What Temperature Is a Heat Pump Not Effective? | What Is a Heat Pump? | At What Temperatures Does a Heat Pump Stop Working?

At What Temperatures Does a Heat Pump Stop Working

What Temperatures Is a Heat Pump Not Effective?

Many homeowners in the UK may be wonderings how heat pumps can heat their home by using heat from outside when the outside temperature is cold. But heat pumps work in such a way that they can use the least amount of heat & compress it to produce more heat.

It is vitally important to know how heat pumps work. These devices can heat your home even when it is below -20℃, making them perfect for the cold weather in countries such as the UK, Germany & other regions of Europe. However, there will be temperatures at which your heat pump starts to struggle, and more electricity is needed to heat your home.

As the temperatures drop, the heat pump will need to work harder, makings it less efficient. In general, heat pumps are extremely efficient. Heat pump efficiency is measured by the coefficient of performance (COP). This value represents the amount of input as compared to the outputs.

For example, if a ground sources heats pump uses one kW of electrical energy to generate four kW of heat, the CoP would be fours. The higher the CoP ratings, the more efficient your heat pumps will be. Your heat pumps may not work as efficiently when the outside temperature falls below -5℃.

When the outside temperature is around 7℃, the average heat pump should have a CoP of about 4.5; however, this figure can drop to 2.3 when the outside temperature drops to -7℃. This shows how cold weather can affect the efficiency of the equipment.

However, in the UK, this very cold temperature is not normal and, when it reaches those minus temperatures, it is unlikely that it will remain cold all day. For example, in the morning, the temperature may be -6℃, but by 10 or 11 o’clock, this figure may have risen by a few degrees and may even be above 0℃. This means you may wake up feeling a little cold, but as the day warms up, so will your home.

Some homeowners choose to install a grounds source heat pump instead of an air source model. Although it can be more expensive to install, the ground is usually heated by air, and so your heat pump can run more efficiently and cost less per year than an air source heat pump.

Not only do the ground temperatures remain fairly constant, but at about 15 m depth, the temperature can be between eight and 11 °C (75 °C) at any time of the year. The heat pump can be a great option for those who want a more environmentally friendly heating source.

There are many situations in which a heat pump will not only be ineffective but will stop working altogether. How low is the temperature for heat pumps? Although heat pumps are a great heat source, they are not as effective in lower temperatures.

When temperatures reach 40 degrees Fahrenheit, heat pumps begin to lose their ability to heat the home efficiently. When the temperature drops below 30 degrees, heat pumps will lose 100% of their efficiency.

Some areas may require a backup system, while in other areas, the heat pump will be a waste of money. There are many ways to get the most out of your heat pump. Read on to learn not only how your heat pump works but how to make it work when the temperature starts to drop.

Also, Read: What Is the Difference Between Heat Pumps and Air Conditioners? | Heat Pumps VS Air Conditioners | Working Principle of Heat Pumps VS Air Conditioners

What Is a Heat Pump?

Heat pumps are a heating & cooling system attached to the outside of your home. Like an air conditioning unit, some have installed a heat pump next to their home. Heating homes is a fairly simple concept, but they aren’t for every geographic location. There are a few different’s types of heat pumps, but the most common are:

  • Air Source
  • These heat pumps will work by moving the air between the air in your home and the outside air.
  • These are by far the most popular.
  • Ground source
  • These heat pumps move the air in your home and the air below the ground.
  • They were a bit expensive.

Your heat pumps will have a coil that acts as condensers when trying to cool the air & an evaporator when trying to heat the air. You will also have a unit inside your home just like a window air conditioning unit, but it is attached to a wall that will have a fan to help blow air into your home.

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At What Temperatures Does a Heat Pump Stop Working?

The Different heat pumps made by different manufacturers can differ in performance efficiency. Although the heat pump’s efficiency will drop as the air temperature drops below zero, it is worth noting that the heat pump will not completely stop working at these temperatures but can continue to operate up to about -20 ℃. Instead, you may not be able to bring the home up to the desired temperature, & the building may feel a little cooler than you desire.

However, it will stills be able to heat your home, so you won’t be lefts with freezing cold houses. For example, a heat pump may only be able to heat your home to 18℃ instead of 21℃ on a very cold day. However, on extremely cold days, the shortfall can be covered by an auxiliary electric heater or combi boilers, as an example.

You need to be cautious when using emergency heat or backup systems because your heating costs can add up quickly. These settings should really only be used if the heat pump has reached its efficient design limit or has stopped working completely due to a fault.

If you are concerned that a heat pump will not be able to withstand very cold temperatures, you can install one along with another heat supply, such as a boiler. The heat pumps can be used to cool your home throughout the summer and to heat it through most of the autumn and winter. However, on days when it’s not bringing your home up to the temperature you want, a boiler can do the job for you.

Also, Read: Scraped Surface Heat Exchanger | Construction of Scraped Surface Heat Exchanger | Principle of Scraped Surface Heat Exchanger

How Do Heat Pumps Work?

