Unvented cylinders
Hot water stored at mains pressure with no tank in the loft, so showers are strong and two taps can run at once. Needs a G3 qualified engineer to fit and service.
G3 unvented qualified · Gas Safe registered
Water heater repair and installation across London.
Vented and unvented cylinders, direct and indirect systems, and instantaneous water heaters, repaired, serviced and installed by G3 unvented qualified engineers.
- G3 unvented qualified engineers
- No hot water? We answer 24 hours a day
- Price agreed before any work starts
- Megaflo, Heatrae Sadia, Gledhill, Joule, Ariston and more
- Gas Safe registeredCheck us on the register
- 24 hours a dayNights, weekends, bank holidays
- All of LondonEvery borough covered
- A limited companyRegistered in England & Wales
Why call EcoBuild for your hot water
G3 qualified
Unvented cylinders run at mains pressure, so the law says only a G3 qualified engineer can fit or work on the safety controls. Ours are.
24 hours a day
No hot water, or water coming out of the tundish? We answer nights, weekends and bank holidays.
Every type
Vented and unvented, direct and indirect, electric and gas, instantaneous and under-sink. One engineer for all of it.
Clear pricing
We find the fault, tell you what it needs and what it costs, and only then start work.
Paperwork done
Benchmark checklist completed, Building Control notified and your warranty registered with the manufacturer.
Left clean
Floors protected, old cylinders and tanks taken away, and every joint tested before we leave.
Water heaters we install and repair
Not sure which you have? Send us a photo on WhatsApp and we will tell you.
Vented cylinders
The traditional setup: a cold water tank in the loft feeds a cylinder in the airing cupboard. Simple and reliable, but pressure depends on how high the tank is.
Direct cylinders
Heated by electric immersion elements inside the cylinder, with no boiler involved. Common in flats and homes on Economy 7.
Indirect cylinders
Heated by a coil carrying hot water from your boiler or heat pump, usually with an immersion heater as backup. Controlled by a cylinder thermostat and motorised valve.
Instantaneous water heaters
Heat water as it flows, electric or gas, so there is no stored hot water to run out and no cylinder to find space for.
Under-sink and point-of-use
Small heaters fitted right where the hot water is used, such as a kitchen, cloakroom or office, so you do not wait for it to arrive from across the house.
G3 unvented qualified engineers
An unvented cylinder holds a large volume of very hot water under mains pressure. The safety controls are what stop that turning dangerous, so Part G3 of the Building Regulations says only a qualified, competent person can install one or work on it.
Our engineers hold the G3 unvented qualification. When we fit or service your cylinder, the controls are set up and tested as the manufacturer requires, the installation is notified to Building Control, and the Benchmark checklist is completed so your warranty stays valid.
- Temperature and pressure relief valve
- Expansion vessel sized and charged correctly
- Pressure reducing valve and inlet strainer
- Tundish and discharge pipe run to regulations
- Overheat thermostats and cut-outs tested
Water heater repairs
Most hot water faults come down to one part: a thermostat, an immersion element, a valve or a vessel. We find which one and replace it, rather than selling you a new cylinder you do not need.
No hot water
We work back from the cylinder to find the cause, whether it is the cylinder thermostat, the motorised valve, the programmer or the boiler itself.
- Cylinder thermostats
- Motorised valves and actuators
- Programmers and wiring centres
Water from the tundish
Water running through the tundish means a safety valve is opening. Usually the expansion vessel has lost its charge or a relief valve is worn. It needs a G3 engineer.
- Expansion vessels recharged or replaced
- Relief and T&P valves
- Pressure reducing valves
Immersion heaters
Lukewarm water, a tripping electric supply or no heat at all on a direct cylinder. Elements and thermostats tested and replaced with the right part for your make.
- Elements and thermostats
- Overheat cut-outs reset or replaced
- Tripping supplies traced
Gas water heaters
Pilot lights that will not stay lit, burners that fail to fire, and poor combustion on gas-fired storage and instantaneous heaters. Worked on by our Gas Safe registered engineers.
- Thermocouples and pilot assemblies
- Gas valves and burners
- Flue and combustion checks
We also repair
- Leaking cylinders, fittings and valves
- Low hot water pressure
- Water too hot or not hot enough
- Noisy cylinders and banging pipes
- Discoloured or smelly hot water
- Hot water running out too quickly
- Secondary return pumps
- Loft tanks and ball valves on vented systems
Hot water pouring from the tundish?
A safety valve is opening. Do this, then call us.
- Turn off the heatSwitch off the immersion heater and the boiler’s hot water, or turn the boiler off completely.
