Heat pumps extract warmth from the air, the ground, or water - a bit like a fridge operating in reverse. They are powered by electricity, so if you have a low-carbon source of electricity they provide greener heating.
Gas-powered heating produces carbon dioxide emissions, which cause climate change. Heating buildings accounts for 21% of the UK's carbon emissions. And right now, thanks to soaring energy prices, your gas boiler may be costing you more than you expected.
The government hopes that if your boiler is nearing the end of its life, you may want to replace it with a more environmentally friendly alternative.
Experts think most homes will eventually have heat pumps.
They are costly - between £6,000 and £18,000, depending on the sort you install and the size of your home.
From next April, homeowners in England and Wales will be offered subsidies of £5,000 to help pay for them, the government has announced. It also said no new gas boilers will be sold after 2035. It's not clear whether heat pumps could be cheaper to run than gas boilers. But the government also said it would consult on a plan to shift levies - charges to help pay for green measures - away from electricity bills over the next decade. It said this would ensure heat pumps are no more expensive to run than a gas boiler.
It's easiest to put them in new builds, but older homes can also be fitted with heat pumps. Most domestic heat pumps will extract heat from the air.
These require good insulation - around walls, roofs and windows. This is because air pumps operate with water at a lower temperature than gas boilers, so it's important not to have heat escaping.
You also need space inside for a heat pump unit and hot water cylinder. The unit will be about the size of a gas boiler - while the cylinder depends on the size of the home. A box of about one metre by one metre needs to be outside (preferably attached to the house) to draw in air. It should be at least one metre from your neighbour's property so they will not be able to hear it, although it shouldn't be much louder than your fridge.
A ground source heat pump needs much more space outside: either a borehole as much as 100m deep; or a horizontal system dug into the ground over a large area.
Information sourced from BBC.