Fitting a new shower - isolating indirect hot water system!

[Bjpuk]

Hi, I have used is website many times before and it has got me out of stuck a few times, this time I am positing with the hope of a little help!

I am fitting a replacement shower at my parents,

The hot water system is an indirect system, there are 2 header tanks in the loft and these are vented.

I need to knock off the hot water before disconnecting the shower.
My understanding was that if I knock off the cold water feed to the copper cylinder and drain the hot water at a tap downstairs (shower is upstairs by the way) this would empty the system to a point where I can work on the shower.

The hot water seems to run out downstairs at a considerable rate still after even 10 minutes, am I missing something? need I isolate other parts of the system?

I have done work on my own hot water system, this is a basic system with no boiler involved though.

I know I am capable of the physical changing over of the shower unit if only I could isolate the hot water!

Any help is appreciated!

 

[seco services]

As you say isolate the gate valve on the supply to the cylinder if it's not stopping the flow from the hot tap fully then the gate valve is more likely not closing fully, common on gate valves.

Have you no iso valves on the shower supplies itself ?
You can always bung the feed pipe in the loft tank to the cylinder, and at the same time change the gate valve for a lever valve.