Jammed Drain Valve

[richie4236]

We have an open vented system that hasn't been drained for some time. The pump is struggling, but before I change it, I wanted to drain and refill the system with X400 for a week or two, then drain and re-fill.

The only drain I can find is on the boiler, which isn't the lowest point in the system, but it'll still let me take most of the water out. I put a rubber hose on the drain and opened it. Nothing. Not a drop of water came out. I opened a rad to see if that helped, but nothing. Put my wet-vac on the pipe, and still nothing. So, carefully, I took the top of the stop cock out. It unscrewed easily enough and revealed a nice clean chamber, with the valve itself still in place at the end of the chamber. The expectation, clearly, is that pressure will push the valve open, but it must be clogged and jammed in place. The boiler doesn't kettle, so the loop itself must be clear beyond the valve. My guess is that it hasn't been opened in ten years.

What's the best way to relieve this? I prodded around to see if it would move, but it's jammed in place, and I have no idea what kind of pressure the water will be under when it's released. I worry I won't be able to get the top back on and end up flooding the utility room with black water.

 

[footprints]

Sounds like you are trying to use the filling loop to drain. Can you post a picture of the boiler connections?
Best way if you cannot find a drain cock is pick the smallest downstairs radiator turn off both ends, open the air vent and undo the rad connection enough to drain into a bowl. Then use the rad valves as your drain tap.
Tips, a roller tray usually fits under the rad, kitchen foil can be used to funnel water into the container, two trays and a bucket to swap while draining, lay a plastic sheet down with old towels on top and don't do it alone if it's your first attempt! You may need to scream more towels and another bucket quick! The last drop of water will be a deep carpet staining black!

 

[richie4236]

Top tip on the foil. Thanks.

I've successfully drained the system and all the downstairs rads.

 

[ChrisJP]

Top tip on the foil. Thanks.

I've successfully drained the system and all the downstairs rads.

So how did you do it?

 

[richie4236]

I gave up on the boiler. It seemed risky, and I couldn't find any installation documents that clearly stated what the valves purpose was. Although, given it's layout and location at the bottom of the boiler I *think* it is intended as a drain.

On closer inspection, I noticed that the downstairs rads have a little silver cap on the bottom of the radiator tail. Wasn't what I was looking for, but looked like it might unscrew. I did the one near the back door first, and that let me drain the whole system down the ground floor level, as we're on a concrete base and the downstairs rads are fed from above on microbore. With every downstairs rad now a dead leg, I tried the same trick on the dining room rad, and that cap sheared of and sprayed water as soon as I applied any torque (getting inky water on a dining chair, but no one has noticed ), so I abandoned that and just started cracking open the nut where the lock-shields meet the rads. I used the valve on the mag-cleaner thing to drain down to just above the boiler, and that got the system mostly empty. I de-slugged a couple of the rads that have always been tepid with the garden hose, refilled, put in X400 and now it's a waiting game.

The pump is still labouring, so I guess I'll replace that when the system is emptied to drain the X400 in about two or three weeks from now.