Water pipes going to attic via hot press

[Possom]

A relative of mine has an attic-located water tank and smaller tank for central heating and a bathroom-located immersion tank. There is no shower head. There is an oil boiler for water heating - not a combi boiler.

I noticed there are a total of 6 copper pipes within the bathroom hot press (airing cupboard) going up into the attic.

They are:
15 mm
15 mm
21 mm
21 mm

22 mm
15 mm

These are in two different clusters as grouped above.

Out of curiosity I was wondering what is the purpose of 6 pipes in this setup?

(I have a combi and I don't have this number of pipes going to the attic).

 

[Elkato531]

The pipes I would expect to see are

Rising main 15mm
Cold feed to cylinder 22 or 28mm
Cold distribution 22mm
Cylinder open vent 22mm
Heating cold feed 15mm
Heating safety vent 22mm

It may be that one of the vent pipes is incorrectly sized.

 

[dilalio]

Well, it can differ, depending on the number of outlets on the tanks (usually cold water tank) but in general you would have the following...

1 Rising main (to take mains water up to the tanks) usually 15mm.

1 vent pipe for the CWSC (cold water storage cistern) this allows for expansion of the domestic hot water to dump into the top of the cistern if necessary. Usually 22mm.

1 vent pipe for the CH system, which also allows for expansion and terminates over the top of the CH F&E (feed & expansion tank) usually 22mm but can be 15mm.

1 feed pipe from the F&E to the CH system, usually 15mm.

1 cold feed from the CWSC to the cold taps, usually 22mm.

1 cold feed from the CWSC to the hot water cylinder (where it gets heated to supply the hot taps. Usually 22mm.

That accounts for 5 pipes. A sixth is usually an additional cold feed from the CWSC to supply a shower pump, which requires a dedicated supply. This ideally would be 22mm but is often done in 15.

But, it could be something else... Additonal rising main, overflow pipe, etc... Each install can differ slightly, according to requirements and/or add ons.

 

[Hugh Jaleak]

Combi's eliminate the need for stored water in the loft, so technically shouldn't need any pipes going up there unless the boiler is in the loft.

For a conventional Open Vented system you would require a Cold Water Storage cistern (usually a minimum of 40 gallon capacity), and a Feed and Expansion Cistern (usually 10 gallon capacity), for the CH system. These are usually located in the loft, hence the required pipework, which is explained very well in the above posts.

 

[muggles]

A few photos would help massively...

 

[Possom]

Thanks guys for the feedback - much appreciated.

It may be that one of the vent pipes is incorrectly sized.

Pipes relating to the central heating were put in ~35 years ago and the water tank pipes ~70 years ago, so perhaps they may have been standard at the time.