part of the house (no exterior wall). Or, I could just stay with my old gas range. Should I stay with what I have?

Thanks for any help.
Janice