Draining Cental Heating System To Replace Complete Sunvic 3 Way Valve Assemly.

[duttonmark]

Hi, I will need to drain down the CH system to install a complete new Sunvic motorised 3 way valve assembly. The only drain tap I can find is on the pipework adjacent to the bathroom radiator. This radiator is permanently hot whenever the hot water system is activated--whether the CH is 'on' or not (I assume to act as a towel rail) If this drain tap is open, with the valve operating spindle manually turned (needs pliers to do!) to match the 'flushing only' position n the actuator, will this drain down the whole system? Thanks.

 

[PlumbBobBob]

it will only drain down the whole system if it is on the ground floor. oh and welcome to the forums.

do you have any smallish rads on the ground floor you could drain down from? you don't need to drain down totally to change the 3 way, only enough to drain the pipework around the valve.

 

[duttonmark]

Thanks for your quick reply--and the welcome!! I'm in a ground floor flat, with access to my own cold water and CH tanks high up in the kitchen, and hot water storage tank in a hall cupboard---so that sounds promising. I was going to take the opportunity to do a chemical flush, and then add an inhibitor. I reckon that's (possibly) never been done---though the (very) occasional radiators bleed does just yield 'clean' water. Thanks once again!

 

[joni os]

Attach length of hose to bathroom radiator drain off and drain into WC . Occasionally lift hose to height of 3 port valve. when water stops draining at that height, you will have drained down enough to change valve.

 

[PlumbBobBob]

also just to add, best to turn your mains water off otherwise when you drain down the tanks will be constantly refilling.