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Heating engineer showing a radiator thermal check to a woman homeowner

SE26 SE23

Boiler Repair in Sydenham and Forest Hill

Gas Safe engineers across SE23 and SE26, 24 hours a day.

Call 0203 868 6134

Answered 24 hours a day by a technical customer service member.

In a tall narrow house the radiator furthest from the pump is the one that never gets hot, and that is a balancing problem.

  • Gas Safe registered engineers
  • An engineer as soon as we can, booked around you
  • Cylinder and unvented systems as well as combis
  • Parts guaranteed for a year, rates agreed before work starts

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.

Google Reviews
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    Day Walker

  • "Engineer excellent and very time efficient."

    Fiona G.

  • "Very professional and would recommend to anyone!"

    Abby M.

Prefer we call you? Request a call back

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.

No obligation. If you have a cylinder we tell you whether it is the boiler or the cylinder before any work is agreed.

We use your details only to respond to your enquiry. See our privacy policy.

We cover Sydenham, and the whole of London

Tell us the address and you will get an honest answer about timing.

View areas we cover

What happens when you call

Three steps. The first one usually tells us most of it.

  1. Tell us where you are and whether there is a cylinderIn SE23 and SE26 many houses still have one. The other useful answer is which radiators are cold, because in a tall house that is usually a distribution problem rather than a fault.
  2. You will know what has probably failed, and when we can comeWe tell you the likely part and a realistic slot. If we cannot reach you today we say so on the phone, rather than after you have waited in.
  3. Nothing starts until you have agreed the costThe engineer runs a full diagnostic, then puts the fault, the part and the labour in writing. Parts are guaranteed for a year.

If a repair is not worth doing, we will say so on the phone. Call 0203 868 6134.

We come to every street around here

Almost nobody says they live in SE26. They say Upper Sydenham, or Kirkdale, or Perry Vale.

Names we hear on SE23 and SE26 calls, and the postcodes around them

Grouped by postcode, because that is the one part of an address everybody knows.

  • SE26Sydenham, Upper Sydenham, Lower Sydenham, Kirkdale and Bell Green
  • SE23Forest Hill, Honor Oak Park, Perry Vale and Devonshire Road
  • SE4Crofton Park and Brockley
  • SE6Catford and Bellingham
  • SE20Penge and Anerley

We work right across London, north and south of the river. If yours is not here, ring and tell us the address.

ASAP Boiler Repairs engineer bleeding a domestic radiator

Tall, narrow, and a long way from the pump to the top

Which is a distribution problem, not a boiler one.

Sydenham and Forest Hill are built up the side of a hill, and the housing is tall Victorian: three and four storeys on narrow plots, many with a lower ground kitchen and bedrooms right up under the roof. That shape produces long pipe runs, and long pipe runs produce a specific and very common complaint.

Water takes the easiest route. The radiators nearest the pump have the least resistance, so they take the most flow, and the one furthest away, the index radiator, takes what is left. In a four storey house that is usually a top floor bedroom, and it is the room that has never been properly warm since anybody can remember.

That is a balancing problem. It is solved with the lockshield valves, the pump setting and sometimes a bypass, not with a bigger appliance. A new boiler on an unbalanced system heats the same rooms and leaves the same one cold, which is why this complaint survives so many replacements.

Did you know

A radiator that is hot at the top and cold at the bottom is sludge. A radiator that is cold all over while its neighbours are hot is balancing. They look like the same complaint and they are two completely different jobs.

Heating fine, hot water gone

The commonest call from SE26, and it is rarely the boiler.

On a stored system, heating that works and hot water that does not points at the cylinder side. Three usual culprits: the motorised valve that diverts flow to the tank, the cylinder thermostat, and the immersion element. Each costs a fraction of a new appliance and each gets mistaken for one.

In a house this tall the secondary circuit is the other candidate. A pump keeps hot water standing ready at the top so the furthest tap does not wait, and when that pump gives up the top floor runs cold while the lower ground kitchen stays perfect.

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.

Water running from a pipe outside? If it comes from a tundish, the cylinder is discharging and a safety device has failed. Turn the boiler off, isolate the cold feed if you can find the stopcock, and call. That is an emergency, not a booking for next week.

