AIRLOCK ADVICE Hot water outlet from header - how do I find?


Postby sbeswick8 » Tue May 20, 2008 11:52 am

:( Hi all, Anyone know where this is on the header as I'm trying to eradicate an airlock which is in the return pipe just outside of my boiler downstairs. Im following advice from previous forum entry as get c heating but no hot water. Prob is, its a one pipe system - so not sure if hot water outlet has any valves,.
Im using Dave Maynaards advice to cover hand on downstairs mixer tap - but also using hose to connect upstairs sink taps to push water through indirect system? is this right?
thanks steve
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Postby htg engineer » Tue May 20, 2008 5:48 pm

An airlock in the hot water pipes can be cleared by placing your hand over a mixer tap or using a hose to connect two taps and back filling the pipes and tank with cold water.

An airlock in the heating system (which is what I believe is wrong with yours) can not. How do you know it's an airlock ? have you drained system recently ??

This airlock can be cleared by,
a)draining and refilling system
b)cracking open the flow and return on the tank/cylinder to let air escape
c) last resort - pulling boiler stat and boiling the airlock out of the system.

The hand and hose over taps will not work for you.

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Postby sbeswick8 » Tue May 20, 2008 8:17 pm

Many thanks for that - think its an airlock as lot of air in system espec in hot water taps in past and has cleared in past and given us hot water. Like you said flushing with cold feed does not seem to be working. Central heating when on seems to give hot but not when just hot water switch on, and i can feel return pipe near boiler is not hot whereas flow is. Tried undoing one valve on tank but no air came out. Any ideas? cheers steve and thanks for your time
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Postby htg engineer » Wed May 21, 2008 6:26 pm

I suggest you get a plumber or engineer out. If there was an airlock in the primaries or heating system that would not affect the water from the hot taps, the air from the taps and the lack of hot water are not linked.

If you get hot water with heating on - it's not airlocked more likely to be a build up of limescale in the primaries stopping the water from circulating without the pump running.

What type of system is it ? gravity hot water ?


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Postby sbeswick8 » Thu May 22, 2008 1:21 pm

Hi Many thanks for that - yes its a gravity system Thing is, it has cleared a couple of times in the past already - which is why I thought it was an airlock. My wife actually says it now does not get hot even when c heat is on. Of course just trying to save calling out if i can try to solve first - if - it is an airlock. Do you think its worth trying to boil it out via taking thermo out like you said to find out if it is an airlock? cheers Steve
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Postby htg engineer » Thu May 22, 2008 3:48 pm

I wouldn't like to say, where I work they've just told us we can no longer pull boiler stats to boil airlocks out of the primaries. It has never happened to anyone who I know - but is possible tank or boiler could fracture, causing hot water to bust through ceilings etc etc - probably a safety precaution after the tank that burst last year that was on the news.

I have done it many times, and it works everytime as long as you don't over do it. Turn stat to maximum, once the boiler is at maximum temperature, taking the stat probe out - the boiler comes back on and it only takes a minute or two then you hear the air clear turn boiler off and replace stat.

Most boilers, you have to undo a gas connection to get to the thermostat so not really a DIY job.

My advice would be to get an engineer out.

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Postby sbeswick8 » Thu May 22, 2008 6:13 pm

Many thanks completely understand what youre saying and I will try that as thermo is accessible. Apprec your help and will be careful!! cheers again for your time Steve
sbeswick8
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Postby sbeswick8 » Tue May 27, 2008 7:51 am

Hi there, just thought I'd feedback re thermo. Took it out and 'cold'pipe did clear - a rush of hot water came down return pipe into boiler. All pipes were then hot - but didnt last and still no hot water. By way - 'do' get hot when central heating on as pipes constantly hot as burner on constantly. Any ideas before a call in? I know you said it could be limescalein primaries - or with it being a gravity system - do you think there is a possiblity I didnt 'fully' clear the air? As i said there was a rush of cold and then hot down the pipe and the pipe then 'expanded' and stiffened- sh i leave thermo out for a couple of mins after the pipes get hot or is it clearly someth else?
cheers Steve :roll:
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Postby htg engineer » Tue May 27, 2008 3:21 pm

Possible the air didn't clear, could still be airlocked - whether or not you decide to try again is up to you.

I imagine it will be quite frustrating if you call someone out and they pull the stat and it clears.

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Postby sbeswick8 » Wed May 28, 2008 5:48 am

OK many thanks Will do
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Postby sbeswick8 » Sun Jun 01, 2008 7:17 am

HI, Just to let you know we now have hot water!!! So many thanks for your help re this - saved me a plumbers charges - just let the water boil a little longer and it cleared the airlock. cheers again steve :lol:
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