B877 - 28mm check Valve (Non Return Valve NRV)

The B877 is a 28mm non-return (check) valve from the Aquamatic range, used on larger-bore softener and filtration pipework to keep water flowing in one direction only. WrekinWater supplies it as a like-for-like replacement for an existing 28mm NRV that has started to weep, stick or perish with age. It's the wider-bore sibling of the 22mm B27, sized for installations with 28mm pipework.

Signs you need this part

• Water backs up or drains the wrong way through 28mm pipework when the pump or mains pressure drops.
• A previously fitted valve is stuck part-open and no longer seals fully when flow stops.
• Weeping or dripping is coming from the valve body rather than a nearby joint.
• The existing NRV is well over a decade old and has never been replaced.

Like all check valves, the B877 relies on a spring-loaded disc that opens under forward flow and snaps shut the instant flow stops or reverses. On 28mm pipework, which often carries higher flow rates, a tired spring or perished seal can let the disc hang open slightly, allowing water to flow backward. Left unreplaced, that can let treated or brine-contaminated water travel back the wrong way through your system, and eventually failure can turn from a slow weep into a sudden, harder-to-ignore leak.

Family run and based in Bettisfield, Shropshire, WrekinWater has supported more than 50,000 customers over 15 years and holds an "Excellent" rating on Trustpilot. Alongside Aquamatic fittings, we stock parts for Pentair Fleck, Autotrol, Clack and Kinetico systems, so genuine replacements are easy to find in one place.

How to fit it

1. Isolate the water supply and open a downstream tap to release pressure from the 28mm pipe run.
2. Cut out the length of pipe holding the failed valve.
3. Deburr both pipe ends and offer up the new B877, checking the arrow points in the direction of flow.
4. Join the valve into the pipe run using the same fitting method as the rest of the installation.
5. Restore the water supply and inspect both new joints for any sign of leaking.
6. Cycle the system briefly to confirm steady flow and no backflow through the valve.