Home › Installations › Unvented Hot Water Cylinders Wokingham
Unvented cylinder installation, service & repair across Wokingham · Earley · Woodley · Finchampstead · Arborfield · Crowthorne · RG40 · RG41
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G3 Qualified · Wokingham · Gas Safe 599015

Unvented Hot Water Cylinder
Installation, Service & Repair

G3 qualified · Mains-pressure hot water · Wokingham & RG40 · Installation from £1,200

Unvented cylinders deliver mains-pressure hot water to every tap and shower simultaneously — no loft tanks, no pressure issues, no waiting. Thermotec’s Stuart Mundy is G3 qualified — a legal requirement for all unvented cylinder work — with 20+ years experience across Wokingham and RG40.

Book Online 24/7 Call 07850 116944
G3 Qualified
Legally required
for this work
From £1,200
Installation
fixed price
120+
5★ Google
reviews
Gas Safe
Reg. 599015
verified
G3
G3 Qualified Engineer
Building Regs Part G · Legally required
Legal requirement
It is illegal for an unqualified engineer to install, service or repair an unvented cylinder. G3 qualification is separate from Gas Safe registration. Always verify your engineer holds G3 before booking.
✓G3 qualified — legally compliant installation & servicing
✓Building Regulations notification included
✓All safety components correctly installed & tested
✓Full compliance documentation on the day
✓Gas Safe Reg. 599015 — verified independently
✓Fixed price — confirmed before work starts

Installation, annual service and repairs across Wokingham and RG40.

Book Online 24/7 Call 07850 116944
★★★★★
120+ five-star Google reviews · G3 qualified · Installation, service & repair · Wokingham & RG40
G3 Qualified Gas Safe 599015 Building Regs compliant Annual service Emergency repairs Gledhill · Telford · Megaflo
G3 & unvented cylinders explained

Why G3 qualification matters — and what an unvented cylinder does

Unvented cylinders must only be worked on by a G3-qualified engineer — it is a legal requirement
Under Building Regulations Approved Document G (Part G3), all installation, servicing and repair work on unvented hot water systems must be carried out by a person holding the G3 competency certificate. This is not a recommendation — it is a legal requirement. An unqualified installation is illegal, invalidates your home insurance and creates a genuine safety risk if safety valves are incorrectly fitted or omitted.
What is G3 qualification?

G3 is the Building Regulations qualification (Part G, Section 3) that mandates any engineer working on an unvented hot water system must hold a specific G3 qualification. Unlike Gas Safe registration (which covers gas appliances), G3 covers the higher-pressure unvented cylinder system itself. Thermotec’s Stuart Mundy is G3 qualified and Gas Safe registered (Reg. 599015) — based in Arborfield, covering the full RG40, RG41, RG2, RG6 and RG45 area.

Vented vs unvented — what’s the difference?

Vented Cylinder
Traditional gravity-fed system with loft tank
Older system type
×Low pressure — limited by loft tank height above taps
×Pressure drops when multiple outlets run at once
×Cold water tank in loft takes up space and can freeze
×Open loft tank — potential contamination risk
✓Lower installation cost
✓No G3 requirement for basic servicing
Unvented Cylinder
Mains-pressure system — no loft tank required
Modern standard
✓Mains-pressure hot water — typically 2–3x the pressure of vented
✓Full pressure maintained with multiple outlets running simultaneously
✓No cold water tank in loft — reclaims valuable space
✓Sealed system — no contamination risk
✓Compatible with combi boilers, system boilers and solar thermal
×Requires annual service by a G3 qualified engineer
What we do

Installation, service & repair — all under one roof

01
New Installation
New unvented cylinder or upgrade from vented. G3 compliant, Building Regulations notification included, all safety components fitted and commissioned. Gledhill, Telford and Megaflo supplied.
From £1,200 · Free survey & fixed quote
Get a quote →
02
Annual Service
G3-compliant annual service covering all safety devices — PRV, T&P valve, expansion vessel, tundish, immersion thermostat and sacrificial anode. Service report provided. Required to maintain cylinder warranty.
From £96 · Fixed price
Book a service →
03
Fast Repairs
Dripping PRV, no hot water, failed expansion vessel, faulty immersion heater — we diagnose and fix all unvented cylinder faults. Common parts carried on the van for Gledhill, Telford and Megaflo systems.
£96 diagnostic · Upfront repair quote
Book a repair →
Services — Wokingham & RG40

All unvented cylinder services

All services carried out by a G3 qualified engineer. Fixed price confirmed before any work starts.

