Whats this fitting

[Monflyer]

Hi - can anyone identify this fitting and its purpose - it is located on the downstream side of a central heating pump. It is fed by 28mm copper but runs into 22mm copper. The lettering is SMC and it has a directional arrow on it. on the far side ( difficult to get a photo) there is a threaded fixture with 10mm bolt head. The system was probably installed

The seal around the square plate which is secured by the 4 screws is leaking ( and dripping onto the pump electrics below) so I need to either replace or reseal it. I presume just unscrewing the plate would result in water everywhere, so I dont want to overtighten and shear anything off. .
Thanks

 

[Monflyer]

Hi - can anyone identify this fitting and its purpose - it is located on the downstream side of a central heating pump. It is fed by 28mm copper but runs into 22mm copper. The lettering is SMC and it has a directional arrow on it. on the far side ( difficult to get a photo) there is a threaded fixture with 10mm bolt head. The system was probably installed

The seal around the square plate which is secured by the 4 screws is leaking ( and dripping onto the pump electrics below) so I need to either replace or reseal it. I presume just unscrewing the plate would result in water everywhere, so I dont want to overtighten and shear anything off. .
Thanks

 

[ShaunCorbs]

Maybe a strainer

 

[Gasmk1]

Could be anti gravity valve ?

 

[Monflyer]

Could be anti gravity valve ?

Thanks - you could be right. Its in the right place for one - but what is the removable cover for ? Guess I have to drain the system down before I reomve the cover ? i.

 

[Last Plumber]

Looks like an old check valve for the reason Gasmk gave. Stopping circulation around heating circuit when DHW only is on?
Guessing! not seen one looking like that before but it could be.

 

[Monflyer]

Looks like an old check valve for the reason Gasmk gave. Stopping circulation around heating circuit when DHW only is on?
Guessing! not seen one looking like that before but it could be.

Thanks, Yep - makes sense as DHW branches off just below the Central heating pump. Was probably installed 30+ yrs ago. Key thing I need to know is can I slacken off those cover screws and attempt to re- seal without draining the system down.

 

[steadyon]

Whatever it is you will need to drain down to inspect / repair it.

 

[Gasmk1]

It’s possibly a flap type so a drain down and a clean and make your own gasket