Gas Safe #939000
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Worcester Bosch Approved
Checkatrade ApprovedGas Safe #939000Ideal Max AccreditedWorcester Bosch ApprovedCheckatrade ApprovedHome › Unvented cylinders
Mains-pressure hot waterPowerful showers on every floor, no loft tank, no pump. We size, install, service and repair unvented cylinders across Wigan and Bolton, and fix the drips and pressure problems other people walk away from.
How it works
An unvented cylinder is a sealed tank of hot water at mains pressure. The safety parts in red are why the law says it has to be fitted and looked after by a qualified engineer.
Size picker
Typical for a family home with a bathroom and an en-suite.
A guide only. We confirm the size on survey with your mains pressure and flow rate, your boiler and how you actually use hot water.
Cylinder fault finder
Almost always the expansion vessel has lost its air charge, so the expansion relief valve lets water go instead. A recharge or a new vessel sorts it.
A relief valve is stuck open or the pressure reducing valve has failed. It wastes water and means the safety system is working flat out. Call us.
The temperature relief valve is doing its job because the water has overheated. Switch off the boiler and immersion heater, don’t touch the pipe, and call us straight away.
Usually the motorised valve, the cylinder thermostat or the high-limit cut-out. If the immersion still works, you’ve got hot water while we fix it.
A blocked inlet strainer or a tired pressure reducing valve. Cleaning the strainer is part of every annual service.
Most cylinder failures we see trace back to a skipped service, and makers can refuse warranty claims without a service record.
Annual cylinder service
Your boiler service doesn’t cover the cylinder. It’s a separate set of safety checks, and it’s what keeps the manufacturer’s warranty valid.
Book a cylinder serviceIs it right for your home?
We fit both, so we’ve no reason to push you either way. Pairing a cylinder with a new system boiler? We price the whole package as one job.
From our jobs
Megaflo is the best-known brand of unvented hot water cylinder, made by Heatrae Sadia. It stores hot water at mains pressure, so you get strong showers and fast-filling baths on every floor without a cold tank in the loft or a pump. People often say "Megaflo" to mean any unvented cylinder.
Yes. Manufacturers require an annual service to keep the warranty valid, and the safety valves and expansion vessel need checking to keep the system safe. The service covers the relief valves, expansion vessel charge, inlet strainer, pressure reducing valve, thermostats, immersion and discharge pipework.
That pipe goes to the tundish, and water in it means a safety valve has opened. An occasional drip usually means the expansion vessel has lost its air charge. A constant flow, or hot water coming through, needs an engineer the same day. Turn off the boiler and immersion if the water is hot.
It depends on how many people live in the house and how many bathrooms are used at once. Use the size picker on this page for a guide. Most family homes with two bathrooms need around 210 to 250 litres. We confirm it on survey along with your mains water pressure and flow.
It depends on the cylinder size, whether pipework needs upgrading and whether it is part of a full system with a new boiler. We survey and give a fixed price. If you are pairing it with a new system boiler, our online quote tool prices the boiler side instantly.
Yes. We remove the loft tanks and old copper cylinder, fit the unvented cylinder and upgrade pipework where needed. Your incoming mains pressure and flow rate need to be good enough, which we test as part of the survey.
A combi suits most homes with one bathroom. An unvented cylinder makes more sense with two or more bathrooms used at the same time, or a big household. We fit both, so we will recommend whichever suits your home.
More reading: Megaflo common issues and why servicing matters.
Gas Safe Reg. 939000 · 132 five-star reviews · Wigan, Bolton & Leigh