CAN'T DRAIN SYSTEM

Maisie's dad · 9 May 2006

Hi hope you can help. I need to re seal a leaking connection to a rad. It's 8mm microbore. None of the rads have drain cocks. I've been told the only way to drain the system is to turn off the valves on one rad, remove it and rig up a hose to the valve and drain it that way. I suppose I could freeze the pipe but those aerosols never seem to work that well.

Can I do it through the boiler?

Many thanks

ollski · 9 May 2006

Only if the boiler is lower than the rad you want to work on....are we on a combi or conventional system?....either way it may well bung.

Maisie's dad · 9 May 2006

Hi there thanks for replying. Yes the boiler is lower but it's an 18 year old Celtic and I can't see any obvious ways of draining.

Stuart

Maisie's dad · 9 May 2006

Sorry, it's a combi (heats water and rads and no hot water cylinder?)

ChrisR · 9 May 2006

TRy making an air lock.. (Like bunging but you have a Celtic..)
Can't remember if there's a drain cock on the boiler or not - would probably leak if you used it anyway.

Go in boiler and find auto air vent on the back end of the pump, It will have a cap like a tyre valve. It will probably be shut because celtic ones leak like a seive if they're left in the proper open position. Shut it.

Lose some water from the htg to reduce the pressure. Beed a rad if you have to to let it out. Absolutely DO NOT use the pressure relief valve to let water out, or you'll have to replace it.

Turn both rad valves off at the rad you're working on. Now you'll have to drain the rad. Shut all vents

No air can get into the system, so probably no water will get out - try it.

8mm pipes are easy to freeze, by the way, which is the way I'd go, but then I have the kit...

Maisie's dad · 10 May 2006

Thanks for that, I'll give it a try. One thing, I did find a filling loop upstairs in a cupboard, but it doesn't appear to have a drain cock on it but if you can fill system from it you must be able to drain??

HarrogateGas · 10 May 2006

You will not find a conventional auto air vent as ChrisR described on the boiler and infact this is one of the few boiler that wont leak if you open any valves. The air vent seal brilliantly on these, just drop the pressure and it should hold it water.

HarrogateGas · 10 May 2006

Maisie's dad said:
Thanks for that, I'll give it a try. One thing, I did find a filling loop upstairs in a cupboard, but it doesn't appear to have a drain cock on it but if you can fill system from it you must be able to drain??

No as its likely (or should) have a double non return valve on it only allowing water into the system and not out of it.

Maisie's dad · 10 May 2006

Thanks for all your help as usual guys have a good day

Stuart

ChrisR · 10 May 2006

Harrogate I've only seen one of thes so You're coming from a position of greater knowledge I daresay, but... That one had a normal sort of float and rising bung affair in what they call the "air separator" which is behind the pump. No chance of it sealing if the system sucks, as far as I can work out. Same in effect if not appearance as a normal aav.
The arrow indicates the normal external bung/screw most air vents have:

I also remembered a comment I saw 3 years ago and

found it:

Bernie said:
"The air vent was always a horror. While doing training at Chaf I was told to always, always, make sure this was open to bleed air. Serious stuff happened to the boiler (like it melting) otherwise. What they did not say was that most systems are contaminted and that this vent doesnt like even slight contamination. To the extent even with a new air separator you could not get out of the door without the blow-off pipe dripping. "

Maisie's dad · 10 May 2006

Thanks for all that info everyone. So just to be be clear, I simply have to undo the screw in the picture which will let air out of the system, then the pipe going into the radiator should not spurt water when I undo it??

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

CAN'T DRAIN SYSTEM

Similar threads