Unvented Cylinder Installation
From £1,200 fixed price
New unvented cylinder installed to full Building Regulations compliance — all required safety valves, Building Regulations notification and commissioning included. Gledhill, Telford and Megaflo supplied and installed across Wokingham and RG40.
Get a quote →
Vented to Unvented Upgrade
From £1,400 fixed price
Replace an existing vented system with a new unvented cylinder. Includes removal of old cylinder and loft cold water tank, new installation, mains connection, all safety components and Building Regulations notification. Full mains-pressure hot water throughout.
Get a quote →
Annual Cylinder Service
From £96 fixed price
Annual G3 qualified service covering all safety components — PRV, expansion vessel, T&P valve, immersion heater, thermostat and sacrificial anode. Written service report provided. Required to maintain manufacturer warranty.
Book a service →
Pressure Relief Valve Replacement
From £180 fixed price
PRVs that drip, discharge constantly or fail to reseat must be replaced by a G3 qualified engineer. A faulty PRV is a safety issue — do not ignore it. Stuart carries replacement valves for all major brands and can typically complete on the same visit.
Book a repair →
Expansion Vessel Replacement
From £200 fixed price
A waterlogged or failed expansion vessel causes the PRV to discharge repeatedly every heating cycle. Replacement requires draining the cylinder, fitting the new vessel and recharging to the correct pressure. G3 qualified work.
Book a repair →
Immersion Heater Replacement
From £160 fixed price
Faulty immersion heater elements or thermostats replaced across Wokingham and RG40. Berkshire’s hard chalk water significantly accelerates element failure through limescale build-up — one of the most common faults in the RG40 area.
Book a repair →
When to call us

8 signs your cylinder needs urgent attention

Unvented cylinders operate at mains pressure. These symptoms should not be left unresolved — some indicate safety device failure requiring immediate attention.

Pressure relief valve dripping or discharging
Water dripping from the outside discharge pipe is not normal in everyday use. It indicates overpressure, a failed expansion vessel or a faulty PRV. Do not block the pipe — call a G3 engineer promptly.
No hot water or water not reaching temperature
Could be a failed immersion heater, tripped overheat thermostat or loss of boiler connection. Limescale build-up on immersion elements is a very common cause in Wokingham’s hard-water area.
Visible leaks from the cylinder or pipework
Any water escaping from the cylinder body, connections or valves requires urgent attention. Turn off the water supply and call Stuart on 07850 116944 directly.
Banging, gurgling or hissing noises
Often indicate limescale on immersion elements (kettling), a failing expansion vessel or trapped air. Very common in Wokingham properties due to the area’s hard chalk water.
Low or fluctuating hot water pressure
An unvented cylinder should deliver consistent mains-pressure hot water. If pressure has dropped or varies significantly, it may indicate a valve issue, blockage or supply problem.
Not serviced in over 12 months
Unvented cylinders must be serviced annually by a G3 qualified engineer. Most manufacturer warranties are void if not serviced annually. Book your service if it’s overdue.
Discoloured or rusty hot water
Internal corrosion — especially common in Wokingham where hard water depletes the sacrificial anode faster than in soft-water areas. Needs inspection before the cylinder body itself is damaged.
Cylinder over 10–12 years old
Expected lifespan is 10–25 years depending on brand and maintenance. In Wokingham’s hard-water area, unserviced cylinders age faster. Have it inspected before it fails unexpectedly.
Hard water & unvented cylinders in Wokingham

Wokingham’s chalk water (350–400 mg/L hardness) affects unvented cylinders in two specific ways. First, limescale builds up on immersion heater elements, dramatically reducing efficiency and causing element failure years earlier than expected. Second, the high mineral content depletes the sacrificial anode — a magnesium rod inside the cylinder that protects the tank from internal corrosion — faster than in soft-water areas. Stuart checks and replaces the sacrificial anode on every annual service in Wokingham. It’s an often-overlooked maintenance item that significantly extends cylinder life and is rarely done by engineers without local hard-water knowledge.

Annual service checklist

What’s included in every G3 cylinder service

Every Thermotec annual service covers all eight safety-critical points below — not just a visual check. This is the standard required to maintain manufacturer warranties across Wokingham and RG40.

