[JshWright]

It is not feasible to run a gas furnace off a battery (short of a "whole house" battery like a Powerball). It's more than just basic management. You need to run either a blower or a pump to distribute the heat throughout the house. You'd need a substantial battery to run a 1/3 HP motor for any length of time.

[Thrymr]

A gas boiler furnace with steam radiators typically only requires power for the thermostat and solenoid valve, which can indeed be powered by a small battery. This is assuming you have a pilot light, which many older furnaces do.

[JshWright]

Residential steam boilers are pretty rare these days. Generally hot water heat uses circulation pumps (which draw less than a forced air blower, but still have a non-trivial continuous current draw)

[monadic3]

Ahh, I see, power companies have simply failed their customers and certainly will receive their commupance.