What are the disadvantages of heat pumps ...

Some of the disadvantages you may have heard of are actually true. Most, however, are not. 

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Electric heating, natural gas and other fossil fuel powered solutions have become prohibitively expensive in many countries. These rising costs, along with new renewable heat incentives have led to increased demand for ground source and air source heat pumps.

Many buyers, however, are skeptical about heat pumps and are concerned that the many heat pump pros are overshadowed by important cons. In this article we’ll look at the top heat pump pros and cons in detail using facts.

Let’s bust some myths and discover the true disadvantages of heat pumps. 

Heat pumps don’t work in cold climates

The ability of heat pumps to cope in cold climates or harsh winters is often – and wrongfully – doubted. Since they extract heat from the air outdoors to transfer it indoors, people often assume that the weather outside must be warm for them to function. To an extent, this may have been the case many decades ago, but today some heat pumps can produce heat even at external temperatures lower than -25°C and even -30°C. 

This isn’t the case for all heat pumps though. If you live in a colder climate, you need to ensure that you pick a system suitable for colder climates. 

Norway, Sweden and Finland have some of the coldest winters in Europe, and yet they are at the top of the list for heat pump ownership per capita. According to the EHPA 60% of homes in Norway and more than 40% in Sweden and Finland are equipped with heat pumps.

Some cold-climate external units such as the Mitsubishi Zubadan series are really pushing the boundaries for heating in extremely cold climates. Mitsubishi’s Zubadan has an extended operating range down to -28°C and even -30°C for some units. That’s one of the reasons why we exclusively combine TermoPlus with Mitsubishi external units.

Advancements in electric heat pump technology have made this possible. Flash-injection technology, optimized defrost cycles, larger evaporators and advanced controls are just some of the innovations that have made heat pumps an excellent choice for cold climates.

Inverter-driven heat pumps employ variable speed compressors and fans, which makes them ideal for tackling colder climates. This gives cold-climate heat pumps the power to effortlessly heat your home in colder climates while also maintaining greater efficiency with lower speeds during the rest of the year. 

Advanced defrost cycles prevent the accumulation of ice on the outdoor unit, which allows the heat pump to reliably operate in colder temperatures.

Auxiliary heating functionality – essentially an additional electric resistance heater – is often featured in heat pumps. This heater compromises efficiency to provide additional heating during extremely cold weather conditions. This offers “emergency heating” and could come in handy in a situation where a less capable or older heat pump struggles with extreme cold. Cold-climate inverter-driven heat pumps such as a Zubadan don’t need the additional heat generated by a resistance heater. 

The view that heat pumps only work in warm climates is completely inaccurate. Quite the contrary, they are the ideal solution for homeowners situated in cold climates where heating bills are a heavier burden.

Heat pumps leak refrigerant

Heat pumps use refrigerant as part of the process of transferring heat from one space to another. It is indeed true that heat pumps can leak refrigerant. This is particularly a problem with older heat pumps that use refrigerants that can be very harmful to the environment and even to health. 

Improper installation and less reliable products may face an increased risk of refrigerant leaks. As with all manufactured products, some brands are better than others at craftsmanship and quality control. 

Nevertheless, leaks may occur to any heat pump, and it is easily repairable in the vast majority of cases. 

Air source heat pumps are composed of two main parts: an internal and an external unit. For split units, refrigerant is circulated between the two units. Monobloc units however keep the refrigerant circulation inside their external units and heat transfer to the hot water is achieved in the external unit. That way, the external unit houses the refrigerant and reduces the risk of leakage significantly. This is why the installation of monobloc heat pumps doesn’t require a refrigerant-qualified technician.  

A 2014 study estimated that the annual leakage rates were 3.5% for domestic heat pumps and 3.8 for commercial / industrial applications.

Picking a reputable brand, having a qualified installer perform the installation and maintaining the unit as required will significantly reduce the risk of a leak. Servicing a heat pump regularly also helps early detection of leaks which will help identify and fix the problem early on.

