Vented and unvented — what's the difference?

Vented cylinders

The traditional setup. A cylinder in the airing cupboard fed by a cold water tank in the loft. Gravity-fed, so water pressure at the taps depends on the height of the tank above them. Common in older properties. Some have pumps or pressure storage vessels to compensate, but that adds complexity without fixing the root cause.

Unvented cylinders

Fed directly from the mains, so no loft tank needed and significantly better water pressure at every tap and shower. The difference is immediately noticeable. The upgrade most customers choose when replacing an old vented cylinder. Requires a G3-qualified engineer to install — we hold that qualification. If mains pressure is poor, there are other solutions — we'll assess and advise.

What we do

Installation & replacement

  • Like-for-like vented cylinder replacement
  • Upgrade from vented to unvented
  • New unvented cylinder installation
  • Loft tank removal when converting to unvented

Repairs & diagnostics

  • Leaking connections and pipework around the cylinder
  • Hot water performance faults — no hot water, not enough hot water, water not hot enough
  • Unvented cylinder components — thermostats, pressure valves, safety valves, bypass valves, blending valves

A split cylinder itself can't be repaired — it needs replacing. But many hot water problems are component faults that we can diagnose and fix. If the issue turns out to be the boiler rather than the cylinder, we cover that too — see boiler repair.

Alternatives worth considering

  • Converting to a combi boiler — removes the cylinder entirely, frees up space, and heats water on demand
  • Not every property suits a combi — we'll advise honestly on what works for your house, water demand, and number of bathrooms

Split cylinder?

If your vented cylinder is leaking, a straight replacement isn't always the best option. Depending on the property, it might make more sense to upgrade to unvented (better pressure, no loft tank) or convert to a combi system altogether. We'll look at the whole picture and explain the options before you commit to anything.

Get in touch

Every cylinder job depends on the property, the existing system, and what you need from it. A like-for-like cylinder swap is typically completed in a day; system conversions may take longer. Call or WhatsApp and we'll talk it through.

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