Unvented cylinders, East London & Essex
G3-certified install,
service & replacement —
mains-pressure hot water, properly commissioned
Megaflo, Telford, Heatrae Sadia, Joule and Vaillant, sized to your incoming main, installed cleanly, annually serviced and properly certificated. The hot-water system the rest of your house is waiting for.
What it covers
Unvented hot water, installation, like-for-like replacement and annual servicing
Unvented cylinders are the single biggest hot-water upgrade most homes can make. No loft tank, no header tank, no air locks in the bedroom showers, just mains-pressure hot water at every outlet, simultaneously, for the whole family. The catch is that they're a notifiable G3 install and a real safety system: get them wrong and the consequences are serious.
We install, replace and annually service unvented cylinders across East London and Essex. Megaflo, Telford Tempest, Heatrae Sadia, Joule and the Vaillant uniSTOR are all routine for us. Every install is preceded by a flow and pressure test on the incoming main, there's no point fitting a 250-litre cylinder to a property that can't supply it.
Annual servicing is a G3 requirement to keep most manufacturer warranties valid. We test the temperature & pressure relief valve, the expansion vessel charge, the inlet group, the immersion (where fitted) and the cylinder itself, then issue a dated certificate for your home file and your home insurer.
What happens if you wait
An unvented cylinder is a pressure vessel, get it wrong and the consequences are real
Unvented cylinders store hot water at mains pressure. Without correctly functioning safety controls, temperature relief, pressure relief, expansion vessel, the consequences of a failure are severe. This is why G3 qualification, proper commissioning and annual servicing aren't optional.
Manufacturer warranties on unvented cylinders are usually void without documented annual G3 servicing. Home insurers increasingly insist on the same.
An unvented cylinder without working safety controls is a pressure vessel that has failed catastrophically in real-world cases, ceilings, walls and worse.
A constantly dripping tundish is a sign of failed expansion vessel or PRV, usually leads to water damage in the airing cupboard within months.
Common mistakes we fix every week
- Letting an unqualified plumber install or service an unvented cylinder.
- Skipping annual service because 'it seems fine'.
- Ignoring a slow drip from the tundish.
- Fitting an oversized cylinder onto a poor incoming main.
- Reusing old immersion heaters without testing them.
- Not registering the install with Building Control.
Our process
A predictable, step-by-step system, no surprises, no upsells
- STEP 01Mains test & survey
Flow and pressure tested at the incoming main; airing-cupboard space measured; system layout planned.
- STEP 02Spec & quote
Cylinder size, brand and warranty options presented in writing, fixed price.
- STEP 03Install
Full G3 install, cylinder, expansion vessel, PRV, T&P valve, tundish, balanced cold feed and immersion (if specified).
- STEP 04Commission & certify
Commissioning checks, Benchmark/G3 certificate completed, Building Control notified.
- STEP 05Annual service plan
First annual service scheduled before we leave; reminders sent direct.
What you get
Concrete outcomes, not vague promises
Notifiable work registered with Building Control on your behalf; certificate issued.
Cylinder volume and recovery sized to family usage, no point fitting 300L if the incoming main can't supply it.
Keeps the manufacturer warranty valid and gives you documented compliance for your home insurer.
Megaflo, Heatrae Sadia, Telford, Joule, Vaillant, all installed with manufacturer warranty registered.
Failed cylinder replaced fast where stock allows, usually under 6 hours' downtime.
Workmanship guarantee on the install and the service.
Technical detail
Everything you need to know about unvented cylinders
An unvented cylinder isn't just a hot-water tank, it's a regulated, notifiable installation with specific safety devices that have to be sized, fitted and commissioned correctly. Here's how it all fits together.
Sizing the cylinder
Cylinder size depends on family size, simultaneous demand and the recovery rate of the heat source. A 250L cylinder serves a family of four comfortably with a typical system heat source; larger families and multiple-shower homes typically need 300L or more. We size by talking through your actual usage, not by bedroom count.
Incoming mains, flow and pressure
Unvented systems deliver mains-pressure hot water, but only if the mains can supply it. A cylinder rated for 3 bar @ 25 litres/minute is useless on a poor incoming main delivering 1.5 bar @ 10 lpm. We test flow and pressure at the meter before quoting, and if the main is the problem, we'll quote a mains upgrade as a separate option.
- Static pressure test (everything off)
- Dynamic flow test (kitchen cold tap open)
- Recovery test (close down and re-measure)
- Recommend mains upgrade where required
Safety controls, PRV, T&P, expansion vessel
Three layers of safety: a pressure-reducing valve at the inlet, a temperature & pressure relief valve on the cylinder, and an expansion vessel to absorb the volume change as water heats. All three are checked at install and again at every annual service, silent failures (a flat expansion vessel, a stuck PRV) are the most common reason a working-looking cylinder eventually leaks at the tundish.
Annual G3 service, what's involved
Annual service is required by most manufacturers to keep the warranty valid. We test the T&P valve, the PRV, recharge the expansion vessel to correct pressure, check the tundish for evidence of past discharge, test the immersion heater, and check the cylinder itself for any sign of fatigue. A dated certificate is issued for your home file.
Frequently asked
Straight answers to the questions East London & Essex homeowners ask us most
What does an unvented cylinder install cost?+
Installs are quoted after a flow and pressure test on the incoming main, typical 200–250L family installs sit in a clear price band including cylinder, all controls, immersion, commissioning and Building Control notification.
How long does a like-for-like cylinder swap take?+
Usually a single day, with hot water back on the same evening. Larger or first-time installs (different position, new pipework, new immersion circuit) run two days.
How often does it need servicing?+
Annually, required to keep the manufacturer warranty valid. We send reminders and book direct.
What brands do you install?+
Megaflo (Heatrae Sadia), Telford Tempest, Joule, Vaillant uniSTOR and the major manufacturers. All come with manufacturer warranty registered on your behalf.
What size cylinder do I need?+
Depends on family size, peak demand and the heat source. Typical 4-person family is 200–250L; larger or multi-bathroom homes 300L+. We'll size on the survey.
Is my mains good enough for an unvented system?+
We test before quoting. If the mains is below the minimum required by the cylinder, we'll quote a mains upgrade alongside, or recommend an alternative.
What's a tundish and why is mine dripping?+
The tundish is an air-break under the T&P valve so any discharge is visible. A constant drip means the safety system is discharging, usually a failed expansion vessel or PRV. Get it serviced before it floods the airing cupboard.
Do you need to notify Building Control?+
Yes, unvented installs are notifiable G3 work. We register the install with the relevant scheme and you receive the certificate.
Can you fit an immersion as backup?+
Yes, and we recommend it on most installs. Gives you hot water if the primary heat source ever fails.
Is there a workmanship guarantee?+
Yes, on every install and service. Plus full manufacturer warranty on the cylinder.
Related services
Mains-pressure hot water, done properly.
G3-qualified install, service and certification across East London and Essex.
Fully insured · Workmanship guarantee · 7 days a week