Gas Safe registered
Main specialists
Eco Compact, Eco Elite and the Multipoint water heaters. Twenty years on Main boilers, rates agreed beforehand, and parts guaranteed for a year.
Answered 24 hours a day by a technical customer service member.
Main shows the code in two parts, E1 first and then the rest, so wait for the whole number before you read it.
No heating or hot water right now? Call 0203 868 6134. We will tell you the earliest realistic slot rather than the one you want to hear.
Two details to start. Add the fault code and your postcode and we can usually tell you the likely part before we attend.
Three steps, no sales pitch, and you will know where you stand before an engineer is booked.
The arithmetic on a Main is different, and we will say so. It shares its components with Baxi and Potterton, so the same failed part costs the same to replace whichever badge is on the front. What differs is what the appliance is worth. That means the point where replacing beats repairing arrives earlier on a Main than on a premium boiler with the identical fault, and pretending otherwise helps nobody.
Main boilers are built to a price with parts shared across a very large group, which makes the failure pattern predictable and the parts easy to get. Six cover most of it.
Main belongs to Baxi Heating, alongside Baxi and Potterton, and a modern Main uses the same E code system as both. That is genuinely good news, because it means a very large parts supply sits behind a budget badge.
The most common code on any modern Main, and the only one most householders can clear themselves.
What you can safely do: find the filling loop, usually a braided silver hose under the boiler, and open it until the gauge reads between 1 and 1.5 bar cold. Close it fully. Reset once.
Wait for the whole code first. Main displays it in two parts, E1 and then the digits that complete it, exactly as Baxi do, because it is the same control system. E119 and E133 both begin E1 and are nothing alike.
If the gauge reads 1.2 bar and E119 is still there, the pressure sensor has failed rather than the pressure. Small part, short job.
What does the gauge read? That number decides which of these it is.
The boiler called for gas, tried to ignite, saw no flame and shut the valve.
First, the gas. Does the hob light? Has a prepayment meter run out of credit? An E133 with no gas anywhere in the property is not a boiler problem.
Second, in cold weather, the condensate pipe. The white plastic pipe running outside freezes and the boiler cannot discharge. Pour warm water along it, never boiling, which splits it.
Third, the electrodes. Worn, cracked or carboned, so the spark never reaches the burner or the flame is never confirmed.
In a rented flat: this is the landlord's repair to arrange. Report it in writing rather than by phone so there is a date on record.
Check the hob first. Ten seconds, and it changes the answer.
The water went past the limit the safety thermostat allows and the burner shut down.
The usual cause: a jammed pump or air in the circuit, so the boiler makes heat faster than the system carries it away and it cooks in one place.
What it almost never is: the safety thermostat itself, which is the part reporting the problem. Replace only that and it trips again within days.
Why this code turns up so often on this brand: a great many Mains went into flats and rented houses where nobody has bled a radiator since the boiler was fitted, and air is the single most common cause.
What helps most: not a part. Clearing the system properly deals with the cause where a component swap usually does not.
Leave it off and tell us whether any radiator was cold before this started.
The board asked the fan for a speed and did not get it back. E161 is the same family.
Worth checking before a fan is ordered: the plug and harness at the fan. On this control system a connection that has worked loose gives the identical code, and that is a very different bill.
The warning you probably had: a fan bearing gets loud before it stops. A Main that has sounded rough for a month was telling you this was coming.
What it almost never is: only the fan. A flue blocked by leaves or nesting material makes a healthy fan work against resistance the board reads as a fault.
Has it been noisy, or did it stop without warning?
The catch-all. It covers a genuine control board lockout, and it also appears while the boiler restarts after the electricity has been interrupted.
What to do first: reset it once. If the power flickered, a breaker tripped, or somebody has been working on the consumer unit, an E168 that clears on one reset and does not come back was the power cut rather than the boiler.
If it returns straight away: the control board, and at that point the age of the appliance matters more than the fault does. On a budget boiler that is a genuine crossroads and we will say so.
