Heat Pumps – Do You Want One?

Heat pumps are an extremely hot topic now in the UK with recent government announcements on reducing carbon emissions and reducing the burning of fossil fuels which I am MASSIVELY in favour of, even as a gas heating engineer. We are having daily conversations with our customers as to whether they should get a heat pump installed instead of a new boiler. So, I am going to put my head above the parapet today and give my view on them.

As mentioned in the previous blog post, Pete and I have been taking part in training courses, watching webinars and videos, doing a lot of reading regarding heat pumps, the hydronics involved with fitting them, and the technical ins and outs. We have also been closely watching some well followed forums and gauging what the opinions are from an installer and public view. Just for the record here, we are not anti-heat pump here at FJM at all. We believe they are a fantastic technology and a step in the right direction as we will soon be fitting them ourselves.

Firstly, a very quick and simple explanation on how a heat pump works. They are basically the reverse of how a fridge or air conditioning unit work. The air around us, even in freezing cold temperatures has a certain amount of energy contained within it. The higher the temperature, the higher the energy within the air that can be extracted. 

Within the heat pump, the major components we have are a large heat exchanger, a fan, a condenser, and a compressor. There are far more components than this but bear with as we are keeping it simple. When heat is required, the fan begins to run and blows air across the heat exchanger. Inside this heat exchanger is either water (with glycol added to lower the freezing point) or refrigerant which is super cooled. The liquid within the heat exchanger absorbs the energy from the air which has been blown across it by the fan, which in turn causes the temperature of the super cooled liquid to rise. The liquid then flows to the compressor which ‘does exactly what it says on the tin’, it compresses the liquid. 

This is where the magic happens, and some clever physics occurs. When we compress something, the pressure rises, and net result of compression is HEAT!!! So, the compressor raises the pressure and temperature of the liquid to create the useful heat which is then sent into your property to be used. When the liquid returns to the heat pump after having some heat used, it goes through the condenser which does the opposite of the compressor. It decompresses the liquid, lowering the pressure and therefore also lowering the temperature, ready to go through the heat exchanger again to gain energy and repeat this cycle.

The lower the air temperature outside, the harder the compressor must work to raise the temperature of the liquid, and thus the more electricity is required for heating. The compressors can be quite juicy and expensive to run. That concludes todays lessons in heat pump operation. Very brief, very simple and by no means in depth as there is far more to it than this. 

Heat pumps are not able to produce heat in the same way that most people will be familiar with when using their gas, oil or electric boilers. You will be far more used to instantaneous heat when you want it. Heat pumps have far lower heat outputs then what is available from fossil fuels, so they take longer to heat and, in most cases, can only heat water to a certain temperature i.e., 50-60 degrees Celsius, as opposed to the 80 degrees your boiler will be capable of. This then means that the heat pumps often need additional electric boost heaters, especially for heating hot water to safe temperatures. Consumers, tenants, and homeowners therefore need to adjust their attitudes to how they use their heating as it works very differently. The heat pumps are better suited to being left on for extended periods and not turned off to make use of their efficiency. It’s very much a marathon as opposed to a sprint.

From an installer point of view, extremely careful thought and mathematics needs to be applied to every property to ensure the property is viable for a heat pump installation. Most importantly, the thermal properties of the building need to be calculated carefully. The general state of British housing stock thermally is terrible to put it bluntly. Our houses are drafty and poorly insulated. The quality of new housing stock being built is still not that great and far below what the likes of Scandinavian countries are doing, especially Finland who are world leaders in terms of heat pumps, house building and thermal insulation. I know we have a different climate to Finland, but the standards are something we should aspire to in my opinion. 

My largest bit of advice for anyone thinking of having a heat pump installed, is to assess and get your home insulated as best you can first. 

That means having double/triple glazing fitted, cavity walls filled, and loft/floor spaces adequately insulated. You would not believe the difference these things can make in the thermal properties and the amount of heat which is not lost and wasted. This will then start to give us the favourable conditions we want for installing a heat pump, not to mention the instant reduction in heating bills and increased comfort levels in your home. There are grants available to help you insulate your home, but even if you are not eligible for them, they are simple and inexpensive options for the savings you will make on bills to recoup your investment.

The installation and considerations are much deeper and complicated then this, but I must not go too far from the point as this blog will turn in to story book and I will bamboozle my lovely readers. But the points I make above (compressors using large amounts of electricity and thermal properties of homes) seems to be the crux of everything revolving around heat pumps and whether they are a good idea in your homes.

Currently, there are incentives potentially available to homeowners including the likes of the Green Homes Grants and RHI (Renewable Heat Incentive). These will give the customer a grant towards the purchase or an annual payback based on energy usage, which is great. But………. I am seeing typical heat pump installations costing upwards of £10,000 and if you are in this wave of customers who can get in on the action now then that’s also great. But what happens when this money runs out and government funding is pulled for the masses??? It’s NOT cheap!

It is well known that our electricity grid and production in this country is barely fit for purpose and needs huge investment (which it is improving and more green energy is becoming available). Going domestically fully electric so quickly as we are being urged could cripple the grid.

The vast number of complaints we are seeing and hearing from end users, particularly in this colder weather, is that they are cold in their homes, the temperature will not rise even when the heat pump is on 24/7, and their electricity bills are in the region of £10+ per day in small properties. And to counter this, the installer replies tend to be that it is not installed properly, has been set up wrong, they advise the customer that they need to find cheaper electric, or my favourite, zero carbon emissions are worth paying for. Even when the electricity has probably come from an inefficient gas power station (Go figure). I would not be happy with any of those responses having been told my £10,000 heat pump is more efficient than my old gas boiler and will save me money. The maths does not lie and I doubt it has been done properly for those customers.

Now I know there are incredible installers out there who do their maths and advise their customers 100% spot on and most of these heat pumps are installed well. But I am under no illusion that heat pumps are a magic bullet and that they should in any way be the go-to technology in all cases, it simply isn’t that by a long way.

For sure, heat pumps are a fantastic technology when the individual property lends itself to the installation with having fantastic thermal properties and the ability to increase the size of radiators or having properly sized underfloor heating. And I would encourage anybody to give them a look and see what the suitability is for your property. You could make it work perfectly, have lower bills, and reduce your carbon footprint all at the same time. You are a winner if that is possible.

But retro fitting poor quality existing UK housing stock is an extremely hard task for any installer no matter how good they are without needing an enormous capital expenditure from the homeowner or government to achieve that.

Heat pumps are here to stay, going to be more prominent, and rightly so. But this is an exciting time for alternative technologies. Many manufacturers are working towards other ways of producing the heat we need through the likes of geothermal, solar thermal, hydrogen fuel cells, hydrogen burning boilers and I have even seen an ice heat store which Viessmann are trialling. I predict there will be some big steps in our industry within the next couple of years which will give more options and a range of different options to suit different applications and properties which will also drastically reduce our household carbon emissions. I think heat pumps are some way off fulfilling needs from a financial, economic, and environmental perspective, particularly in the UK for various reasons which I have eluded to. Heat pump technology needs to further improve, and costs needs to reduce first before they become a viable option for the masses. This is happening gradually, particularly as more installers become qualified and the industry becomes more competitive as a result.

The Takeaway……

Before you look at a heat pump, new gas boiler or indeed any form of heating technology. The best value for money and best environmental decision you can make is by insulating your property well first. It IS as SIMPLE as that!!!!

See you next time