Lots of UK homes are hard to treat with heat pumps, right? Well no, not really. What we have historically suffered from is a lack of UK-specific products.
In the gap between growing demand and the delivery of new UK-specific products, many properties, particularly older homes, have been branded as ‘hard to treat’ because they don’t fit the profile of the European market for which existing heat pumps had been designed.
In fact, all they need is a different approach, combining new solutions and cultural change in the way we operate our heating.
There are a large number of so-called hard-to-treat homes in the UK, simply because we differ from the European market in three main respects.
Firstly, single-phase supply limits the amount of power a heat pump can deliver for heating and hot water production.
With a three-phase supply, every home has three lines of electrical energy linked up to their heat pump and the load is shared between the three lines.
In single-phase systems, the three lines generated by the turbine at the power station are not run into each house. Instead, different properties are supplied by just one of the lines.
The difference between single- and three-phase supply means products designed for the European market are often unsuitable for UK domestic supply.
As a result, there has until recently been a dearth of products suitable for domestic use in the UK.
But with burgeoning interest and government commitment to greener sources of heating, and the continuing rise in fuel bills, manufacturers have begun to respond to demand.
Secondly, we are used to turning off the heating when we go out and expecting it to be powerful enough to heat up our home quickly when we get back.
The most obvious solution is simply education of the client. Whereas efficiency is paramount, there is a sweet spot where running a pump slightly outside optimum conditions still maintains a good return on investment and reduces carbon footprint.
Strike a balance with the client early on in the design process between efficiency and response times and a solution can be found.
Thirdly, another issue with older homes is that it can be prohibitively expensive to raise the insulation value of the building.
This makes it harder to maintain comfortable temperatures compared with newer homes. Therefore the pump for an older home needs to have a higher kW output for the size of project than a newer home of similar size.
This poses an engineering challenge on our single-phase supply to reduce the start-up current of a more powerful electrical motor so it does not overload the system. These high-power and single-phase heat pumps are now available and the range continues to grow.
John Felgate is technical director at Stiebel Eltron