Unvented Cylinders & Megaflo in South West London

Hot water cylinders provide reliable, on-demand hot water at high pressure to all outlets, so multiple taps or showers can run simultaneously without losing temperature or flow. They offer consistent hot water, improve energy efficiency, and meet the demands of busy households. Key benefits include:

• Powerful mains-pressure showering: Faster filling of baths and running taps without the need for booster or shower pumps.

• Balanced flow rates: Hot and cold water delivered to all outlets at high pressure (up to 72 litres/min).

• Fast recovery rates: For example, the Megaflo CL125HE can recover in just 15 minutes.

• No water storage tanks or external expansion vessels needed.

• Hygienic: Water is not stored in tanks, reducing the risk of bacterial growth compared to conventional vented systems.

• Energy efficient: Heats water quickly, retains temperature longer, and reduces running costs.

• Durable construction: Duplex stainless steel cylinders provide excellent heat retention and longevity.

• Low maintenance and reliable: Require minimal upkeep and often come with a 25-year transferable warranty.

Vented cylinders rely on gravity and a cold water tank, while unvented cylinders are pressurized and connected directly to the mains, providing higher water flow and faster heating.

Yes. Unvented hot water cylinders are designed to deliver high-pressure hot water to all outlets in the home simultaneously, so multiple taps or showers can run without losing temperature or flow. This makes them ideal for busy households, ensuring consistent hot water even when several fixtures are in use at the same time.

The right size depends on your household’s hot water demand. Small homes or 1–2 occupants typically need 90–120 litres, while larger homes with 3–5 people may require 150–210 litres (approx. 45 lt consumption per person per day). Factors include the number of bathrooms, taps, showers, and how many outlets are typically used simultaneously. As B-PEC certified installers, we can assess your home and recommend the ideal cylinder size for consistent hot water at high pressure.

A professional unvented hot water cylinder service typically includes inspection of the cylinder, valves, and fittings, checking for leaks or corrosion, testing the pressure and temperature controls, and ensuring the cylinder is operating safely and efficiently.

You may need to book a repair or replacement if your cylinder shows signs such as leaks, corrosion, or rust, reduced hot water output, fluctuating water temperature, unusual banging or gurgling noises, or pressure problems. Other indicators include slow recovery times or frequent tripping of the pressure relief valve. If you notice any of these issues, please call us to carry out a full inspection, diagnose the problem, and recommend whether repair, servicing, or full replacement is the best solution to maintain safe and efficient hot water in your home.

If your immersion heater isn’t working, first turn off the power at the isolator for safety. Check the thermostat and fuse to see if they’ve tripped or failed. Sediment build-up or limescale can also reduce efficiency. For safety and to avoid damaging your cylinder, please call us as soon as possible to inspect, repair, or replace the immersion heater.

Yes. By law, unvented hot water cylinders must be installed or repaired by a qualified and registered engineer that holds BPEC certification. At Russell Haskins, we are fully qualified to install, service and repair your unvented unit. With our expertise you can trust that the system meets safety regulations, operates efficiently at high pressure, and protects your home from risks like leaks, over-pressurisation, or equipment failure. Attempting DIY installation is unsafe and could invalidate warranties or insurance.