Autotrol Piping boss - 3/4" BSP Noryl - 1/2" BSPT Drain (Female) 40FN4-OPT 1040283 (Old Style)

The 1040283 (40FN4-OPT) piping boss is the old-style 3/4" BSP connector fitted to the inlet or outlet of older Autotrol and compatible control valves, moulded in Noryl with an integrated 1/2" BSPT female drain port. It's the fitting that lets the valve body connect to household or commercial pipework while also providing a threaded take-off for the drain line, and is a common item to need replacing on older valves where the drain thread has been cross-threaded or the boss itself has cracked. This old-style version is stocked by WrekinWater for servicing older Autotrol-pattern valves still in use.

Technical specifications

Symptoms that mean you need this part

• The piping boss is cracked, split or weeping where it screws into the valve body
• The 1/2" BSPT drain thread is stripped, cross-threaded or won't hold a watertight seal
• You're servicing an older valve and the existing boss is the discontinued or brittle early-style part
• The o-ring seal keeps failing because the boss face is worn or scored
• You're replacing a damaged boss found only when disconnecting pipework for a service or valve swap

Why it fails / why it matters

The piping boss is the interface between the control valve body and your household or commercial pipework, sealed with an o-ring and also carrying the 1/2" BSPT drain connection in this old-style design. Because it's threaded directly into the valve body and takes the strain of both the main pipework connection and the drain line, repeated disconnection for servicing or over-tightening during installation can crack the Noryl body or strip the drain thread. A damaged boss typically shows up as a weep at the valve inlet or outlet, or an inability to get a watertight drain connection, and replacing the boss itself is the reliable fix rather than trying to reseal a damaged thread.

Why buy this from WrekinWater

WrekinWater has supplied Autotrol, Fleck, Clack and Kinetico parts to installers and DIY customers for over 15 years from its Bettisfield, Shropshire base, and keeps older, discontinued-style fittings like this old-style piping boss in stock alongside current parts. With more than 50,000 customers served and an Excellent Trustpilot rating, WrekinWater is a reliable place to find the exact old-style part rather than a modern equivalent that may not fit.

How to fit it

1. Isolate the softener at the bypass valve and shut off the mains supply before disconnecting any pipework
2. Unscrew the damaged piping boss from the valve body, noting the orientation of the drain port
3. Remove the old o-ring and inspect the valve body's boss seat for damage or debris
4. Fit a new o-ring to the replacement piping boss and lubricate lightly with silicone grease
5. Screw the new boss into the valve body and reconnect the drain line to the 1/2" BSPT port
6. Reconnect the inlet or outlet pipework, restore the mains supply, and check both the pipework and drain joints for leaks