Aylesbury/ Keraflo Valves

Aylesbury (equilibrium) valves use a piston design that balances water pressure on both sides, so they shut off cleanly even on high-pressure mains without the hammering or noise you can get with a basic ball valve. This makes them the preferred choice for larger tanks and cisterns where consistent, quiet shut-off matters. Keraflo's range covers the same principle with some detail differences in seating and servicing.

Sizing depends on the inlet pipework and the fill rate you need, not the tank capacity itself — most domestic cold water storage tanks use 3/4" or 1" valves, while larger commercial or agricultural tanks often need 1.5" or 2". Check the existing inlet connection or pipe diameter before ordering, as fitting an oversized valve into a smaller boss won't work without a reducer.

Yes, but you need to specify the correct version — Aylesbury and Keraflo valves are available in both high-pressure and low-pressure variants, and fitting the wrong one can cause poor shut-off or premature wear. High-pressure versions are designed for mains-fed applications, while low-pressure types suit gravity-fed or header tank setups. If you're unsure which your system needs, check the supply pressure at the inlet before choosing.

If the tank is storing wholesome (drinking) water, the valve must carry WRAS approval to comply with the Water Supply (Water Fittings) Regulations. We stock WRAS-approved Aylesbury and Keraflo valves suitable for potable installations, so check the product listing confirms this before fitting to a drinking water system. Non-potable applications such as rainwater harvesting don't carry this requirement, though a quality valve is still worthwhile.

Most competent DIYers and tradespeople can fit these valves without issue — they typically thread into a tank boss or bulkhead fitting with a backnut and washer, and the float arm is adjustable to set your shut-off level. That said, if the valve is feeding a potable water system or connects to mains plumbing, it's worth having a qualified plumber check the installation to ensure it meets Water Regulations. Always isolate the water supply before starting work.

Dripping or failure to shut off is usually down to a worn washer, a damaged seat, or grit lodged in the piston mechanism, and many Aylesbury and Keraflo valves have servicing kits or replacement washers available rather than needing a full swap. If the valve body itself is cracked, corroded, or the float arm mechanism is worn beyond adjustment, replacement is more reliable than repair. Check whether your specific model has a service kit before ordering a whole new unit.