Confusing pipework

[amateur02]

I'm trying to understand my pipework. Can you help?

There are, of course, four pipes entering the (system) cylinder, boiler flow, boiler return, cold supply, hot water out. However, there is another pipe that tees into the boiler flow pipe between two motorised valves.

What is this, where does it come from, and what does it do?

 

[Killy Bing]

Likelihood it Should go to an automatic bypass valve which the. Goes to the return to allow pump overrun when the motorised valves close.

Post a photo

 

[amateur02]

You've caught me out in a white lie. There are actually five pipes going into the cylinder, but the extra one is part of the hot water circulation system. I left it out having decided that it was not relevant to the question, and an unnecessary complication.

Hope the picture helps.

 

[Dotty]

Why are you needing to know?

 

[Simon F]

the pipe between the 2 valves is the flow pipe from the boiler.
you have an unvented cylinder!
what are you wanting to do?

 

[amateur02]

the pipe between the 2 valves is the flow pipe from the boiler.
you have an unvented cylinder!
what are you wanting to do?

Yes, it is an unvented cylinder.
I don't intend to do anything myself (heaven forbid). I'm thinking of getting a professional in to look into problems of knocking, and feel that I should know what all the pipes do so that I understand what he (or maybe she) proposes.

 

[Dotty]

Get him or her to show you on site, it'll honestly be easier to take in.

 

[gassafe]

No bypass in the picture, could be a cause of knocking when system switches off

 

[PhoenixServices]

Looks like boiler flow to me but get whoever looks at the knocking to confirm.

 

[Best]

Pump could be worn, or you have no bypass, which your system probably needs.
And the pipe between the motorised valves is likely the flow going to a tee off with a motorised valves either side to different zones