The first cold week of the year is when boilers fail, because they have been sitting idle since April and then get asked to work flat out. Most of the calls we get in that week are things the homeowner could have caught in ten minutes in October. Here are the four.
1. Pressure (two minutes)
Find the pressure gauge on the front or underneath of the boiler. With the heating off and cold it should read between 1 and 1.5 bar. Below 1 and the boiler will lock out at some point this winter with a low pressure code (F.22 on a Vaillant, E119 on a Baxi, F1 on an Ideal). Top it up with the filling loop, the small tap or lever on the pipes under the boiler, until it reads about 1.2, then close the loop fully.
If it is dropping every couple of weeks, water is going somewhere. That is one for us, and it is cheaper to find in October than in January.
2. Radiators (five minutes)
Turn the heating on and walk round after 15 minutes. Cold at the top means air: bleed it with a radiator key until water comes out, then check the pressure again. Cold at the bottom or in the middle means sludge, which a bleed will not fix. One or two sludgy radiators is a flush; most of them is a conversation about the system.
While you are there, make sure every radiator valve is actually open. Furniture gets moved, valves get knocked.
3. The condensate pipe (three minutes)
This is the white plastic pipe that runs from the boiler to a drain, often outside. In a hard frost it freezes, the boiler cannot get rid of its waste water, and it locks out with an ignition or flame code (EA, F.28, E133, L2). If yours runs outside, check it is insulated with foam pipe lagging and that it drops steadily to the drain with no sags where water can sit. Lagging costs a few pounds from any DIY shop.
4. Controls (five minutes)
Check the room thermostat has fresh batteries if it takes them, that the timer still matches your week (the clocks went back on 25 October), and that the heating is set to come on 20 to 30 minutes before you get up rather than at 5am. If you have a combi, this is also the moment to turn the flow temperature down to 60°C; our guide walks through it.
Already showing a code?
Run it through our free fault code checker. Pick the make, type what is on the display, and it tells you in plain English whether it is a two-minute fix or one for an engineer.
How toastd can help
A boiler service before the cold sets in is the cheapest insurance there is, and it includes all four of these checks plus a combustion check and a proper look inside. Send your postcode and number and our team rings you back today.