Heat pumps are noisy

Older heat pumps were noisy indeed, but the technology has matured over the years with heat pumps becoming much quieter. 

Manufacturers have put a lot of effort into reducing noise levels over the years. The advancements in insulated enclosures, the use of variable-speed compressors and fans as well as the improvement of vibration-dampening mounts have all played a role in the reduction in noise. 

All sounds between 30dB and 60dB are considered quiet. Mitsubishi external split units typically produce around 54-58dB of noise which is about the sound level of a normal conversation. The Mitsubishi monobloc units are even quieter, starting at 45dB. Internal units only produce around 30dB which is roughly the sound level of a whisper. These noise levels are nowhere near where they used to be a decade ago.

It’s safe to say that for most people, modern heat pumps don’t produce enough noise to be a concern. 

Heat pumps cost a lot to buy

The cost of installing a heat pump system is significantly higher than installing a more traditional heating system such as a gas furnace, electric heater, or air conditioning system. This is also the single most important reason why heat pumps have not completely replaced other heating methods. Since heat pumps don’t use much electricity, they are much more efficient at providing heat.

Over time, the initial cost of buying a heat pump is easily recouped, and the savings are significant. 

Installing a heat pump for your home is an investment that will pay for itself 2–3 times over the life of the heat pump system.

Even with subsidies though, the investment required is still higher than what many people can afford and the cost of financing can eat into the savings gained. Many purchases happen when an older system reaches the end of its life and breaks down. Since a replacement may urgently be needed homeowners may often look at replacing the existing system quickly and at a reasonable cost. 

Heat pumps are ideal for homeowners that are willing to invest more upfront to increase their future savings.  

Heat pumps are expensive to operate

Heat pumps may be expensive to buy but certainly not to own and use. Overall, they use significantly less energy to heat your home and are better for the environment. The purchase cost is indeed high but the 20+ years of lifetime a system offers, combined with the extremely low running energy consumption, make them an ideal investment for homeowners that want a lower overall heating cost.

Let’s compare the energy efficiency of various heating alternatives:

Electric resistance heaters: These are the baseline for energy efficiency and are 100% efficient. This means that for each kW of energy they consume, the produce another kW of usable thermal energy.

Wood Boilers and furnaces: 60-85%, but with advanced gasification boilers this could reach 90%

Oil boilers and furnaces: 80-90%

Gas boilers and furnaces: 80-98%

Heat pumps: 300% to 500%. The magic of the heat pump is that it produces three to five times more thermal energy than the electric energy it consumes. Heat pumps work by moving heat rather than generating it. This means that they use less energy to provide the same amount of heat as other heating systems, such as furnaces or boilers.

Geothermal heat pumps: Ground source or water source heat pumps can have a whopping efficiency of 300% to 600%. 

Similarly, heat pump technology for heating domestic hot water is also extremely efficient.

• Electric resistance water heaters are 95-100% energy efficient
• Gas water heaters are 50-60% energy efficient
• Heat pump domestic hot water heaters are 300-400% energy efficient

Many heat pumps are designed to heat domestic hot water as well as provide heating and cooling making them a very practical solution.

Maintenance costs are also extremely low for heat pumps. In addition, a heat pump can also replace the need for a separate air conditioner by extracting heat from within the house. The total ownership cost for a heat pump is the lowest than any other option.

However, it’s important to note that the purchase cost is prohibitive for many homeowners. Government subsidies, rebates and incentives can reduce this cost and with various financing options heat pumps are still an extremely popular solution for reducing heating bills. Financing is often available, which makes the investment in a heat pump a great choice for many homeowners that would rather pay the cost of financing than the cost of fuels.

Heat pumps are not as powerful as other heating and cooling systems

This is not true. Heat pumps must be appropriately sized when installed so that their capacity can match the required heating needs of a home or business. Undersized systems will indeed fail to provide the heating capacity needed and will also be less efficient as they struggle to meet the output demanded. Oversized systems will have greater capacity than needed but will also cost more than is necessary. 

