Boiler reviews: How we test
Our lab testers take many measurements
Each of the boilers we've tested has been carefully monitored to record its gas and electricity consumption, efficiency and emissions, as well as being evaluated by a registered gas installer on how easy it is to install, service and use in the home.
Efficiency
We conduct tests according to European Standards to measure how much of the gas each boiler burns is converted into heat.
One of the strange quirks of condensing boilers is that while in condensing mode, they can be more than 100% efficient – they achieve this because as well as using heat from the fuel they're burning at the time, they also reclaim heat from the flue gases to heat your water.
In theory, a condensing boiler can have a maximum efficiency of 107%, providing it uses all the heat from the fuel and the flue gases to heat your water. In practice, most of the boilers we tested don't reach this level.
Getting to grips with each boiler's interior
Ease of use
Our gas fitter installed each appliance, checking that the gas and electrical connections were easy to make and had plenty of room.
Each boiler was assessed for how straightforward it was to install and service, and how easy it was to replace common spare parts, as well as the noise it produced, the warranty provided and the ease of using the controls.
Durability
Boilers are expected to last for a long time, so we run a limited durability trial that involves turning the boilers on, running them for five minutes at full capacity and switching them off again.
We do this 2,920 times – the equivalent of using a boiler for almost a year (though combis will be fired up much more frequently).
Most of the boilers made it through unscathed, but the temperature display on two models both developed a minor fault after 300 cycles, and the casings of two of the boilers were showing signs of wear and tear after the durability trial.