Changeing a motorised valve body + system drain ?

[SWOLLENGLAND]

I need to change a motorised valve body .
Its in the airing cupboard on the upstairs landing .
I am trying to work out if i can avoid a complete draining of my CH system ,as far as I can see there are three 22mm pipes going into the body (its a three port mid position ??)
1 pipe goes straight down to where I dont know?

1 comes in from the adjacent emersion heater tank
and the last goes to the ajacent CH pump.


I changed the pump last year and there are isolation valves either side so I am confident that I can cut off that supply.

My theory is if I drain the emersion tank and switch off the main house stop tap to stop it refilling that should take care of that

And surely nothing will come up the pipe that goes down ?

Any advice would be appreciated.

 

[cjb1971]

No need to drain the tank,u can turn off the mains and drain system untill water level is below the vale,i usually crack the bottom joint so it is dripping into some sort of container-when the dripping stops u can stop draining down.

 

[SWOLLENGLAND]

When you say drain the system do you mean the emmersion tank until its below the level of the valve ?surely if I dont turn off the mains it will just refill as I run the hot taps off?
As I say i am confident that I can isolate the pipe on the pump side and I am guessing (hoping nothing will come up the other one which should mean the only spillage I get is whats sat in the valve body and the few inches of pipe either side .

 

[SWOLLENGLAND]

Mission accomplished with some minor mopping up ,which i could have avoided if I had realise the pipe that comes from the emmersion is capable of being turned up wards so allowing the excees water to go back in.

Ah well lesson learned and a few quid saved .