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A bespoke digital atelier providing precision engineering and climate control services for London's most discerning luxury estates.

How often should a Megaflo or unvented cylinder be serviced?

Heatrae Sadia and most cylinder manufacturers recommend an annual service by a G3-qualified engineer. In London, where hard water accelerates limescale build-up, annual servicing is especially important to protect the immersion elements and cylinder components.

What does a Megaflo service include?

Our Megaflo service includes testing the T&P relief valve, inspecting and testing the PRV, checking and re-pressurising the expansion vessel, testing the thermal cutout (TCO), inspecting the tundish and discharge pipework, checking immersion elements, and issuing a written service certificate.

Does my Megaflo need a G3 qualified engineer?

Yes — by law. Unvented hot water cylinders must be worked on by a G3-qualified engineer under Building Regulations Part G. Working on an unvented cylinder without G3 certification is illegal and will invalidate your home insurance.

Do you service other unvented cylinder brands?

Yes — alongside Megaflo (Heatrae Sadia), we service OSO, Santon, Gledhill, Telford, Range Tribune and other leading unvented cylinder brands.

Why is water coming from my tundish?

This means your T&P relief valve or PRV is lifting — a safety response to excess pressure or temperature inside the cylinder. Switch off the cylinder's power supply immediately and call us on 020 7458 4949.

Can you replace the expansion vessel?

Yes. Expansion vessel replacement is one of the most common cylinder repairs we carry out. A failed or waterlogged vessel causes the PRV to lift repeatedly and must be replaced to protect the system.

What is the best time to service my Megaflo?

Summer is ideal. Demand is lower, appointments are more flexible, and servicing now means your hot water system is fully prepared before winter when showers and hot water demand increases significantly.

Do you issue a service certificate?

Yes — we issue a full written service certificate after every visit, recording all tests performed, component condition and any recommendations. This is important documentation for warranty purposes, insurance and property records.

020 7458 4949

18°C020 7458 4949 Book Now

RARE Plumbing London G3-qualified engineer servicing a Megaflo unvented hot water cylinder in a luxury London home

G3 Qualified — Building Regs Part G

Megaflo & Cylinder
Servicing
London

Annual unvented cylinder servicing by G3-qualified engineers. Megaflo, OSO, Santon and all major brands. Service certificate issued. Protect your hot water supply.

Book your annual service now

Summer is the ideal time — better availability and your cylinder protected before high winter demand.

020 7458 4949 Book Online

G3 Qualified

Certificate Issued

4.7★ Rated

13+ Years

Book a Cylinder Service

G3-qualified engineers. Summer appointments available now.

G3 Certified EngineersAll unvented cylinder brandsService certificate issuedHard water specialistsMayfair · Knightsbridge · Hampstead · Marylebone

Megaflo and unvented cylinder servicing in London costs from £180 + VAT and takes around 60 minutes, carried out by a G3-qualified engineer under Building Regulations Part G. Annual servicing is legally required for unvented cylinders and protects the T&P valve, expansion vessel and immersion elements from London's hard water damage.

Quick Facts

Suitable for: Megaflo, OSO, Santon, Gledhill, Telford, Range Tribune, Vaillant uniSTOR, ATAG
Typical duration: 60–90 minutes for a full G3 service
Cost: From £180 + VAT (standard hourly rate)
Frequency: Annually — legally required under Building Regs Part G
Qualification: G3-certified unvented cylinder engineer
Certificate: Written service certificate issued for warranty and insurance

Annual Service

What's included in a cylinder service?

Every cylinder service is carried out by a G3-qualified engineer to manufacturer specification. We issue a full written service certificate at the end of every visit.

Test T&P relief valve — lift and reseat
Inspect and test the pressure reducing valve (PRV)
Check and re-pressurise the expansion vessel
Test the thermal cutout (TCO)
Inspect tundish and discharge pipework
Check all pipework connections for leaks
Inspect immersion elements for scale and deterioration
Assess cylinder insulation and casing condition
Issue written service certificate

London hard water note: Properties across NW, W and SW postcodes should service annually. London's hard water significantly accelerates scale deposits on immersion elements and internal cylinder components.

Brands we service

Megaflo (Heatrae Sadia)OSOSantonGledhillTelfordRange TribuneVaillant uniSTORATAG

Why annual servicing matters

Safety compliance

Pressure and temperature safety devices must be tested annually. Failure to do so may invalidate home insurance and building regulations compliance.

Protect your warranty

Most cylinder manufacturers require annual servicing by a G3 engineer to maintain the product warranty.

Prevent costly repairs

A waterlogged expansion vessel or seized PRV caught at service costs a fraction of emergency replacement mid-winter.

Ready to book?

G3-qualified engineers. Summer slots available now.

020 7458 4949 Book Online

Client Reviews

What London clients say

"Our Megaflo PRV was starting to drip. RARE came out, serviced the whole cylinder and replaced the expansion vessel. Sorted it before it became a serious problem."

Sarah B.

Knightsbridge

"Annual Megaflo service carried out brilliantly. Found the expansion vessel losing pressure before it caused any issues. Neat, professional, on time and great communication."

Nadia W.

Marylebone

"RARE service cylinders across all the properties we manage. Always reliable, correct certification and no surprises. Highly recommended for any estate manager."

Estate Manager, NW3

Hampstead

FAQ

Cylinder Servicing Questions Answered

Common questions about Megaflo and unvented cylinder servicing in London.

Still have questions?

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Cylinder reaching end of life? Time to plan a replacement

If your Megaflo is over 10–15 years old, or if our service identifies wear that makes further servicing uneconomical, a planned replacement is far better than an emergency failure. See our Hot Water Cylinder Installation page for options and pricing.

Cylinder Installation

Property Care Membership

Prefer proactive care? RARE members receive planned servicing, detailed property records and priority access when problems arise. Explore Property Care Membership for professionally managed plumbing and heating maintenance.

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Megaflo & CylinderServicingLondon