Air Source Heat Pumps Explained

In this guide I will give you the knowledge of the units themselves and their installation along with handy tips and how to get funding in a simple and easy-to-absorb way.

Table of Contents


The Best Choice For Homes

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Why are they gaining popularity? Well, it’s partly because they’re a clever choice for reducing energy bills while keeping warm when it’s cold outside. But don’t just take my word for it. There’s a big boost coming from government grants, helping to cover costs, which makes the initial investment not as steep as you might think.

By grabbing heat from thin air (literally!), these pumps are reshaping how UK homes are kept warm and cosy. They tie right into the global push toward cleaner energy solutions. And with electricity getting cleaner by the day, thanks to all those wind and solar farms popping up, heat pumps are becoming the go-to for forward-thinking homeowners.


Harnessing Energy from the Environment

A heat pump’s outdoor unit is like the brain of the operation, quietly working hard while you kick back indoors. Sitting somewhere around your house, this unit plays its part by drawing energy from the air outside. Rain or shine, it’s all good—these guys are built to be tough, made to handle the UK’s notoriously unpredictable weather.

The Simple Science

Animated drawing of the heat pump refrigerant cycle with detailed labels A line-art diagram of the four main components of an air source heat pump refrigerant cycle - evaporator, compressor, condenser, and expansion valve - draws itself in sequence, with connecting pipework and a short explanation appearing under each label. Evaporator cold liquid refrigerant absorbs heat from outside air and boils into a low-pressure gas Compressor squeezes the gas, raising its pressure and temperature Condenser hot gas gives up its heat to the heating water and condenses back into a liquid Expansion valve drops the pressure sharply, cooling the liquid before it re-enters the evaporator Refrigerant cycle

Inside this outdoor marvel is a fan and some high-tech stuff that looks complicated, think compressors and evaporators. They get to work by pulling in air and absorbing its heat via a refrigerant, which basically functions as the delivery for thermal energy transfer.

Now, you might be wondering, 'Where exactly do I fit this thing?' Well, finding the perfect spot is important. Ideally, it lands somewhere with good air flow, away from noise-sensitive areas like bedrooms. The garden or a back patio can do the trick nicely.

There will always be expert advice from your heat pump installer, but the unit is usually what we call a monoblock heat pump, which has all the required components inside and simply sends the already heated water to the inside of the home.

You'll need the electrical setup to stay safe. Professional installation is key, not just for regulations but to make sure everything runs smoothly from day one. The electrical system includes outdoor work as well as indoors.


Delivering Warmth Throughout the Home

Even though the unit does all this tech wizardry outside, remember it won’t be showing off its skills alone:

Bringing the magic indoors, heat pumps can integrate with your existing heating setup to save on complete pipework replacement. Hydraulic units are available to enable hydraulic separation between the new heat pump system and the existing heating system.

Older vented heating systems will typically undergo an upgrade to unvented to accommodate the new heat pump setup. A new hot water cylinder will almost always be fitted with any extra volumiser units that may be needed to allow the pairing of the two systems.

For those well-worn radiators or the latest underfloor heating systems, heat pumps work well with both. Some or all of the radiators may need to be renewed, but on the plus side, underfloor heating is a perfect pairing because it distributes heat evenly.

New builds will have already had the design built in with underfloor heating and pre-plumbed cylinders. The home's pipework will have the required bore size for heat pump flow rates. A full heat pump installation is much easier on a new build than retrofitted in existing homes

Heat pump installations come with many different adaptations for inside the home; the upfront cost will depend on how much of the original heating system can be used and what needs to be added to make it all work effectively.


Air to Water System

how an air source heat pump works

Jargon buster

  • MONOBLOCK: The most commonly used heat pump that contains all of the refrigerant cycle components within one unit, sending heated water into the house.
  • SPLIT UNIT: These look similar to the monoblock but send the heated refrigerant to a heat exchanger in the house to heat the air or water.
  • AIR-TO-AIR: These are heat pumps that send heated refrigerant from the outside unit into an inside fan blower unit to warm the house using warm air.
  • AIR TO WATER: These can be either monoblock or split systems, which send the heated refrigerant to a heat exchanger to heat the water used in the home.

Domestic Hot Water

Part of the efficiency of a heat pump setup is the trusty hot-water cylinder. Think of it as your home’s very own hot water reservoir, quietly working away. It holds heated water, ready to spring into action when it’s time for a hot shower or a load of dishes.

Where should it go? These hot water cylinders are pretty flexible when it comes to location. Whether tucked away in a garage or snug inside a ground-floor cupboard, they fit into your home without needing much fuss. Just make sure you've got that 80 x 80 cm space covered.

But what if fitting a hot water cylinder just isn’t on the cards? Don’t worry, alternative options like hybrid heat pump systems can swoop in to save the day. Here, a combo plays out with the heat pump doing its thing for your heating only, while a boiler provides hot water on demand. It keeps things nice and steady without requiring a tonne of space.

