Which Drain Cock?

[hyperbole]

Hi,

Trying to drain open vented system to replace some radiator valves. None of the radiators have drain cocks on them but found 2 drain cocks next to the mains supply pipe among tons of spaghetti piping. (See attachment)

Is there a way to tell which one to use? One of the drain cocks is attached to the pipe that goes up (presuming 1st floor or maybe boiler, can't tell), the second one also goes up but there is a split to another 10mm pipe which goes into ground (concrete) presuming to one of the radiators as all downstairs rads have 10mm pipes.

Is it safer to just remove one of the downstairs rads and drain from the valve?

Thanks!

 

[CBW]

You could try to work it out by putting the heating on, but probably a bit laborious for what you’re doing. I would drain from a rad valve. A few ways of doing it. Obtain a compression stop end, or better still utilise one of the new valves:

• Turn off the water to the feed and expansion tank, or the house mains (although you may not be popular).
• Turn off both valves, and check water stops by opening the bleed vent - expect some water discharge so an old towel or a small container to hand.
• Disconnect one of the valves (my preference 1st is a lock shield valve), use the new lockshield valve, making sure it’s turned off (fully clockwise) and fit this to the radiator.
• Attach a hose to the old rad valve, or using a large container and some old towels down and slowly open the valve, and wait until the water stops, emptying the container where necessary.
• Remove the old nut & olive, if needed, or attach new valve to older nut and olive using ptfe on the olive just in case.
• Do the same for all other valves, and turn water back on.
• Vent any rads required
• Check for any leaks.

 

[Elkato531]

Agree with CBW. I wouldn't be touching those drain offs. Drain via a rad valve.