Monobloc v Split System Heat Pumps

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Monobloc v Split System Heat Pump

So you’ve decided that air source heat pumps are right for you (rather than their ground source heat pump counterparts), and you were hoping that would be the end of it, right? Not just yet. But don’t worry, even though the different air source heat pump types can feel like you’ve opened a can of worms, it isn’t so complicated, especially when experts like us here at Heat Pumps UK are guiding you through it all. 

Today it’s monobloc v split system heat pumps’ turn, and below we’ll look at what each heat pump does, how they differ, and their pros and cons so you can decide which is best for your home. 

What Are Monobloc Heat Pumps? 

Monobloc heat pumps work like all other heat pumps in that they draw on the heat from the outside air to heat a home, and expel that heat when cooling a home. But the reason a monobloc heat pump system gets its name is how the system does the same job as all other heat pumps, just differently. 

A monobloc air source heat pump is a complete package packed away into a single unit that is stored outside of the property. The compressor, heat exchanger and water are all contained in this single outdoor unit and connects directly to the home’s central heating system which can be controlled with a thermostat indoors. 

What Are Split System Heat Pumps? 

A split system heat pump system – as you might have already guessed – does exactly the same job, but across more than one unit. The system is split, hence the name. Here, a condenser collects the heat from the air outdoors, before sending heated gas to an indoor unit inside the home, where the water is then heated and your home heats up, too. 

Monobloc v Split System Heat Pumps: How They Differ 

So, the main difference is the way the system actually works. The end result will be the same: a warmer home with green energy, rather than fossil fuels. But the journey is the difference. 

With a monobloc system everything happens in the same unit and the water is heated outdoors before moving inside your house to heat it. With a split system heat pump the process is split in two, where the heat from the air is separated and sent indoors where it will then heat the water for your heating system. 

Pros & Cons Of Monobloc Heat Pumps


There are few pros in monobloc heat pumps’ camp, showing why monobloc air source heat pumps are so popular. 

They Don’t Take Up Indoor Space 

Space inside the home often comes at a premium, so any heating system that doesn’t require indoor units will already look good to many of you reading. The fact that a monobloc heat pump only requires one unit, and that unit is installed outdoors, is a huge benefit. 

One Unit Maintenance 

An all-in-one unit will always be easier to maintain and troubleshoot than a system that’s split across multiple units – that’s just basic engineering. If something goes wrong with your heat pump, with a monobloc system it will be fixed much sooner than a split system. 

Quick Installation

Self-contained monobloc units are much quicker to install because of their all-in-one nature. They don’t connect at multiple points – just a simple installation to work with your current central heating system. Because they are so easy to install, it takes less time for a heat pump installer to get the system up and running, and therefore they’re even cheaper to install. 


There are, of course, some drawbacks to monobloc heat pumps too.

Unique Installation Requirements 

Since monobloc systems connect directly to your current central heating system, the single unit needs to be installed at a specific place on the outside of your property where it can be connected easily to your central heating system. There is practically 0 flexibility here, too, meaning if you don’t have the space outdoors to install it where it needs to be, then you simply can’t have a monobloc heat pump system installed. 

Size Of The System 

Whilst an all-in-one system has many benefits, one thing that can’t be changed is the sheer size of the unit. So much technology has to fit into the single unit, making it much larger than split system heat pumps which can split the system across two units, resulting in two much smaller units. These larger systems then need to fit in your outdoor space, taking up a significant amount of room, and monobloc heat pumps need additional space around the unit for it to work efficiently. 

Louder Operation

A monobloc heat pump has all of its technology inside one large unit, and because of that, they make significantly more noise than split system heat pumps. If your system is going to be installed in a place where the noise won’t bother you, then it’s less of a concern, but it’s certainly worth bearing in mind. 

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Pros & Cons Of Split System Heat Pumps 


Split system heat pumps also have their benefits.

Integrated Hot Running Water 

Plenty of split system air source heat pumps come with an integrated hot water storage tank included (notice we said plenty not all). This means that you can get hot running water for your home as standard, but most monobloc systems will need a separate water storage tank in order to provide you with hot running water as well as heat. Having a water tank incorporated saves on space, whilst also being much more convenient for you. 

More Flexible Installation 

Unlike monobloc heat pump systems, there is much greater flexibility when it comes to where the units can actually be installed. It’s only the indoor unit that actually connects to the central heating system, but the outdoor unit can go almost wherever you like. That means less noise and greater flexibility, so you can place it somewhere that’s truly convenient for you. 

Smaller Units

Splitting the system allows for two much smaller units than a monobloc system can have. And whilst, yes, that does mean you need to find space for two units rather than one, they’re much smaller and more convenient to house – both indoors and outdoors. Their smaller sizes also contribute to their quieter operation, too. 


As with anything, split system heat pumps also have a number of drawbacks that must be considered before purchasing. 

Requires An Indoor Unit

Whilst we’ve already highlighted the benefits of installing two smaller systems, there’s no denying that having to find space for a unit inside can be frustrating. Thankfully, most split system heat pumps can have their indoor unit installed where your old boiler once was. The problem comes if your split system heat pumps don’t have an integrated water tank (not all of them do). When this happens, you’ll need to find additional storage for a water tank inside your home, creating a bit of a headache if your home is already limited on space. 

More Time Consuming Installation 

Split system heat pumps are slightly more complicated to install because of the separate units which will need your installer’s attention. Because of the added complexities, the installation will also take longer than a monobloc heat pump system, which will then push costs up a little more. 

Higher Upfront Costs

Speaking of costs, split system heat pumps are also just inherently more expensive than monobloc systems too. Their technology is a little more complex and therefore a little more expensive. With upfront and installation costs adding up, you can expect to pay more for a split system heat pump than a monobloc heat pump.

Which Heat Pump System Is Right For Me?

Choosing the right heat pump is important – get it right and you’ll be benefiting from a greener heating system in your home for years to come. The thing is, when it comes to monobloc or split system heat pumps, it isn’t really you that gets to decide: it’s your house. 

As we’ve already mentioned, both have installation requirements attached to them, meaning if you don’t have the outdoor space at a specific point on your exterior wall, then a monobloc system won’t work for you. Likewise, if you don’t have the interior space because you’ve opted for a split system heat pump without an integrated water storage tank, then it won’t be appropriate for you either. 

The point is, your house ultimately makes the final call. And if you’re unsure which call it will make, the best thing you can do is contact a heat pump installer to carry out an inspection of your home to give you an idea of which heat pump system is best for you.

Trust Heat Pumps UK to put you in touch with the best heat pump installers in your area today.  

Monobloc v Split System Heat Pumps: Final Verdict

Ultimately, neither system is better than the other. Both heat pumps will provide you with better air quality in your home, better regulated temperatures, wonderful energy efficiency and all that whilst saving you money and making your home a greener place. 

By filling out your details with us today, Heat Pumps UK can put you in touch with heat pump installers in your area with the best deals. A quick inspection (usually free) from the installer you choose will tell you whether a monobloc or split system heat pump is best suited to your home, too, giving you added peace of mind that you’re making the right choice when installing heat pumps at home!

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Ollie Creevy
Ollie has been writing content online about home improvements for over 3 years. With a real interest and in-depth knowledge of heat pumps and ECO home improvement measures you can use to save on your energy bills. Ollie also keeps up to date with all the Government grants available for you to take advantage of like ECO4 and the Boiler Upgrade Scheme.