Draining hot water cylinder

[AP77]

I need to replace my shower pump located in the airing cupboard.

The existing pump has a hot feed taken from a pipe which goes into the top of the hot water tank in the airing cupboard.
I am not sure how to isolate this hot water supply to the shower pump. Do I just need to drain the hot water tank, after stopping the supply from the cold water tank in the loft? If that's right what's the best way to do that, just open the hot tap on the bath? I have found a drain tap near the bottom of the water tank but am wondering if this could be a drain tap for the upstairs radiators (it comes from round the bank of the hot water tank but I can't see exactly where it comes from).

Very many thanks.

 

[Iamchamps]

I am under the impression stopping the supply from the cold water tank will kill the pressure so when you let a bit out no more will come out, you do not need to drain the whole tank. The hot water comes out the top of the tank due to the pressure of more water coming in.

Someone can tell me if I am wrong as that is how I always thought it worked.

 

[AP77]

Thanks for your reply.

I've been scouring the web for info and I think you right.

Sounds like after I have stopped the cold supply I need to run the hot taps in the bathroom and this should empty enough hot water from the top of tank for me to remove the hot supply to the shower pump.

 

[dpsservices]

Some pumps flexi pipes have isolation valve fitted on them

 

[copea]

Be ready with a bucket as well, because even though the taps will have stopped running, there will be a fair amount of residual water in the pipework.

 

[AP77]

Very many thanks to all the replies, all helps to give me confidence to do the job myself!

Useful to know there will still be a fair amount of residue water. I would not have been expecting much so may have lost my nerve after a certain amount! Any ideas how much residue there will be? Half a bucket full?

Also, thanks 'dpsservices' re. the flexipipes. The Salamnder pump I am replacing does already have flexipipes with isolating valves, but as I want to put the identical replacement Salmander (RSP75) on a paving slab and some carpet to try and reduce the noise I will need to shorten the feed pipes, hence will need to remove the existing push-fit flexipipes. After some further research it looks like I need to either pull the red collar towards the end of the flexipipe or push the red collar away in order to unlock the push-fit connection.....not sure yet which is correct. Presumably then twist and pull the flexipipe off?

Just picked up the new pump this evening so hopefully will have a go in the next couple of days.