- Do not touch the pipeThe water coming out of the discharge pipe can be close to boiling.
- Leave the cold onUnless water is escaping somewhere it should not. Then turn off the stopcock.
- Call us, 24/7079 1616 8585, any time, anywhere in London.
Water heater installation
Sized for how many people live in the house and how many bathrooms you have, fitted neatly and handed over with the paperwork.
New unvented cylinders
Mains-pressure hot water to every tap and shower. We check your incoming water pressure and flow first, because an unvented cylinder is only as good as the mains feeding it.
- Mains pressure and flow tested first
- Direct, indirect and heat pump ready
- Commissioned and Benchmark signed
Vented to unvented upgrades
Swap the airing cupboard cylinder and loft tank for an unvented system. Stronger showers, no tank in the loft to freeze or leak, and the space back.
- Loft tanks removed
- Pipework upgraded where needed
- Discharge pipe run to regulations
Like-for-like replacements
When a vented cylinder is past saving, a new one goes in on the same connections, usually in a day, with the old one taken away.
- Copper and foam-lagged cylinders
- Direct and indirect
- Old cylinder removed
Instantaneous and under-sink heaters
For a kitchen at the far end of the house, an office, a cloakroom or a garden room. Small, quick to fit, and hot water in seconds.
- Under-sink unvented heaters
- Electric instantaneous heaters
- Gas multipoint heaters
We can also fit
- Heat pump and solar ready cylinders
- Horizontal cylinders for lofts
- Secondary return circuits
- Commercial gas-fired water heaters
More cylinder work
Swipe or use the arrows.
Annual unvented cylinder service
Manufacturers require a yearly service by a G3 qualified engineer to keep the warranty valid, and it is what keeps the safety controls working.
Safety valves tested
The temperature and pressure relief valve and the expansion relief valve are manually operated to prove they open and reseat cleanly.
Expansion vessel checked
The air charge is measured and topped up. A flat vessel is the most common reason water ends up in the tundish.
Inlet group cleaned
The strainer is cleaned and the pressure reducing valve checked, so the cylinder sees the pressure it was designed for.
Controls and paperwork
Thermostats, cut-outs and the discharge pipe checked, then the Benchmark service record filled in and signed.
Water heater brands we install and repair
Including Megaflo, Tempest, Ultraflow and ThermaQ, alongside the makes below.
What affects the price
We look at the problem, tell you what it needs and what it will cost, and only then start work.
| What we look at | Why it changes the cost |
|---|---|
| Repair or replace | Most faults are a single part. A leaking cylinder body, or one old enough that parts are no longer made, is usually better replaced. |
| Vented or unvented | Unvented work needs a G3 engineer and more safety components. Converting from vented also means removing loft tanks and running a discharge pipe. |
| Cylinder size | A larger cylinder costs more, but one too small for the household runs out. We size it to how many people and bathrooms you have. |
| Access | A cylinder in an open airing cupboard is quick. One boxed in, in a loft or behind kitchen units takes longer. |
| Pipework | Old or undersized pipework may need upgrading to get the full benefit of mains pressure. |
Common questions
What is the difference between vented and unvented?
A vented cylinder is fed by a cold water tank in the loft, so its pressure depends on gravity. An unvented cylinder is fed straight from the mains, so it delivers mains pressure to every tap, with no loft tank. Unvented systems need extra safety controls and a G3 qualified engineer.
What does G3 qualified mean?
It is the qualification an engineer needs to install and maintain unvented hot water systems under Part G3 of the Building Regulations. Always ask to see it before letting anyone work on an unvented cylinder.
Direct or indirect: which do I need?
If you have a gas boiler or a heat pump, an indirect cylinder heated by it is usually the cheapest to run. If you have no boiler, or you are on an electric tariff like Economy 7, a direct cylinder heated by immersion elements makes more sense.
Is my water pressure good enough for an unvented cylinder?
Most London homes are, but not all. We test your incoming pressure and flow rate before recommending one. If the mains is weak, we will tell you rather than fit something that disappoints.
How long does a cylinder installation take?
A like-for-like swap is usually one day. Converting from vented to unvented is normally one to two days, depending on the pipework and where the discharge pipe has to run.
How often should an unvented cylinder be serviced?
Once a year. Manufacturers make it a condition of the warranty, and it is the only way to know the safety valves and expansion vessel are still working.
Related services
One number, every London borough, 24 hours a day. Call 079 1616 8585 or message us on WhatsApp.
No hot water?
Cylinder, immersion, tundish or a new water heater. Call us any time, day or night, anywhere in London.
Call 079 1616 8585
