I have an older Weil Mclain gas steam boiler for the radiators in my house. If the electricity goes out, it won't run -- I believe it needs electricity to operate the gas valve, and the thermostat is also wired into a circuit.
Should electricity go out to the house during the winter, I could certainly get by for a few days with flashlights and coolers as long as there is heat. I have instructions for running the boiler manually, and could connect a battery operated thermostat, but would prefer to run it on a backup electrical connection if possible so I don't have to babysit it in the dark.
There is a single electical conduit running into the boiler which is connected to a box with an on-off switch above the boiler, as well as a line running from the thermostat.
The thermostat is obviously a straightforward job, but is it a straightforward job to switch the power at the on-off switch from the regular house current to a backup source? How much capacity will this backup need -- does it pretty much need to be a gas generator, or can I get by with a battery backup of some sort?
Is this just a quick project in the event of a major winter outage (assuming I buy the parts ahead of time) or should I get the guy who does the annual inspection do the work? I've done plenty of basic wiring like running cable for new outlets and lights and switches, so I'm not intimidated by basic stuff, but also know better than to mess with stuff beyond my pay grade.