What Size Generator For 3 ton Heat Pump Should You Use? 

Generators are becoming more and more popular devices for obtaining an additional source of energy, especially in critical situations when you can no longer depend on the city’s electrical system.  

What’s more, the generator can not only charge individual devices but also power the whole house along with a heating system, such as heat pump units.

However, to run a heat pump with a generator, you need to know which size generator is right for you. In this article, we’ll look at generator sizes, how to choose the right generator for your heat pump system, and which generator is right for you if you have a 3 ton heat pump.

What are a heat pump and A generator? 

Before we start discussing what types of generators are for a heat pump, we need to understand what a heat pump and generators in general are.

Heat pump

The heat pump is a device that uses energy from outside through a cooling cycle and releases heat to the whole building. The size of the heat pump only depends on the size of the object it should create heat energy for.  

Also, you may have heard about the heat pump device along with the operation of the air conditioning unit, since both of these devices work as an HVAC system.

Mini split ductless heat pump

The mini split ductless heat pump is the same system that works as a conventional pump, however, it is a small heat pump, which consumes much less electricity and can be wall-mounted. Due to their compactness and the use of a transfer switch, they are often used for trailers.


A generator is a device that uses diesel, fuel, or another energy source to convert mechanical energy into electrical energy. Most often, generators are used during a power outage, as they can create sufficient power to recharge your devices, and large generators in general can create enough power flow for the whole house.

Moreover, there are many types of generators, depending on their size, for example, portable generators, and energy production resources, for example, diesel generators.

Different generators for different heat pumps 

To understand what generator size you need for sufficient heat pump power, you first need to understand all types of generators, from a small portable generator to a large standby generator.

Portable generators

A portable generator is a small generator that is most often used as a portable source of energy. A portable generator is much cheaper than the rest, but it cannot provide electricity to a large area.

The portable generator run a maximum of 10,000 watts, which is not quite enough for even the smallest apartment. However, for camping, a portable generator is ideal.

Heat pumps for portable generator 

Portable generators produce enough electricity for a mini split heat pump as it is the smallest kind of heat pump and a portable generator will be able to power it.

Home standby generators 

A home standby generator, unlike a portable generator, requires installation and proper connection. This generator is often called a backup generator, as it is quite suitable for providing electricity to the whole house.

Although the cost of a standby generator is quite high, it can be justified by its power, which almost reaches the figure of 20,000 watts.

Heat pumps for Home standby generators 

A standby generator can run a heat pump with different sizes as this generator is specially made to be able to run many large appliances in the house at the same time.

Recreational inverter 

The Recreational inverter is even lighter than portable generators and can produce up to 2000 watts. Their big plus is a quiet operation and ease of installation, you can also use such a generator for a mini split heat pump.

Of course, these generators will not be able to ensure the operation of the whole house, however, to activate individual devices, this type of electricity resource may well be suitable, the main thing is to understand in advance exactly how many watts your devices require.

Of course, these generators will not be able to ensure the operation of the whole house, however, to activate individual devices, this type of electricity resource may well be suitable, the main thing is to understand in advance exactly how many watts your devices require.

Heat pumps for recreational inverters

A recreational inverter can run a heat pump, which is lighter than 1 ton, because if the pump is too heavy, the generator may overheat.

Midsized inverter 

This alternator is slightly larger than the previous one as it weighs about 150 pounds and can still produce about 3500 watts of power. It also needs gas to work, but it will work longer than the recreational.

This type of generator may be suitable for charging individual devices.

Heat pumps for midsized inverter 

The size of the heat pump, which is suitable for a midsized inverter should be around 1 ton. Since this is the only pump size that the inverter can activate with electricity and provide a resource for stable operation.

Difference between starting wattage and running watts 

To properly match a generator to your heat pump, you need to understand how much power your heat pump requires. And in order not to get confused in the numbers, you need to understand in advance what starting watts and running watts mean and how they differ.

Starting wattage 

Starting watts is the amount of power the generator must supply to successfully start the heat pump, which lasts a few seconds. And although it seems to you that it takes a little energy to start, you are mistaken, since starting wattage is weighing a lot more than running.

Purpose of starting watts 

To activate the heat pump, a large amount of electricity is needed, since you start the whole process inside again, which is why the device needs a powerful charge of electricity.

Picking up a generator that can’t provide enough watts to power the devices in the house can overload the generator itself.

Running watts 

Running wattage is the amount of electricity that is needed for the normal operation of the device.

Purpose of running wattage 

Running wattage allows you to understand how much you will need to consistently spend to run a heat pump and another appliance at the same time, so you can immediately find the generator you need.

How to find the right generator size for a heat pump? 

To get a good source of energy for your heat pump, you need to be able to calculate the correct size of the generator, for example, portable generators, for your device.

Step 1

First, you need to calculate how much total load of electricity will be needed for the normal operation of your heat pump.

