The different types of hot water Cylinder Installations

There are two various types of hot water Cylinder Installations in homes across the UK. They operate to provide hot water to your home with slight differences. Each type has its advantages and disadvantages. The price for replacement Cylinder Installations will differ for each type as they are fundamentally different hot water Cylinder Installations.

Vented hot water Hot water cylinder installations

Vented hot water Cylinder Installations and costs for replacement

A vented hot water cylinder system consists of a cold water tank located commonly in the loft which feeds cold water to the cylinder. The cylinder is typically situated in an airing cupboard, with the cold water feed at the bottom of the tank. Heated water rises to the top of the reservoir where it is drawn off for feeding the heating system.

A vent pipe acts as an outlet for air bubbles, and steam should the cylinder overheat and also keeps the cylinder pressure at atmospheric pressure. There are two methods of heating water with vented hot water systems, namely:

  • Direct heating – immersion heaters are fitted in the cylinder, and they solely provide the hot water. Alternatively, a gas boiler is connected to the system and provides the hot water to the cylinder. Commonly a boiler-heated cylinder has immersion heaters to provide redundancy.
  • Indirect heating – a coil within the hot water cylinder is fed via the central heating system and heats the water in the cylinder. An immersion heater is also provided so that the boiler can be switched off in the summer and the cylinder takes over providing domestic hot water.

Price for replacing hot water Cylinder Installations  with a similar type and size

A plumber will usually quote a day rate for this sort of job. A straight-forward cylinder swap should be complete within one day. The price below includes labour and secondary materials such as washers, fittings and PTFE tape. Also included is the cost of scrapping the old tank and any waste created during the job.

Standard copper water cylinders are available for around £200 and a thermostat for the cylinder costs under £40.

For the total job excluding the tank, you should expect your plumber to charge you around £350. If you prefer to let the plumber get on with providing everything they will need for the job then expect a quote of between £500 and £600 for the complete job.


Unvented hot water cylinders

Costs for replacing an unvented hot water cylinder

An unvented hot water cylinder connects to the mains cold water rising mains and supplies hot water at mains pressure. Similar heating methods to the vented cylinder also apply to this type of cylinder. Indirect heating, however, is not possible if you use a solid-fuel boiler to produce your hot water.

The difference between vented and unvented systems is that there is no water storage tank or vent pipes. Instead, an expansion vessel is connected to the top of the cylinder. The purpose of the expansion vessel is to accommodate expanding water coming from the cylinder. The following safety devices are necessary for unvented cylinders:

  • Primary and secondary thermostats. The main thermostat maintains the temperature of the water below 65 degrees while the secondary switches off the heater or cuts off water supply if the temperature exceeds 90 degrees Celsius.

It is possible to upgrade your hot water cylinder from a vented to a vented system, and a plumber should detail the work involved. For stainless steel, unvented, insulated and pressurised cylinder it will take two plumbers a day to complete the installation. You should expect to pay around £650 for labour, fittings and sundries excluding the cylinder.

Unvented hot water cylinders and Megaflo

If you want to increase the hot water pressure and flow in your home or you are having your loft converted, you should consider installing an unvented hot water cylinder or Megaflo. Fortune and Co are BPEC certified installers of unvented hot water cylinders. Call us now on 07856 717136 or complete the contact form for a non-obligation quote.

What is an unvented hot water cylinders? What is a Megaflo?

High pressure hot water storage cylinders provide a highly efficient way of storing and distributing domestic hot water throughout your home at mains pressure.

Because water comes directly from the mains supply, and not from a cold water storage cistern/tank, the flow rate and pressure from an unvented cylinder to the outlets (taps and shower heads) is much greater than from the cold water storage tank.

Unvented hot water cylinders are ideal for properties with more than one bathroom/shower or with a loft conversion as they can provide flow rates in excess of 22 litres per minute and meet demand for simultaneous use of hot water from different outlets.

An unvented cylinder can be directly heated by electric immersion heaters or indirectly heated by a central heating boiler.

Megaflo (often misspelt Megaflow) is the brand leader in unvented domestic water heating and it is manufactured by Heatrae Sadia.

What are the Benefits of Megaflo Cylinders?

  • Powerful mains pressure showering, faster filling baths and faster running taps, no need for booster or shower pumps
  • Balanced hot and cold flow rate to all outlets at relatively high pressure (up to 72 litres/min)
  • Fast recovery rates
  • No need for water storage tanks or external expansion vessels
  • More hygienic when compared to conventional vented hot water systems as the water is not stored in tanks which can allow bacterial growth
  • Quicker and more energy efficient at heating water and retain the water temperature for longer
  • Duplex stainless steel construction of the cylinder gives maximum heat retention. This increases the efficiency of your boiler and lowers running costs
  • Very reliable, require very little maintenance and come with a 25-year transferable warranty
  • Cylinder can be sited almost anywhere within the property

Annual service unvented hot water cylinder

The annual service for unvented water heaters includes testing safety valves, recharging pressure vessels, cleaning the pressure reduction valve, checking electrical connections and providing a service certificate.

