Unvented water cylinder servicing & repairs

Published on March 6, 2025

Unvented water cylinder servicing and repairs

Your water cylinder is an appliance that is easy to overlook.

But it’s a piece of kit which is essential in keeping your home comfortable and warm, ensuring that you have a reliable, plentiful supply of hot water to heat your home and serve hot water taps any time you wash, take a shower or fill your washing machine with laundry.

Knowing a little about how your water cylinder works, as well as what might stop it from working to its best and what you can do keep it in the best of health, can be valuable in maintaining a smooth, reliable central heating system.

RJ Martindale’s engineers have put together this guide, answering questions like “What is an unvented water cylinder”, and why it’s important to regularly service and repair your unvented water cylinder with a trusted engineer such as RJ Martindale.

Book your unvented water cylinder’s service or repair

What is an unvented water cylinder & what are its benefits?

This type of hot water cylinder is relatively new, having come into use from the mid-1980s. Its main advantage over older, vented hot water cylinders is that it is fully enclosed, and connected directly to your cold water supply that flows into most homes from the mains pipes under the road.

By dispensing with the need for a separate cold water tank, which receives water by gravity through a series of pipes running from the mains, it means that the flow of water can be maintained at a steady rate, which is often higher than when it has to pass through a longer network of pipes.

What are the benefits of installing an unvented water cylinder?

  • An unvented water cylinder takes up less space, so can be installed just about anywhere in your home
  • The consistent flow of water means it can keep up with even the most demanding household’s needs
  • No more frozen pipes in winter, as there is no need for pipes to be connected to a loft tank which is often the most vulnerable part of the system
  • The fact that the unvented water cylinder is self-contained means that it’s fully sealed, so eliminating any risk of contamination
  • The system is quieter overall, as the once-familiar sound of the cold water tank refilling is eliminated

What size of unvented water cylinder is recommended for my household?

Unvented water cylinders come in a number of different sizes, and the one that’s right for your needs will depend largely on how many bedrooms and bathrooms it will supply.

A 120- to 150-litre unvented water cylinder is big enough to supply a one-bedroom property with a single bathroom. For a two-bedroom home with just a single bathroom you should look at a cylinder of between 150 and 180 litres. If you have two or more bathrooms used by people in up to four bedrooms, then we suggest a 180- to 200-litre tank, while a four-bedroom, two bathroom home would need a tank of between 200 and 300 litres capacity.

Even bigger unvented water cylinders are available for five-bedroom homes with two or more bathrooms, making this type of cylinder ideal for homes of any size where mains water pressure is good.

Image explaining what an unvented cylinder is for
RJ Martindale explains what an unvented cylinder is

Servicing & repairs for unvented water cylinders

You’ll find an unvented hot water cylinder the best all-round type of water cylinder f you have a good, regular flow of water from the mains.

Because there is no separate cold water tank, and all the pipework and controls are integrated into the tank itself, maintenance is much easier than for the older, vented systems.

However, you can think of your unvented water cylinder as much like the engine and exhaust systems on your car. Just because all the workings and internal moving parts are hidden away, that doesn’t mean you can afford to ignore them.

Being largely self-contained, unvented water cylinders are certainly easier and quicker to install, helped by the fact that you can choose where your unvented water cylinder can be fitted so that it’s in the least obtrusive but most practical place possible.

With very hot water flowing through your unvented water cylinder though, it’s essential to avoid leaks which may cause significant damage to carpets, floors and ceilings. That’s why many home insurance policies insist that unvented water cylinder servicing is carried out by a qualified engineer every year.

Despite most unvented water cylinders having a good warranty, you’re only likely to be able to claim under it if you keep your cylinder properly serviced and maintained.

What does unvented water cylinder servicing involve?

As it’s considered a permanent fixture of your home, Building Regulations say that you should bring in a Gas Safe Registered engineer every year to:

  • Check that the unvented water cylinder’s temperature controls are working properly
  • Inspect all the pressure controls and relief valves, and test that they’re fully functioning
  • Take a close look to see that the unvented water cylinder’s safety systems are working as they should, and
  • Examine the unvented water cylinder itself and tell you about any signs of damage or undue stress on it, which might lead to problems in the future.

 

Book your unvented water cylinder’s service or repair

Can anyone carry out vented water cylinder servicing & repairs?

No, because parts of the system are working under high-pressure and their self-contained nature means that a fault in a single part can affect the workings of your entire hot water and heating system. Servicing and repairs of unvented water cylinders should only be carried out by a Gas Safe Registered engineer.

Gas Safe is the current name for the former CORGI registration scheme, certifying an engineer as qualified to work on a variety of appliances that depend on a pressurised gas supply.

Having a new boiler and unvented water cylinder fitted is the best time to also consider how and when you’ll have your unvented water cylinder servicing and repairs carried out in the future.

Your trusted, certified Gas Safe Registered engineer from RJ Martindale deliver expert advice and recommendations, and will also suggest a Homecare servicing plan that’s right for your budget, household and property.

Service & repair your unvented water cylinder with RJ Martindale’s Gas Safe Registered team in Bolton, Horwich, Chorley & Preston

Servicing and repairs of unvented water cylinders should be carried out by an accredited Gas Safe Registered engineer, ensuring your unvented water cylinder, boiler and central heating system operates safely and to its best. RJ Martindale’s unvented water cylinder servicing and repair engineers throughout the North West are Gas Safe Registered, fully trained and accredited, giving you the reassurance you need that your home’s in safe hands.

Servicing and repairing unvented water cylinders, as well as vented cylinders, boilers and central heating systems in Bolton, Horwich, Chorley and Preston, RJ Martindale is one of the North West’s most trusted water cylinder, boiler and central heating installation organisations, protecting homes, families and investments with fully-qualified, reliable and experienced heating and plumbing services.

With hundreds of five-star Google reviews for our work, our trusted team takes the heat out of caring for unvented water cylinders across the Bolton, Horwich, Chorley and Preston areas.

Time to service or repair your unvented water cylinder?

Book your unvented water cylinder’s service or repair

 

Call Us