How Does Monobloc Heat Pump Work?

When deciding to purchase a heat pump, building owners can choose between a single appliance (monoblock) or a two-part split version. Both systems have their benefits and drawbacks, particularly with respect to difficulty of installation and space requirements. The question of whether to go with a monoblock or split heat pump is a complex one that should be considered on a case-by-case basis depending on the conditions at hand. We will show you what is important when making this decision.

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Before we go into the specifics of the different designs, we will briefly explain the working principle of a heat pump. Regardless of which type of heat pump you use, they are always efficient heating systems that extract free environmental heat by consuming a small amount of energy in the form of electricity.

The heat pump works like an inverted refrigerator, extracting thermal energy from the ambient medium and routing it to the heating system in the building. There, the energy can be used for DHW heating and/or central heating backup. In the private sector, the primary energy sources used are the ambient air, groundwater and geothermal heat.

Since the initial investment is higher for water-to-water heat pumps and brine-to-water heat pumps (also known as a geothermal heat pumps), many building owners opt for air-to-water heat pumps. They have many plus points, particularly in terms of flexible installation. This can be a deciding factor when renovating existing buildings, for example.

When we talk about monoblock heat pumps, we are actually referring to air-to-water heat pumps in which all components are housed in a single compact housing. This means that the entire refrigerant cycle takes place within the appliance. Therefore, fitters do not need a refrigeration certificate (generally only held by qualified refrigeration technicians) to install these appliances.

If refrigeration piping has to be installed, non-professionals are not permitted to carry out this work because there is a risk of climate-damaging gases escaping into the environment. The effort and expense of installing and maintaining monoblock heat pumps is therefore inherently lower than that of other variants. In principle, the design of monoblock heat pumps makes them suitable for both indoor and outdoor installation.

The entire refrigerant circuit is located inside the housing of a monoblock heat pump whether it is installed inside or outside the building. If you opt for a monoblock heat pump installed indoors, you will need to install air ducts in the building to supply and discharge the required ambient air. For outdoor installation, on the other hand, you will need to lay connection lines to the heating system through the walls. The most suitable type of installation usually depends on the space available in the building. Even if you opt for outdoor installation, you will need to allow for space for the associated indoor unit of the appliance. However, the indoor unit is significantly smaller than an indoor monoblock heat pump.

In new buildings, the space required for indoor installation of a monoblock heat pump can be taken into account from the outset. In contrast, outdoor installation is particularly suitable for retrofitting such heat pumps in existing buildings. However, indoor installation is also possible in existing buildings if there is sufficient space in the cellar, for example, or if an oil tank is discarded when modernising the heating system.

Overall, the installation costs for monoblock air-to-water heat pumps are lower because neither installation nor maintenance require a refrigeration certificate. However, the space requirements and weight of a monoblock heat pump are comparatively high, which can make it difficult to find the ideal installation site.

There are several advantages to the appliance components being divided into an indoor unit and an outdoor unit. The outdoor unit is much lighter and more compact than a monoblock heat pump with a comparable output. The noise level in the house is lower if the compressor is situated outdoors.

Inside the building, space requirements are lower for a split heat pump than for the indoor installation of a complete monoblock appliance. Split appliances cannot be installed entirely outside or entirely inside. Therefore, heat pumps of this kind are mainly installed where the available space necessitates a compromise between indoor and outdoor installation.

One disadvantage is that installation and maintenance are more complex and costly as technicians working on the refrigerant line require a refrigeration certificate. If the amount of refrigerant in the appliance exceeds the applicable reference value for the CO2 equivalent, building owners may be subject to an obligatory refrigerant test, which will result in additional costs every year.

The efficiency of both types of appliance is similar, but they are very different in size – the footprint and weight of monoblock appliances is always greater. Although monoblock heat pumps can be positioned more flexibly (indoor installation vs. outdoor installation), the size and weight of the monoblock version can slightly increase the complexity and cost of planning, depending on the space available on the property and inside the building.

In terms of noise, there is not much difference between monoblock and split heat pumps as long as their performance is suitably similar. Noise regulations in densely built-up areas can preclude outdoor installation, preventing split appliances from being used at all. A monoblock heat pump, on the other hand, could be installed indoors.

There is no point in making direct price comparisons of the two heat pump types as this does not reflect the whole picture. Monoblock and split heat pumps with similar performance rates and energy efficiency have very different installation costs that depend on the structural conditions on site. Maintenance costs and other elements must also be factored in.

Monobloc heat pumps are single unit heat pumps that contain all of the parts; like the heat exchanger, main pump, evaporator, condenser and compression valves in a single system. The single unit normally sits outside of your home.

Monobloc heat pumps are quite large and require outdoor space against an external wall so they can be installed correctly.

Monobloc heat pumps need professional installation but are simpler to install than air conditioning or ground or water source heat pumps.

The monobloc heat pumps outdoor unit will connect directly with your home’s conventional heating systems to provide heat through radiators or underfloor heating from external air.

Here’s What is a heat pump which explains the basics of heat pumps.

Pros and Cons of a Monobloc Heat Pump

The pros and cons of a monobloc heat pump system include;

Pros of Monobloc Heat Pumps

Some of the benefits of a monobloc heat pump system include;

• Freeing up space inside your home – usually installed externally, monobloc systems don’t require internal exchangers or storage systems so can free up interior space inside your property.
• Easy installation – because monobloc heat pumps are a single unit, containing the refrigerant and exchanger, they just need pipeworks to connect with your heating system.
• Easy maintenance – a single system all self contained can be checked more quickly than a system with multiple parts inside and outside the property.
• High efficiency and energy savings – because heat pumps extract heat energy from the air (or ground) you can make your home more energy efficient and spend less on heating and energy costs each month.

