System draining problem....

27 Nov 2006
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United Kingdom
Hiya - hope someone can help! :D

We have drained our ch system partially but can't drain the lower radiators.

We turned off the boiler, tied off the ballcock in header tank, opened the drain cock downstairs and drained some water out, we then opened the upstairs bleed points, this drained out more water. Now we seem to have empty upstairs radiators but the downstairs ones are still full - but won't drain! We have emptied some water into the header tank to test for blockage, but we got a similar amount out at the drain point so presumably no blockage there. Any suggestions are gratefully received. :LOL:

Thank you
SAM xx
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Have you got concrete floors downstairs?

Are your downstairs radiators connected to pipes that come down from the ceiling?

If so, the only way an ordinary drain cock could drain those radiators is if the water ran upwards from the rads into the pipes and then down again to the drain cock.

You need a drain on each downstairs rad.

These are very handy and will probably fit in place of your lockshield valves.

Thank you!

We have got concrete floors and drain cocks on each rad - we are happy to admit we are thick enough to not realise we needed to drain every one :oops: ! Do we also need to drain the boiler? Also, do we fill up the system in the standard way?

Many thanks
SAM xx
Look at it logically.

Every drop will need draining from the lowest point.

I had to sack an apprentise who thought the open vent was filled with air!

Blocked cold feeds were not his speciallity.

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As John says, you have a drop fed system, they need draining one by one. You've only drained the primary feed. Why do you want to drain the whole system btw?
We are wanting to drain the whole system because we screwed up! We took off a radiator to replace some buckled 10mm pipe and to decorate. That went well and we replaced the radiator with no problems. Refilled the system, again no problems. When we tried to re-start the ch/hw the boiler wouldn't fire up. We managed to get it to fire a couple of times but it only stayed on for about 2mins then switched back off - therefore no heat or hot water!
After asking questions on here and looking all over the net, also talking to local plumers merchant, the concensus of opinion was that there was an air blockage somewhere in the system and the only way to sort it was to drain the whole system in its entirety...

Suggestions welcomed...

SAM xx
Hmm, so you drained the system, got an airlock, now you are told to drain it again? :oops:

My advice would be to vent all availble rads, pump, boiler, air bleeds etc.
Is your boiler high or low situated in the circuit?

You may find if you struggle into your loft vent pipes to the radiator flow/returns connected that you can bleed or unscrew to let air out.

Turn your pump on/off between ch/hw.

Failing that take out the thermostat on the boiler and let it boil over, only kidding :p
Try bleeding the pump. If the pump is full of water it will probably be able to push any air along until it gets into a rad and you can bleed it out. You many have to turn off all rads and open them one at a time.

It is possible to fill a syst from the bottom up by putting a garden hose on the lowest draincock and filling from there. This method is said to reduce airlocks.

When running the pump to push air out, set the boiler stat to "off" if you can so it does not try to fire.
We bled all the rads, the boiler, the pump - the boiler is downstairs.

I've been in the loft and can't find any vent pipes...

We've tried both the hw and the ch, timed, on continual, on frost and over-riding to put the heat/water on no luck at all.....

A plumber is the very last resort as we don't know any - and no one else seems to know one that is good enough to recommend, also we can't afford it! Anymore suggestions would be great!

Thanks for your help
SAM xx
Your motorised valve(s) open when you drained/refilled? How did you bleed the boiler btw? Sometimes airlocks are arses to get rid of, patience/talking to god helps at 8pm on a Friday night. :D

Keep the system running without the boiler stat on, as i say vent what you can, there is some tricks, but they not for the DIYer, also they haven't worked for me, persevere i'm afraid or paaaaaaaaaaaay up.
if your boiler ran for two minutes with no water circulation,the chances are the overheat stat has tripped , check the instructions in how to reset it
To bleed the 1st time, we took a rad off and used the rad valves to bleed the system (we tied off the header tank). We though we'd bled the whole system, but obviously not. We also bled the boiler when it wouldn't fire by turning the bleed valve on the front of the boiler.

There isn't a boiler reset and if you leave it for about 20 mins or so you can make it re-fire, again for about 1 1/2 - 2 mins. No manual available to check out any details - sorry!

How do you keep the boiler running without the stat on? If you turn the stat of doesn't it just stop the system running?

Not sure where the motorised valve is.... possibly under bathroom floor. We'll go have a look now.

SAM xx
Sam, i'm getting tired. Post EVERY detail on what system you have. Start with the boiler, make, model. What clock you have, room stat, trvs? Have a look in the airing cupboard or loft for possible pump/valve(s). Where is the small header tank? Trace all pipework etc . We can't see the set-up don't forget so it's hard to diagnose, for free anyway :LOL:
Sorry to mess you about, your help is greatly appreciated.

The boiler is: Ideal mexico Super 2 CF60
Controller is: British Gas comfort controller
Boiler/controller by the back door downstairs.
Room Stat: ? no idea. Its a strange little gadget near the garage door. No dial, nothing. I've never seen one like it before.
TRV's : yep, we have them on all radiators except one upstairs.
Downstairs: 4 rads
Upstairs: split level by 2 steps, top level 3 rads, bottom 2 rads.
Small header tank: in loft
Airing cupboard:Lifestyle mid position valve, has black `slider' but won't slide. AlsoCelica multi head TF110 pump.

Thank you, hope this is of use..

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