✓
Pressure relief valve (PRV) test
Manually tested to confirm correct operation and reseating. Replaced if faulty or discharging.
✓
Expansion vessel pressure check
Pre-charge pressure checked and recharged if required. Replaced if waterlogged.
✓
Temperature & pressure relief (T&P) valve
Tested for correct operation. Critical safety component — must function correctly.
✓
Thermostat accuracy check
Water temperature verified at the correct setpoint (60–65°C to prevent Legionella growth).
✓
Immersion heater inspection
Element checked for limescale build-up (critical in Wokingham’s hard-water area) and correct operation.
✓
Sacrificial anode inspection & replacement
Checked and replaced if depleted. Essential in Wokingham to protect the cylinder from internal corrosion.
✓
Discharge pipe & tundish inspection
Checked for obstruction, correct fall and visible external termination from all safety valves.
✓
Written service report
Provided on completion confirming all checks. Acceptable to all major cylinder manufacturers for warranty purposes.
Brands we work on

Gledhill, Telford & Megaflo — all major brands covered

We carry common parts on the van for all three major brands — expansion vessels, PRVs, immersion heater elements, thermostats and sacrificial anodes — to aim for a same-visit repair.

Gledhill
Most common in RG40
The most frequently installed unvented cylinder across Wokingham and Berkshire. We service and repair all Gledhill models including Stainless Lite Plus, Torrent and EnviroFoam. Common faults in RG40: expansion vessel failure, PRV weeping from hard-water scale, immersion thermostat failure.
Telford
Copper & stainless models
Telford Tempstor and Triton ranges are common in Wokingham properties built in the 1990s and 2000s. We carry parts for both copper and stainless steel versions. Common faults: expansion vessel waterlogging, thermostat calibration drift, PRV replacement.
Megaflo (Heatrae Sadia)
High-performance cylinders
Megaflo cylinders are known for longevity when properly maintained. We service and repair all Megaflo models including the Eco and Solar ranges. Common faults in RG40: external expansion vessel failure, immersion heater element limescale, control thermostat drift.
Other brands
Worcester, Vaillant & more
We also service and repair Worcester Bosch Greenstore, Vaillant uniSTOR, Joule, Ariston and other major unvented cylinder brands across Wokingham and RG40. Call to confirm parts availability for your specific model.
Transparent pricing

Fixed prices — confirmed before we start

No hidden call-out charges, no hourly rates, no surprise costs. Every price agreed upfront before any work begins.

Annual cylinder service
From £96
G3 compliant · All safety devices · Written service report
Boiler + cylinder service
£168
Both in one visit · Save vs booking separately · Digital records issued
Cylinder diagnostic / repair
£96
Fixed fee · PRV, expansion vessel, immersion · Upfront repair quote
New installation
From £1,200
Supply & fit · Building Regs compliant · Free survey first
Landlord CP12 combo
£150
Boiler service + Gas Safety Certificate · Same day cert issued
Why Thermotec?

Why Wokingham homeowners choose Thermotec for cylinder work

Unvented cylinder work is specialist — not every plumber is qualified to do it. Here is why Thermotec is the right choice across Wokingham and RG40.

01
G3 qualified — legally compliant
All unvented cylinder work requires G3 qualification under Building Regulations. Stuart holds G3 certification and carries out all work to full legal compliance, with Building Regulations notification included on every installation.
02
Hard-water knowledge — Wokingham specific
Wokingham’s very hard chalk water affects cylinders faster than most UK areas. Stuart checks sacrificial anodes and immersion elements every service — items often missed by engineers without local hard-water experience.
03
Parts on the van
Stuart carries the most common replacement components — PRVs, expansion vessels, immersion heaters, sacrificial anodes — for Gledhill, Telford and Megaflo. Most repairs are completed on the same visit without ordering parts.
04
Fixed price before we start
Whether it’s a full installation or an annual service, the price is fixed and confirmed before any work starts. No surprises on the invoice. No hourly rates.
05
20+ years in Wokingham
20+ years serving Wokingham homeowners. Stuart knows the property types, typical cylinder configurations and the specific hard-water challenges of RG40 better than most engineers covering the area.
06
120+ five-star Google reviews
Real reviews from homeowners across Wokingham, Earley, Woodley and Finchampstead — visible directly on Google Maps. Not curated on a managed platform.
Customer reviews

What Wokingham customers say about our cylinder work

120+ five-star Google reviews from homeowners across Wokingham, Earley, Woodley, Finchampstead and RG40.

