Who you are calling

G3 Engineer London is a London plumbing firm built around the part of the system most people never think about until the morning it stops. Cylinders, immersion heaters, thermal stores, the valves and expansion vessels around them, and the leaks that come with all of it. Burst pipes, bathrooms, mains supply and boiler work sit alongside that, because a property does not divide its faults neatly, but hot water is what the firm is organised around and it is the work we are strongest on.

We cover every London borough. That is a statement about where we work rather than a promise about how quickly anyone arrives, and the rest of this page is written the same way.

Why hot water, and why that decides everything else

Hot water is the least well served corner of domestic plumbing in London. Most plumbers are competent on a tap, a radiator or a toilet. Far fewer are comfortable standing in front of an unvented cylinder working out whether the expansion vessel has lost its air charge, whether the temperature and pressure relief valve is discharging because of a genuine overpressure or because its seat is scaled, or whether the immersion element has furred to the point where it heats the limescale and not the water.

The symptom that brings most people to us is heating that works while the taps run cold, and that one points away from the boiler almost every time. On a stored system it is usually the cylinder thermostat, a motorised valve stuck mid travel or a coil that has silted. On a combi it is the diverter. Knowing which before anyone opens anything is most of the job.

London makes it harder than the textbook. The supply is hard across almost the whole of the capital, so scale is a live factor in every stored system here in a way it is not in a soft water region. Purpose built blocks are full of Pulsacoil and similar thermal stores, which behave nothing like a cylinder and fail in their own way. Victorian conversions have pipework buried in solid walls and running under boarded floors, often through a neighbour. New builds put liquid screed over underfloor heating, which changes what a repair looks like before you have even found the leak.

20 engineers, and what that changes

We are 20 engineers spread across the boroughs rather than a call centre taking a booking and selling it on to whoever answers. The practical difference is that the engineer nearest the work takes the work, and the person who quotes you is the person who does it.

It matters most on a second visit. Some jobs cannot be finished first time: a manufacturer specific expansion vessel, a control board for a thermal store or a cylinder in an obsolete size is ordered, not carried. A single van operation has to fit that return around everything it has already committed to, which is how a small job becomes a long wait. With a team this size the return is scheduled work for somebody, and the engineer who comes back already knows the property and the pipe runs.

What qualification actually matters on an unvented cylinder

An unvented cylinder stores hot water at mains pressure. That is what gives a decent shower without a pump, and it is also what makes it the one item of domestic plumbing that can injure somebody if its safety devices are defeated in the wrong order. The expansion vessel, the pressure reducing valve, the temperature and pressure relief valve and the thermal cut out are layered protection. Each exists because the one before it might fail.

For that reason the installation of an unvented hot water storage system is notifiable work under the Building Regulations, and the person doing it is expected to hold the specific unvented hot water storage qualification on top of a general plumbing ticket. Using somebody who does not hold it is a legal problem and a safety one. The work goes unnotified, which surfaces at the point of sale or at the point of a claim, and the fitter has not been taught what the devices are for.

The shortcut we are called out to undo most often is a relief valve that has been capped, wedged or swapped for a higher rated one because it kept weeping. The weeping was the system telling somebody the expansion vessel had lost its charge. Removing the last line of defence is not a repair. Recharging or replacing the vessel is, and it is usually a short visit.

Ask any firm to confirm they hold the unvented qualification before they touch your cylinder. That includes us. If a plumber is vague about it, that is your answer.

We do the repair and we put the building back

A good part of the leak detection market in London sells you a survey. You get a report, a photograph of a thermal image, a marked spot on the floor and an invoice, and then you need a second trade to actually open it up and a third to make it good. Three appointments, three sets of scheduling, and nobody owning the outcome.

We trace it, we repair it, and the floor, wall or ceiling goes back. Where the pipe run allows it we would rather repair without digging than chase out a screed we then have to reinstate, and where opening up is unavoidable, making good is part of the job rather than a separate conversation afterwards. On a screeded floor over underfloor heating that distinction is not cosmetic: cutting into the slab without knowing where the circuits run turns one leak into two.

Why the rate is on the website

£150 per hour and a £50 call-out, both published on the pricing page rather than worked out on your doorstep once the engineer has seen the postcode and the state of you. The rate is fixed before we attend and does not rise for a difficult property, an awkward access or an evening visit. The total depends on how long the job takes; the rate cannot change.

Leak detection and general plumbing both carry the same £50 call-out. Cylinder replacement and anything running beyond a day is quoted as a job rather than by the hour, so the figure is in front of you before anything is ordered. If the work turns out bigger than it looked from the front door, you hear that while there is still a decision to make, not on the invoice.

We are new and we have no reviews yet

This is a new trading name. You will not find a star rating on this site, a review count, a badge claiming decades of experience or a wall of first names. We have not earned any of that yet, and writing it ourselves would be worth nothing to you.

When reviews exist they will come from a verified public profile that you can open and read yourself, with the work still attached to a real job. Until then, the things you can actually judge us on are the ones on this page: the rate is published before you call, the method is described rather than implied, and the qualification question is put in front of you with the instruction to ask us about it.

What we will tell you not to spend money on

A new cylinder, when the vessel has lost its charge and can be recharged, or an external expansion vessel can be fitted for a fraction of a replacement. A new boiler, when the boiler is firing correctly and the fault is a cylinder thermostat, a seized motorised valve or a diverter. A repipe, when a single compression joint under a floor has let go and the rest of the run is sound. A leak detection survey, when the water is arriving from something visible in the airing cupboard and an engineer can see it in the first few minutes.

Some of the faults on this site you can clear yourself without paying anybody: a programmer knocked onto the wrong schedule, an immersion switched off at its isolator during a decoration job, a boiler sitting on a lockout that needs one reset. We say so on the page rather than sell a visit, because the small honest job is how a plumbing firm ends up being the number somebody keeps.