When you ask for heat pump quotes, installers will need to accurately size your requirements. A properly sized system will have exactly the right heating capacity while at the same time offering the optimal level of efficiency.

It is true that for buildings using radiators a higher temperature needs to be met, but again this is something that is accounted for in the system design phase. So, unless there was a poor system sizing, there is absolutely no reason for a heat pump not to be powerful enough to heat a home or business.

Heat pumps require backup heating

Heat pumps do not require backup heating for the vast majority of homeowners. While indeed some older heat pump units could not reliably heat a home in extremely cold conditions, this is far from true for heat pumps sold over the last decade or so.

In very few extreme cases where heating is deemed essential, and the environment is extremely cold it may be prudent to have a backup system – but this is the case for any other heating system. One great advantage of heat pumps in this situation is that they can coexist with older systems that they are meant to replace. 

It’s worth mentioning that heat pumps can reliably provide heating at lower temperatures than some coal, gas, or oil-powered solutions, only losing some efficiency at extreme temperatures. Even when the efficiency is lowered though, it is still far greater than any other heating option. 

Some cold-climate heat pumps such as a TermoPlus Hydrobox or Hydrotank paired with a Mitsubishi Zubadan could even provide reliable heating in extreme temperatures as low as -30°C. 

Installing a heat pump requires extensive works

The vast majority of heat pumps do not require extensive works. As a matter of fact, in most cases it just takes a few hours (1-2 days at most) and doesn’t require any alterations other than a few holes drilled to allow for pipes to be connected.

A common misconception is that heat pumps require underfloor heating. Heat pumps can work with radiators, possibly even your existing radiators. This makes them extremely flexible and easy to install. 

Air source heat pumps are typically installed within one or two days and don’t need any structural modifications. These include monobloc and split heat pumps, which are most commonly installed. Usually they only need a few pipes and wires to be installed, connecting the external unit to the internal one as well as a connection to the radiators or manifold. 

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Monobloc air source heat pumps in specific are even easier to install. Heat is extracted from the air from outside and transferred to the water within the external unit. The refrigerant is all located within the external unit, so there is no need for a refrigerant-certified technician to connect refrigerant lines between the external and internal unit. This type of installation could be a matter of a few hours.

Even if a domestic hot water system needs to be installed alongside a heat pump, the installation is easy, clean and requires no modifications to the building whatsoever.

There are some heat pump installations that require more extensive works though. If you plan on installing underfloor heating to replace radiators, that would be more inconvenient for you as a process. Also, if you opt for a ground-source heat pump, then you are likely looking at extensive landscape work. You will either need to have excavation work done to place a horizontal loop underground or have vertical boreholes created.

Heat pumps are unreliable

Luckily, heat pumps are extremely reliable and have a very long expected lifecycle of around 20 years. Cheap unbranded generics can last around 15 years and time-tested quality-oriented brands such as Mitsubishi and TermoPlus can last up to 25 years in operation.

As with any other HVAC system, there are some occurrences where heat pumps can fail. All heating and cooling systems require regular maintenance or else problems can arise. The maintenance process for heat pumps is straightforward and very economical, so there is no excuse not to maintain them properly. 

With heat pumps in particular, installation and sizing can play an important role in the reliability of the system. If  a heat pump is not installed properly, it may face issues down the road. This also goes for any type of heating and cooling system really though. 

An improperly sized heat pump installation can result in over-stressing the compressor to generate heat at a greater level than planned.

To make the most of your heat pump’s expected lifetime without any hassle all you need to do is:

• Work with a reputable installer that focuses on heat pumps,
• do some research to pick a reliable brand and
• make sure to maintain the system regularly.

Heat pumps rely on electricity to provide heat

There are two downsides to relying on electricity to power your heat pump. In the event of a power grid outage, you won’t be able to heat or cool your home. The other downside is that your heat pump may not be as environmentally-friendly as you had hoped and becoming carbon neutral may take a bit more work. 

