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Unvented hot water · London
Hot water planned around your home — not just a larger cylinder.
A second shower should not become a daily negotiation. A new bathroom should not expose the limits of an old hot-water system. And replacing a cylinder should leave you with more than a newer version of the same problem.
Unvented hot-water qualified
Heating · Plumbing · Electrical controls
01 · Installation · Replacement · Conversion
PEP designs, supplies and installs unvented hot water cylinders across West, Central and North West London. From electric cylinders in apartments to boiler-fed systems in family homes and coordinated plant rooms, we match the installation to the property, the available water supply and the way you use hot water.
New installations, cylinder replacements and vented-to-unvented conversions — with plumbing, electrical connections, controls and commissioning considered together.
A refurbishment is the right time to plan storage, pipe routes and controls before cupboards, bathrooms and finishes make those decisions difficult. We coordinate the cylinder with the heat source, electrical requirements, bathroom demand and available space.
For larger projects, this forms part of our central heating and plant-room installation service, bringing hot water and heating into one coordinated scope.
A replacement is an opportunity to check why the existing arrangement no longer works for you. The cylinder may be leaking, unsuitable for changed demand or difficult to maintain. Equally, poor performance may come from a control, valve, immersion heater or supply restriction rather than the vessel itself.
We assess the problem before specifying a replacement. Where a new cylinder is appropriate, we review the associated equipment and connections rather than assume everything around it can remain unchanged.
Replacing gravity-fed hot-water storage can suit a home being modernised for different bathroom demands. However, the incoming supply, existing showers, pipework, heat source and safety arrangements must support the change.
An unvented hot-water cylinder does not automatically require the central heating to become a sealed system. The heating expansion tank may still be needed if that circuit remains open-vented. Our vented-to-unvented conversion guide explains the options in more detail.
02 · Specify the system before the product
An unvented cylinder stores hot water under pressure, supplied from the mains or a suitably designed water-supply system. Its performance still depends on what that supply can deliver.
Before recommending an installation, we consider:
This establishes whether a straightforward replacement is suitable or whether the project needs additional work. It also helps prevent an attractive-looking quotation from becoming a series of unexpected extras once installation starts.
03 · Choose the right arrangement
A direct cylinder heats water using electric immersion heaters. It can suit an apartment without a boiler connection, provided the electrical supply, controls and storage capacity are appropriate.
We consider heating schedules, any suitable off-peak arrangement and how the household uses boost heating. Electrical connections and protective requirements are part of the installation scope, not something left for the customer to resolve afterwards.
An indirect cylinder uses a coil connected to an external heat source, commonly a boiler. The cylinder, coil performance, boiler and control sequence need to work together so that hot water recovers as intended.
We assess compatibility with retained equipment, including Vaillant and Viessmann boiler systems. If the project also involves a new heat source, our boiler installation service covers the wider upgrade. A cylinder intended for a heat pump needs suitable specifications; not every boiler cylinder is interchangeable.
If you are considering a Megaflo installation in London, we assess the appropriate model against your property and existing system. Megaflo is a particular product range, not a generic name for every unvented cylinder.
Depending on the project, the specification may include Megaflo, Vaillant uniSTOR or another suitable cylinder. Capacity, dimensions, recovery, expansion arrangements and servicing access matter more than choosing a familiar name in isolation.
04 · Storage · Recovery · Supply
Two homes with the same number of bedrooms can have very different requirements. A large bath, high-flow shower and busy morning routine may create a different load from several bathrooms used at separate times.
We consider three things together: the usable hot water stored, the rate at which it can be replenished and the flow the supply can sustain. The largest cylinder that fits is not automatically the best choice.
A larger cylinder will not remove a restriction in the incoming main. Where the supply is the limiting factor, we assess it before promising a particular shower performance. Our guide to water pressure boosters and storage systems explains why different supply problems need different solutions.
In a larger house, long pipe runs may also justify hot-water circulation. That decision needs to account for heat loss, insulation, controls and access — not simply the addition of a pump.
05 · Access matters as much as capacity
In a London property, the practical constraints can be as important as the cylinder specification. A unit that fits an airing cupboard may still be impossible to bring up the staircase or service once the joinery is complete.
We assess the route into the property, the installation position and access to valves, electrical components and service points. Slimline options can help in some spaces, but their dimensions and performance still need checking against the whole installation.
For flats, we identify where the private installation meets communal services. Freeholder or managing-agent requirements, shared water supplies and access arrangements need resolving before work starts. A property served by a communal heat network, HIU or thermal store requires its own assessment rather than an assumed like-for-like cylinder swap.
Where work affects finished rooms, we agree pipe routes, opening-up and responsibility for making good. Relocation is considered as a complete installation change, including services and safety arrangements.
