Unvented Hot Water Cylinder Installation and Servicing
An unvented cylinder can give mains-pressure hot water, but only if your incoming main has enough flow to feed it. We measure static and dynamic pressure before recommending one, then install and service the safety valves, expansion provision and controls as one system.
Why we test your mains first
A larger cylinder cannot fix a restricted incoming main. Before quoting, we measure incoming pressure and flow and work out likely peak demand. That tells us whether an unvented cylinder will actually improve your showers, and what capacity makes sense.
Choosing the right size
Capacity reflects the number of bathrooms, how many people live in the house and how much hot water is likely to be drawn at the same time. A family running two showers at once needs something different from a couple in a smaller home.
Safe installation
Unvented cylinders store hot water under pressure, so the safety controls matter. We take a G3-qualified approach to the valves, expansion components and discharge. Discharge pipework is traced to a visible and safe termination, and everything is commissioned and tested before handover.
You get a commissioning record and a walk-through of the controls, the annual servicing and the warning signs to look out for.
Annual servicing
An unvented cylinder should be serviced every year, separately from the boiler. The visit covers:
- Expansion vessel charge
- Safety valves and the tundish
- Control operation
Warning signs between services
Water running from the tundish or discharge pipe, a cylinder that makes unusual noises, or hot water that suddenly becomes erratic all need looking at promptly. These usually point to the expansion provision or a safety valve, which is exactly what the annual service is there to catch. If you see water discharging, call us rather than leaving it until the next service is due.
If you are moving from a vented system with a cold-water tank in the loft, we explain what changes, where the new cylinder and its discharge will go, and whether the loft tank can be removed.
Cylinders with heat pumps
Heat pumps need a cylinder with a coil sized for lower-temperature operation. We specify that as part of any heat pump installation. We are based in Kelso and work across the Scottish Borders and East Lothian.
Unvented Cylinders questions
Will an unvented cylinder improve shower pressure?
It can where the incoming main has enough dynamic flow. That is why we test before quoting.
How often should it be serviced?
Annually, with the expansion provision and safety controls checked as part of the visit.
Can it work with a heat pump?
Yes, using a cylinder with a coil sized for lower-temperature heat-pump operation.
Where does the discharge pipe go?
It is traced to a visible and safe termination, so any discharge can be seen and dealt with.
What size cylinder do I need?
It depends on bathrooms, occupancy and likely simultaneous use, which we work out at the survey.
What should I do if water comes out of the tundish?
Call us. Water discharging through the tundish usually points to the expansion provision or a safety valve, which needs checking promptly rather than waiting for the next service.
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