Unvented Hot Water Cylinder Installation in London

Mains-pressure hot water at every tap, no loft tank, showers that feel like showers.

No call-out feeNo night or weekend surchargeFixed price before we start12-month workmanship guarantee

Unvented cylinders are the upgrade older London homes feel most, installed by G3-qualified engineers, because the law and physics both insist.

Unvented cylinder installation in London: what the price includes

01
G3 qualified installation
Unvented work legally requires the G3 ticket, ours carry it, and the Building Regs notification is included.
02
Sized for the household
Bathrooms, occupants and mains flow measured; an undersized cylinder runs cold, an oversized one runs bills.
03
Safety stack done right
Tundish, discharge pipework and expansion controls installed to spec, the parts that make “unvented” safe.
04
Annual service available
The expansion vessel and safety valves want a yearly check, pairs with the boiler service visit.
05
G3 registered, and the paperwork filed
Unvented cylinder work is notifiable under Part G of the Building Regulations and requires a specific G3 qualification on top of Gas Safe registration. We hold it, and we notify building control, which matters when you sell the house and the buyer's solicitor asks.

Local conditions we work around

Unvented cylinders and hard water are a demanding combination. At London hardness the coil scales, heat transfer falls away, and performance degrades long before anything actually fails, which is why the annual service genuinely matters here rather than being a formality, and why a scale reducer on the mains is worth its cost. The G3 requirement applies regardless: unvented work is notifiable and must be done by a qualified operative, with the discharge arrangement properly terminated.

Where we work in London

One rate card for all of these areas, with no extra charge for distance. Every area page lists the streets it covers.

St Albans Hemel Hempstead Borehamwood Potters Bar Hertford Harlow Brentwood Upminster Dartford Gravesend Orpington Sevenoaks All London areas →

Unvented cylinder installation in London, your questions

Unvented vs a combi?

Two showers running at once is the deciding question. Combis serve one outlet well; a cylinder serves the whole house simultaneously. Big household, more than one bathroom, cylinder wins.

What does it cost?

From £1,450 fitted replacing an existing cylinder; full conversions from vented (removing tanks, upgrading pipework) £2,500–£4,000. Fixed after survey.

Why does mine dribble from an outside pipe?

The discharge pipe running means a safety valve is passing, commonly the expansion vessel has lost its charge. It's the system telling you it needs its annual service; ignore it and the next part to fail is pricier.

How is it different from a normal hot water tank?

It is sealed and fed at mains pressure, so every hot tap and shower runs at the same pressure as the cold. No loft tank, no pump needed, and a far better shower. It also has safety devices that a vented tank does not, which is why the annual service is not optional.

Does it need servicing every year?

Yes. The expansion vessel, the temperature and pressure relief valve and the tundish all have to be checked annually. In hard-water London the discharge components scale up faster, and a seized T and P valve on a mains-pressure cylinder is genuinely dangerous.

Will my mains cope with it?

That is the first thing we measure. An unvented cylinder needs adequate incoming flow rate and pressure, and if your supply cannot deliver it the system will disappoint however good the cylinder is. We test at the stopcock before quoting.

Unvented Hot Water Cylinder Installation? Call.

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020 3674 8514

Or WhatsApp 07865 292684

From	£1,450 fitted
Next availability	2 weeks
Guarantee	12 months
Quote	Fixed, in writing