Unvented Hot Water Cylinders
Unvented hot water cylinderinstallation and servicing
Mains-pressure hot water to every outlet, installed and serviced to G3 requirements across the West Sussex coast.
An unvented cylinder gives you mains-pressure hot water at every tap and shower without a loft tank, which is why most larger homes with more than one bathroom end up with one. It is also a pressurised system, which is why the work is notifiable and why it has to be serviced annually.
The parts that matter are the ones nobody sees: the expansion vessel, the pressure reducing valve, the temperature and pressure relief valve, and the discharge pipe run. Get any of those wrong and the cylinder either underperforms or discharges water across your landing.
We install, service and repair unvented cylinders, and we check the incoming mains flow rate before recommending one, because a cylinder fed by a weak supply will refill slowly no matter how large it is.
What’s included
- Mains flow rate and pressure testing before specifying a cylinder
- Cylinder sizing based on actual bathroom count and usage, not a rule of thumb
- Full installation including expansion vessel, PRV, tundish and discharge pipework
- Discharge routed and terminated to G3 requirements
- Building control notification and certification
- Annual servicing including expansion vessel recharge and valve testing
- Immersion heater, thermostat and control repairs
- Fault diagnosis on discharging or underperforming cylinders
What this covers
Everything that falls under unvented cylinders
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New cylinder installation
Replacing a vented cylinder and loft tank with a mains-pressure unvented system, including removal of the old tanks.
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Cylinder replacement
Like-for-like swaps where an existing unvented cylinder has failed or corroded.
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Annual servicing
Expansion vessel pressure checked and recharged, all safety valves tested, immersion and thermostat checked, and the service recorded in the benchmark log.
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Discharging cylinder repairs
Water running from the tundish almost always means a failed expansion vessel or a failed pressure reducing valve, both of which are fixable.
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Immersion heaters
Replacement immersions and thermostats, useful as a backup even where the cylinder is heated by the boiler.
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Poor hot water performance
Diagnosis where an existing cylinder is not delivering the flow or the recovery time it should.
How it works
How a unvented cylinder job runs with us
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Get in touch
Call or send a few details and photos. We will tell you straight away if it is something we cover and roughly what is involved.
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Free site visit and written quote
We come out, measure up, talk through what you actually want, and put a fixed price in writing. No pressure and no sales visit.
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Booked in and delivered
An agreed start date, materials ordered ahead, and the same team on site from the first day to the last.
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Signed off and guaranteed
Everything tested and commissioned, certificates issued, the site left clean, and your workmanship guarantee confirmed in writing.
Unvented Cylinders questions
What people ask about unvented cylinders
Because the expansion vessel slowly loses its air charge. When it does, the system has nowhere to expand into and starts discharging hot water through the tundish, which is both wasteful and a sign the safety devices are doing work they should not routinely have to do. An annual service recharges the vessel and tests the valves. It also keeps most manufacturer warranties valid.
It is the tundish discharge, and it means a safety valve has opened. It is not an emergency in the sense that the cylinder is about to fail, but it should not be happening and it will be costing you hot water. It is usually a flat expansion vessel or a failed pressure reducing valve.
Yes. Unvented cylinder installation is notifiable work under Part G. We are G3 qualified and notify it as part of the job, and you get the certificate.
It depends on bathroom count and how they are used rather than on the number of bedrooms. As a broad guide, a two-bathroom family home is usually in the 180 to 210 litre range, and three bathrooms with simultaneous use pushes toward 250 to 300. We check the incoming mains flow rate too, because that governs how fast it refills.
Often yes, but the discharge pipe is the deciding factor. It has to terminate safely and visibly, which is straightforward at ground level and can be awkward several floors up. We check the discharge route before quoting.
Still have a question? Call 07769 266111
Unvented Cylinders across Lancing, Sompting, Worthing, Goring-by-Sea, Ferring, East Preston, Angmering, Rustington, Littlehampton, and the wider coast from Brighton to Chichester.
Related services
Free quote
Get a free quote for your unvented cylinder
Tell us what you need and we’ll call to discuss the next step. For planned work, we’ll arrange a visit and put your quote in writing.
Free quotes for planned work. Repair and diagnostic charges are agreed before a visit.
Monday to Friday 7.30am to 6pm, Saturday mornings 8am to 1pm. Emergency callouts outside these hours by arrangement.
We answer or return every enquiry the same working day.
Covering Brighton to Chichester, with most work between Lancing and Littlehampton
