Any ideas?

Picture ?

Graeme Hulls said:

Hi all - need to know which pipe is hot water out of my gravity fed hot water tank please - have horizontal two pipes out at the top and one vertical pipe 🤔 roof is boarded so struggling to trace to the tanks 😔 thanks in anticipation 👍🏻P0

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Can't say without seeing it. If this is a tank fed/open vented cylinder, then the pipe off the top will be a supply to the draw off points and a vent over the tank above.
Picture will help.

ShaunCorbs said:

Picture ?

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On way this morning 👍

Graeme Hulls said:

On way this morning 👍

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Hi there- the hot off the tank has a vertical vent back in to the cold water tank in the roof - any help would be greatly appreciated as our plumber is saying he doesn’t know how to do it - said if he puts a boost pump on the hot will it just boost into the tank in the roof ? ive Spoken to the pump manufacturer and they said it won’t thanks Graeme

If your plumber thinks that get another plumber.

Problem with drawing HW from the top outlet is depleting the cylinder and then potentially damaging the pump by drawing air so you he'll need to fit a flange.


Looks like you have secondary hot water outlet so best leave that alone.

If you have a plumber, then seems they know nothing about gravity hot water systems.
On looking at the photos, I think you have 2 hot outlets - the usual hot outlet horizontally from top of cylinder with vent, plus you have a second separate hot outlet at left side of cylinder (immediately above a heating pipe to top of cylinder coil connection) maybe not used as a secondary outlet for a hot circuit circulation, but as possibly as an air free supply (to a shower valve perhaps?). The red headed gate valve is on the second hot outlet, but I would advise you don’t attempt to turn it and have it replaced with lever full flow type valve later.
A pump can be installed in airing cupboard using that side outlet perhaps as hot inlet supply to pump and outlet to the shower or whatever it supplies, but also needs cold pumped as well, therefore a twin pump.
Best you have a plumber look at it all who is experienced in gravity systems and pumps for such.