There is more confident nonsense written about heat pumps than about almost anything else in the building trade. One side promises transformative savings; the other insists they do not work in cold weather. Neither is much use when you are trying to decide what to do about a fifteen-year-old boiler.
The useful version is narrower and less dramatic. Heat pumps work extremely well in properties that hold heat reasonably, when they are sized against a real heat loss calculation and run at low flow temperatures. They perform badly in leaky buildings and in systems specified by guesswork. Almost every disappointing installation you read about is one of those two failures, not a failure of the technology.
How they work, briefly
A refrigerant circuit absorbs low-grade warmth from outside air — of which there is plenty, even well below freezing — and a compressor raises it to a temperature useful for heating your home. Because it is relocating heat that already exists rather than burning fuel, a good system delivers substantially more energy than it consumes. That is also why a boiler can never exceed 100% efficiency and a heat pump routinely reaches 300% or more.
It is the same technology as air conditioning — genuinely the same, just pointed in a different direction. That is why one team of engineers works on both, and why the choice between them is worth one conversation rather than two separate projects.
Grants, and where we stand
The Boiler Upgrade Scheme offers eligible property owners in England and Wales £7,500 toward an air source heat pump, applied for by the installer and deducted from the quote. Kelvara is not currently MCS certified, so we cannot claim that grant on your behalf. If the £7,500 is central to your plans you will need an MCS certified installer for that part of the work — we would rather say so here than at quotation stage.
We install units from Daikin, Mitsubishi Electric, Panasonic and LG. Manufacturer technical data is worth a look if you like comparing specifications, though sizing and installation quality will affect your bills far more than the badge on the unit does.
Questions
Common questions
Are air source heat pumps worth it in London?
It depends almost entirely on the building. A reasonably insulated house with a sensible outdoor position and a properly sized system is a good outcome — comparable running costs to gas and far lower carbon. A poorly insulated solid-wall property with an undersized system is a worse outcome than the boiler it replaced. The survey decides this, not the brochure.
What's the difference between a heat pump and air conditioning?
Technically very little — both move heat using a refrigerant circuit and a compressor. The difference is what they're optimised for and where the heat goes. Air-to-water heat pumps feed radiators and a hot water cylinder and are heating-focused. Air conditioning is air-to-air: it heats and cools directly into rooms, costs far less to install, and gets no government grant.
How much is the government grant for a heat pump?
£7,500 through the Boiler Upgrade Scheme for eligible air source heat pump installations in England and Wales. It's applied for by an MCS certified installer and deducted from your quote rather than claimed back by you. Eligibility hinges on owning the property, having a valid EPC with no outstanding insulation recommendations, and replacing a fossil fuel heating system.