Vented hot water system help

[tireetim]

Can any plumbers please help me? What is this component (see pic) on the vent pipe of my vented hot water system? It is a very simple system, just an immersion with hot water cylinder on the ground floor and cold tank in the loft. This piece is just before the hot water pipe (from the top of the cylinder) goes back into the top of the cold water tank.
I’m not 100% sure what it is (shut off valve or some sort of pressure valve) and why it is there. The diagrams I can find online don’t include this bit.
Thanks !

 

[Dan Robinson]

Looks like a check valve. Get a plumber to have a look and most likely remove it. There should be no valve on the vent of any kind.

 

[CWHEATING]

Is this a wind up?

 

[tireetim]

Thanks Dan, I thought it shouldn’t be there.
CWHEATING - no, no wind up. Why do you say that?

 

[CWHEATING]

Thanks Dan, I thought it shouldn’t be there.
CWHEATING - no, no wind up. Why do you say that?

Because as plumber/ heating engineer this kind of thing is one of the FIRST things taught not do. A valve of any sort should not be fitted to a cylinder draw off unless it’s situated after the vent. This was obviously fitted because one of your mixer valves was passing causing mains cold water to be sent back to your cylinder. Removing this could potentially cause hot water issues.

 

[tireetim]

Thanks CW. I’m not a plumber but have no choice but to do a bit here and there as I live on an island where there aren’t any plumbers (so bodge jobs are common). I am replacing the cylinder and noticed this, thought it was wrong but wanted to check before rectifying it. I understand about the mixer issue and will check that out and install check valves as required. Thanks for your help, it really does help out people like me in this situation.

 

[CWHEATING]

Thanks CW. I’m not a plumber but have no choice but to do a bit here and there as I live on an island where there aren’t any plumbers (so bodge jobs are common). I am replacing the cylinder and noticed this, thought it was wrong but wanted to check before rectifying it. I understand about the mixer issue and will check that out and install check valves as required. Thanks for your help, it really does help out people like me in this situation.

No problem. Just can’t see any reason to fit a check valve to a hot water cylinders draw off unless some sort of mixer valve or tap is passing. Fitting one is a cheap fix but potentially dangerous unless fitted after the vent as it has the potential to fail. Maybe reinstall check valve but move it to the waters draw off and not the open vent.

 

[Dan Robinson]

No problem. Just can’t see any reason to fit a check valve to a hot water cylinders draw off unless some sort of mixer valve or tap is passing. Fitting one is a cheap fix but potentially dangerous unless fitted after the vent as it has the potential to fail. Maybe reinstall check valve but move it to the waters draw off and not the open vent.

I've seen a few with 15mm AAVs fitted. Cylinder looked like a fat lass in a tight t shirt

Shouldn't laugh but really.

 

[CWHEATING]

Auto air vent on an open vented cylinder? ‍

 

[tireetim]

Thanks for your help everyone.