What hard water is doing to your boiler

And to the far end of a long circuit first.

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. In a tall Sydenham house it does something else too: scale and magnetite settle where flow is slowest, which is the far end of a long circuit. So the index radiator that was already the weakest is the first to silt up, and the complaint gets steadily worse rather than staying still.

Two parts stop it, and they do different jobs. A scale reducer on the mains protects the hot water side. A magnetic filter on the return catches the magnetite that blocks exchangers and seizes pumps. Both go in during a yearly service, and a power flush deals with what is already in there.
Google Reviews
  • "Very happy with this company very and professionally service. Fixed my leaking TRV and after draining my system and the refilled and vented the air . Thank you I have heating now"

    Jamie K.

  • "Efficient and amiable service all round. Even managed to save me money by fixing a thermostat that we thought was broken."

    Graziano B.

  • "Steve was very helpful and responsive"

    Richard E.

Heating engineer making a final radiator adjustment while a family relaxes nearby

Repair or replace

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.

If one room has never been warm, a replacement will not change it. Balancing, the pump setting and the state of the far end of the circuit decide what that room gets, and none of those improves because the appliance is new. Getting the system right first is cheaper and it is the only way to know whether the boiler was ever the problem.

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.

Nearby areas

Next door to here we cover Blackheath and Greenwich and Dulwich. 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.

One radiator that has never worked?

In a four storey house that is almost always the index radiator, starved by the ones nearer the pump. Rebalancing fixes it, and it is not a boiler job.

Call 0203 868 6134
Safety

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.

Common questions

Do you cover my street in Sydenham?

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.

One bedroom has never been warm. Is the boiler too small?

Usually not. In a tall house the radiator furthest from the pump takes whatever flow the others leave it, and that is almost always a top floor room. It is a balancing problem, solved with the lockshield valves and the pump setting. A bigger appliance heats the same rooms and leaves the same one cold.

What is the difference between a radiator that is cold at the bottom and one that is cold all over?

Cold at the bottom with a hot top is sludge settled inside it, and that is a flushing job. Cold all over while its neighbours are hot is balancing, and that is a valve and pump job. They sound like the same complaint and they are two different repairs.

My radiators are hot but there is no hot water. Do I need a new boiler?

Almost certainly not. 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.

Will a power flush fix a room that has never been warm?

Only if the cause is sludge. A power flush clears what has settled in the system, but if the room was cold from the day it was plumbed the problem is distribution rather than debris, and flushing changes nothing. It is worth establishing which before spending on either.

Do you repair Worcester Bosch and Vaillant boilers in Sydenham?

Yes, and every other major make, including the ones most firms will not touch. Those two are what we open most in SE23 and SE26. Glow-worm and Potterton are common on the older installations, and Alpha, Main and Ariston turn up in the flats. If your boiler is showing a fault code, the brand pages explain what it means.

I am a landlord with a flat in SE23. Can you do the certificate too?

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.

Are you available at night and at weekends?

The line is answered 24 hours a day by a technical customer service member, not a call centre reading from a script. In the middle of the night we will tell you honestly whether it is a tonight job or a first thing in the morning job.

The makes we see most in SE26

Every major make, and the fault code pages often name the part before you ring.

The whole houses that kept a cylinder run system boilers, and here that is mostly Worcester Bosch, Vaillant and Glow-worm, with Potterton still on older installations. The conversions run combis, where Ideal and Viessmann are common.

We also work on the makes most firms will not. Alpha, Main and Ariston all turn up in the flats and smaller conversions, and parts for every one of them are still obtainable.

If your boiler is showing a code, the make decides what it means. A Vaillant F75 and a Glow-worm F1 are different faults with different fixes, and neither of them on its own means a new boiler. 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.

Google Reviews
  • "He was very professional tidy and polite. Would recommend!"

    Anna M.

  • "Took his time to listen to my concerns hence it was a nice job. Thank u so much"

    Frank E.

  • "Very polite and respectable engineer...had two other heating company that struggle to find the issue with my boiler but ASAP repaired it on the same day thanks absolute life saver"

    JA Morris

Book an engineer in Sydenham

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.

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