Boiler Repairs in London and Kent

The repair visit, in order

A boiler is a fairly orderly machine, which is why most repairs start with a look rather than a spanner. We read the display first, and the code on it if there is one, and we read the pressure gauge. Then we check that the boiler is being asked for heat at all, because a thermostat with flat batteries, or a programmer that lost its settings in a power cut, will leave a perfectly good boiler sitting on the wall doing nothing. Past that point the work is inside the boiler, which is gas work, and the engineer follows the order the boiler itself works in: gas arriving at the appliance, the fan running, the ignition sparking, the flame being sensed, the pump moving water round the system. Each step depends on the one before it, so working down the list in that order finds the failed part without guessing. Once it is found, you are told what it is, what it does, whether anything else on the boiler is close behind it, and what the repair will cost, written down before a new part goes in. If the part is a common one the repair is often finished on the same visit. If it has to be ordered, we say so plainly, the boiler is left safe, and you are told what will still work in the meantime. On a combi that is sometimes nothing at all. On a system with a hot water cylinder it is often the immersion heater, which will keep the taps hot until the part arrives.

The price comes before the part, every time.

Repairs, replacements and the bit in between

Not every dead boiler needs replacing. A great many of them need a pressure top up, a new expansion vessel, a diverter valve, a pump, or a fault traced back to a thermostat that has quietly stopped talking to it. Those are repairs, and they are worth doing on a boiler that still has years in it.

Where a replacement genuinely is the right answer, the job is the whole job: the old unit out, the new one in, the system flushed so the new heat exchanger is not fed a decade of black sludge, controls set up, and everything left working before anyone leaves.

When the honest answer is the second of those, we also arrange boiler installations, and the page for them sets out what a replacement involves, from the first visit to the day it goes in.

Fault codes on common boilers

A fault code tells you which step of the boiler’s routine failed, not which part needs replacing. One code can have a dozen causes, so it is where the diagnosis starts, and it is a useful thing to read out on the phone. Codes also differ between models of the same make, and newer boilers often show three digits or a line of plain words instead.

Vaillant ecoTEC: F.22 is low water pressure. F.28 means no flame was detected when it tried to light, and F.29 means the flame went out while it was running and it could not light again. Newer ecoTEC models show the same codes with three digits, F.022 and F.028. Vaillant’s manual for those models allows a reset after F.028 at most three times before you call someone in.

Worcester Greenstar: on the i, Si and CDi ranges the display shows two characters with a number under them. EA with 227 is no flame after ignition, EA with 229 is the flame lost while it was running, and A1 with 281 is the pump stuck or running dry. The newer 4000 and 8000 boilers show a number and a line of text instead, such as 1017 for low system pressure.

Ideal: F1 is low water pressure, not a lockout. L2 is an ignition lockout after five failed attempts, F2 is a flame loss, and LC means the boiler has been reset five times in fifteen minutes and wants looking at. Some Ideal models show F01 and L02, and the newest show plain words such as Ignition Lockout. Baxi: on most of the older ranges E133 is an interrupted gas supply or a flame failure, and low pressure is E118 or E119 depending on the age of the boiler. The newer Combi 2 boilers use a different set altogether, such as E.04.10 when the burner has failed to light four times.

A frozen condensate pipe shows up as an ignition code on all of them.

Whatever the code, the casing stays on. Every one of these makers says so.

• Vaillant F22, low water pressure: one of our jobs

Heating that never quite gets there

Radiators cold at the top usually means air, and bleeding them is a five minute job you can do yourself. Radiators cold at the bottom is the opposite problem, sludge sitting in the base of the panel, and that one needs the system cleaning rather than a spanner.

One room that never warms up while the rest of the house is fine is nearly always a balancing problem or a seized valve rather than a failed boiler. Worth knowing before anyone quotes you for a new one.

Hard water, and what it does

This part of Kent and outer south east London sits on chalk, and the water is hard. Over years that scale settles in heat exchangers, on immersion elements and inside shower valves. It is the single most common reason a boiler in this area loses performance long before it reaches the end of its life. It is also why a system flush at replacement time is not an upsell, it is the thing that protects the new unit.

Safe checks before ringing

None of these needs a tool or a panel taken off.

Read the pressure gauge. Most sealed systems want somewhere around one to one and a half bar with the heating cold, though the figure varies by make and the boiler’s manual gives yours. A reading near nothing explains a boiler that has stopped.

Check the thermostat and the programmer: fresh batteries in a wireless thermostat, the right time and an on period on the programmer, and the thermostat set above the temperature of the room. One maker’s own manual says no fault is found on the boiler in over 30% of its service calls.

Check the boiler has power, a lit display and the switch on the fused spur beside it turned on.

If the gas is on a prepayment meter, check it has credit, and see whether the hob lights.

If you smell gas, leave all of this. Do not touch switches, open the windows, turn the gas off at the meter if you can reach it safely, get out, and ring the National Gas Emergency Service on 0800 111 999.

• A frozen condensate pipe in a hard frost, on the Barnehurst page