PEP work · Chiswick · London
PEP combines heating, plumbing and electrical expertise within the same team. Our heating discipline includes qualified unvented hot-water work, while our electrical team coordinates power supplies and control interfaces.
That matters when a cylinder must work alongside heating zones, underfloor heating, motorised valves and a modern boiler controller. We plan the operating sequence and check it during commissioning, so the correct equipment responds when hot water is required.
Our London heating and plant-room project collection shows PEP installations from first fix through to completed work, including unvented cylinders and multi-zone systems. For more detail on the control side, see our guide to heating controls and zoning.
06 · From first assessment to handover
We review the existing system, your reason for changing it and the practical conditions on site. For a refurbishment, drawings and the proposed bathroom layout help establish the scope early.
The proposal identifies the cylinder and associated work, together with access requirements, responsibilities and exclusions. We clarify the programme and any further information or permissions needed before installation.
We coordinate isolation and removal of redundant equipment with the agreed pipework, controls and electrical work. The new installation is arranged for operation and future maintenance, with access to the components that need inspection or replacement.
Commissioning covers the manufacturer's required checks, watertightness, heating operation, controls and safety arrangements. Where the cylinder forms part of a wider heating system, we check the relevant interactions rather than treating it as a disconnected appliance.
We explain normal operation, schedules, any immersion boost function and the maintenance requirements. The handover includes the relevant commissioning records, product information and applicable compliance documentation.
We agree the expected interruption to hot water, cold water and electricity before the work. A conversion, relocation or restricted-access installation can need a different programme from a straightforward replacement.
We agree the expected interruption to hot water, cold water and electricity before the work. A conversion, relocation or restricted-access installation can need a different programme from a straightforward replacement.
07 · Understand the complete scope
The price depends on the complete scope, not just the cylinder's purchase cost. A replacement in an accessible cupboard is a different project from moving the cylinder, changing the supply or converting an older vented installation.
Our quotation sets out the relevant elements:
Send your postcode, a brief description of the existing system and what you would like to improve. Photographs of the cylinder label and surrounding space can help us prepare for the assessment; there is no need to remove covers or disturb any components.
08 · Documentation · Warranty · Maintenance
Unvented systems require appropriate competence, correctly specified safety arrangements and the relevant Building Regulations process. In England, Approved Document G provides guidance on hot-water safety. We establish the appropriate notification or certification route for the work; a commissioning checklist and Building Regulations compliance documentation have different purposes.
Manufacturer warranties also need reading carefully. Cover for the cylinder vessel can differ from cover for controls, valves, immersion heaters and labour. We identify the terms applying to the chosen product, including registration and maintenance conditions, rather than describe the entire installation with one headline warranty period.
The Hot Water Association recommends checks every 12 months, with the manufacturer's instructions guiding the work. Our unvented cylinder servicing guide explains the maintenance and records to plan for after installation.
Before you book
Often, yes, if it is suitable and in serviceable condition. We assess its compatibility, output and controls alongside the proposed cylinder. A cylinder upgrade does not automatically require a new boiler.
It can change the performance available from an old gravity-fed arrangement, but the result depends on the incoming supply, pipework and fittings. We assess pressure and available flow before making a recommendation.
A suitably designed system can. We check combined shower demand against the supply, usable storage and recovery performance. Cylinder capacity alone cannot establish whether two showers will work well together.
Yes. We assess the existing cylinder, electrical supply, controls, available space and water connections. Communal services or building-management requirements may affect the scope and programme.
Potentially. The new location needs suitable access, support, services, maintenance clearances and a compliant discharge arrangement. We assess the complete route before recommending a move.
No. The cold-water storage cistern and the heating feed-and-expansion tank serve different purposes. What can be removed depends on the completed hot-water and heating design, including any remaining services they supply.
That depends on access, the existing installation and the work around the cylinder. We confirm the expected programme after assessment, including interruptions and any work needed before normal service resumes.
Not necessarily. A valve, expansion, pressure or control problem may be repairable without replacing the vessel. Unexplained discharge or leakage needs professional assessment; do not cap, block or bypass a safety outlet.
Yes. We provide the relevant commissioning and handover information, with the applicable Building Regulations compliance documentation through the appropriate process. We also explain the product's maintenance and warranty requirements.
London · Hot water planned properly
PEP carries out cylinder installation and replacement across West, Central and North West London, including Kensington, Chelsea, Notting Hill, Fulham, Hammersmith, Chiswick, Ealing, Acton, Maida Vale, St John's Wood, Hampstead and surrounding districts. See our full London service coverage.
Whether you are replacing an ageing cylinder, adding bathrooms or planning a complete refurbishment, bring us in while the options are still open. Send the postcode, your existing arrangement and the demands the new system needs to meet.
We will help define the right system, the installation scope and the next step.