Heat pumps, you’ll no doubt have heard a lot about them, but its not always clear why the government is making such a big push for their installation. Hopefully this short article can provide some clarity.
The magic of a heat pump is that it does not generate heat, it harvests it.
If you are generating heat in a conventional way then you can never get more energy out than energy in, meaning that typical electric heating is exactly 100% efficient and typical combi boilers are about 90% efficient.
Whereas if you harvest heat you gather the heat energy that is already there in the atmosphere which enables much higher efficiencies.
But how does that work when it is freezing outside? Well, heat pumps can still harvest from cold air because they have refrigerants inside them that hover around -40c meaning that so long as it’s above -40coutside they can still grab some ‘excess’ heat.
So, the magic happens thanks to chemistry, physics and taking advantage of the heat difference between the refrigerant and atmosphere. The result is that heat pumps can regularly output four times more heat energy than the energy they consume to run themselves.
So in theory – if you already heat with electric – you can cut your electric heating bill by a factor of four, or you can have four times the heat for the same price.
What next? The harvested heat energy can be used to warmwater that is then pumped around a system of radiators or can be used to warm air that can be blown into rooms.
The latter method is more typically known as air-conditioning which is simply run in reverse to produce warmth rather than cold. Today there are roughly 2 billion aircon units in the world, so the technology is tried, tested and robust. It is often used in commercial premises in the UK and is finding its way into more homes being known as an Air-to-Air heat pump system.
If you heat your home using simple electric heaters, then fitting an Air-to-Air heat pump can be a great solution that pays for itself after just a few years.
If you heat your home with a conventional gas boiler then you would more likely be looking to install an air-to-water system. These are the heat pump systems that the government is currently offering grants for, which for straightforward properties would bring the cost of installing down to about £5,000.
The running costs of a heat pump should come in similar to that of gas, that’s because although gas is four times cheaper than electric, heat pumps are four times more efficient hence the similar running costs.
As electricity prices fall relative to gas - which is a certainty in the coming years - that will make heat pumps cheaper to run in all cases.
Lastly, for those that are carbon conscious it is worth mentioning that the like-for-like CO2 emissions from a heat pump are around six and halftimes less than that of a gas boiler, and that figure grows as the grid progressively decarbonises.
If interested you can read a bit more about the Air-to-Air system fitted at my house here.
