Unvented Cylinder Service Cost

Start with the checks, then the price

A service price is only comparable once the inspection behind it is known. The manufacturer sets that inspection. The Heatrae Sadia guide for its Megaflo Eco Plus range recommends maintenance every 12 months by a competent person and lists the work: operate the temperature and pressure relief valve and the pressure relief valve and confirm they flow and reseat, clean the strainer in the pressure reducing valve, and check the expansion vessel charge against the inlet pressure. In hard water areas it adds descaling of the immersion heater elements.

A thorough service therefore covers the list below. If a quote leaves any of it out, ask why.

• Data label read, with set pressures noted
• Temperature and pressure relief valve operated and checked for reseating
• Expansion relief valve operated
• Tundish and discharge pipe checked for flow, scale and visible discharge
• Strainer in the pressure reducing valve cleaned
• Expansion vessel charge tested and matched to the inlet pressure
• Thermostats and thermal cut-outs confirmed in circuit
• Immersion element and terminals inspected for scale and heat marking
• Stopcock, isolation valves and unions checked for limescale and weeping
• Service record completed and handed over

How much does an unvented cylinder service cost?

Only one public guide found for this page prices it. BestBuilders, updated on 22 August 2026, gives a typical UK market range of £80 to £150 for an annual unvented cylinder service. The same guide says London and the South East typically add 15 to 25 percent to cylinder work, so a London figure will sit above that range.

A second source would help and none could be fetched. Firm-specific prices that appear in search results are not a fair basis for a range. Treat the typical UK market range of £80 to £150 as a single data point from a commercial site, not an average.

Labour rates give a rough cross-check. Squote, last verified on 17 May 2026, gives a typical UK market range for a plumber day rate of £240 to £360 outside London and £300 to £440 in London. A service is a fraction of a day, so a quote far above or below the BestBuilders range is worth a question.

What counts as extra?

Findings. A service finds problems and fixing them is not in the base price. Squote gives a typical UK market range of £180 to £320 for the unvented safety kit supplied, covering a temperature and pressure relief valve, expansion vessel, balanced cold supply and tundish, and £80 to £180 for an external 18 to 24 litre expansion vessel. Those are parts prices, before labour.

A fixed service price should come with an answer to three questions: is a failed part a separate quote, is it fitted the same visit, and do you agree the cost first? Descaling elements, a worn stopcock and a scaled tundish are the common additions. The costs of valves and the vessel are covered in TPRV and expansion vessel replacement cost.

What moves the price of a service?

Access: a cylinder in a boxed-in cupboard, under stairs or in a loft takes longer to reach and test, and a second cylinder or a solar coil adds checks.

Scale: where it is heavy, the manufacturer advises descaling the elements, which means draining the cylinder and removing them. That is more than an inspection and is normally priced separately.

What turns up: a vessel that needs only a recharge is a small job, one that has lost its diaphragm is a part, and a relief valve that drips after being lifted has a failed seat. Location comes last, with BestBuilders applying a 15 to 25 percent uplift for London and the South East.

What London Cylinder Specialist charges

The annual cylinder service from London Cylinder Specialist is £180. No VAT is charged.

The guide range quoted earlier comes from one commercial site and is not a London figure, so it is kept apart from this price. Between any two service quotes, the inspection list above is what to check, since the checks behind a service price matter more than the price.

Where a fault turns up during the service, cylinder troubleshooting and diagnosis is a fixed £180. There is no call-out fee.

Is an annual service worth paying for?

On an unvented cylinder it is the routine point at which the safety valves are operated and the vessel charge is tested, and manufacturers such as Heatrae Sadia say the valves need periodic inspection. A vessel that has lost its charge makes the expansion valve discharge every heat cycle, and a weeping tundish found early is a part, not a damp wall. Check your warranty card as well, because the conditions on servicing differ between makers. If the card asks for a service record, a missing or incomplete one is a cost of its own later, which is another reason to compare what each quote hands over.

For the safety question behind it, see are unvented cylinders safe, and for frequency see do hot water cylinders need servicing.

How do I compare two service quotes?

Put the two inspection lists side by side. A quote covering the relief valves, vessel charge and strainer and one that says only a visual check are different jobs. Ask whether a service record is completed and given to you, what is charged if a part fails, and whether the common parts are carried or the visit has to be repeated. Ask too whether the price covers one cylinder or the whole hot water system, since a boiler service and a cylinder service are different inspections even when one visit covers both.

Price comes last. A cheaper service that skips the vessel test is not a saving. What the visit looks like is described under unvented cylinder service.