Can You Run a Hot Water Heater on a Generator – Answered

A generator can power a water heater, but the generator’s available continuous output power requirements must be greater than the water heater’s continuous watt demand. To provide on-demand hot water, the typical household water heater requires approximately 4 kilowatts of continuous power. As a result, any generator must be capable of continuously supplying at least that much wattage. So, the question is arise: Can You Run a Hot Water Heater on a Generator?

What Size Generator To Run Hot Water Heater?

A generator with a power range of 3000-5000 watts is ideal for a small water heater that draws water from the town supply water system. However, a 5500w to 7000w generator is required to power a large water heater that draws water from the water tank pump.

A gas-powered generator with 1500 watts, on the other hand, will be enough to power a gas-powered water heater.

SIZE         WATTAGE       Recommended Product
Small          3000 wattHonda EU2200i 2200-Watt 120-Volt Inverter Generator
Medium       5000 wattChampion Dual Fuel Portable Generator
Large           7500 wattWestinghouse WGen7500 Portable Generator
Maximum       9000 wattWEN 420cc Transfer Switch Portable Generator

To run a large water heater, you may need to consider a larger generator, especially if it gets water from the water pump. Though it is uncommon, running both the water heater and the water supply system can require up to 10,000 watts of power. In most cases, the 75000-watt generator is more than enough to power a water heater without causing any problems.

How Big of a Generator Do I Need to Power a Hot Water Heater?

Can You Run a Hot Water Heater on a Generator

We already know that the generator’s output wattage must be greater than the water heater’s demand, but what does that mean?

Every device sold in the United States must be U.L. approved and in any other countries also, which simply means that the manufacturers must follow a set of rules to ensure that all appliances work. These rules include the appliance’s important specifications on the label.

Water heater labels are typically bright yellow and contain a wealth of information about the device. The information on this label will describe the water heater’s energy efficiency, how much wattage it requires to function properly, and how much water it can hold.

Generator labels will contain similar information, but the most important specification will be the generator’s output. Most portable, gasoline-powered generators can produce between 2 and 5 kilowatts. Because the average residential water heater only requires about 4 kilowatts, the water heater can theoretically be powered by a power generator.

This is not done by simply plugging a water heater into the plug, because water heaters are considered permanent appliances and are directly connected to the Motorhome’s or home’s electrical service.

How Much Power Is Required to Run a Hot Water Heater?

One common issue that consumers meet when attempting to connect a water heater to their portable generator is that many hot water heaters require a 220-volt power source, but portable generators frequently do not have a 220-volt output. Despite the fact that some of these portable generators have a 220v outlet, a standard water heater will not have a power cord to plug into the generator.

Portable water heaters specifically designed to work with portable generators are an exception. These portable water heaters are typically used for camping and are not suitable for general household use.

Water heaters are “hard-wired,” which means they miss the typical plug found on other electrical items. Water heaters are directly wired to the RV’s power source via the house wiring and cannot be unplugged.

As a result, in most cases, the only practical way to power a water heater with a generator is to use a natural gas or LP-powered generator.

>>Read More: How Often Should You Drain Fuel Water Separator- Is This Important?

Types Of Water Heater And Required Power

The amount of energy necessary to keep the water heater running is based on various factors, including the number of equipment that will be connected to the generator.

Aside from that, the type of water heater you will use is critical. Keeping this in mind, consider the following water heater types and their power requirements:

Gas Heater

If you want to use a gas-powered generator with your gas heater, make sure it has a 1500-watt output. It means that a gas heater does not require as much power as other types, and a small and portable generator alike will fit the bill. Except for a gas heater, using such a generator means you won’t be able to run multiple tools at once.

Electric Water Heater

To work effectively, an electric water heater must have at least 4500 watts. A generator capable of producing such power can also power other appliances, particularly those that require hot water, such as washing machines.

Water Heater with Intelligence

A smart water heater, like an electric water heater, requires 4500 watts to deliver hot water suitably.

Is it permissible to purchase an overpowered generator for a water heater?

Is it permissible to purchase an overpowered generator for a water heater?

The most important factor to consider when selecting a generator for a water heater is the required wattage. However, most generators capable of powering water heaters are not portable.

A portable generator has a lower wattage and is primarily used for light-duty tasks. There are, however, exceptions. There are some portable generators available that can power the water heater.

Basic Hot Water Heater Maintenance

The first step is to turn off the power to your hot water
heater before performing any maintenance. In general, propane water heaters require a little more maintenance than electric water heaters. This is primarily because you’ll want to clean out the heating tube once a year to ensure there’s no dust blocking your gas flow.

Are There Any Safety Considerations Of Using A Generator?

All portable, standby, and inverter generators should be tested monthly and serviced annually in the open air (NEVER in a garage or other enclosed space due to the risk of carbon monoxide poisoning). Aside from that, portable generators require little maintenance.

In addition to a monthly 10-minute run, turn off the fuel supply or get a stabilizer, then drain the carburetor if you aren’t planning on taking your RV out anytime soon. For your RV adventures, it is best to use fresh fuel, as well as if you use it for your mobile home also Annually service your generator to ensure that it has enough oil, that the batteries are charged, and that everything is running smoothly.

Things to consider

Fuel type

Some portable power generator models are powered by gasoline, while others are powered by liquid propane tanks. The fuel type you choose for your portable generator will most likely be determined by your available resources. You could buy a solar generator that is powered by a solar panel or panels. However, in terms of power, solar generators lack the punch of a gasoline-powered portable generator, which is why we didn’t include them on this list.


Watts information can be found on a sticker inside your appliance or in the owner’s manual. If your appliance does not specify watts but only amps and volts, multiply the two to get the wattage. Whatever the total of your required watts is, that is the minimum running wattage your generator must produce.

In my home, for example, I would need to power an 864-watt dishwasher, a 1,440-watt refrigerator, and a 3,600-watt oven. That means my generator’s power output must be at least 5,904 running watts.


Of course, the cost is a factor, and in general, more peak power will cost more. You can find good generators for as little as $300, or you can go all out for maximum power and end up with a $2,000 model. Alike- Briggs & Stratton, DuroMax DS4400E, and Sportsman 4000W Duel fuel are all you can purchase from amazon easily.

Frequently Asked Questions:

Can a 5000-watt generator power a water heater?

ANS: Yes, an electric water heater can be powered by a 5,000-watt generator.

What Size Generator Is Best For A Tankless Water Heater?

ANS: If your electric tankless water heaters are hard-wired to the electrical system and provide hot water to the entire house, use a 7500-watt inverter generator or higher. You could also get a Tesla power wall.

How Do You Calculate Generator Wattage?

ANS: The wattage of a generator or other electric device is calculated by multiplying the voltage by the device’s load capacity. Watts = Volts x Amps is the formula in short.

Last Words

A generator can save your life, especially during storms or power outages, as well as in the winter. When it comes to running a water heater, however, the right size generator is required to run this electric device smoothly and provide hot water to the entire house.

Hopefully, you now know what size generator to use to power your hot water heater and other household appliances.

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