Draining upstairs central heating

[clink]

Do I drain the central heating from the drain valve on the bottom of the boiler?

What is the procedure for refilling the system?

Thanks

 

[marios_kin]

What system do you have? Combi or tanks and Cylinder?

 

[clink]

Tank in the loft, and hot water cylinder in upstairs cupboard.

 

[marios_kin]

Depending on why you want to drain the system now dictates where to drain it from (and what draincocks you have fitted).

First turn off the boiler.
Second, isolate the water supply to the small tank in the loft.
If you need to drain the boiler itself, attach a hose to the drain cock and open the valve (be sure to have something to catch the drips).
If you dont need the boiler draining then you should find a draincock on each of the downstairs rads pipework or if the pipe run under the floor downstairs you should find a single draincock at one of the system extremities.
Once the water has gone from the loft tank and slowed down its flow, open the bleed valves on upstairs rads (this allows them to empty). Once the system is emptied, do up the bleed valves again. If draining from down stairs rads, you will need to open bleed valves on them as well (but not until water is below their level in the pipework. Dont forget to do them up again.

Refilling the system
Make sure all draincocks and bleed valves are done up (and any joints that have been disturbed are secure).
Turn on the water to the loft tank, allow it to fill till it stops. Then starting with the lowest and furthest from the header tank, bleed the air out.

DO NOT start the heating back up until all rads are bled. Any air still in the system should find a radiator to go to a short while after the system is running again. Only bleed the rads when the heating and pump are off.

PS Why do you want to drain it?

 

[clink]

I want to change a ( I hope) blocked valve, or try and clear a blocked pipe.