Gas Safe registered
Sime specialists
Murelle, Brava Slim, Brava One and Format. Twenty years on Sime boilers, rates agreed beforehand, parts guaranteed for a year.
Answered 24 hours a day by a technical customer service member.
ALL is short for alarm, so ALL 06 reads as alarm six.
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.
Add the alarm number and your postcode and we can usually name the part before we attend.
Three steps, and you will know where you stand before anyone is booked.
ALL is not an English word, and that is why you cannot find your fault online. It is short for alarm, so ALL 06 reads as alarm six. People search the whole string, find nothing that fits, and conclude their boiler is too obscure to repair. It is not. We are the London firm that tells you whether it is the boiler or the cylinder before anyone attends.
Sime are Italian and the display abbreviates alarm, so read the number not the letters. Brava prints ALL, Murelle Pro HE prints AL, and the numbering is identical, so AL 01 and ALL 01 are one fault. ALL 01 is the smoke thermostat, a flue cut-out no other make names that way: heat that should reach your water is going up the flue, and it needs a combustion analysis, not a parts swap.
It tried to light, never confirmed a flame and shut the gas off. The most common Sime alarm. Try a hob first, and in winter thaw the condensate pipe. Otherwise it is the ignition or ionisation probe, then the gas valve.
ALL 08 is different: a fault in the flame detection circuit, so the boiler cannot trust what it is told rather than seeing nothing.
The only Sime alarm most householders can clear themselves. Sime's own target is 1.0 to 1.2 bar cold, lower than most guides quote. Fill cold, close both valves firmly, reset. Dropping again within days means a leak, and repeated topping up draws oxygenated water in, which is how sludge forms.
ALL 03 is the opposite, one digit away: too much pressure, usually a loop left open or a tired expansion vessel. The instinct on any pressure alarm is the filling loop, and on an 03 that makes it worse.
Sime call it the smoke thermostat, a direct translation no other make uses. It watches flue temperature and stops the boiler if it climbs too high, which means heat that should be reaching your water is going up the flue.
That points at combustion set up wrongly, a fouled heat exchanger or a restricted flue. It needs a combustion analysis, not a parts swap.
02 and 03 sit next to each other and mean opposite things. The instinct on any pressure alarm is the filling loop, and on an 03 that makes it worse.
Usually a loop left open, or an expansion vessel that has lost its charge so pressure climbs as the water heats. Bleed a radiator back toward 1.2 bar cold and check both loop valves are shut.
The boiler overheated and the safety thermostat stopped it. As on every make, the thermostat is the messenger: the cause is almost always circulation.
A jammed pump, a closed valve, air or sludge will all do it. Let it cool fully, reset once, and if it returns stop resetting and have the circulation checked.
ALL 06 means no flame was seen. ALL 08 means the circuit that does the seeing has itself failed, so the boiler cannot trust what it is being told.
Different part, different job. It points at the ionisation probe, its lead or the board input rather than at the gas supply, and it is not one to keep resetting.
| Number | What it means | What it usually turns out to be |
|---|---|---|
| 01 | Smoke thermostat | Combustion or the flue, not the burner |
| 02 | Low system pressure | Usually a householder fix. Fill to 1.0 to 1.2 bar cold |
| 03 | High system pressure | A filling loop left open, or the expansion vessel |
| 04 | Hot water sensor | The sensor. On T models it is the return sensor |
| 05 | Delivery sensor | The flow sensor, not the heat exchanger |
| 06 | No flame detected | Gas supply first, then the probe, then the valve |
| 07 | Safety thermostat has operated | Circulation. Pump, air, sludge or a closed valve |
| 08 | Flame detection circuit fault | The sensing side. Engineer rather than reset |
Sime state a cold pressure of 1.0 to 1.2 bar, lower than the 1 to 1.5 bar most general advice gives. Fill to 1.5 on that guidance and you are close to the point where it complains the other way as the water expands. If you topped up to a figure read elsewhere and now see ALL 03, that is the reason.
Two account for most.
Hot water never properly hot, heating faultless. The plate heat exchanger is scaling. The heating circuit is sealed so it scales once and stops; the hot water side takes fresh mains water at every tap. A diverter fault gives none at all, and an annual service catches it while it is still a flush.
Told nobody works on Sime? Ask which part and which supplier was checked. A genuine availability problem names both; a vague answer about the make being obscure is not a diagnosis.
ALL means alarm, not all
The same three letters appear every time, so the number carries it. Read us that and the range name and we can usually name the part before anyone attends.
The label is behind the front panel, and the range decides whether it says ALL or AL.
