Three types, three completely different answers
Before buying anything, find out which one you have. It is printed on a plate inside the unit or in the manual, and it decides everything.
| Type | In an outage | What it needs |
|---|
| Standing pilot (millivolt) | Works normally — lights and burns with no power at all | Nothing. The pilot generates its own millivolts |
|---|
| Electronic ignition (IPI / DSI) | Will not light, and shuts down if already running | A few watts for the module, or a battery backup kit |
|---|
| Either, with a blower | Burns, but the heat stays at the fireplace | Tens of watts for the fan |
|---|
| Direct vent with a powered exhaust | Will not operate | Whatever the fan draws — check the plate |
|---|
The first row is the good news and it is common in older units. A millivolt system uses a thermocouple or thermopile in the pilot flame to generate the tiny voltage that holds the gas valve open. It is elegant, it predates household electronics, and it does not care about the grid.
Why newer fireplaces stopped doing that
Electronic ignition replaced standing pilots for a good reason: a standing pilot burns gas continuously, all year, whether or not you use the fireplace. Intermittent pilot ignition lights only on demand and saves that fuel.
The trade is exactly the one this page is about. You gain efficiency every day and lose function on the day the power goes out.
Many electronic ignition units are sold with an optional battery backup that holds a few AA cells and keeps the ignition module alive. If your unit has one, check it — those batteries sit unused for years and are usually flat.
The loads, which are trivial
| Component | Draw | Over 12 hours |
|---|
| Ignition module and controls | A few watts | Under 50 Wh |
|---|
| Convection blower | 30-80 W | 360-960 Wh |
|---|
| Remote receiver or wall control | Under 5 W | Negligible |
|---|
| Powered direct-vent exhaust | Varies — read the plate | Varies |
|---|
Ranges are typical for residential gas fireplaces. Your own unit prints its electrical requirement on a plate — reading a nameplate explains where to look.
The blower is the whole load, and it is still small. A 286Wh battery runs a 50W blower for nearly five hours; a kilowatt-hour runs it overnight. This is among the cheapest heat you can back up.
The blower matters more than people expect
A gas fireplace without its blower is a radiant heater: pleasant directly in front of it, and doing very little for the rest of the room.
The fan is what pushes warm air out into the space, and in a winter outage that is the difference between one warm chair and one warm room. For tens of watts, it is the best return on backup power in the house.
This is the same principle that makes backing up a gas furnace such good value — the fuel does the heating and the electricity just moves air.
Getting power to it
The practical obstacle is access rather than capacity. A fireplace is usually wired to a receptacle inside the enclosure or hardwired, neither of which you can reach with an extension cord.
Three routes, in ascending cost.
1. The manufacturer's battery backup kit, if your model offers one. Cheapest by far, and it addresses the ignition module specifically. Fresh batteries before every winter.
2. An accessible outlet. An electrician can fit a receptacle you can actually reach, after which a power station plugs straight in. This also makes servicing easier.
3. The fireplace circuit on a transfer switch. Worth doing if you are already having a switch installed for the furnace and the well pump — the marginal cost is one circuit. The transfer switch page covers sizing.
The safety part
A gas fireplace is a combustion appliance, and an outage is when people do unwise things with heat.
- Never run it with the flue blocked or the glass removed unless the unit is designed for it. Direct-vent units are sealed for a reason.
- A working CO alarm in the room. Battery or battery-backed, because the mains ones will be dead.
- Do not leave it burning overnight unattended unless the manufacturer explicitly allows it and a CO alarm is present.
- Do not improvise. A fireplace that will not light is not an invitation to bring in a grill or a camp stove — the staying warm page covers the safe alternatives.
- Know where the gas shutoff is, and know it before you need it in the dark.
Check it before the season
Two minutes, once a year, and it is the difference between discovering this in October and discovering it in January.
Find the breaker for the fireplace and switch it off, then try to light the unit. If it lights and burns, you have a standing pilot and no problem. If nothing happens, you have electronic ignition and a decision to make.
While the breaker is off, note whether the blower runs — it will not — and decide whether a warm chair is enough or you want the fan backed up too.
The short version
- Standing pilot works without power. Electronic ignition does not.
- Test it with the breaker off before winter, not during.
- The blower is the load worth backing up. Tens of watts, and it heats the room rather than the hearth.
- CO alarm in the room, always. Battery-powered, because the mains one is out.