Another clever option is the heat battery. It’s compact and efficient, genuinely a modern-day hot water hero. And if you’re looking to serve up small portions of hot water—maybe just for your kitchen—an instantaneous water heater could be the way to go. They’re easy to tuck under sinks and great for giving that bit of hot water without a big setup.


Key Considerations Before Investing in a Heat Pump

Thinking about leaping into the world of heat pumps? It’s not just a purchase; it’s an investment in lifestyle and sustainability. But before jumping in, there are a few important things to mull over.

Starting Out

First up—your budget. Initial costs can seem hefty, but remember, there are government grants to lighten the load. These incentives can make it more accessible, so dive into what’s on offer and see how much of a dent they can put in the initial expense.

What about the nitty-gritty of your existing setup? Have a good look at your current radiators. Heat pumps work at a lower temperature than old-school boilers, so you might need to supersize those heaters to keep everything nice and warm. It’s normally a one-off expense, and in the grand scheme of things, a smart move for long-term efficiency.

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"Also, sizing up your space is crucial. Every home is different, and what works for one may not tick all the boxes for another. Whether it's available space for the outdoor unit or the hot water cylinder inside, consider the logistics."

Beyond the hardware and numbers, the most crucial factor is your lifestyle. How you cook, shower, and generally go about daily life will dictate what sort of system works best.

This tech is all about fitting seamlessly into your routine without you even having to think about it. So explore all the options and figure out which system aligns best with how you live and what you value in a home setup.


Cost Analysis and Financial Support Options

Dishing out the cash upfront for a heat pump might make you flinch a little, but let's break it down. The initial price tag can start around £4,000 when you factor in those handy government grants. It sounds like a big bite, but it’s actually more affordable when you compare it long-term to traditional systems.

Grant Funding and Finance

Worried about that lump sum payment? No need—for those who prefer spreading costs with monthly payments, many suppliers offer financing plans. Some plans kick off around £40 per month, easing you into the transition without tying up all your resources at once.

But it doesn’t stop at just monthly payments. Financial support comes from several directions, such as the UK government’s efforts and their motivation to push greener solutions. Look into the specifics of these incentives since they can be the key to making heat pump ownership more financially possible.

In deciding how to finance your home’s energy future, calculate both the immediate implications and the long game. Consider your plans for the property, like if it's where you want to stay long-term, because heat pumps are an investment that pays dividends over time. You're looking at not just potential energy savings, but also enhancing your comfort.


Optimising Heat Pumps with New Radiators and Underfloor Heating

Getting the most out of your heat pump system means working with what you already have and sometimes upgrading a few things along the way. It's all about creating harmony between the traditional and the new, especially with radiators and underfloor heating.

If you're keeping radiators, some might need upsizing. Heat pumps run at lower temperatures than traditional boilers, so larger radiators encourage the gentle spread of warmth, ensuring those chilly corners stay warm. Bigger isn't always prettier, but it's often the best move for energy efficiency.

Underfloor Heating: Now, if you’re lucky enough to consider underfloor heating, heat pumps, and this method are like peas in a pod. Floors cover a larger surface area, spreading warmth and love from toe to toe without having to crank up the heat. It’s efficient and feels good underfoot in wintertime.

Balancing the two: Radiators and floors call for a bit of planning. It helps to map out your rooms, considering which areas are best suited for radiant flooring (think kitchens and bathrooms) versus radiator heat. In many homes, you tend to find the underfloor heating at ground level and radiators upstairs.

"So, whether updating radiators or shifting to underfloor heating, you’re putting together a system custom to you. Consult with a professional who can plot the path wisely and tailor the system to your home's unique style and needs."


Heat Pumps Vs Boilers for Hot Water

While heat pumps excel in efficiency, they play by slightly different rules when it comes to heating water compared to traditional boilers.

The water heated by a heat pump might hover between 48 and 55°C (although some heat pump manufacturers offer higher temperature options), a tad cooler than the 60-70°C you're used to with boilers. But don't think you're trading luxury for sustainability—instead, you're just rebalancing the hot-to-cold ratio. Mixing in a bit less cold water when filling a bath or running a tap compensates nicely.

This might mean a small adjustment in how you manage hot water use. Bigger baths or extended showers might call for a little planning on when to heat the water, a minor trade-off for a greener, more efficient home setup.

Other forms of water heaters can be utilised, such as solar thermal systems that can have their own coil in the hot water cylinder to maximise hot water production and save energy, especially in the summer months.

If on-demand hot water is more your style, consider incorporating systems that work with a heat pump, like hybrid options blending pump efficiency with boiler-like immediacy. Or look into compact gadgets like heat batteries that heat up quickly and save space.


Why Choose Air Source Heat Pumps?

Wondering why you should edge towards heat pumps? First up, there's the potentially lighter grip on your energy bills – a solid win if you’re swapping from oil or traditional gas systems. Economic relief alongside daily warmth – who can argue with that?

There is no better time

  • Financial: There is almost certainly never going to be funding grants in the future as large as the ones on offer today.
  • Source of Energy: There is a major push in developing advances in electricity supply and the options for its use in all aspects of our lives.
  • Efficiency: As technology develops, there are endless opportunities to connect all new energy products to your existing systems.

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