Step 2

Secondly, you need to determine how much energy the heat pumps will spend for a simple start since this figure is twice as much as the amount of electricity for normal operation.

You must be sure that in the event of a power outage and activation of the generator, it will be able to start the heat pumps.

Step 3

Thirdly, study the models of the company from which you want to buy a generator. You must understand exactly how the energy resource works and what opportunities it gives.

For example, if you are buying a gas-powered generator, you must stock up on it, if you want to buy a Solar portable generator, you also need to understand how to use solar panels.

Step 4

Finally, you need to understand exactly where the generator will be located to be prepared for how much space it can take.

Heat pump sizes 

Below you can see the different heat pump sizes and how much power they require.

  1. 1 ton (SW: 2571W; RW: 857W)
  2. 2 tons (SW: 5143W; RW: 1714W)
  3. 3 tons (SW: 7714W; RW: 2571W)
  4. 4 tons (SW: 10286W; RW: 3429W)
  5. 5 tons (SW: 12857W; RW: 4286W)
  6. 6 tons (SW: 15429W; RW: 5143W)

What generator will suit 3 ton heat pump? 

Finally, we come to one of the main questions of this article, namely which generator is suitable for heat pumps, which are 3 tons. To begin with, a 3 tons heat pump size requires 7714 watts to activate and 2471 watts to operate continuously and stably.

From this, we can immediately conclude that a portable generator will not work in any way, since it simply cannot provide energy costs. It is best for a 3 ton heat pump that a standby generator is suitable, as it will allow you not only to provide electricity to the pump but also to connect other devices, such as an air conditioner.

Why is the generator size important? 

Perhaps you think that the size of the generator does not matter and this is a matter of chance, that is, you want to take a chance and use, say, a 3 ton heat pump with the recreational inverter. Then you need to look at the reasons why you should choose the right generator size.

Power supply

Firstly, with insufficient supply power, your device, in particular a heat pump, due to a lack of electricity, can degrade its performance so much that it cannot be repaired later. Also, it will adversely affect the operation of the generator itself, causing overheating inside its system.


If the generator is constantly overloaded due to attempts to power the heat pump, it will wear out much faster and even if you want to use it for its intended purpose for smaller devices, the generator may no longer work as it used to.


On the other hand, if you choose a generator that is too big for your heat pump, you also run the risk of getting too high costs, since the larger the generator, the more resource it requires, like diesel or gasoline.


Finally, if you choose the right size generator for your heat pump, you won’t run the risk of overloading your home’s electrical system, and you’ll be able to use the HVAC system in your home with confidence.

Installation of a generator with a heat pump 

To get a complete and successful operation of the heat pump, you need to immediately understand what to look for during installation, so as not to get into unpleasant situations with a generator breakdown. Below you can find tips to help you properly install all generators except portable generators with heat pumps.


First, you need to pay attention to the conductor system, namely the type of voltage on your generator, because if your heat pump only fits 120 watts, and your generator has a different input voltage, then they simply cannot connect.


Secondly, the generator with heat pumps must be synchronized with the power grid of the place where you live. You can try to synchronize it yourself or contact a specialist.

User manual 

It is best to refer to the owner’s manual or call a specialist, as it is unlikely that you will be able to properly install a generator designed to provide a large heat pump on your own. This can be dangerous not only for electrical appliances but for you too.


Also make sure that the place where you installed the generator will not interfere with your neighbors in any way, moreover, that the generator will not be able to damage the electrical system to which people who live in your area are also connected.

Transfer switch generator 

Before you start using the generator with heat pumps, it is worth understanding exactly how the transfer switch works. The transfer switch connects to the power panel and is used to transfer power directly into the home, making it very easy to install generators.  

Also, during power outages, the generator switch is very useful, since you can monitor the activation of the generator through the transfer switch. Moreover, incorrect installation of the transfer switch can lead to damage not only inside the generator but also to the heat pump, as there will be an overvoltage of energy.


We hope that after reading this article, you now understand how to choose the right generator for heat pump size, what are the sizes of generators and you understand how powerful your generator needs to be to run a heat pump, and which size is 3 tons or even bigger. Read about best quiet RV generator for camping

Frequently Asked Questions (FAQs):

How many watts does it take to run a 3 ton heat pump? 

To activate a 3-ton heat pump, 7714 watts of electricity is required, and for stable operation, there must be a constant flow of 2571 watts.

What size generator do I need to run a 3.5 ton heat pump?

You can use 15 kW generators like standby generators if your heat pump size is 3.5 tons.

What size generator do I need for heat pump?

It all depends on the size of your heat pump, i.e. the larger the heating system that requires electricity, the larger the generator will be.

How many amps does a 3 ton heat pump require?

Your heat pump requires between 7 and 12.3 amps, which is quite a large amount of electricity and requires a powerful resource.

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