Boilers do not usually fail on a mild day in September. They fail in the first proper cold week, when they are asked to run flat out for the first time in months, and when every engineer in South East London is already booked. If yours has been giving you hints, this is the time to read them. Here are the signs we see most, what they usually mean, and what to do before the temperature drops.
1. It is well past its expected life
A gas boiler that is serviced every year will typically run for somewhere around ten to fifteen years. Some go longer. But past that point, parts become harder to get, efficiency drops, and the chance of a mid-winter failure rises every year. If yours went in before 2012 and has never been replaced, treat everything else on this list as more serious than it would be on a five-year-old boiler.
Not sure how old it is? The data plate on the boiler or the inside of the casing door usually has a manufacture date or a serial number that gives it away. Send us a photo and we will tell you.
2. It keeps locking out or showing an error code
A boiler that needs resetting every few days is telling you something is failing. The code on the display points to the fault (ignition, fan, pressure, overheating and so on) and some are cheap fixes. But a boiler that repeatedly locks out in autumn is very likely to stop altogether in January. Write down the code each time it happens. It saves the engineer time and it shows the pattern.
3. It loses pressure again and again
Topping up the pressure once a year is normal. Topping it up every week is not. Repeated pressure loss means water is going somewhere, either through a leak in the system, a failing expansion vessel or a faulty pressure relief valve. Some of those are simple repairs. On an old boiler, a tired expansion vessel and a weeping valve often arrive together and the repair bill starts to approach the value of the boiler.
4. Banging, whistling or kettling noises
A boiler that sounds like a kettle coming to the boil usually has limescale or sludge built up on the heat exchanger. The water inside is overheating and boiling in pockets. It can sometimes be improved with a flush and a descaler, but on an older boiler it is often a sign the heat exchanger is near the end. Loud banging on start-up is worth a look sooner rather than later.
5. Hot water that comes and goes
On a combi, water that runs hot, then cold, then hot in the shower usually points to a worn diverter valve or a scaled plate heat exchanger. Both are replaceable parts. On a boiler that is already old, it is one more repair on a machine that is going to need another.
6. A yellow or orange flame, or black marks on the casing
This one is a safety sign, not a wear-and-tear sign. A healthy gas flame burns blue. A yellow or lazy orange flame, soot or scorch marks around the boiler, or a pilot light that keeps blowing out can mean the gas is not burning properly, which can produce carbon monoxide. If you see this, switch the boiler off, open a window, and have it checked by a Gas Safe registered engineer before you use it again. If you smell gas at any time, leave the property and call the National Gas Emergency Service on 0800 111 999. Do not wait for us or anyone else.
A carbon monoxide alarm near the boiler costs very little. If you do not have one, get one this week regardless of the age of your boiler.
7. The repair bills are adding up
There is no magic number, but a useful rule of thumb: if the last couple of repairs together cost a large fraction of what a new boiler would, and the engineer is warning you the next part is not far behind, you are paying to keep an old boiler alive rather than paying for heating. At that point a replacement stops being a luxury and becomes the cheaper option over the next few winters, especially once you count the gas an inefficient old boiler burns.
8. The parts are obsolete
Manufacturers stop making parts for old models eventually. When your engineer says "I can't get that part any more", the boiler's life is over whether or not it is still running today. Do not wait for it to prove the point in December.
Some things that are not the boiler
A few common winter complaints look like a dying boiler and are not:
- Radiators cold at the top usually need bleeding
- Radiators cold at the bottom usually mean sludge, which a flush deals with
- One room never warm is often a stuck radiator valve or an unbalanced system
- The boiler stops on a freezing morning and restarts later is very often a frozen condensate pipe outside, not a boiler fault. Insulating the pipe fixes it
We would rather tell you it is a £90 service and a bleed than sell you a boiler you did not need.
Why now, not December
Three practical reasons to deal with a doubtful boiler in September or October rather than waiting for it to fail:
- Diaries. From the first cold snap, every heating engineer in South East London is fully booked. A planned replacement in early autumn goes in within days. An emergency replacement in December can mean a week or more without heating while you wait
- Choice. When the boiler is still limping along, you can choose the boiler, compare quotes and pick a day. When it has died with the family at home, you take whatever can be fitted soonest
- Stock. Popular boilers and parts run short in the busiest weeks. In September they are on the shelf
What to do this week
If you have ticked one or two of the signs above, book a boiler service (£90). It is a proper safety and efficiency check, and the engineer can give you a straight opinion on how many winters the boiler has left. Landlords can combine it with a CP12 gas safety certificate for £160 together.
If you have ticked three or more, or the boiler is over twelve years old and has already needed repairs this year, ask us for a fixed price on a like-for-like replacement at the same time. There is no charge for the survey and no obligation. Most straight swaps are done in a day. Our guide to like-for-like swaps versus full upgrades explains what that involves, and our South East London new boiler cost guide sets out honest price ranges.
We are based in Bromley and cover South East London, including Catford, Lewisham, Hither Green, Grove Park, Eltham, Blackheath, Bromley and Penge. If you would rather not wait for a survey, send a photo of the boiler and its data plate on WhatsApp and we will tell you what we think. See our new boiler installation and replacement page for what every install includes, or boiler repair if you just want it fixed.
Thinking about a new boiler? We give you a fixed written price after a free survey, and nothing is added on the day.
See our boiler installation service or get in touch for a free quote.