This lookup covers two propane RV furnace classes while their blowers and controls are operating:
- Compact 12,000–19,000 BTU/h furnace: 2.8 A at 12 V DC, represented as up to 34 W at 12 V DC.
- Ducted 30,000 BTU/h furnace: 7.0 A at 12 V DC, represented as up to 84 W at 12 V DC.
These are maximum running values for the registered classes, not universal ratings for every furnace in those output ranges. Starting current, time-averaged power and daily energy are not supplied. Because the blower cycles with the thermostat, its running watts cannot be treated as continuous all-day consumption. This lookup also does not produce a direct generator-sizing result because the furnace is a 12 V DC load.
12 V current and running watts by furnace class
| Registered furnace class | Operating scope | 12 V DC current | Maximum running power | Starting demand |
|---|---|---|---|---|
| Compact, 12,000–19,000 BTU/h | Blower and controls operating | 2.8 A | up to 34 W at 12 V DC | Unknown |
| Ducted, 30,000 BTU/h | Blower and controls operating | 7.0 A | up to 84 W at 12 V DC | Unknown |
Propane provides the heat in this scenario. The listed electrical load runs the furnace's 12 V blower and controls. The tool supplies maximum running values only; it does not supply minimum or typical running values.
“Unknown” starting demand does not mean zero. No starting-current or starting-watt figure is registered for either class. This lookup therefore does not confirm that a battery, converter, fuse or wiring path can handle startup.
Why this is a DC load, not a direct generator load
Both furnace classes are 12 V DC loads. For the compact class, the tool describes it as a 12 V DC load: the generator powers the converter/charger, not this load directly. The same boundary applies to the ducted class: it is a 12 V DC load: the generator powers the converter/charger, not this load directly.
That power path is the decisive constraint. When an AC generator supports the RV, it powers the converter/charger; the furnace draws from the RV's 12 V system. We therefore do not treat the furnace as a 34 W or 84 W AC appliance plugged directly into the generator.
This page does not calculate the converter/charger's AC input demand. That demand depends on the equipment, conversion losses, other simultaneous 12 V loads and any battery charging. No connector, converter, wiring, fuse or battery-capacity check is performed here.
What the watt figures do—and do not—tell you about battery use
Amps and watts describe demand while the furnace is running. Energy describes electricity used over time and is expressed in watt-hours (Wh) or kilowatt-hours (kWh).
The blower cycles with the thermostat, so neither registered running value is a daily-energy result. This lookup does not supply blower operating time, thermostat duty cycle or time-averaged power. It therefore does not calculate daily energy or battery runtime.
For practical planning:
- Use the amp rating when comparing the furnace with the limits of the battery's 12 V output path, converter output, fuse and wiring.
- Use watts to compare power demand with relevant converter, charger, inverter or portable power-system limits.
- Obtain the expected blower operating time or duty cycle before estimating trip energy. Duty cycle is the share of time the furnace actually runs, such as part of each hour rather than continuously.
- Include applicable conversion losses when power passes through a converter or inverter.
In colder conditions, more frequent or longer thermostat cycles increase energy use even if the running amp draw stays the same. Because this page has no operating-time input, it cannot promise a number of hours from a battery.
How to check your own furnace rating
If your furnace does not clearly match one of the two registered classes, use its model-specific rating instead:
- Find the furnace make and model. Look for the data plate on the furnace cabinet or in an accessible service area. The owner's paperwork may also identify the model.
- Locate the 12 V DC electrical rating. Look for a value labeled amperes, amps or A. Do not substitute the propane input or heating-output rating in BTU/h for the electrical rating.
- Match the documentation to the exact model. A furnace with similar heating capacity can still have a different blower current.
- Keep missing startup data unknown. Do not enter zero merely because startup current is absent from the label.
- Check the complete 12 V path. Compare the model's requirement with the applicable converter, battery, fuse and wiring limits. This lookup does not declare those components compatible.
A nameplate rating is a planning input, not a measurement of how much energy the furnace used during a particular night or trip.
Limits and next planning step
First, identify your furnace class or exact model. Use its 12 V amp rating for the DC-side capacity check, and keep startup demand unknown unless matching documentation supplies it.
For battery planning, record how long the blower is likely to run instead of assuming maximum running power for 24 hours. A runtime estimate also requires usable battery energy and any applicable conversion-loss assumptions.
If an AC generator will support the RV, size it from the actual AC loads and the converter/charger's AC demand—not by treating this furnace as a direct AC appliance. For terminology and an explanation of why unpublished startup demand matters, see Running Watts vs Starting Watts.