WIRING TO A GAS FURNACE

Circuit breakers and fuses are 15 amps or more. 0.7 amps is like one traditional incancdescent 75 (or 85) watt lightbulb. So you wouldn't have to do it becuase of high amperage used. Maybe there is some other reason you have in mind?

First, you don't have a gas hot water furnace. You have a boiler. Furnaces heat air, boilers heat water.

The circulator is usually wired to a relay on the boiler and works in conjunction with the thermostat. The boiler main power should be on a dedicated circuit. If you have something different, please be more specific as it would be very unusual.

As Ed said, the circulator pumps and other boiler controls would generally be wired to the same circuit as the burner, unless you have more pumps or equipment than a single circuit can handle, in which case you would add more circuits