If you are considering investing in a heat pump for environmental reasons, you may wish to consider the source of power that electrifies your grid.  Heat pumps are electric so unless your power source uses renewable energy it won’t achieve the potential it has for sustainability. It will still use significantly less power than electric heaters and will still be a more sustainable option. Ideally though, if you’re looking at using a heat pump for sustainability reasons you should either choose a power provider that provides 100% sustainable electricity or you can also consider using solar panels to power your heating and cooling needs.

Also, if you are situated in a remote location and the power grid isn’t very reliable, you may need to consider a secondary heating solution or a backup power system. Most boilers and furnaces require electricity to operate too and also won’t work without a source of electricity.

Heat pumps and solar panels are a match made in heaven. It is a fantastic way to reduce those growing heating and power bills. If you also install battery storage, you will reduce your risk due to power outages. 

Heat pumps require a lot of maintenance.

Heat pumps are pretty robust and don’t require a lot of maintenance – but they do require scheduled maintenance. 

The ownership cost of a heat pump is extremely low. Maintenance involves an annual inspection and servicing, typically once a year. 

Heat pumps also don’t produce any combustion byproducts, such as carbon monoxide, so they don’t require regular inspections for safety reasons.

Research and system design

Whether you are interested in an air-source heat pump or ground source heat pump, you will find that the sizing of the system significantly affects its efficiency. Over-sized and under-sized systems cost more to run, not to mention the higher purchase cost of a larger system.

Not only that, you will need to ensure your system design will tick all the boxes regarding your needs. Will you combine it with solar PV or not? Will you choose a system that includes a Domestic Hot Water (DHW) too? Do you need cooling?

All this research will determine the pros and cons of installing a heat pump for each case. Working with a reputable HVAC installer that specializes in heat pump installation should give you more options and guidance as to what system suits your situation best. 

Why are some contractors skeptical about heat pumps?

We discussed the many alleged disadvantages of a heat pump solution and most of these concerns are completely unfounded. So why are some HVAC contractors skeptical of heat pumps?

Some HVAC installers are complacent with traditional heating technologies and are reluctant to advance into heat pumps which have a steeper learning curve. Installing a heat pump would require training in new skills. It is also no secret that some traditional heating system salespeople perpetuate some of these myths as they compete for sales commissions.

The truth is that some of these concerns may have been valid in the past, but heat pump technology has evolved significantly over the last few decades and can offer unbeatable benefits.

Genuine heat pump disadvantages

There are also some real disadvantages to investing in a heat pump. The high purchase cost is certainly a disadvantage for many people that can’t afford one. Getting proper system sizing and design can also be a challenge if the installer doesn’t match the required standards. That is because poor sizing or using the wrong type of system can result in an insufficient level of heat or poor efficiency. These are probably the two most important challenges a homeowner faces when considering investing in a heat pump.  

Heat pump advantages

There are many more advantages to investing in a heat pump system than there are disadvantages. Their superb efficiency and their very long life make them an ideal choice for anyone looking to save money in the long-run. Their immense flexibility to produce heat, cold air, and domestic hot water is excellent. They can be used in combination with other systems as part of a remodel or as a new build. A heat pump can combine heating and cooling into one system. Heat pumps do require regular maintenance, but it is very economical compared to other options.

Their potential as a carbon-neutral renewable heat source is higher than any other solution.

Finally, there is no risk of gas leaks and carbon monoxide poisoning.   

If you’re in the market for a heating system, it is a good idea to spend a bit of time with an experienced heat pump installer that can provide you with a sound proposal around your needs. 

Awareness of air source heat pumps is increasing as more and more homeowners are talking about low carbon heating systems. A heat pump system is different to a traditional central heating system that uses a gas or oil boiler so to help homeowners fully understand the advantages and disadvantages of this renewable technology, we have summarised some in this article.