What it almost never is: a reason to keep resetting. One attempt tells you what you need to know.
Did the power go off recently? Say so, it changes the likely answer.
Main make gas water heaters as well as boilers, and the Multipoint range is the one that catches people out.
How to tell: a water heater does no central heating at all. It feeds taps and showers only, it is usually smaller than a boiler, and there is no pressure gauge and no filling loop because it is not connected to a sealed heating circuit.
Why it matters when you call anybody: the fault codes on this page are for the boilers. A Multipoint has its own parts list, its own faults and often its own flue arrangement, and an engineer arriving expecting a combi has brought the wrong van.
The common faults are different too: on a water heater the usual suspects are the gas valve, the thermocouple on older models, and scale in the heat exchanger, which in London arrives faster than the manual assumes.
Does it do your radiators, or only the taps? That one answer tells us which appliance it is.
| Code | What the boiler is saying | What it usually turns out to be |
|---|---|---|
| E117 | System pressure too high | A filling loop left open, more often than a fault |
| E118 | System pressure low, on some models | Read exactly as E119 above |
| E125 | Primary circulation fault | Pump, closed valve or a silted heat exchanger |
| E128 | Repeated loss of flame while running | Recorded after many failures, so it is not new |
| E130 / E131 | Flue thermostat tripped | The flue, or the thermostat on it |
| E134 / E135 | Gas valve open with no gas, or supply interrupted | The supply first, the valve second |
| E164 | Water pressure sensor fault | The sensor, when the gauge reads normal |
| E270 | Dry fire | Stop using it and call somebody |
| E385 | Incoming voltage too low | Your electricity supply, not the boiler |
A budget badge does not mean a scarce parts supply. Main sits inside Baxi Heating with Baxi and Potterton, and a great many components are shared across the three, so the parts network behind your boiler is far larger than the price suggests. If you have been told parts are hard to find for a Main, ask which specific part and which supplier was checked, because the answer is usually a Baxi part number.
Main is the boiler most often chosen by somebody who was not going to live with it, and that produces a particular set of problems.
A Main fitted new with a flat or a development tends to reach its eighth or ninth winter and then produce three faults in one season, which feels like the boiler falling apart.
What is actually happening: every wear part in it went in on the same day and has done the same hours. The electrode, the fan bearing, the pump and the expansion vessel all reach the end of their lives within a year or two of each other, because they started together.
Why it matters for the decision: the first of those three faults is a repair. By the third, the question is no longer what has failed but what has not failed yet, and that is a fair reason to look at replacing the boiler even though each individual repair was small.
What breaks the pattern: having it serviced. A boiler that gets looked at annually has its wear parts replaced as they go rather than all at once in one bad winter.
How many faults in the last two years? That number matters more than the age. Call 0203 868 6134.
Main is treated as an unfamiliar badge by people who do not work on them often, and that shows up in quotes as long lead times and inflated parts prices.
The reality: it belongs to Baxi Heating and shares components with Baxi and Potterton, which between them account for an enormous share of the boilers in this country. The supply chain is deep.
What to ask: which part, and whether an equivalent from elsewhere in the group will fit. A specific answer is a diagnosis. A vague one about the brand being obscure is not.
Where it is genuinely true: the older ranges and the discontinued water heaters, where availability does start to decide things. We will tell you when you have reached that point.
On a Main combi this is the plate heat exchanger scaling up, and it is the most misread fault on any combi.
Why the heating stays faultless: that circuit is sealed, so the same water goes round, scales once and stops. The hot water side takes fresh mains water every time a tap opens, which in a hard water city means fresh scale every time.
Why it is not a dying boiler: it is one component on an appliance that is otherwise sound, and on a budget boiler the temptation is to write the whole thing off over a single part.
How to tell it from the diverter valve: a scaled plate gives you water that is there but never properly hot. A diverter fault more often gives you no hot water at all, or hot water only while the heating is running.
Never properly hot, or nothing at all? Different parts. Call 0203 868 6134.
