THE WORK
What the job involves
An unvented cylinder gives you mains pressure hot water at every tap, with no loft tank. We are ERS qualified for unvented hot water, which is a legal requirement for this work, and we size, fit, commission and service them properly.
What's included
Correct sizing for your household and outlets
The cylinder, expansion vessel, valves and discharge pipework
Full commissioning and a benchmark record
Annual service reminder so the warranty stays valid
Building regulations notification handled
Why this work needs its own qualification
An unvented cylinder stores hot water under mains pressure. That makes it a pressure vessel, and a stored volume of water above 100 degrees releases an enormous amount of energy if the safety devices fail. This is why the work sits under Part G3 of the Building Regulations and why installing, replacing or servicing one requires a specific G3 qualification on top of any plumbing or gas registration.
The safety chain has several layers and every one of them matters:
An expansion vessel or an internal air gap to take up the expansion as water heats, because water expands by around 4 per cent going from cold to hot and it has nowhere to go in a sealed system.
A pressure reducing valve setting the incoming mains down to the cylinder's working pressure, commonly around 3 bar.
An expansion relief valve to dump pressure if the vessel fails.
A temperature and pressure relief valve, the last line of defence, typically set to operate around 90 to 95 degrees.
A tundish, the open gap in the discharge pipe that lets you see when something has released, and prevents backflow. It sits within 500mm of the relief valve, and the discharge pipe below it has to run to a safe visible point outside, sized and routed to Part G3 rules.
If you see water in or under the tundish, something has operated and it needs looking at. It is not a drip to be ignored.
Installation is notifiable under Building Regulations.
Unvented, vented or combi
A vented system is the old arrangement: a cold tank in the loft feeding a cylinder by gravity. Cheap and simple, but the pressure at the shower depends on how far below the tank it sits, which is why upstairs showers are so often weak.
An unvented cylinder runs at mains pressure, so every outlet gets proper pressure and several can run at once. It needs a good incoming main to be worth having, and it needs somewhere to put the cylinder.
A combi has no cylinder at all and heats on demand, which suits smaller properties. It struggles when two showers run together, and the flow rate is limited by the incoming main.
Cylinders are commonly sized from about 120 litres for a small property up to 300 litres and beyond for a house with several bathrooms. The deciding question is usually the number of bathrooms and whether they get used at the same time. The second question is what your incoming main can actually deliver, which is a measurement rather than an opinion.
Servicing, and why it is not optional
Unvented cylinders need annual servicing, and most manufacturer warranties depend on it.
The service checks the expansion vessel charge, which is the component that fails most often and quietly. A vessel that has lost its charge sends the relief valve into operation every time the water heats, which shows up as water at the tundish and, eventually, a noticeable jump in the water bill. The temperature and pressure relief valve is exercised, the pressure reducing valve checked, and the immersion and thermostat inspected where fitted.
Scale matters as well. Greater Manchester is largely a soft water area, which is kinder to cylinders than the south east, but immersion heaters and internal surfaces still scale over time and a scaled cylinder takes longer to heat and costs more to run.
REVIEWS
Rated 9.86 from 483 Checkatrade reviews
Every review below is from a real Nelson Plumbing and Heating customer across Greater Manchester.
CheckatradeCommunication with the company was fantastic. Turrell came round to complete the job for us and was very professional and friendly. Would use again.
CheckatradeI had a great experience from start to finish. Communication was excellent, they always arrived on time, and I am very happy with the quality of the work. A special mention to Ryan, who was professional, friendly, and amazing with my German Shepherd.
CheckatradeGreat service from start to finish. I had inadvertently purchased the wrong replacement part, but the plumber sorted it with the minimum of fuss. He cleared everything away once the job was complete and shared some useful information for future maintenance.
CheckatradeJob completed to a high standard, operatives were prompt, polite and professional.
CheckatradePrompt answer, arranged for a plumber to visit the next morning, plumber arrived on time and carried out the work efficiently and to a great standard.
CheckatradeSuper friendly, quick response, sorting my leaking shower quickly. Thanks.
GoogleI arranged for a plumber from Nelson Plumbing and Heating to replace an isolation valve at a property in Salford. The plumber turned up on time, did a fast and professional job. Price was cheaper than the estimate. Great service and will be my go to plumber for any further work required in the Manchester area.
GoogleThey arrived promptly as arranged and both introduced themselves and interacted very well with our dog. They installed our new boiler very efficiently and professionally, giving honest advice on which services we may require in the future.
GoogleI cannot recommend Turrell highly enough. He was an absolute pleasure to deal with and professional from start to finish. He took his time to explain everything clearly, which immediately put me at ease, something that is a massive deal for me when dealing with the building trade.
GoogleReally happy with the annual boiler service provided by Tom. Turned up on time, got everything done quickly. Friendly, professional and would definitely use again.
GoogleVery happy with Nelson Plumbing. I am always a bit wary when it comes to jobs around the house, but these guys were very professional, prompt on arrival, got the job done nice and tidy and very pleasant. Would recommend, and the price was very reasonable.
GoogleFriendly and helpful service. I was really impressed with Tom who undertook diagnostic testing and then the replacement of parts on my water system in the house. Thank you for the quick turnaround and efficient service.
FAQS
Questions we get asked
Straight answers before you book. If yours is not here, pick up the phone and ask.
Call 0161 515 9977
GUIDES
Worth reading first
Questions we get asked all the time, answered properly.
SERVICE AREA
Where we work
Manchester, Salford, Trafford, Stockport, Sale and the towns around them.
MORE
Other things we do
Plumbing, heating and gas across Greater Manchester, all handled by the same team.
