Gas Safe registered
SW12 SW18
Gas Safe engineers across SW12 and SW18, 24 hours a day.
Answered 24 hours a day by a technical customer service member.
Where the pressure keeps dropping and there is nothing to see, the pipework under a solid floor is the usual answer.
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 your postcode and whether there is a cylinder in an airing cupboard and we can usually tell you the likely part before we attend.
We cover Balham, and the whole of London
Tell us the address and you will get an honest answer about timing.
View areas we coverThree steps. The first one usually tells us most of it.
If a repair is not worth doing, we will say so on the phone. Call 0203 868 6134.
Almost nobody says they live in SW12. They say Nightingale Lane, or the Heaver estate, or off the common.
Names we hear on SW12 and SW18 calls, and the postcodes around them
Grouped by postcode, because that is the one part of an address everybody knows.
We work right across London, north and south of the river. If yours is not here, ring and tell us the address.
Which is where the pressure goes when there is nothing to see.
SW12 and SW18 are Victorian terraces off the common, and almost every one of them has had the side return filled in to make a wider kitchen. That extension is the defining feature of this housing, and it is nearly always built with a solid concrete floor rather than suspended timber.
Solid floors mean buried pipework. The flow and return to the extension radiators, and often to a relocated boiler, runs in screed under the concrete. When one of those joints weeps there is nothing to see: no damp patch, no drip, no stain. What you get instead is system pressure that falls week after week, and a boiler that eventually locks out on low pressure.
Topping it up treats the symptom and hides which of three causes you actually have: a buried leak, an expansion vessel that has lost its charge, or a pressure relief valve passing and discharging outside. They are three different repairs, and the rate at which the pressure falls is the first clue to which.
A system that needs topping up more than about twice a year is losing water somewhere, and every top-up brings fresh oxygenated water in with it. That is what turns a small leak into a corroded system, so the topping up is not a harmless habit.
The two commonest calls from SW12, and neither is usually a new boiler.
Falling pressure has three usual causes and they are told apart by how fast it falls. A slow drop over weeks is normally a buried leak. A drop that only happens when the heating runs is usually an expansion vessel that has lost its air charge. A drop with water discharging from a pipe outside is the pressure relief valve passing.
Where there is still a cylinder, heating that works and hot water that does not points at the cylinder side: the motorised valve that diverts flow to the tank, the cylinder thermostat, or the immersion element. Each costs a fraction of a new appliance.
An unvented cylinder is a pressurised store, so working on one is notifiable and needs a G3 qualification on top of Gas Safe registration. Plenty of firms hold one and not the other, which is why a cylinder call so often becomes two visits. Our engineers hold both, so it is one visit and one charge. See unvented cylinder repair.
The one thing a yearly visit genuinely prevents.
London water comes off the Thames and the Lea, both of which run through chalk. It measures roughly 277 milligrams of calcium carbonate per litre, and that figure is much the same across the city.
Where it lands is what differs. In a combi it furs the plate heat exchanger and the hot water goes lukewarm. In a Balham terrace with buried pipework it does something quieter: every top-up after a leak brings fresh oxygenated water into the system, and that is what turns scale and magnetite into a blocked exchanger and a seized pump.
Age does not decide it. The failed part does.
A pump, a diverter valve, a thermostat or a fan is a repair on almost any appliance, whatever its age. A failed main heat exchanger on a boiler well past ten years is the point where the arithmetic stops working, and we will tell you that rather than sell you the repair.
Where the pressure has been falling for months, a replacement fixes nothing. A new boiler on a system with a buried leak will lock out on low pressure exactly as the old one did, and its warranty will very likely not cover it. Finding the leak first is not an upsell, it is the only order that works.
Our boiler replacement page sets out what a replacement actually involves, including what changes when a stored system is converted, and the costs guide explains what moves the figure.
That answer costs nothing. It is the one most people ring us for. Call 0203 868 6134.
Next door to here we cover Clapham and Battersea and Crystal Palace. Everything else is on boiler repair in south London and areas we cover.
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.
Topping the pressure up every week?
That is a leak, an expansion vessel or a discharging valve, and topping up hides which. Tell us how fast it falls and we can usually narrow it to one before anybody attends.
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.
Yes. The names listed above are the ones we hear most, and they are nowhere near a complete list. We work right across London, north and south of the river. Ring and tell us the address and you will get a straight answer about timing.
Because topping up treats the symptom. There are three usual causes and the rate tells them apart. A slow fall over weeks is normally a leak, often in pipework buried under a solid extension floor where there is nothing to see. A fall only when the heating runs is usually the expansion vessel. A fall with water outside is the pressure relief valve passing.
Yes, and in these houses it usually is. Pipework buried in screed under a concrete extension floor can weep for months without showing anything at all, because the water goes into the ground rather than into the room. It is traceable, and it is a pipework repair rather than a boiler one.
Yes. Every top-up brings fresh oxygenated water into a system designed to be sealed, and oxygen is what corrodes radiators and produces the magnetite that blocks heat exchangers and seizes pumps. A system needing more than about two top-ups a year is losing water and should be traced.
Almost certainly not. In a house with a cylinder that points at the cylinder side: the motorised valve that diverts to the tank, the cylinder thermostat, or the immersion element. All three cost a fraction of an appliance. Our unvented cylinder repair page explains what is involved.
Yes, and every other major make, including the ones most firms will not touch. Those two are what we open most in SW12. Vokera, Biasi, ATAG, Keston, Ravenheat and Heatline all turn up here as well. If your boiler is showing a fault code, the brand pages explain what it means for your make.
Yes, and on the same visit where the appliance passes, so a let property is not off the market twice. See landlord gas safety certificates. If it has no gas supply we cover electric boilers as well.
The line is answered 24 hours a day by a technical customer service member, not a call centre reading from a script. If the boiler has locked out on low pressure we will talk you through checking the gauge before anybody sets off, because sometimes that is all it needs until morning.
Every major make, and the fault code pages often name the part before you ring.
These terraces mostly run combis, sized to fit a kitchen cupboard in the extension, so Worcester Bosch, Vaillant and Ideal are what we open most, with Baxi common on anything swapped a decade or more ago. The larger houses off Nightingale Lane still keep a cylinder.
We also work on the makes most firms will not. Vokera, Biasi, ATAG, Keston, Ravenheat and Heatline all turn up here, and parts for every one of them are still obtainable.
If your boiler is showing a code, the make decides what it means. Low pressure shows as a different code on each make, and on all of them it is a symptom rather than a fault. Each brand page lists the codes for that make and what actually causes them.
The full list is on our boiler brands page, and general repairs are on boiler repair in London.
Tell us where you are and whether there is a cylinder in an airing cupboard. With those two answers we can usually name the likely part, give you the rate, and book somebody in, all on the one call.
Gas Safe registered. Unvented cylinder qualified. Parts guaranteed for a year. Covering London, north and south of the river, 24 hours a day.
