Old House 1 pipe system airlock

[mutt & jeff]

Hi all,

I hope you can help as I've just had a pretty bad day on the job...a freeze pack let go after 10 minutes, half-way through a 3 radiator bay window removal. We managed to complete the installation of new valves after a drain down.

We re-filled & have got the central heating working downstairs....but upstairs is cold..so it's probably an airlock. We've bled the rads...but they all fill from the top & exit from the bottom which doesn't make it straight forward. Any suggestions would be most welcome...please!?

Regards

Doug

 

[Centralheatking]

Have you shot it up with mains water ? connect a hose to the filling point - witha jubilee clip
and give it plenty of squirts - if you go too far the overflow from the f& e will drop water
outside - if the overflow is connected

Its a good way of gettin things like airlocks sorted

centralheatking

 

[tamz]

Drain it down completely and refill.
TBOE makes no difference to the filling. The airlock(s) will be on the legs to the rads off the main run which you can't push with the pump.

 

[mutt & jeff]

Thanks for the suggestions...the only access to the system is via the F&E tank...so I don't know how I'd get mains water to it? It's a very old 1 pipe system...i.e. there is a mostly visible pipe running round the house with T's off to and returned from each radiator...it didn't even have a drain off point!?...we had to drain it from the top of the radiator (which was already open when the freeze pack failed!) & then work our way down.

Any more suggestions welcome?

 

[lame plumber]

use a self tapping/cutting doc at the lowest/furthest point in the system and hose onto that.

http://www.toolstation.com/shop/Self+Cutting+Drain+Off+Cock+/p50376 found on recent post

 

[TBServices]

In hindsight, should have fitted a drain off while drained down. Above advice is good but means leaving in what I would consider to be a temp fitting.

 

[lame plumber]

u could always freeze it and use a comp fitting

 

[mutt & jeff]

u could always freeze it and use a comp fitting

What a refreshing idea! :90:

So draining and having another go is my best bet then?

Can I ask why I wouldn't just get the same result again?

I'm more of a bathroom plumber than a heating engineer & the few drain downs & refills I've done before have all been pretty much by the book...so excuse me if I'm asking silly questions.

 

[Best]

You could just try isolating any of the rads not working & opening a rad valve into a hose to clear airlocks.
Might be a pain if you have to do a lot of rads though!

 

[justlead1]

Choose a rad and room where a bit of water would not cause drama. freeze the one pipe between the rad branches. Crack the valve unions, or remove air valve bush screw in C to Iron and piece of short copper (having turned of valves) aim the open end of valve or copper into a bucket turn on, turn off and do other one. Turn heating on and hope for the best. (You will notice when pulling air, both noise and visual)
Good Luck

 

[Centralheatking]

An other way we use is to choose a radiator - usually a single small one.

Close both ends at the valves make sure the bleed is closed..... loosen off the
big knucle joints to finger tight .........and very quickly do the last turn to undo
pull of the valves and flip the rad upside down ! bingo

access to the system to drain down do what you will

centralheatking

 

[Mikefas]

Yes do what chking above says but on an upstairs rad that isnt working then open each valve in turn into a basin and you will draw out the air. pain in the butt but will do the job.

 

[tom609]

cap the vent and connect up to the mains at the point of the air lock or nearby connect in by taking the air vent plug out and using a male iron to copper fitting that way you can still run the heating system and check if its worked

 

[tom609]

another thought is the pump ok

 

[mutt & jeff]

Hi Guys,

Thanks for all the suggestions. I'm happy to say that when I went round today I could feel warm water in the pipe that runs under most of the radiators. I just bled each rad in system order (easy to spot due to the exposed pipe) & gradualy filled them up.
As it's such an old system & gravity fed it took about 90 minutes...but all done now!

 

[Centralheatking]

Its always nice to read the end to a story - thanks for letting us know your sorted
centralheatking

Hi Guys,

Thanks for all the suggestions. I'm happy to say that when I went round today I could feel warm water in the pipe that runs under most of the radiators. I just bled each rad in system order (easy to spot due to the exposed pipe) & gradualy filled them up.
As it's such an old system & gravity fed it took about 90 minutes...but all done now!