Unvented cylinder and Megaflo installation, servicing and repair

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  • 1. Book online in a few clicks

    Organise a survey visit through our booking form

  • 2. Get personal quote

    The unvented cylinder engineer will arrive, inspect the boiler and give you an estimate

  • 3. Schedule immediately

    Once everything is confirmed, you can schedule the day of the service

  • 4. Results in a safe manner

    The engineer will arrive to complete the service.

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Unvented hot water cylinder problems you might be experiencing

Here is a list with the most common issues you might have with your unvented hot water cylinder:

  • Water dripping from the expansion pipe;
  • Leakages from the combination valve;
  • Low-pressure leaking shower;
  • Strange noises from the vessel;
  • Clogged inlets and inconsistent water stream;
  • General leaks and corrosion;
  • Limescale damage;
  • Difficulties setting and maintaining the right temperature.

Whatever the situation you are experiencing, Fantastic Services can resolve it for you. We can send a qualified engineer to install, replace, maintain or repair your unvented hot water cylinder.

Why choose us for your unvented cylinder servicing?

Fantastic Services is London's most trusted name for plumbing and heating services. With over a decade of experience, all our gas-certified engineers provide high-quality unvented cylinder installation and repair services. You can trust our expert team with everything from the initial consultation to the installation of your new hot water cylinder, ensuring safety, reliability, and optimum performance. Other reasons to book our unvented cylinder service:

  • Experienced plumbers - All our London boiler engineers have decades of experience with unvented hot water cylinder repairs, installation and servicing.
  • Seven-day service - We offer appointments every day from Monday to Sunday, including bank holidays and weekends.
  • Guaranteed & Insured - We have a 12-month guarantee on all labour and parts we supply.
  • No hidden charges - We work only at transparent hourly rates.
  • Professional and trained - All our plumbing engineers are polite, helpful, presentable and uniformed
  • Fully equipped - During the service, you can expect the engineer to bring high-quality tools and equipment to get the job done.
  • Always at your service - Experienced to serve both domestic and business customers.

Unvented hot water cylinder and Megaflo installation

The use of unvented cylinders continues to grow in the UK. This is because the pressure and the flow of water in this system can be higher since the water comes from the mains. Furthermore, there is no water tank, so you can install it anywhere in your home.

Unvented cylinder systems are also quieter as there is no gurgling due to the water tank being refilled slowly. Also, there is no risk of pipes freezing as the water pipes are built into the loft. There is extra insulation which reduces the risk of water pipes freezing during the colder months.

We install, maintain and repair all types of unvented hot water cylinder systems, including Megaflo. The engineer can install both direct water tanks that are powered by electric immersion and indirect water cylinders that work with gas. Whenever you need a replacement of your hot water system, it's best to speak with us first, as every home is unique, and everyone has their own needs. We will send one of our technical experts over to discuss your requirements. After reviewing your property's specifications, he'll recommend the most suitable solution.

Unvented hot water cylinder service and maintenance in London

Unvented cylinders are pressurised systems, which require regular maintenance by a G3-qualified engineer. In addition to inspecting all safety devices on the cylinder, the engineer will also be able to discuss any concerns you may have regarding the cylinder's performance. This is not just a visual check. The engineer will carry out a full assessment, including:

  • Removal and cleaning of any filters or strainers;
  • Checking the integrity of the cylinder for leaks or damage;
  • Checking air charge pressure in the expansion vessel, top up if necessary or checking operation of float operated valve in cistern;
  • Checking the internal expansion facility, resetting the expansion gap, and testing the temperature/pressure relief valve;
  • Checking expansion relief valve to ensure it opens, closes and reseals correctly;
  • Performing a pressure check downstream of the limiting/reducing valve;
  • Checking and cleaning flow diffusers on taps if fitted and more.

Unvented hot water cylinder repair and troubleshooting

Unvented hot water cylinders may require additional maintenance due to their sophisticated technology. We recommend that you contact us as soon as you discover or suspect that something is wrong with your unvented hot water cylinder. You can count on us to solve any unvented hot water cylinder problem quickly and effectively without causing major disruption to your home. Some of the most common unvented cylinder and Megaflo faults we can repair are:

  • Malfunctioning controls and safety devices;
  • Faulty thermostats;
  • Loss of power due to circuit breakers tripping;
  • Failed expansion vessels and faulty expansion valves.

There are several ways that these problems can manifest, including:

  • The boiler is on but no hot water;
  • Hot water only lasts for a few minutes
  • Water escapes through a tundish;
  • Water is not heating up when the electric element is on.

    • It can be disruptive and miserable to be without hot water at home. Whatever the problem is, we can send a qualified engineer to investigate and repair faults in your unvented hot water cylinder within 24 hours. Our professional team will ensure your water cylinder is back up and running again as soon as possible and is heating and storing water effectively.

Frequently asked questions

  • Q: What is the difference between a vented and an unvented hot water cylinder?

    A: Unvented and vented hot water cylinders have different setups. A vented cylinder reacts to the current atmospheric pressure through a vent pipe. Mains water is pumped into a cold water tank where it is stored until it is needed for an appliance in your home. Compared to vented cylinders, unvented cylinders use mains water directly, which produces a better flow of water.

  • Q: Can I install a hot water cylinder myself?

    A: According to the G3 Building Regulations, a container that can fit more than 15L of water under pressure, must be installed by a qualified engineer who has accomplished CITB training and has a G3 certification.

  • Q: Does my Megaflo or unvented system need to be serviced?

    A: It's highly recommended to service your Megaflo or unvented cylinder every year. This usually involves cleaning filters and checking and testing safety components, valves, and thermostats. We also check the thermostat wiring and overall system performance. For annual services, we currently charge £94 per hour plus parts if required.

  • Q: Is my mains water supply suitable?

    A: At peak times, your mains water pressure should be a minimum of 1.5 bar dynamic pressure, although unvented systems can operate at pressures as low as 1 bar dynamic. To ensure an adequate flow, the incoming main should be at least 25mm MDPE or 22mm copper.

  • Q: What is the price for installing an unvented hot water cylinder?

    A: Megaflo installation costs vary based on the job. There are several factors to consider, such as proximity to an external wall (for safety discharge outlets), proximity to electrical wiring, and the size and location of the main water pipe inside the house. Our team will conduct a full survey to provide you with an estimate.

  • Q: Are there any special deals on this service?

    A: If you subscribe to our Fantastic Club, you will receive special rates not only on our unvented cylinder solution but on all our services as well. For one year, you'll also be able to take advantage of various other benefits.

  • Q: Why do we recommend Megaflo?

    A: Megaflo is the market leader in unvented domestic water heating. If you have more than one bathroom, an unvented cylinder can provide a greater amount of hot water than a combi boiler.

  • Q: Where can an unvented cylinder be installed?

    A: Unvented cylinders or Megaflo can be installed almost anywhere, including lofts, garages, large airing cupboards, basements, etc.

  • Q: What size Megaflo do I need?

    A: There are various sizes available ranging from 70L to 2,500L. It is likely that the size of a Megaflo you will find in a domestic setting will not exceed 250 litres.

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