A large share of the Mains in London are in rented property, which changes who does what rather than what is wrong with the appliance.
What is fixed in law: the landlord is responsible for the boiler and for a gas safety check every twelve months by a Gas Safe registered engineer, and you are entitled to a copy of that certificate.
What helps in practice: report it in writing rather than by phone, so there is a date on it, and say whether you have heating, hot water or neither, because no heating in winter is treated more urgently than a dripping tap.
What we can do: deal with a landlord or agent directly if you would rather not go back and forth. We attend rented property constantly and are used to invoicing whoever is actually responsible rather than whoever answered the door.
Same parts as a Baxi, different arithmetic
A Main shares its components with Baxi and Potterton, so the same failed part costs the same to replace. What differs is what the appliance is worth, which means replacement wins earlier here than it would on a premium boiler.
The label is behind the front panel. The first thing to establish is whether you are looking at a boiler at all.
Main make both, and they are not variations of the same thing.
If yours does no heating at all and there is a separate appliance somewhere else doing the radiators, you have a water heater and the fault codes on this page do not apply to it.
Main name the range, then the type, then the output. An Eco Compact 30 is an Eco Compact rated 30 kilowatts.
Eco Compact and Eco Elite are the ranges most often on London walls, in combi, system and heat only versions. The Compact is exactly what the name says and goes into cupboards other boilers will not fit.
Combi, System or Heat tells you the rest. If it says System or Heat there is a hot water cylinder somewhere in the property, and the cylinder is as likely to be the fault as the boiler is.
The older ranges turn up in flats that have not been touched this century, and on those availability rather than cost tends to decide a repair.
Range names have been carried across several revisions, and one fitted early does not always take the same parts as one fitted years later.
The serial number and GC number on the label identify exactly which revision is on your wall, and they are what a supplier matches against the Baxi Heating catalogue, which is the fastest way to settle any question about availability.
Read us the serial from the label when you ring. It takes a moment and it is the difference between one visit and two. We work on every make of boiler and the same advice holds for all of them.
London is a hard water city almost everywhere, and that is the single biggest difference between repairing a Main here and repairing one in Manchester or Glasgow.
Chalk is the reason. The Thames and the Lea both run through it in the Chilterns and the North Downs before the water reaches your tap, and the result is roughly 277 milligrams of calcium carbonate per litre, ranging from about 250 to over 350 depending on the district. Inside a combi that means one thing: the plate heat exchanger furs up faster than the manual's service intervals allow for.
It is the same story in Hampstead and Belsize Park as it is in Wimbledon. The water is hard, the plate heat exchanger scales, and the only question is whether anybody checks it before condemning the boiler.
Hardness is not uniform, and it does not follow borough boundaries. It varies by supply zone and can change over a short distance, so your supplier publishes a figure for your own postcode and it is worth reading before anybody guesses.
Scale drops out of solution faster the hotter the water gets. A combi set to deliver taps at 65 degrees furs up its plate heat exchanger noticeably faster than one set to 50, which is still hot enough to scald. Turning that dial down costs nothing and is the most effective thing a householder in a hard water area can do. This applies to the tap setting, not to a cylinder, which must reach 60 degrees for safety.
Stored hot water is normal in larger London houses, and no combi replaces it whatever the output figure says.
A great many London firms will only touch combis, which is awkward in a city with this much older housing stock. A Main system or heat only boiler feeds a separate cylinder carrying its own thermostat, immersion element and, where it is unvented, its own safety devices. Two appliances rather than one, which is why no hot water so often turns out to have nothing to do with the boiler at all.
The cylinder sensor lives in a pocket on the tank. If it fails or works loose the boiler stops heating the cylinder while every radiator stays warm, which is the single clearest sign the fault is not in the appliance.
The motorised valve sends the heat to the radiators, the cylinder or both. When its motor or microswitch goes you get heating with no hot water, hot water with no heating, or both at once, and the head usually changes without draining anything.
