The wattage that a heat pump unit requires depends on various factors. The three most important aspects are size, type, and efficiency. There are several general reasons you might want to know how many watts a heat pump uses. But in this article, due to its growing popularity, we will be thinking in terms of a solar power source for those watts.
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What type of unit should you go for? How many solar panels are you going to need to run a heat pump? Are there ways to lower your electric bill even more?
You’ll find many relevant answers below. But first, let’s start with efficiency.
What Is the CoP?
The coefficient of performance shows how efficient a heat pump is.
It defines the relationship between the power that is supplied to the compressor (electricity) and the power that is drawn out of the unit (heating or cooling units).
If a heat pump has a CoP of 3, for example, it means that for every unit of electricity the system can produce 3 units of cooling or heating power.
The efficiency of the heat pump and its coefficient of performance depends on a wide range of factors:
- The type of the heat pump
- The difference between condensation and evaporation temperatures
- The type of refrigerant
- The quality of installation, and others.
In a nutshell, if the CoP is over 1, it already means that a heat pump is efficient. For comparison, gas furnaces with a 96% AFUE are considered to be extremely efficient which means that for every unit of power consumed, they can produce 0.96 units of heat.
Read: The Most Efficient Way To Use A Heat Pump
How Many Watts Does a Heat Pump Use?
Generally, the bigger your house, the higher your heat pump’s output has to be.
However, the right output for your house would also depend on the quality of insulation, the desired indoor temperature, the climate you live in, and a lot of other factors.
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Here are some rough numbers that you can use as a benchmark:
| The Type of the House | Air-Source Heat Pump Recommended Output | Ground-Source Heat Pump Recommended Output |
| 2-bedroom house | 5 kW | 4 kW |
| Poorly insulated 3-bedroom house or well-insulated 4-bedroom house | 9 kW | 8 kW |
| Poorly insulated 4-bedroom house or well-insulated 5-bedroom house | 16 kW | 15 kW |
An average house requires around 12,000 kilowatt-hours of heat annually. So, if you have a heat pump with a CoP = 3, then the unit would be using 4,000 kilowatts of electricity every year.
The coefficient of performance and the output of a heat pump are not the only values that can be used to describe the efficiency of a heat pump.
To make things a bit easier and gain some perspective, let’s take a look at the following examples.
How many watts does a 12,000 BTU heat pump use?
A BTU or a British Thermal Unit measurement describes the output size of the heat pump.
1 BTU refers to the amount of energy that is needed to heat up 1 lb of water by 1 F, which is approximately the same amount required to cool or heat 30 cubic feet of air.
Additionally, 1 British Thermal Unit is equal to around 0.2931 Watt-hours.
So, a 12,000 BTU heat pump is going to use about 3.5 kW every hour.
How many watts does a 3-ton heat pump use?
Tons are used to describe how much heat can be removed from a house in an hour.
12,000 BTUs are equal to 1 ton. That means that a 3-ton heat pump can remove 36,000 BTUs of air every hour.
Such a heat pump needs 7200 startup watts and 5400 running watts.
Now you have a general idea of sizing and how the different measurement relate to each other.
What about environmental Efficiency?
If before getting a heat pump, you had a gas or an oil furnace, the new unit will eliminate your need for fuel. However, a heat pump still needs electricity, in order to function.
It is arguably more environmentally friendly (and safe) to switch to electricity than to continue using propane. But if you’re concerned about emissions, take note that the majority of power stations still produce electricity by burning fossil fuels.
Is there a way to not only save money on electricity but also reduce the air contaminants around your home and in general?
First of all, even though heat pumps require electricity, they don’t need as much as ordinary electrical heating systems such as electric furnaces, baseboard heaters, or wall heaters.
Heat pumps are approximately 3 times as efficient as these systems. That means that you’ll be able to lower the power consumption by about two-thirds.
The only homeowners who won’t benefit economically from a heat pump are those who are used to heating with natural gas (as the price of this fuel is usually lower than that of electricity).
However, you can always choose to switch to a solar heat pump that will not only help you save money but could also be beneficial ecologically.
How many solar panels are needed to run a heat pump?
The wattage rating of the solar panels that your house is going to need would depend on a wide range of factors:
- The size and type of the heat pump
- The climate you live in (the irradiance at your location)
- The efficiency of the heat pump
- What other forms of heating your house has, and so on.
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As a general rule of thumb, you are going to need 1500 watts of solar power (that’s eight 200-watt solar panels) for every ton.
Therefore, if you have a 2-1/2 ton unit, you’ll typically require a minimum of nineteen 200-watt solar panels.
You will also require an inverter in order to convert the DC voltage generated into AC voltage for your heat pump. Due diligence is essential to make sure all components are compatible, for an efficient and safe system.
Getting deep cycle batteries (for energy storage) is recommended as well, if the budget allows. That way you can store the unused energy produced for use at a later time.
For example, electricity produced during the day while you’re at work can be utilized later in the evening or another day.
However, there are significant costs involved with storage batteries which can make this a challenging economical option.
How to Lower Your Electric Consumption
Even though switching from an electric heater to a heat pump is already going to save you approximately $815 per year, you can try lowering the operational costs of your unit even more.
Insulate Your House
Properly insulating your house is something that you should consider doing before investing in a heat pump.
Your home is going to become ‘heat pump ready’, as soon as you have assessed the state of your existing insulation and modernized it (don’t forget to find your climate zone and check the required R-value).
Loft and wall insulation will help you drastically lower the heating needs. Also, don’t forget about the gaps between the doors and windows.
Get the Proper Size
There are a lot of things that you have to take into consideration when choosing a heat pump, starting from the square footage of your place and ending with the number of people living in the house.
However, you can always use this general rule as a benchmark:
For every square foot of living space, you are going to need around 30 BTU of heating output.
Does your house have 1000 square feet? Then go for a 30,000 BTU (2.5-ton) heat pump.
You should also hire a highly-skilled professional to install the unit. As an incorrectly installed heat pump won’t be able to work as efficiently.
Read: What Size Heat Pump Do I Need?
Change the Filter Regularly
Your heat pump would have to work harder to get air flowing through a clogged filter.
The system might simply get worn out (or even damaged) much quicker and such a dirty filter won’t be able to filter out various airborne particles as efficiently.
Perhaps, one of the simplest things that you can do to help your heat pump live a long and happy life is change the filter regularly. Usually, that’s once every 1-3 months.
Read: Why Does My Furnace Filter Get Dirty So Quickly?
Opt for a Programmable Thermostat
A programmable thermostat is a smart device that is, basically, going to keep your house at a comfortable temperature all year round.
For example, the thermostat can make your home nice and toasty during the day and automatically lower the temperature at night.
Moreover, you can program the device to turn the heating or cooling on around 15 minutes before you plan on being in the room.
This will help you avoid coming back home to a freezing house and raising the thermostat’s settings to a ridiculously high temperature which, in its turn, makes the energy bills skyrocket.
Read: Why Does The Room Temperature Not Match The Thermostat Setting?
Keep Doors, Curtains Closed
Finally, your doors and curtains can help you maintain the right temperature or decrease the heat pump’s efficiency.
Keep the doors shut to avoid drafts and close the curtains when it’s cold outside. If you have a window that tends to get a lot of direct sunlight, you can spend a few seconds on either closing or opening the curtains (depending on whether you need your house to be cooler or warmer).
No matter how many watts your heat pump uses, you can drastically decrease the unit’s electricity consumption even more by following the simple tips mentioned above.
Also Read: Heat Pump Effectiveness in Cold Weather