G3 qualified · Exeter, Devon
Unvented hot water cylinders need to be serviced annually by a G3 qualified engineer — I'm G3 qualified and I service and repair these systems across Exeter and surrounding Devon. Megaflo, Telford, Gledhill, Heatrae Sadia and similar makes.
Unvented cylinders operate at high pressure. Building Regulations require a G3-qualified engineer for this work.
Gas SafeHappy to confirm Gas Safe registration and insurance details when we arrange your visit.
Annual servicing
Unvented hot water cylinders — the type that runs at mains pressure without a cold water tank in the loft — need to be serviced annually by a G3 qualified engineer. This isn't a general recommendation; it's a Building Regulations requirement. Work on unvented systems by an unqualified person is illegal, and an improperly maintained cylinder carries a genuine safety risk.
I work on Megaflo (Heatrae Sadia), Telford, Gledhill, Joule, Range Tribune and similar makes across Exeter and surrounding Devon.
This is the cylinder's main line of defence. Should it overheat or the pressure climb too high, the T&P valve lifts and lets water out safely. It has a replacement interval set by the maker — usually somewhere around every two to three years.
The vessel absorbs the expansion of water as it heats up. If the pre-charge pressure drops, the vessel fails to do its job and the T&P valve starts dripping unnecessarily. I test the charge pressure and advise on replacement if needed.
I check the PRV is holding the correct setting, and inspect and clean the fine-mesh filter that protects the cylinder components from debris.
Tested for correct operation and set temperature. The pipe from the T&P valve to a safe discharge point is checked for obstruction and correct routing.
Repairs
Lukewarm water, a steady drip from the discharge pipe outside, or pressure that keeps falling away — whatever it is, I'll get to the bottom of the cause before suggesting a thing. Anything I supply and fit comes with a year's guarantee behind it.
What looks like a cylinder problem can just as easily be the boiler or the controls. I'll take in the whole setup — programmer, motorised valve, thermostat, boiler — so it's clear exactly where the fault really sits.
Fitting brand-new cylinders or boilers isn't part of what I do. This is the servicing and repair of unvented systems that are already in place, nothing more.
Questions
Building Regulations Part G requires that work on unvented hot water storage systems is carried out by someone who holds a relevant qualification — in England and Wales, that's G3. An unqualified person working on an unvented cylinder is acting outside the law, and the work won't be signed off.
Annually. The T&P valve typically needs replacing every two to three years. Your cylinder's instruction manual sets out the specific schedule for its components — if you don't have it, the manufacturer's website usually carries a copy.
Possibly. A drop in hot water pressure on an unvented system can be caused by a failed expansion vessel, a partially closed isolating valve, scale accumulation or a failing pressure reducing valve. Call me and describe exactly what's happening — that narrows it down considerably before I visit.
It's a sign the system is working harder than it should be. Usually it means the expansion vessel has failed and the T&P valve is relieving pressure that the vessel should be absorbing. It's not immediately dangerous but it should be looked at — a continuously dripping T&P valve can eventually cause it to fail to seal.
Yes, if that's all that's needed. But if you're calling me out for a valve replacement, it usually makes sense to carry out the full service at the same visit rather than pay a second call-out fee.
No. I service and repair existing cylinders but I don't supply or install new systems. If you need a new cylinder fitted I can recommend you to an installer.
Call 01392 321121 to arrange a cylinder service or discuss a fault. Mon–Fri, 9am to 5pm. If I'm on a job, leave a message and I'll call back the same day.
