Unvented cylinder installation in Macclesfield
In short
An unvented cylinder is fed straight off the mains, so every tap and shower runs at mains pressure and the loft tanks disappear. Installation is notifiable under Part G3 of the Building Regulations and requires a G3-qualified installer — it is a pressure vessel, and the safety devices on it are not optional.
Also called: Megaflo installation · mains pressure hot water · pressurised cylinder · unvented hot water system
The difference from a traditional system is immediate and obvious in use. A gravity-fed cylinder gives you hot water at whatever pressure the height of the loft tank provides — often well under half a bar upstairs. An unvented cylinder holds stored hot water at mains pressure, so a first-floor shower runs properly, two outlets can be used at once, and no pump is needed.
It also frees the loft. The cold water storage cistern, the feed and expansion tank and their pipework all come out, which removes the most common source of overflow and freezing problems in the house, and returns useful space.
The safety side is why the qualification exists. A cylinder holding 200 litres at mains pressure and 60°C contains a great deal of energy, and it is protected by a layered set of devices: an expansion vessel or internal air bubble to take up expansion, a pressure reducing valve on the inlet, an expansion relief valve, a temperature and pressure relief valve, and a discharge pipe arrangement that must terminate safely. Each has to be correctly specified, and the discharge arrangement in particular is frequently done badly.
Sizing matters as much as installation. A cylinder is chosen from the household's peak hot water demand — number of bathrooms, bath size, how many people shower in the same hour — and from the reheat rate the heat source can supply. Undersized, you run out; oversized, you pay to keep water hot that nobody uses. It is a short conversation that pays for itself.
The one thing to check first is the incoming mains. An unvented cylinder can only deliver what the supply gives it, so a property with a small or restricted supply pipe may need that upgrading for the system to perform. Measuring flow and pressure is the first step, not an afterthought.
Annual servicing is part of ownership. The expansion vessel charge, the relief valves and the temperature controls all need checking yearly, and most manufacturers make it a warranty condition.
What the job covers
- Mains flow and pressure test to confirm suitability
- Cylinder sizing against your actual peak demand
- G3-compliant installation with full safety device set
- Correctly routed and terminated discharge pipework
- Removal of redundant loft tanks and pipework
- Commissioning, Building Regulations notification and handover certificate
What it costs
We don't publish a price for this yet, because a number pulled out of the air is worse than no number at all — your plumber has to honour it. You'll get a firm price for your actual job when they ring you back, before any work starts. The quote itself is free and there's no obligation either way.
Common questions
Will an unvented cylinder improve my shower?
Almost always, if your current system is gravity fed. It delivers mains pressure to every outlet, so no pump is needed and simultaneous use is far better. The limit is what your incoming mains supply can deliver.
Does it need servicing?
Yes, annually. The expansion vessel loses charge over time and the relief valves need testing. Most manufacturers require it for the warranty, and it is a genuine safety item rather than a formality.
Need this doing in Macclesfield?
Tell us the job and it goes straight to our local plumber — one call back, usually the same day. Free quote, no obligation.