Heat Pumps: Things to consider….

Heat pumps are currently a very popular and efficient way of heating your home. They are often a very good replacement to the old fashion fossil-fuelled systems (particularly for those heating their homes with oil or electricity). As you will be told upon visiting any website selling heat pumps, they can have a Coefficient of Performance (COP) of up to 5, meaning it produces 5 times more energy than it consumes (500% efficient). This is far higher efficiency than that of an energy efficient boiler, which may reach up 99% at best. Naturally this seems a no-brainer and it most definitely is if you are replacing an oil-fired or electric heating system but you must always consider the less obvious issues. I would endorse an efficient heat pump but keep the following factors in your mind before agreeing to install one in your home, especially if you are retro-fitting a system to an existing home.

1) How is your current insulation? – I know I have repeated myself but this is a very important point. There is really very little sense in looking to invest in a fairly expensive and elaborate heat pump system before addressing the insulation of your property. You may be able to improve the insulation of your cavity wall or loft or both. As mentioned previously, the relatively low cost of doing this (grants are also available-more on that later) will not only set your house up for maximum efficiency of a heat pump but will also significantly lower your heat requirement and reduce your carbon emissions. Two fairly good side-effects!! You may also need to look at your windows, especially single-glazed ones that have huge heat loss. The most responsible heat pump manufacturers/installers I have talked to will not (and should not) consider selling a heat pump to you unless your home is sufficiently insulated. Beware of heat pump companies who do not insist on prerequisites of having a highly insulated home.

2) Underfloor heating – As heat pumps are generally only able to reach temperatures of around 55 degrees Celsius, far lower than the 80+ degrees possible with traditional systems of condensation boilers. Due to this reason, Heat pumps should only be installed in conjunction with the fitting of under floor heating. The cost of this, which can run in the £1000’s must be considered before deciding on installing a heat pump. The idea of a heat pump system is to keep the temperature in your home at a constant level as it takes a significant time to build up a desired temperature throughout a large home.

3) Single-Phase vs 3-Phase electricity – As per Wikipedia: “In electrical engineering, single-phase electric power refers to the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors. A single-phase supply connected to an alternating current electric motor does not produce a revolving magnetic field; single-phase motors need additional circuits for starting, and such motors are uncommon above 10 or 20 kW in rating. In contrast, in a three-phase system, the currents in each conductor reach their peak instantaneous values sequentially, not simultaneously; in each cycle of the power frequency, first one, then the second, then the third current reaches its maximum value.” In the UK, unlike many other European Countries, existing residential homes have single-phase electricity powering their homes. This can cause problems for owners of large residential properties where the heat consumption requires a large heat pump that can only be run on 3-Phase electricity. Heat pump brands such as IVT, Nibe, Vaillant and Viessemann all manufacture high quality pumps that can heat very large properties of 20KW and much higher but the prerequisite is that 3-phase electricity is available at the property. As 3-phase is common in the residential homes of Nordic Countries, this is not an issue for them but it is worth keeping in mind in the UK. Make sure you know what form of electricity is supplied to your home before making a large investment. There are twin-compressors available which put two 8-9KW units together to cover the heat requirement of a larger residential home but make sure you understand how they work together before investing. One company that has identified this problem in the UK is Kensa Engineering based in Cornwall, UK. They have manufactured heat pumps for the UK market, with the ability to run on single-phase electricity with capacity up to 24KW, enough to heat a very sizable home, provided of course, the property is well insulated!!

4) Plot size- Do you have a big garden or surrounding land on your property? As a heat pump requires the laying of pipes in the earth (at least 1 metre below the ground), it is necessary to consider how much space you have. There are two ways of laying these pipes, either straight pipes or “slinky” pipes. The slinky or looped piping naturally will require less space but both need a fairly significant amount of land, especially for larger homes with large heat requirements. It is safe to say that with a property requiring an 18KW heat pump, piping of 300+ metres is required. An alternative to a ground source heat pump is an air source heat pump, which, as the name suggests, sources its heat from the air as opposed to the ground. Technological advancement in the last few years has resulted in the development of very efficient and powerful heat pumps. They are definitely worth considering, especially if your property has limited land area. As they do not come with hundreds of metres of piping, they can be significantly cheaper as well.

5) Electricity consumption of your heat pump – before patting yourself on the back for creating massive savings on your heating bill, consider the increased cost of electricity from running a ground source or air source heat pump. Some air source heat pumps have recently claimed to offer a COP of 5 and have the ability to reach temperatures of over 80 degrees Celsius, which means they can be retro-fitted to existing radiators without needing under-floor heating. This sounds good in theory but some of the larger heat pumps may need up to 5KW power input in order to run, which equates to 120kwh/day or 43,000kwh/year. With electricity in the UK costing roughly 11p per kwh, this would equate to a cost of around £4,800 just to run the heat pump!!

The above are some of the main points to consider before deciding whether a heat pump is right for your property. Remember that if you first turn your attention to the energy efficiency of your home, your eventual heat requirements may be significantly less. Upgrade old appliances, invest in smarter thermostats and look at ways of improving insulation before taking the next step into heating your home with a renewable system such a heat pump.