Manufacturers of unvented water heaters recommend that you have your water heater serviced once each year, and many home insurance policies require this. Note that failure to ensure that your hot water heater and the pipework are inspected and maintained each year can result in failure to cover damage if something were to occur.

Annual maintenance will help to keep the water heater safe and in line with the requirements of the G3 building regulations relating to hot water systems. Details of what is included in the annual service are shown below.

Other types of water heaters such as thermal store or combination water heaters are not required to have an annual service. For these water heaters, we offer a ‘system health check’, which enables us to investigate all aspects of the heater and provide a report showing the condition of the water heater and enables you to keep on top of maintenance.

Risks associated with unvented systems

Unvented water heaters are safe to use if installed and maintained correctly though an annual service. They incorporate three levels of safety. Thermostats that prevent the water being heated above 60 – 65°, high level cut-outs that operate when water reaches 80 – 85° because the thermostat has failed and a temperature relief valve, which operates if both of the other safety features fail and the water reaches 90 – 95°. In addition unvented water systems also incorporate a pressure relief valve which operates at 6 – 7 bar.

If these safety features are missing or have become faulty then there is a risk that the water will overheat and pressure will build up in the tank.

What is included in an annual service of unvented water Cylinder Installations?

The following tasks will be completed during the annual package of your unvented water heater and hot water heater maintenance, repair and service:

  • Expansion relief valve testing
  • Temperature and pressure relief valve testing
  • Storage tank draining as needed
  • Combination valve and pressure reduction valve stripping and line strainer cleaning
  • Pressure expansion vessel check (if so equipped)
  • Expansion vessel pressure top up
  • Leak check
  • Main and boost immersion heater and thermostat function testing
  • Main and boost immersion heater resistance check
  • Electrical ground check
  • Service record completion and signing

As you can see from the information above, we offer one of the most comprehensive service packages on the market, designed to help ensure that you enjoy convenience and safety at all times with the unvented hot water heater in your home.

Note: The replacement of sacraficial annodes is not included in an annual service. If the sacrificial annodes do need to be replaced, this will be quoted for separately. The majority of water heaters do not have sacrificial annodes. Owners of Ariston water heaters should be aware of this point.

Water heater makes and models

We are familiar with most makes and models of unvented water heater found today. These include Gledhill, OSO, MegaFlo, Santon Premier Plus, Albion, Range, Manco, Telford and many more.

Note: If there are faulty parts or if safety valves do not function correctly the plumber will inform you and show you the fault. A quote will be provided for further work as we do not undertake additional work as part of an annual service.

Attention: If an unvented water heater has not had a regular annual service there is a possibility that the rubber seals in the safety valves will have hardened. If the seals have hardened, they will not sit back correctly in the valve and will pass water. In this instance water will be visible through the tun-dish in the discharge pipe and the valve in question will need to be replaced. We will provide a quote for the additional work to supply and fit a replacement valve.

In some instances, this may require the replacement of more than one valve, and it may also require the replacement of additional parts and components. Each situation is different, and our experienced technicians will provide a full quote for all parts and labour prior to performing any work to ensure you know precisely what to expect when it comes to serving and maintaining your home’s unvented hot water heater.

Warning: The task of cleaning the line strainer in the pressure reduction valve requires the plumber to remove the cartridge from the body of the valve to gain access to the foil filter. If the unvented water heater has been serviced annually or if the heater is reasonably new this does not usually cause a problem. However in unvented heaters that have not received regular annual services or in older unvented water heaters the rubber seal or spring may have become worn or misshaped. If this has occurred the valve when reassembled may not be water tight. If the valve is not water tight then the main water stop tap will have to be left in the closed position until a replacement pressure reduction valve is installed. This will mean that the water supply is turned off and the client will incur additional expense. We will provide a quote for the additional work to supply and fit a replacement pressure reduction valve. Manufacturers recognised this issue in older valves and changed the general design of the valve body and seals about four years ago.

Fortune and Co Ltd

24 Hour Emergency Call Out Service

The 24 Hour Emergency Call Out Service is for assistance to customers outside of our normal working hours.

Call 07856 717136 and use the menu options during out of hours.

You will be given the option to speak directly with our Out of Hours Engineer in the event of an emergency situation, or leave a message on an answering machine to be dealt with when the office re-opens.

Why choose Fortune & Co Ltd?

  • Fully insured
  • Fully qualified Engineers
  • Experienced Engineers
  • Gas Safe Registered Engineers
  • 24 hour Emergency Call Out Service
  • Free Quote
  • High quality
  • Lowest price possible


Please call or email us for a no obligation quotation and we'll do our best to meet your requirements.

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The areas we cover

We are based in Epsom and Ewell and cover areas such as;

Chessington, Banstead, Sutton, Ashtead, Oxshott, Tadworth, Leatherhead, Morden, New Malden, Mitcham, Croydon, South Croydon, Purley, Coulsdon, Merstham, Redhill, Reigate, Betchworth, Brockham, Great Bookham, Fetcham, Downside, Cobham, Esher, East Molesey, Surbiton, Kingston upon Thames, Wimbledon, Walton-on-Thames, Weybridge, Byfleet, East Horsley, Wotton, Dorking.

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