An unvented cylinder gives you hot water at mains pressure at every tap and shower in the house, with no tank in the loft. If your upstairs shower has never been more than a dribble, this is usually the fix.
Unvented work is legally restricted to engineers holding a G3 qualification, because an unvented cylinder is a pressure vessel. We hold it. Mr. Mullah and our engineers are fully G3 certified.
| Feature | Vented (traditional) | Unvented |
|---|---|---|
| Water supply | Fed by a cold tank in the loft | Fed directly from the mains |
| Pressure | Determined by the height of the tank above the tap, so weak upstairs | Mains pressure at every outlet |
| Loft tank | Required | None |
| Space | Cylinder plus loft tank | Cylinder only |
| Shower | Often needs a pump | Usually no pump needed |
| Installation | Any competent plumber | G3 qualified engineer only |
| Servicing | Minimal | Annual check of expansion vessel and safety valves |
| Requirement | Works anywhere | Needs adequate mains flow and pressure |
The single deciding factor is your incoming mains flow rate. An unvented cylinder in a property with weak incoming mains will not perform, and no amount of cylinder does anything to fix that. We measure it before quoting.
Poor hot water pressure upstairs, particularly in the shower
You want to remove the loft tank, often to convert the loft
Two or more bathrooms, where a combi would run out of flow
Replacing an old copper cylinder that is corroding or has lost its insulation
New builds and full renovations
You want a decent shower without fitting a pump
Flow Rate Assessed First
We survey your water mains before quoting.
We will tell you if it is not the right answer. If your incoming mains cannot supply enough flow, or if the pipework in the property is old microbore that would restrict it anyway, an unvented cylinder will disappoint you and we would rather say so before you spend the money. In those cases the honest answer is often mains pipework upgrade first, or a different approach entirely.
Mains flow and pressure test before quoting
Correctly sized cylinder for the number of bathrooms and occupants
Removal of the old cylinder and, where applicable, the loft tank
Expansion vessel, pressure relief valve, temperature relief valve and tundish, installed to specification
Discharge pipework routed and terminated in accordance with Building Regulations Part G
Immersion heater as a backup heat source
Cylinder thermostat and controls wired in
Full commissioning and pressure testing
Building Control notification
Warranty registration and handover
Unvented cylinders need an annual check, and most people do not know this until something goes wrong. The expansion vessel loses its charge over time, and when it does the pressure relief valve starts discharging and you get water running to the tundish or outside.
Faults we see regularly:
Water dripping from the outside discharge pipe or into the tundish — almost always a discharged expansion vessel or a failed pressure relief valve
No hot water — immersion or thermostat failure, or a heating system fault
Water not hot enough — thermostat setting, a failed coil, or the boiler not heating the cylinder
Noisy operation — expansion or a failing valve
Leaking cylinder — usually terminal, and it needs replacing
Expansion vessel charge check and recharge, safety valve test, temperature and pressure relief operation, tundish and discharge pipe inspection, thermostat check.
Call 07866 623870 to book your annual cylinder serviceRing 07866 623870 or message us on WhatsApp. We measure your mains flow rate and provide a fixed written quotation for unvented cylinder installation or servicing.
Areas: Dewsbury · Wakefield · Huddersfield · Bradford · Halifax
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