How Heat Pumps Compare To Gas Boilers | Clade Blog

Gas boilers are everywhere. 85% of homes in the UK are heated by carbon-heavy natural gas. In the non-residential sector, two thirds of all space heating uses natural gas.

There’s a good reason for that. Burning natural gas has historically been a cheap, reliable and relatively safe way to heat buildings in this country. But things are going to have to change – emissions from fossil-fuel based heating systems and stoves account for around 17% of the UK total. If we’re going to have a net zero economy by 2050 we’re going to have to replace these natural gas boilers in residential homes, commercial buildings, public buildings and the industrial sector.

The government has clocked on to this, announcing a ban on gas boilers in new buildings that would come into effect at some point between 2023 and 2025. The exact date is, at this point, unclear – in the originally published document the government gave the date of 2025. They then said they would bring that date forward to 2023, but also removed any mention of the specific date from the document announcing the ban. But it will happen, and soon, because it has to.

Aside from government restrictions, businesses will have to phase out gas boilers anyway. Most businesses are (or should be) looking for ways to drastically reduce their carbon footprint, and phasing out natural gas heating will be a big part of that.

We have already discussed one of the most talked about alternatives to natural gas boilers – hydrogen – in this blog here. In short, it seems unlikely that hydrogen boilers will replace gas boilers at scale anytime soon, and that if we’re going to decarbonise our heating system we will need to use heat pumps.

This article discusses how heat pumps compare to gas boilers across key measurables. Let’s dive right in.

How do heat pumps work compared to gas boilers?

There’s a reason why gas boilers are so popular. Relatively cheap to install, cheap to run, heat on demand whenever you want it – that’s all great. But they’re wasteful, polluting and actually not as efficient as other methods of heating buildings.

Gas boilers are designed so that at the flick of a switch, they can heat water and heat your home. But in order to do this they wastefully burn huge amounts of fossil fuels at massive temperatures. In order to do that they’re generally way overpowered – a house that needs 4kw of energy to heat will typically have a 30kw boiler.

Heat pumps work very differently. They heat water using a combination of electrical power (which is increasingly renewably produced in the UK) and energy from the air/ground around the building. This is used to heat up fluid (refrigerant) in the heat pump, which is then used in a vapour compression cycle to warm water and heat the building. Because they combine electricity with energy from the air/ground, heat pumps are able to operate at efficiencies over 250%.

At Clade we use CO2 as the refrigerant in our heat pumps, which makes them more efficient (typically 350%), environmentally friendly and safe. We’ve written about why we use CO2 on this page.

How well do heat pumps warm buildings compared to gas boilers?

A criticism that some have levelled against heat pumps, in comparison to gas boilers, is that they can’t heat water to the same temperatures, can’t do it as quickly, and therefore your home will be colder in winter and take longer to heat up. The Daily Mail even claimed that individual homes would have to get used to turning down their radiators by 10 degrees.

This is completely misleading in two respects. Firstly, natural gas boilers have a flow temperature of up to 85 degrees, and CO2 heat pumps can achieve the exact same temperature. And when they do achieve that temperature they do it three times as efficiently as gas boilers.

Whilst CO2 heat pumps can reach high flow temperatures there is a question, should they? Modern building standards, and future improved ones, make lower temperatures viable. This only makes heat pumps more suitable for building heating. Thermal stores and instantaneous domestic hot water generation can also do away with high temperatures for pasturisation. CO2 heat pumps are efficient at 60degC flow and 30 deg return, just get the control right and you have a much better solution than a gas boiler. Plus there are no nasty flue gases generated either.

What advantages do heat pumps have over gas boilers?

Crucially, heat pumps are far more environmentally friendly than natural gas boilers. A natural gas boiler releases 280g of carbon per KWh of heat energy. Currently, CO2 heat pumps release 83 g/kwH and this will only get lower as the electricity supply continues to become more renewable.

Heat pumps also have far lower operational costs than boilers. While they are currently more expensive to purchase, they have far lower failure rates, need far less maintenance and the total cost of ownership is much much lower than that of a traditional gas boiler.

Finally, heat pumps open up the opportunity of using flexible input tariffs. This means that, by learning your habits and reacting to wholesale energy prices, your heat pump can use off-peak energy when the costs are at their lowest, while still maintaining a consistent ambient temperature.

Conclusion

Heat pumps are going to be the future of green heating in the UK and across much of the world. The government knows this, which is why it is aiming for 600,000 heat pump installations per year by 2028. They are more efficient, cleaner and have a lower total cost of ownership than gas boilers, and there is no other green heating technology that will be ready and available in time for us to hit our emissions targets.

Demand for heat pumps is set to rise substantially in the next few years. If you want to reduce your organisation’s carbon footprint, the time to enquire about a heat pump installation is now. You can read about our heat pumps here or get in touch for a consultation.