The immersion element furs up in London water and then either trips out or stops working. Test it before condemning a tank, because the element is a fraction of the cost. In larger houses across Chislehurst and Beckenham we generally fit a scale reducer on the same visit.
An unvented cylinder is a pressure vessel. It carries an expansion vessel, a pressure reducing valve, an expansion relief valve and a temperature and pressure relief valve, all discharging through a tundish. Water running at the tundish means one of them has failed. Do not leave it and never cap it off.
Unvented work is notifiable and needs a G3 qualification on top of Gas Safe registration. Our engineers hold both, so the boiler and the cylinder are dealt with on one visit rather than two appointments and two charges. That is why unvented cylinder repair sits alongside the boiler work instead of being farmed out.
Swapping stored hot water for a combi to free an airing cupboard is the change people most often ask us to reverse. A combi cannot run two showers at once, whatever the output on the box, because it heats water as it passes rather than storing it. In a house with three bathrooms the honest answer is usually to keep the cylinder and spend the money replacing it if it is old, rather than removing it.
This is the brand where the decision comes up soonest, and where an honest answer matters most. Age alone does not decide it, but on a budget boiler the arithmetic turns earlier than it does elsewhere.
| What has failed | Under 8 years | 8 to 14 years | 15 years and older |
|---|---|---|---|
| Pressure sensor, thermistors | Repair | Repair | Repair if parts exist |
| Ignition and sensing electrodes | Repair | Repair | Repair if parts exist |
| Expansion vessel, pump | Repair | Repair | Borderline, we will be straight with you |
| Fan, or fan wiring | Repair | Repair | Depends on the rest of the boiler |
| Diverter valve, plate heat exchanger | Repair | Repair | Depends on the rest of the boiler |
| Gas valve | Repair | Borderline, we will be straight with you | Replace |
| Control board | Check the guarantee first | Usually replace | Replace |
| Main heat exchanger | Guarantee claim if registered | Replace | Replace |
Every component is still made, and at this age you are looking at one failed part, not a tired boiler. An electrode, sensor, fan or pump on a six year old Eco Compact is a repair, and the budget badge changes nothing about that.
Ask about the guarantee position when you ring, ours included. Main registered guarantees run for a set term from installation, and in a flat bought new the paperwork is often still in a folder from the developer that nobody has opened.
If somebody quotes you for a new boiler at this age, ask which single part has failed and what that part costs on its own.
Still a clear repair: electrodes, pressure sensor, fan, pump, expansion vessel, diverter valve. Ordinary wear items that say nothing about the rest of the boiler.
Here is the honest part. A control board or a heat exchanger costs roughly the same to replace on a Main as on a premium boiler, because they are comparable components. What differs is what the appliance around them is worth. On a Main at twelve years old, one of those two failures is usually where replacement starts to win, and on a premium boiler it would not be.
What that means in practice: the cheap repairs stay worth doing for as long as they do on any make. It is only the expensive ones where the badge changes the answer, and we will tell you which side of that line you are on before anybody attends.
Past this point availability takes over from cost, as it does on any make. A Main of that age with a cheap part failure is still worth putting right, and plenty are.
The discontinued water heaters are the exception. Parts for those are genuinely harder to come by, and it is worth establishing whether the part still exists before anybody charges to attend, because a diagnosis that names an unobtainable part has told you nothing you can act on.
We will answer that question on the phone for free. Our repair and replacement cost guide explains what the figure is actually built from.
Boiler problem? We're here 24/7
Emergency boiler repairs across London, north and south of the river
Call 0203 868 6134London, north and south of the river. These are the districts we work in most.
These are where we work most, not a boundary. An engineer attends anywhere in north London and south London. Tell us where you are and we will say plainly when we can get to you.
If you smell gas: do not touch any switches. Open the windows, leave the property, then call the National Gas Emergency Service on 0800 111 999. That line is free and open 24 hours. Call them before you call us.
If a carbon monoxide alarm is sounding: get everyone out immediately, then call 999 if anyone feels unwell. Do not go back in until the property has been ventilated and checked.
