Air Source Heat Pumps - the drawbacks

Are there any downsides to installing an air source heat pump?

With energy costs stubbornly high many homeowners are looking at renewable technologies, such as air source heat pumps, to reduce their bills and their carbon footprint.

But are air source heat pumps (ASHP) really all they’re cracked up to be?

As with any major purchase it’s important to look at all the pros and cons before making a decision.

Why an air source heat pump?

• An air source heat pump (ASHP) can work in air temperatures as low as minus 20C and still happily supply your heating and hot water.
• They can be installed in a matter of days and can run for up to 20 years, twice as long as an average boiler, and require minimum maintenance.
• If well designed and properly installed in an averagely insulated house – loft insulation, double-glazing and cavity-wall  insulation – they will be cheaper to run than a fossil fuel boiler and do so with minimal damage to the environment.
• Running your ASHP with electricity from renewable sources, such as solar panels or using a green electricity tariff, means you can go completely carbon neutral.  
• And right now, the Government will give you £7,500 towards the cost of installing a new heat pump    
  
  

So, with credentials as good as these, why doesn’t every home have an air source heat pump?

The big question is: How much does this great technology cost?

Air source heat pump costs can be broken down to:

• The heat pump itself, and parts such as a hot water cylinder
• Installation costs including labour and ancillaries such as pipework, pumps, valves, wiring, lagging etc.
• Running costs  - which we have mentioned above, and

RUNNING COSTS

When installed properly by experts such as ourselves at Biosun Energy, air source heat pumps are definitely cheaper to run than any oil or LPG boilers and are often cheaper to run than a gas boiler in a house with loft and wall insulation and double-glazing.

How can that be, you may ask, when they run on electricity, which is three times more expensive than gas?

Well the trick with heat pumps, and why they are considered renewable, is that for every 1 kilowatt (kW) of electricity used to run the unit they can produce about 4 kW of energy – meaning 3kW of free, renewable energy.

So, for example if electricity is 20p per kWh, then the cost of running the heat pump is in effect 5p per kWh – as it produces 15p worth of energy for free.

It is actually more efficient than that as boilers are only 80-90 per cent efficient. And even bigger savings can be made by using free electricity from solar panels and a heat pump-friendly green energy tariff.

Obviously, much depends on the relative prices of the two fuels but it’s safe to say that heat pumps are cheaper to run than oil and LPG boilers and can be cheaper to run than a gas boiler depending on the insulation levels of the house. And on new builds with underfloor heating (UFH) they are absolute no-brainers!  

COST OF KIT and INSTALL COSTS

Air source heat pumps are the cheapest form of renewable heating to install, compared to ground source heat pumps or biomass boilers, but are more expensive to install than a fossil fuel boiler.

A good quality European air source heat pump with associated buffer tank and controller, costs on average £5,000-£7,000 depending on its size but installation costs can bump up the price considerably.

If you are replacing an existing boiler you may need a new hot water cylinder and may need new, larger, radiators and new pipework. This is especially true if you have an existing vented system (with tanks in the loft) as a heat pump is an unvented or pressurised system. This gives you great, mains water pressure at your taps but you may need to reconfigure your existing pipework.

You might expect to pay a further £3,000-£10,000 depending on the complexity of the job, existing infrastructure and the size of the property.  

It’s fair to say that air source heat pump installation costs are initially high. For many homeowners it simply isn’t something they feel is affordable, particularly when compared to a traditional combi gas boiler, which incur a spend of around £3,000.

The Government has recognised this and is therefore offering a £7,500 grant under the Boiler Upgrade Scheme (BUS) to even thing up.

Over the life-cycle of the heat pump, with lower running costs and a longer life span of up to20 years, a heat pump will work out cheaper than a fossil-fuel boiler but finding the upfront costs can be a barrier to the adoption of heat pumps.

A DIFFERENT KIND OF HEAT

A key difference of air source heat pumps, compared to a fossil fuel boiler, is that they provide a comfortable, ambient background heat. It’s not necessarily a disadvantage but many people are not used to it. Radiators may not get really hot and homeowners cannot get a burst of heat by whacking up the thermostats – heat pumps work on a “low and slow” basis. They can happily get your home as toasty as you want but they respond more slowly.

That means that provided your home is well insulated, you will enjoy warm, comfortable temperatures at all times - rather than the peaks and troughs that traditional gas boilers can incur.

COLD WEATHER EFFICIENCY

In winter the efficiency of an air source heat pump drops. Their source of fuel (the air) is colder and the flow temperature through the radiators needs to be higher to keep you warm – so the heat pump is working harder. You could say the same for gas boilers too, as everyone’s heating bills are higher in winter.

While we design heat pumps to be big enough to cope with the heat demand in winter, they will cost more to run when it's cold and you may see a spike in your bills. Conversely, they will be cheaper than a fossil-fuel boiler to run in Spring and Autumn so the overall cost over a year is still cheaper.

This slow and steady approach ends up being more cost effective than the boiler constantly firing up as we’ve grown used to doing.

The efficiency of a heat pump is known as the Co-efficient of Performance or COP. That may be 4 or 5 in milder months (remember the 1kW of electricity in and 4 or 5 kW of heat out?) but may drop to 3 in winter. To get an overall picture we use the Seasonal Co-efficient of Performance or SCOP to give a yearly figure. You may see this referred to by heat pump manufacturers.

INSULATION

Insulation is essential with an air source heat pump, so we can ensure that every kilowatt of heat generated is used to the maximum. Insulation may be an additional cost to factor in if you don’t have enough.

NOISE

One thing that concerns many people is the potential noise of an air source heat pump. That is why at Biosun Energy we only fit very quiet, good quality, European heat pumps, which make no more noise than a gas boiler venting.

We also position the heat pump away from bedrooms and in so doing the low noise there is simply doesn’t bother the homeowner.

REGULATIONS

Most homeowners do not require planning permission to install a heat pump – they are “permitted development”.

They do need to adhere to some regulations which include:

• making sure the installation is at least one metre from the boundary of their home;
• is under the noise limit, and the size limit;
• is installed on a suitable flat surface etc.

All those factors are taken into account when we at Biosun Energy design any heat pump system.

If you live in a Conservation Area, the permitted development  rules on siting are stricter, such as it must not face on to the highway.

If you live in a Listed Building you will most likely need to get permission to install a heat pump, although all authorities are encouraged to approve renewable projects where possible.

APPEARANCE

The final draw back (if it could be considered as one), is the appearance of the air source heat pump, which tends to look like an air conditioning unit. Designs are improving and the Stiebel-Eltron units we fit are quite stylish.

Most people are used to seeing their heating systems tucked away in some cupboard and not on the outside of their house. That said, if they are found to be truly unappealing, it is possible to box them in with a bespoke container case or even some tasteful fencing or hide it behind a few bushes!

SUMMARY

We’re sure you’ll agree that overall the benefits of an air source heat pump well out weigh any negatives. Low-cost heat and hot water are environmentally sustainable and energy efficient.

And by taking advantage of the £7,500 offered under the Boiler Upgrade Scheme (BUS) you can make a big dent in the upfront costs.

For a full, no obligation heat pump quote, or any other upgrade for your property with renewable energy, why not give our expert team a call today. on 01892 347219 or use our contact form to get in touch.

‍