★★★★★

“Upgraded from an old vented cylinder to a new Megaflo. Stuart removed the old cylinder and loft tank, installed the new unvented system and sorted the building regulations notification. The difference in pressure is extraordinary — mains pressure hot water throughout the house. Brilliant job, exactly as quoted.”

Richard & Clare T.
Wokingham, RG40
Vented to unvented cylinder upgrade
★★★★★

“Our pressure relief valve was dripping constantly. Stuart was here the same day, diagnosed a waterlogged expansion vessel, replaced both the vessel and the PRV and the system has been perfect since. Fixed price, no fuss, and he explained exactly what had failed and why.”

Helen M.
Earley, Wokingham
Expansion vessel & PRV replacement
★★★★★

“Stuart services our Megaflo every year. He’s thorough — checks all the safety valves properly and always checks the anode which our previous engineer never even mentioned. That anode replacement has saved us from a very expensive cylinder failure. Trustworthy and honest.”

James & Sarah W.
Finchampstead, RG40
Annual unvented cylinder service

See all 120+ reviews on Google →

FAQ

Unvented cylinder Wokingham — common questions

Questions from Wokingham homeowners about unvented hot water cylinder installation, servicing and repair.

What is a G3 qualification and why does it matter?
G3 is the Building Regulations qualification (Part G, Section 3) legally required for anyone working on unvented hot water cylinder systems in the UK. It is separate from Gas Safe registration — Gas Safe alone does not qualify an engineer to work on unvented cylinders. Without G3 certification, the work is illegal, the installation won’t comply with building regulations and creates a genuine safety risk. Always verify your engineer holds G3 before booking any unvented cylinder work.
How much does an unvented cylinder installation cost in Wokingham?
Thermotec installs unvented cylinders from £1,200 fixed price including the cylinder, all required safety components, installation and Building Regulations notification. A vented-to-unvented upgrade (including removal of the old cylinder and loft tank) starts from £1,400. A free survey and fixed price is provided before any work starts.
How often does an unvented cylinder need servicing?
Annually. Unvented cylinders must be serviced annually by a G3 qualified engineer. The service checks all safety components — PRV, expansion vessel, T&P valve, thermostat, immersion heater and sacrificial anode. Most manufacturer warranties require annual servicing to remain valid. Annual service from £96 fixed price. Combined boiler and cylinder service available for £168 — both in one visit.
Why is my pressure relief valve dripping?
A dripping PRV is not normal during everyday use. It most commonly indicates a waterlogged expansion vessel (the vessel is no longer absorbing the thermal expansion of heated water, so the PRV opens to release the pressure every heating cycle) or a faulty PRV that is no longer reseating. Do not block the discharge pipe. Call Stuart on 07850 116944 — both issues can usually be resolved on the same visit.
Can I replace a vented cylinder with an unvented cylinder?
Yes — this is one of the most common upgrades Thermotec carries out in Wokingham. Replacing a vented system with an unvented cylinder removes the loft tank, provides mains-pressure hot water throughout and eliminates risks associated with open loft tanks. The work requires a G3 qualified engineer and must be notified to Building Control. Thermotec handles both as standard. From £1,400 fixed price.
What areas do you cover for unvented cylinder work?
Thermotec provides G3 qualified unvented cylinder installation, annual servicing and repair across Wokingham, Earley, Woodley, Winnersh, Finchampstead, Barkham, Arborfield, Shinfield, Spencers Wood, Crowthorne, Swallowfield, Reading, Bracknell and Mortimer — the full RG40, RG41, RG2, RG6, RG7 and RG45 postcode area.
G3 Qualified · Wokingham & RG40 · Gas Safe 599015

Book your unvented cylinder
service or installation

G3 qualified · Annual service from £96 · Boiler + cylinder from £168 · Installation from £1,200 · 120+ five-star reviews · Wokingham & RG40

Book Online 24/7 Call 07850 116944
Coverage

Unvented cylinder specialists across Wokingham & Berkshire

Based in Arborfield, 10 minutes from Wokingham town centre. Covering the full RG40, RG41, RG2, RG5, RG6, RG45 and RG12 postcode area.

Wokingham Earley Woodley Winnersh Finchampstead Barkham Arborfield Shinfield Spencers Wood Crowthorne Swallowfield Reading Bracknell Mortimer Woosehill Yateley
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