Cons of Monobloc Heat Pumps

Here are the disadvantages of monobloc heat pumps;

• Lower overall heating capacity – compared to some types of heat pump monobloc heat pumps can have a lower heating capacity, making them less suitable for larger properties with many rooms.
• Hot water storage is required – because monobloc heat pumps connect directly to your heating system, you won’t get hot water from your taps on demand. You will need a hot water tank to store hot water heated by the heat pump to feed hot taps in your property.
• Not flexible – if your home gets larger after an extension or your heating needs change, you may need a new system. Monobloc heat pumps aren’t adaptable to heating increased space.
• Outdoor space required – monobloc heat pump systems can be quite large. Properties without outdoor space won’t be able to have a monobloc heat pump installed. Properties with exterior space will require a ground floor exterior wall to have the monobloc system installed. These systems can also be very large because of the technology they contain.
• Noise – monobloc heat pumps can be noisy when operating so if you’re heating your home overnight and you have a downstairs bedroom near where your monobloc heat pump is installed, your sleep may suffer. Here is how noisy heat pumps can be.
• Cost – because of the technology the cost of monobloc heat pumps can be high. Check prices carefully and ensure you’re paying only for a monobloc heat pump you need for your property to try to keep costs down.
• Very low temperatures can affect efficiency – if you’re considering a monobloc air source heat pump, then be aware that very low external temperatures can affect the output and efficiency of your heat pump. External pipes required to transfer heat inside your home will also mean heat energy is lost.

Do monobloc heat pumps produce hot water?

Monobloc heat pumps only heat water to pump around your central heating system which goes directly to your radiators or underfloor heating.

Contact us to discuss your requirements of Commercial Air Source Heat Pump. Our experienced sales team can help you identify the options that best suit your needs.

To get running hot water you will also need to install a separate hot water storage tank. The only element of a monobloc heat pump that will be located within your home is the connected hot water cylinder.

What is a Split heat pump?

Split heat pumps conversely are different to monobloc heat pumps because they have two separate units. The split system usually has an internal unit and an outdoor unit which works as a heat exchanger and compressor.

Split heat pumps are better for situations where more complex installations are necessary or when there’s no obvious place for a monobloc heat pump unit and they can also be very quiet.

They can be preferable if you only have a small outside space as the outside unit is generally smaller.

Split systems are often referred to as HVACs. Find out more about split HVAC heat pump systems.

What is a Monobloc Air Source Heat Pump?

Monobloc air source heat pumps include all of their essential parts and equipment within a single unit that can be installed outside your home.

The majority of monobloc air source heat pumps, don’t require traditional gas to work instead they use refrigerants so monobloc heat pumps do not require F gas qualifications (fluorinated gas) to install.

This makes many monobloc heat pump systems cheaper and easier to install than air conditioning units or ventilation systems.

Most monobloc heat pump systems will need to be installed by professional heating installers.

Where can a Monobloc Heat Pump Unit be Situated?

Air source monobloc heat pumps will need external air so the majority of systems are designed as a single outdoor unit that is installed outside the property.

The external unit will need to be installed at ground floor level and somewhere that is easy to access for ongoing maintenance and servicing.

Many people choose to have their heat pump unit situated outside their utility or boiler room is a popular choice because it is easy to connect the heat pump to the heating system.

The outside unit is generally reasonably large due to housing all of the components necessary to get your home’s heating up and running.

Monobloc heat pumps can work well on large properties where you have plenty of outdoor space to house the system and let it operate successfully.

Can you get Monobloc Ground Source Heat Pumps?

You can get monobloc ground source heat pumps and water source heat pumps. However, they will need to connect to a suitable heat source, through boreholes, aquifers, lakes, rivers or waste heat through a series of pipes.

A monobloc ground source heat pump can still be considered a split system because ground and water source systems require underground or underwater pumps in boreholes to access heat from the ground or a body of water to generate heat.

You will also need an internal hot water tank to store hot water from your heat pump to feed hot water taps in your home.

Monobloc Heat Pump FAQs

Can a Monoblock heat pump be installed in cold climates?

Most monobloc heat pumps can work effectively in temperatures as low as -25° C. Many heat pumps designed for lower temperatures feature enhanced vapour injection (EVI) technology that helps to maintain the pressures of the refrigerant even at low temperatures.

In a much colder climate, a ground source monobloc heat pump could be a better option as ground temperatures are more stable throughout the year than air temperatures.

Air sealing and insulation, as well as correctly sizing the heat pump for your home are also important considerations.

How to make your home ready for a heat pump?

If you’re replacing a traditional boiler with a heat pump, you shouldn’t have too many changes to make. However, you may wish to;

Improve your home’s insulation; this will help your home retain more heat so your heat pump won’t have to work so hard to keep your home at a comfortable temperature. Many UK homes are currently poorly insulated.

Upgrade your radiators; heat pumps work best when they have a larger surface area to distribute heat. So upgrading your radiators can help your home feel warmer more quickly. Replacing existing radiators with aluminium radiators can also help distribute heat from your heat pump quickly and efficiently as aluminium is an effective conductor.