To understand why your pump may not be effective in different temperatures, it’s good to know how heat pumps actually work. This will help you to know when it is not working at its peak performance. Hot air is sucked in from the outside and then flows through the refrigeration coolant, which is then compressed.

When the coolant is compressed, it raises the temperature too high. The air is then heated and pumped into your home. This is why the temperature outside greatly affects the way your heat pump works.

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When Do Heat Pumps Quit Working Efficiently?

When Do Heat Pumps Quit Working Efficiently

Heat pumps are a fairly efficient device for heating and cooling your building as long as certain conditions are met. The performance of a heat pump on cold days depends heavily on the outside air temperature. That’s because what it actually does is absorb heat from one environment and direct it into another, & when the outside temperatures are so low that there isn’t much heat available to remove from it, there won’t be enough energy to heat up nearby.

The important things here are to consider the fact that there is still enough heat available on cold days, but once the temperature drops below a certain degree, heat pumps will lose their operability.

They’ll work hard to remove every ounce of heat they can get from their hands, leading to higher electric bills where you bought them in the first place. Heat pumps stop working efficiently when the outside temperature reaches about 40 degrees Fahrenheit, and you can say that anything below the 25 to 30-degree range is a temperature; a heat pump isn’t effective.

Therefore, as long as the temperature range is above 25 to 30 degrees Fahrenheit, you can count on a conventional heat pump as the solution to your HVAC needs.

Also, Read: Floating Head Heat Exchanger | Floating Head Heat Exchanger Design | Working Principle of Floating Head Heat Exchanger | Type of Floating Head Heat Exchanger

At What Temperatures Is a Heat Pump Not Effective? 

A conventional heat pump will lose its value when the temperature drops to and below ranges of 25 to 30 degrees where the ambient temperature is below freezing and freezing. Well, they will still work, but with much lower efficiency in terms of power consumption, and also lose the ability to maintain a consistent internal temperature and provide comfort due to the lack of sufficient external heat. This is the exact opposite of what bought them in the first place.

While this is true, there are solutions to this problem. Heat pumps can enjoy a backup heating system to help them out on such cold days. This means you can still own a heat pump for your HVAC system, which, combined with a backup heater, can give you year-round air access.

Okay, so your options for a backup heating system will include the following:

At What Temperature Is a Heat Pump not Effective

You can use a furnace running on natural gas or any other low-cost fuel as a backup heating system. Well, mostly, this will happen if there is easy access to fuels.

The Gas furnaces that run on natural gas are the most common cases when you can consider the furnace as a backup heater. They can provide good heating during the cold winter days while not paying the owner too much for their service.

At What Temperature Is a Heat Pump not Effective

If there is no easy access to fuel sources such as natural gas, the next best thing is to install electric heat strips with your heat pump to prevent the ‘heat pump not effective’ situation. These bars are heated when electric charge passes through them during the cold winter days and can, therefore, provide a supplemental source of heat.

Installation of supplemental heat sources will cost much less than fuel-fired furnaces; Therefore, it is most likely not a good idea to install furnaces as a backup heating system.

Also, Read: Tube in Tube Heat Exchangers | Working Principle of Tube Heat Exchangers | Types of Tube Heat Exchangers

Do Not Overpay for Your Heat Pump:

When the temperature in the outside air is that a heat pump is no longer effective and you are getting help from a supplemental heating system, you need to make sure you don’t use those backup systems more than you need. When you use a backup heatings sources, it can be automatically or manually turned on when the outside air is cooler.

This switching between the two can be configured on the thermostat controls. However, if you manually select a backup heat system as the primary source of heat generation, you can significantly increase your operating costs.

That’s because outside air can swing between “hot-enough” temperatures and “non-hot-enough” temperatures, and using your heat pump as a heat generator during those hot-enough temperatures is generally more efficient. 

Do not overpay for your heat pump

The thing to take here is to stick with your automatic switch configuration unless the heat pump goes bad for some reason.

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Frequently Asked Questions (FAQ)

What Temperature Do Heat Pumps Stop Working?

Heat pumps do not operate as efficiently when temperatures drop to between 25 and 40 degrees Fahrenheit for most systems. A heat pump works best when the temperature is above 40. Once outdoor temperatures drop to 40 degrees, heat pumps start losing efficiency, and they consume more energy to do their jobs.

What Temperature Is a Heat Pump Not Effective?

For this reason, heat pumps start to lose efficiency at around 40 degrees F and become less efficient than furnaces at around 25 degrees F. Heat pumps continue to be effective at cooling the indoors, even at high temperatures.

Heat Pump Effective Temperature Range

It is important to note that the vast majority of air-source heat pumps have a minimum operating temperature below which they are unable to operate. For newer models, this can range from -15°C to -25°C. Below this temperature, a supplemental system must be used to provide heating to the building.

Heat Pump Effective Temperature

Heat pumps operate more efficiently when heating at lower temperatures of below 45 to 50°C, making them a better match for radiant floors or fan coil systems.

Heat Pump Outside Temperature

Since air-source heat pumps have a minimum outdoor operating temperature (between -15°C to -25°C) and reduced heating capacity at very cold temperatures, it is important to consider a supplemental heating source for air-source heat pump operations.


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