If the boiler locks out repeatedly: try one reset. If it locks out again straight away, stop. Repeated resets hide a fault that is still there, and on a gas appliance that is not a risk worth taking.
Under the Gas Safety (Installation and Use) Regulations 1998, only a Gas Safe registered engineer may work on gas appliances. Never open the boiler casing yourself.
Usually, yes. E119 means system water pressure has fallen below the minimum needed to fire safely. Open the filling loop under the boiler until the gauge reads between 1 and 1.5 bar cold, close it fully and reset once. Wait for the whole code before acting, because Main shows it in two parts and E119 and E133 both begin E1. If the gauge already reads 1.2 bar and E119 is still showing, the pressure sensor has failed rather than the pressure.
No, and the budget badge is misleading here. Main belongs to Baxi Heating alongside Baxi and Potterton, and a great many components are shared across the three, so the parts network is far larger than the price suggests. If you have been told parts are scarce, ask which specific part and which supplier was checked, because the answer is usually a Baxi part number. Genuine scarcity applies mainly to the older ranges and the discontinued water heaters.
Possibly not, because it may not be a boiler. Main make gas water heaters as well as boilers, and a Multipoint feeds taps and showers only. If yours has no pressure gauge and no filling loop, and something else in the property does the radiators, you have a water heater and it was never meant to heat anything else. It has its own parts list and its own faults, so say which you have when you call, because it changes what an engineer brings.
Cheap repairs are worth doing for as long as they are on any make, so an electrode, sensor, fan or pump is a repair whatever the badge says. The difference comes with the expensive parts. A control board or a heat exchanger costs roughly the same to replace on a Main as on a premium boiler, but the appliance around it is worth less, so replacement starts to win earlier. We will tell you which side of that line you are on before anybody attends. See our boiler replacement page.
Because every wear part in it went in on the same day and has done the same hours. On a boiler fitted new with a flat, the electrode, the fan bearing, the pump and the expansion vessel all reach the end of their lives within a year or two of each other. The first fault is a repair. By the third, the question is what has not failed yet, and that is a fair reason to look at replacement even though each individual repair was small. Annual servicing breaks the pattern by replacing wear parts as they go.
The label is behind the front panel. Main name the range, then the type, then the output, so an Eco Compact 30 is an Eco Compact rated 30 kilowatts, and Combi, System or Heat tells you the rest. If it says System or Heat there is a hot water cylinder somewhere in the property. Read us the serial from the label when you ring, because the serial number is what matches your appliance to the right parts in the Baxi Heating catalogue. We work on every make of boiler.
The landlord, both for the repair and for a gas safety check every twelve months carried out by a Gas Safe registered engineer, and you are entitled to a copy of that certificate. A tenant does not need to arrange or pay for a boiler repair. Report the fault in writing rather than by phone so there is a date on record, and say whether you have heating, hot water or neither, because no heating in winter is treated more urgently. See our gas safety certificate page.
The truthful answer is that it depends, and anyone who gives you a fixed price before asking what the boiler is doing is guessing at your expense. Three variables, and only three: the component, whether it has to be ordered in, and how long the work runs. On a Main the shared parts supply keeps component costs down, and we will say plainly when an expensive part makes replacement the better spend. The rate is agreed beforehand and parts we fit are guaranteed for a year, so nothing is carried out on the assumption that you will approve it afterwards. There is no charge for telling you a repair is not the right call. Our repair and replacement cost guide explains what the figure is actually built from.
Main, Baxi and Potterton all belong to Baxi Heating, which is why the fault codes and many of the parts are shared between the three.
No gas supply? Plenty of London flats run without one, and we also cover electric boiler repair.
The cheap repairs on a Main are worth doing for as long as they are on any make, and only the expensive ones turn earlier. Tell us whether it heats radiators or only taps, then the code and the model.
Gas Safe registered. Unvented cylinder qualified. Parts guaranteed for a year. Covering London, north and south of the river, 24 hours a day.
