Heat & Water on Backup Power: Furnace, Sump Pump & Water Heater
Last verified: September 2026
Everything you actually need to know, in plain English — no jargon, no rabbit holes. If you'd rather have someone help in person, my number is (330) 200-8042.
Heat & Water on Backup Power: Furnace, Sump Pump & Water Heater
Here's a surprise a lot of folks with gas furnaces learn the hard way: gas heat still needs electricity. The blower, the igniter, the controls — all electric, even though the flame itself is gas. Add a sump pump keeping your basement dry and a water heater you'd like to keep working, and you've got the three systems this guide is built around. There's a printable, 29-page guide up top if you'd like to keep the whole thing on hand.
Common Questions
1 I have gas heat — why would I lose it in a power outage?
Because the gas only supplies the flame. The blower fan that pushes warm air through your ducts, the ignition system that lights the burner, and the thermostat and control board all run on electricity. No power, no heat — even with a full tank or a working gas line.
2 What happens to my basement if the sump pump loses power?
Groundwater keeps rising in the pit with nothing pumping it back out, and storms that knock out power are often the very same storms pushing the most water toward your foundation. A sump pump losing power in a heavy storm is one of the more common ways basements flood.
3 Can I run the furnace, sump pump, and water heater all at the same time?
Often yes, if the generator is sized for it — but check the label on each one for its running and starting watts, and plan for the single biggest starting jolt among them, not all of them added together. There's a dedicated sizing guide with the full method.
4 What about a tankless water heater?
Both gas and electric tankless units need power for their controls and ignition. Electric tankless units draw quite heavily, though, and are often a stretch for a typical portable generator alongside everything else. Check your own unit's label and talk to your plumber if you're unsure.
5 Is this the same as backing up a well pump?
No — a well pump gets its own dedicated guide because of its 240-volt needs and big surge. This guide covers the furnace/boiler blower, sump pump, and water heater. If you're on a well, read both — the well pump usually takes priority on the generator.
6 This is a lot of systems to think about. Can you just help me sort it out?
Absolutely — untangling which of these matters most for your home, and setting up a safe way to power them, is exactly the kind of visit I enjoy. $99 flat. Call or text (330) 200-8042.
Want Me to Help With Yours?
Getting a backup generator picked, set up, and safe is one of the things I'm glad to do in person. I bring the patience and the know-how — you keep your seat. We'll get it starting, sort out the fuel and the safe hookup, walk through running your essentials, and make sure everyone knows the carbon-monoxide basics. $99 flat, and every visit is 30-day come-back-free. (330) 200-8042.
Would you rather I just do this for you?
No shame in it — plenty of folks would rather hand it off, and that's what I'm here for. I'll come to your home, set it up right, and make sure it's working before I leave. Flat $99 per visit — no jargon, no upsell, and every visit is 30-day come-back-free.
Not a hardware job? I can often fix it remotely for $49 — a secure screen-share, up to 2 hours, that you watch the whole time and can end whenever (included free for $39/mo Support Plan members, and it counts toward the $99 if it turns out I need to come out).