Murelle and Murelle Pro HE print AL. Brava, Brava Slim and Brava One print ALL. Format, Planet and Metropolis are older. HE marks condensing, R heat only, T a system boiler, so anything but a plain combi means a cylinder somewhere. Read us the serial when you ring; it matches your appliance to the right parts. We work on every make of boiler.
The big difference between here and Manchester.
Water here carries roughly 277 milligrams of calcium carbonate per litre, from chalk the Thames and the Lea run through, so the plate heat exchanger scales faster than the manual allows, the same in Chislehurst and Beckenham as in Hampstead and Belsize Park.
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 faster than one set to 50, which is still hot enough to scald, and turning that dial down costs nothing. It applies to the tap setting, not a cylinder, which must reach 60 degrees.
Age does not decide it. The failed part does, and we would rather keep a boiler running.
| What has failed | Under 8 years | 8 to 14 years | 15 years and older |
|---|---|---|---|
| Sensors, pressure sensor | Repair | Repair | Repair if parts exist |
| Ignition and ionisation probes | Repair | Repair | Repair if parts exist |
| Expansion vessel, pump | Repair | Repair | Repair |
| Fan, smoke thermostat | Repair | Repair | Depends on the rest of the boiler |
| Diverter valve, plate heat exchanger | Repair | Repair | Repair if the part is still made |
| Gas valve | Repair | Borderline, we will be straight with you | Replace |
| Control board | Check the guarantee first | Borderline, we will be straight with you | Replace |
| Main heat exchanger | Guarantee claim if registered | Worth a second opinion | Replace |
Under eight years old it is a repair without argument. Between eight and fourteen only a board or heat exchanger changes that. Past fifteen availability decides, and the older Format and Planet ranges are where it bites. Several Sime ranges use a stainless steel heat exchanger, the part that usually ends a boiler's life elsewhere, so an older one deserves a proper look. See boiler replacement and our cost guide.
Most firms here are combi-only, which does not suit a city of large houses.
A Sime R or T model runs a stored cylinder with its own thermostat, immersion element and, if unvented, its own safety devices. When the hot water goes the boiler takes the blame and is usually fine: a cylinder sensor out of its pocket, a failed motorised valve, or a scaled immersion element, none of which shows an alarm number.
Water at its tundish means a safety device has failed, and is never something to cap. That needs G3 as well as Gas Safe registration; we hold both, so unvented cylinder repair happens on the same visit, and larger houses across Dulwich usually get a scale reducer with it.
Local boiler repair specialists
Clear advice. Careful repairs. Family-friendly service.
Call 0203 868 6134London, north and south of the river.
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.
It is not the English word. Sime are Italian and ALL abbreviates alarm, so ALL 06 reads as alarm six. The letters are the same on every fault, so the number carries the message. Some ranges print AL, same numbering. That is why searching the full string finds nothing useful. We work on every make of boiler.
No flame detected: it tried to light, never confirmed a flame and shut the gas off. The most common Sime alarm. Try a hob first, because no gas anywhere is not a boiler fault, and in cold weather thaw the condensate pipe. Otherwise it is the ignition or ionisation probe, then the gas valve. Reset once only. No heat at all? See emergency boiler repair.
Sime state 1.0 to 1.2 bar cold, lower than the 1 to 1.5 bar most advice quotes. Fill to 1.5 and you are close to the point where it complains the other way. ALL 02 means too little, ALL 03 too much, one digit apart, so check which you have before reaching for the filling loop. Repeated topping up means a leak and causes sludge.
No. Both abbreviate alarm and the numbering is identical, so AL 01 and ALL 01 are one fault. Brava prints ALL, Murelle Pro HE prints AL. It matters only because searching for one turns up nothing about the other. An annual service is when the range and serial get recorded properly.
Under eight years old it is a repair without argument. Between eight and fourteen only a board or heat exchanger changes that. Past fifteen availability decides, and the older Format and Planet ranges are where it bites. Several Sime ranges use a stainless steel heat exchanger, the part that usually ends a boiler's life elsewhere, so an older one deserves a proper look. See boiler replacement.
Yes, and it is a large part of what we do. A Sime R or T model runs a stored cylinder with its own thermostat, immersion element and, if unvented, its own safety devices. Unvented work needs G3 as well as Gas Safe registration and we hold both, so the cylinder is diagnosed on the same visit. See unvented cylinder repair.
Sime abbreviate in Italian rather than English, which catches out more owners than any fault it reports.
No gas supply? Plenty of London flats run without one, so we also cover electric boiler repair.
Read us the number after ALL or AL, and the range name from the label. With those two we can usually name the part before anyone is on the way.
Gas Safe registered. Unvented cylinder qualified. Parts guaranteed for a year. Covering London, north and south of the river, 24 hours a day.
