CH draining - this OK?

[Hallsy]

My central heating system is an old conventional boiler, pumped, with a header tank in the loft feeding water to cylinder.

I need to drain the rads.

I had located the drain cock on one of the downstairs rads, but there is no radiator currently on that leg.

Will it still drain OK?

 

[Fluffster]

Yes but you will only drain whatever side it is ,flow/return.
Have you removed the rad if so open the rad valve to drain the rest of the system fully.
I take it you have read the faqs about opening blled screws etc.
Pete

 

[John_D]

as long as there is a boiler and other rads joining flow to return the heating will drain to the bottom of the radiators but not underfloor

 

[Hallsy]

Rad has never been there since we've lived here.

That's what I was wondering whether it would drain both sides or not.

Method I have gathered is open drain cock with hose on end, then open upstairs bleeders, then downstairs bleeders.

I'm only working on the upstairs circuit anyhow so hopefully it will drain enough.

 

[Hallsy]

One other thing, obviously I'll turn the boiler controls off but do I need to blow out the pilot light?

 

[Softus]

I'm only working on the upstairs circuit anyhow so hopefully it will drain enough.

In that case there's no need for you to open the downstairs rad vents.

...do I need to blow out the pilot light?

No.

 

[Hallsy]

Oh, well every write up I read said turn off gas & elec, so I turned the gas off anyway.

Got a new problem now, tried both the downstairs rad drain cock & one on the boiler but getting no water out?

If I open the upstairs rads vents I just get water come out of those just as you would if you were bleeding it.

Do these drain cocks get stuck/blocked?

 

[Softus]

Got a new problem now, tried both the downstairs rad drain cock & one on the boiler but getting no water out?
.
.
.
Do these drain cocks get stuck/blocked?

Yup. Welcome to our world.

When this happens I drain the system through a rad valve, as follows.

Expect there to be some mess, so pick a downstairs room without any carpet - preferably a ceramic tiled floor. It will make life easier for you if the rad is a small one.

Lay a dust sheet and some towels around the rad. Shut both rad valves. Open the vent to confirm that the valves work. If they don't then find a rad where they do.

Get some paint trays and a bucket. Even better, a wet vac. Slowly open the joint between one of the valves and the rad - NOT the joint of the valve to the pipe. Catch the water that comes out using trays/wetvac/towels/hands etc., until it stops. Uncouple valve from rad. Uncouple other valve from rad (more towels underneath).

Close rad vent. Keeping it level, remove rad from wall with drip trays catching the black yuck that will drip from the holes. Turn the rad upside down to prevent further drips, and put it to one side.

Obtain a suitable connector to couple a hose onto the rad valve. This will usually be either a 3/4" or 1/2" BSP thread, but some rad valves are different - if it is then remove the tail from the rad, gently, connect it back onto the valve, and then join the hose to the rad tail (1/2" BSP).

Now you have control.

Shut off the supply to the F&E cistern, poke the open hose end into the nearest WC, and open the rad valve. Boil kettle and drink tea until system is sufficiently empty.

You might need to drop the hose into the garden to get all of the water out, but you should limit the amount you put on the garden because this is Fluid Category 3 water.

Before refilling the system I would change every DOC washer I could find, so that next time you can drain using one of them.

 

[JohnD]

Do these drain cocks get stuck/blocked?

yes.

If you unscrew it all the way, it will fall out. Water will then probably squirt up your arm. If not, you can cautiously poke a bit of wire up, and then, water will probably squirt up your arm. You will need to put your thumb over it while you change buckets. You can also screw the plug back in if it hasn't rolled away under something immovable. The water that comes out will probably cause permanent staining of anything it touches.

A long time ago, I was advised that it is useful to fit a full-bore valve (like a garden tap or a washing-machine tap, or a spare radiator valve in new condition) on a low pipe, this will drain out the system much faster than those piddly little drain cocks. It is also much more satisfying to see it gush out, washing away quite a bit of old sludge as it comes.

You can of course attach a hose to the garden or washer tap.

edited, bah, too slow

 

[Hallsy]

Cheers guys, well after some poking around I found that if I nearly fully unscrewed the drain cocks, the washer would unseat, but then the only way to get it to drain down hose is to have it open enough that it also drains out of screw

Softus, I have a point in my kitchen where the rad is removed so if I can find a suitable connector I may well do as you suggest

 

[JohnD]

... the only way to get it to drain down hose is to have it open enough that it also drains out of screw...

put a bucket under it. Also the hose will probably generate some suction, as it drains downwards. If you can attach the hose firmly, you can unscrew the plug and put your thumb over the end.

You will probably find that a Washing Machine Hose; or a Garden Tap Hose connector, will fit the rad valve.

 

[Hallsy]

I jubilee clipped the hose.

I did have some old washing mc hoses but I seem to have lost them.

Wasted cause this morning now anyway as I have to go to work at 1pm, and by that time I needed to have drained the system, modify some rad pipework, refill all ready before I go to work.

It's taken me this long to get the bloody system drained

I'll get some fittings from work later to attach a hose directly to a rad valve, then I can wake up tomorrow knowing full well that all will go smoothly

 

[JohnD]

all will go smoothly

 

[Hallsy]

haha, this is my first big(ish) plumbing job in my house (renovating bathroom, moving basin, rads, etc) and not a lot is going right so far.

Nothing fundamental just a few little things that should be straightforward end up holding me up!!

The missus never understands, she just wants her bathroom back!

 

[Softus]

Wasted cause this morning now anyway as I have to go to work at 1pm, and by that time I needed to have drained the system, modify some rad pipework, refill all ready before I go to work.

It may be interest for you to know that I would never attempt that size of job with any constraint on my time, if I hadn't been the person maintaining the system for at least the previous six months, and only then if I'd been the last person to drain it down. There are too many things to go wrong with a system in poor condition.

I can wake up tomorrow knowing full well that all will go smoothly

I know you winked, but bear this in mind: what can go wrong, will go wrong.