An air source heat pump cleverly uses the heat energy in the air and captures this to be used in a central heating system. Instead of using a fossil fuel, heat pumps are a renewable energy source and require electricity to power them. They do operate differently to a traditional heating system so living with a heat pump is not the same as a gas or oil-fired system.

There are many benefits that homeowners can enjoy when they own a heat pump but it is important that they understand the differences too, so let us take a look at some air source heat pump pros and cons.

Advantages of heat pumps

1. Save costs on fossil fuels

If your home is currently heated by a fossil fuel, such as gas, oil or LPG, then swapping to a heat pump will mean you will no longer need to order these fuels, allowing you to heat your home more sustainably. You can therefore enjoy not having these fuel costs to pay each month as your gas bills will be no more!

2. Heat pumps are very efficient

When an air source heat pump is installed and set up correctly, they are very efficient units, maximising output for the energy consumed. For example, the Grant Aerona³ 6kW air source heat pump produces 6kW at a SCOP of 4.62 when tested at a low temperature and in average climate conditions (SCOP refers to the efficiency of a heat pump, calculating its overall performance during a particular season and dividing this by the annual energy consumed to run the heat pump). In summary, what this means is that for every kilowatt of energy used to run the heat pump, over 4kW of energy is being given to the heating system in return.

To view the performance data of Grant heat pumps, please download the data sheet here.

3. Sustainable heating solution

An air source heat pump appliance itself burns no fossil fuels and uses electricity. With more and more of the electricity generation in the UK now being produced via renewables, this makes a heat pump a better choice for the environment than gas boilers.

4. Low maintenance and user-friendly

Grant heat pumps are user-friendly being both straightforward to control and simple to maintain. When an installer sets up and commissions a heat pump, they will set the core parameters of the system so that the end-user has minimal interaction with the controls. Thereafter, the homeowner can adjust their desired room temperatures via third-party controls, which may be app enabled, and they can sit back and enjoy their renewable system. The only thing to remember is to arrange the annual servicing of the heat pump.

Disadvantages & considerations of heat pumps

1. Increased electricity 

usage

As mentioned above, heat pumps do need electricity in order to work so if you install a heat pump, you will likely see an increase in your electricity usage. It is recommended that homeowners contact their energy supplier to see if a heat pump electricity tariff is available which may be a cheaper and more suitable tariff for an electric based renewable heating system.

2. You may need to install new radiators

A term you will often hear of with heat pumps is ‘low temperature system’. Unlike boilers which are high temperature systems, a heat pump operates at a lower flow temperature so to ensure that this heat can be effectively transferred into the space within the home, sufficient heat emitter surface area is needed and this is why correctly sizing the heat emitters is so important. It is not always possible to use existing radiators with a new heat pump as larger radiators, or an underfloor heating system, may be better suited.

3. More preparation is needed to design the system

Compared to traditional boiler replacements, a heat pump installation requires significantly more planning and preparation. The design of the system must be thoroughly completed with a detailed heat loss calculation carried out on the property to ensure it is well insulated, as well as a correct assessment of the heat pump output required and the correct sizing of the chosen heat emitters.

Ensuring your property is well insulated is key for an effective heat pump. We recommend as a minimum checking your loft, cavity wall and window insulation. You can find out more on our blog – how to prepare your home for a heat pump.

It is important that no corners are cut during the design phase to ensure that the system installed is the right one to meet the heat demand of the property most effectively and efficiently.

Provided the unit is installed correctly, adhering to all the do’s and don’ts which are detailed in our heat pump brochure, a heat pump will deliver years of reliable, sustainable home heating.

Homeowners need to be well informed about heat pumps so if you are interested in learning more about this renewable technology, visit our Knowledge Hub.

If you are interested in learning more about air source heat pumps, you may be interested in taken a listen to our Net Zero Heating Show podcast. The podcast is aimed at installers and heating professionals but homeowners looking to learn more about this renewable technology will also find it an interesting listen. 

If you are looking for more details, kindly visit Monobloc Heat Pump.