Question 1

What is an unvented hot water cylinder?

Accepted Answer

It’s a sealed cylinder fed straight from the cold main, so your hot taps and showers run at mains pressure with no tank in the loft. Megaflo is the name everyone knows, much like Hoover, but there are plenty of good makes — the Telford Tempest is a regular on our vans. The traditional alternative is a vented cylinder: a cold water tank in the loft and gravity doing the work, which is why old systems often manage little more than a dribble upstairs.

Question 2

Why does unvented work need a special qualification?

Accepted Answer

An unvented cylinder stores a large volume of hot water under pressure, so the Building Regulations treat it as controlled work: it has to be installed by an engineer holding the G3 qualification and notified to building control. That’s not paperwork for its own sake. A cylinder with failed safety devices is genuinely dangerous, which is why the qualification exists and why our engineers hold it.

Question 3

Does an unvented cylinder really need servicing every year?

Accepted Answer

Yes, and it’s probably the most commonly skipped job in the house. The relief valves need testing, the expansion vessel slowly loses its charge (that’s behind most dripping tundishes and pressure complaints), and manufacturers require an annual service to keep the warranty valid — which on a good cylinder can run to 25 years.

Question 4

There’s water dripping from the tundish — is that serious?

Accepted Answer

It’s the cylinder telling you a safety device is doing its job, usually because the expansion vessel needs recharging or a valve is letting by. The fix is normally straightforward. What you must never do is cap or block the pipe — it’s the cylinder’s safe route for releasing excess pressure. Give us a call and we’ll sort the cause rather than the symptom.

Question 5

Can I swap my old loft-tank system for an unvented cylinder?

Accepted Answer

In most homes, yes. The main thing we check first is your incoming mains supply, because an unvented cylinder is only as good as the flow and pressure feeding it. If your mains isn’t up to it we’ll say so and talk through the alternatives, rather than fit something that’ll disappoint you every morning.

Question 6

I’m a landlord — do my unvented cylinders need checking?

Accepted Answer

There’s no unvented equivalent of the CP12 certificate, but you still have a duty to keep the installation safe, and an unserviced cylinder with failed safety devices is exactly the sort of risk that duty covers. Most of our landlords have the cylinder checked during the same visit as the annual gas safety check, so it stays one appointment.

Question 7

What does a service or a new cylinder cost?

Accepted Answer

It depends on the cylinder, the access and what heats it, so we quote over the phone rather than publish one figure. Call 01622 474008 or request a call back — and if you’re still at the weighing-it-up stage, that’s fine, we’re happy to talk it through with no obligation.

Unvented Hot Water

Unvented hot water services offered

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