Have a system boiler with a megaflow cylinder. Had to replace a leaking Pressure Relief Valve 95.605.021 - this in the cold water feeding to the bottom of the megaflow. The replacement valve is 95.605.817 and is slightly different. The problem is the new valve has a water-in + water-out with a black plastic 3 bar hand adjuster ( all as you would expect ) but opposite the hand adjuster is an outlet port - but this port is blanked off - going nowhere... I would assume that this port should be linked into the megaflow overpressure drain. Hope I've described the problem so you can understand.. Look forward to any comments - hope you can help. Regards Ken Meek

Please include manufacturer and model of your boiler.

Thanks for looking at the problem...
The boiler is a Worcester Greenstar 30CDi System Boiler
This then feeds into a
Megaflo Unvented Indirect Cylinder - Model CL250HE
Hope you have enough information - if not then please let me know
Kind regards
Ken Meek

https://www.heatingspares247.com/prv-safety-valve/worcester-greenstar-pressure-relief-valve-prv-87161064310-p-1148.html

This is the correct PRV for your unit, according to the manufacturer, the one you replaced and the one you replaced it with were not from the manufacturer. It's possible this part was changed before, and functions with your system, as will this one as this appears to be designed for an additional water cylinder, probably from the loft, which is not needed for your unit from what I have read.

http://www.worcester-bosch.co.uk/installer/boilers/gas-boilers/greenstar-30cdi-classic-system

Logically though, if your previous part didn't have the extra port, this one should not need a connection either. Thats my theory, but you should follow up with the manufacturer of your unit, or provide me with the manufacturer of the PRV you are using.

Sorry couldn't provide a picture as my attempts at resizing failed.