Choosing a boiler
Find out why you should consider a boiler-fired heating setup for your self build or renovation
One of the biggest decisions you’ll need to make with your home heating is whether to go with a boiler or opt for a renewable appliance. It might sound surprising, but if mains gas is available on your plot or property, in many cases it makes sense to tap into it. A gas-fired boiler is still one of the cheapest forms of heating to install and run, requires no effort to use and is ideal for producing the higher temperatures needed for domestic hot water. What’s more, modern boilers work efficiently with both radiant and underfloor heat distribution. ey also work effectively alongside technology such as mechanical ventilation and heat recovery (MVHR) and solar hot water panels.
Types of boiler
e most common option in the UK is a combi boiler, which can provide both space heating and on-demand domestic hot water (DHW). Combis are compact, quick to install and don’t need a separate DHW storage cylinder – so they’re great for flats and smaller homes. And because they only heat water when you require it, they can be cost-effective to run, too. In medium and large houses, you’ll want to go for a system boiler. You’ll need space for a hot water cylinder (perhaps in an airing cupboard or utility/plant room), but the big benefit is that you can easily feed mainspressure water to several outlets at the same time. So, there won’t be any arguments when someone runs the kitchen tap while you’re in the shower.
What size boiler do I need?
Both types of appliance are suitable for new builds, and can happily replace old-style regular boilers in existing homes, too. e key is settling on which type best suits your household’s space heating and hot water demands. is decision will come down to discussion with your designer and heating engineer, and must take into account the arrangement as a whole. How well insulated is your house? What size should the hot water cylinder be and how quickly should it recharge? Are you including any renewables, such as solar panels? All of these factors, and more, will come into play. Installation must be completed by a fully-certified tradesperson: Gas Safe for gas boilers and OFTEC for oil-fired appliances. As a rough guide, installing a system boiler (including pipework) into a new build home will cost around £2,500. You’ll pay less on a renovation project if it’s a straight swap for an older model and you can reuse the existing heating and hot water distribution networks.
Can boilers be green?
At current grid carbon intensity factors and depending on the building, gas is higher in carbon emissions per kwh (kilowatt-hour) of heat produced compared to heat pumps or biomass. However, it’s much better than both oil and electrical resistance heating. Carbon emissions in use are only part of the equation, though, and it’s worth noting the embodied energy required to manufacture and install boilers is lower than with renewable appliances. Much like the electrical grid, the UK gas network is being decarbonised (by adding low-carbon hydrogen into the mix). A new wave of boilers is now coming onto the market that operate on either natural gas or full hydrogen – so if and when the network switches completely to sustainably-produced hydrogen, you can be ready for the next generation of eco heating. What if your property is off the mains gas network? Oil is a common solution and currently has similar running costs (due to the collapse in global oil prices), but it is more carbon intensive. LPG is a popular alternative (you’ll need regular deliveries into a tank located on your property), and BIOLPG is now available to minimise emissions. But an off-mains location is a prime candidate for renewable heating (turn to page 6), so be sure to explore the options fully before finalising your decision.