Change hot water tap upstairs

[RajaStyle]

I don't seem to have a red gate cog next to the cylinder upstairs to isolate the hot water and change the hot water tap.

I have a grey flexi pipe though with 2 black flaps, if I turn one of the flaps down will it stop the cold water refilling the cylinder and allow the cylinder to naturally drain? Pic in link below ;

https://drive.google.com/file/d/1OyTBlXmBu_BK8sJM1h-LabpcBV0C-ny8/view?usp=drivesdk

I would rather not turn the cold mains off and drain the cylinder on demand just to change the hot tap in the bathroom. Thanks

 

[Madrab]

No ... That's the filling loop for your central heating, nothing to do with shutting off your hot water supply.

Looking at those valves it looks like you have an unvented HW cylinder? If so all you need to do is turn the mains cold water off and then run the hot water until it stops. Normally there would be a stop tap upstream of the combination valve but doesn't look like you have one.

 

[RajaStyle]

No ... That's the filling loop for your central heating, nothing to do with shutting off your hot water supply.

Looking at those valves it looks like you have an unvented HW cylinder? If so all you need to do is turn the mains cold water off and then run the hot water until it stops. Normally there would be a stop tap upstream of the combination valve but doesn't look like you have one.

Thanks yes it is unvented HW cylinder, so i have to turn the mains off and let the hot water run until the cylinder is empty ?

Do you have a link to a stop tap i can't see anything on the pipes they just run constant without anything on them that I can see that would isolate the HW.

 

[Madrab]

until the cylinder is empty

The cylinder won't empty, the hot water will just run until the pressure is released from the cylinder.

A stop tap is one these

Or possibly one of these

 

[RajaStyle]

The cylinder won't empty, the hot water will just run until the pressure is released from the cylinder.

A stop tap is one these

Or possibly one of these

No nothing like that and no isolator valve on tap end, what would you say is the way forward?

Turn off the cold water mains and just let the hot water run until it stops something like 250 litres?

 

[Madrab]

When you turn off the mains the HW cylinder will only run until all the pressure to it has been released, then it will stop. It can run for up to a min getting less as the pressure decreases, say 20 odd Litres , no when near the whole cylinder.