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The lights go out at dinner time and the fridge stops humming, and how efficient are propane generators decides how much power you get from each tank of fuel. The short answer is that a propane generator makes a little less power than the same machine on gasoline, and how long it runs depends on the size of the propane tank and the load on it. The makers state watts, run time and noise, not an efficiency figure, so the honest answer comes from those stated figures, machine by machine.
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The quick answer
On the dual fuel machines here, propane peak and running watts sit below the gasoline figures on the same machine. Westinghouse lists its iGen2800DFc at 2800 peak watts and 2,200 running watts on gasoline, and 2,520 peak watts and 1,980 running watts on propane. Pulsar lists its PG2200BiS at 2,200 peak watts on gas, and 2000 peak watts and 1600 rated watts on LPG. WEN lists its DF475T at 4750 surge watts and 3800 running watts on gasoline, and 4350 surge watts and 3500 running watts on propane. The pattern is the same on each machine: propane gives the lower watts, and the load you run on propane has to fit the propane running watts.
A propane generator runs outdoors only, far from doors and windows, because of carbon monoxide.
Step 1: Compare propane watts with gasoline watts
Start with the propane running watts, not the gasoline peak watts. The running watts are what the machine sustains, and they decide which loads it carries on propane.
| Generator | Gasoline peak watts | Propane peak watts | Propane running watts |
|---|---|---|---|
| Westinghouse iGen2800DFc | 2800 | 2,520 | 1,980 |
| Pulsar PG2200BiS | 2,200 | 2000 | 1600 |
| WEN DF475T | 4750 | 4350 | 3500 |
A load that needs the full gasoline running watts may not fit the propane running watts, so check the propane column when you add up the loads you plan to run. The Westinghouse machine is an inverter generator with Eco Mode, which adjusts engine speed to match power demand, and the benefits of an inverter generator guide explains that design.
Step 2: Work out run time from the tank and the load
Run time follows the tank and the load, and the makers state run time at a stated load, so read the load with the hours. Pulsar states 8 hours of run time on a single tank of gas, and 75 minutes of run time on a 1 pound LPG tank at 1/2 load. WEN states up to 11 hours of half load run time from its 4-gallon tank, and its propane side feeds through a 47-inch LPG connection hose from an LPG tank. Westinghouse states up to 12 hours of run time at 25% load, and Oxseryn states up to 14 hours at 25% load with ECO mode from a 2 gallon fuel tank. Only Pulsar states a propane run time outright, so for the other machines the propane run time depends on the size of the propane tank you connect and the load you run.
Step 3: Use Eco Mode and match the load
Eco Mode is the feature that stretches a tank. Westinghouse states its Eco Mode adjusts engine speed to match power demand and uses up to 50% less fuel than a traditional generator. Oxseryn lists ECO mode with up to 14 hours at 25% load. The gain shows up at light load, when the engine slows down instead of holding full speed, so switch Eco Mode on for small loads and off when the load needs full power.
Match the load to the propane running watts. The Pulsar machine gives 1600 rated watts on LPG, the Westinghouse gives 1,980 running watts on propane, and the WEN gives 3500 running watts on propane. Westinghouse names a refrigerator, a sump pump and electronics as the essentials its machine backs up at home, so add up the running watts of the loads you plan to run and compare them with the propane running watts, not the gasoline peak watts. Sensitive electronics need clean power, and Westinghouse states less than 3% THD for phones, TVs and computers, while Pulsar states a stable sine wave for sensitive electronic equipment.
Westinghouse states its machine is as quiet as 52 dBA, Pulsar states 60 dB, and Oxseryn states under 72 dBA from 23 ft away, so check how each maker states the distance before you compare the figures. See the best inverter generators for quiet machines in this class.
Step 4: Check the outlets and the propane hookup
Count the outlets against the loads, and check the propane hookup before you buy. Westinghouse lists a 120V TT-30R 30A outlet and a 120V 5-20R 20A standard duplex outlet, and its machine is parallel capable, with parallel cables sold separately. WEN lists two 120V GFCI outlets, a 120V/240V NEMA 30A twist lock and a 12V DC plug, plus a wheel and handle kit. Pulsar lists two 120V 15A AC outlets and a 5V USB outlet, and its box includes a propane hose. WEN includes a 47-inch LPG connection hose, and the machine switches between gasoline and propane with the turn of the selection dial.
Weight decides how far the machine moves by hand. Westinghouse lists 45 pounds and Pulsar lists 44.0 pounds, while WEN lists 105.8 pounds and comes with a wheel and handle kit, and Oxseryn lists 56 pounds. WEN lists electric start with the turn of a key, while Pulsar lists recoil start, so check the starting method with the weight before you choose.
How efficient are propane generators when you stretch a tank
- Run in Eco Mode at light load: Westinghouse states Eco Mode uses up to 50% less fuel than a traditional generator, and Oxseryn lists ECO mode with up to 14 hours at 25% load.
- Match the load to the propane running watts: Pulsar gives 1600 rated watts on LPG, Westinghouse gives 1,980 running watts on propane, and WEN gives 3500 running watts on propane.
- Size the propane tank to the hours you need: Pulsar states 75 minutes on a 1 pound LPG tank at 1/2 load, so a bigger tank is the way to a longer run.
- Switch off loads you do not need, so the engine holds a lower speed for longer.
FAQ: power away from the grid
Does a propane generator make less power than a gasoline generator?
Yes, on the machines here. Westinghouse lists 2800 peak watts on gasoline and 2,520 on propane, Pulsar lists 2,200 peak watts on gas and 2000 on LPG, and WEN lists 4750 surge watts on gasoline and 4350 on propane. Check the propane running watts when you size a load.
How long does a propane generator run on a tank of propane?
It depends on the tank and the load. Pulsar states 75 minutes of run time on a 1 pound LPG tank at 1/2 load. A bigger propane tank runs longer at the same load, and a heavier load empties the tank faster.
Does Eco Mode save fuel on a propane generator?
Westinghouse states its Eco Mode adjusts engine speed to match power demand and uses up to 50% less fuel than a traditional generator. Oxseryn lists ECO mode with up to 14 hours at 25% load. The saving shows up at light load, when the engine slows down.
What size propane generator do I need for home backup?
Add up the running watts of the loads you plan to run, then compare the total with the propane running watts: Pulsar gives 1600 rated watts on LPG, Westinghouse gives 1,980 running watts on propane, and WEN gives 3500 running watts on propane.
How loud is a propane generator?
Westinghouse states its machine is as quiet as 52 dBA, and Pulsar states 60 dB. Oxseryn states under 72 dBA from 23 ft away for its gasoline machine. Check how each maker states the distance before you compare the figures.
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