Air in system help

Z

zooankski

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Cambridgeshire
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United Kingdom
Hi all

I have an open vented system and a problem i cannot figure out :?
Basically i seem to be getting air in to the system continuously and i can vent a little off after the system is used for an hour or so (definately air as have done the lighter test!).
This occurs if i use the boiler for hot water or heating so i am guessing the problem is not in the heating circuit?
I tied up the header tank ballcock and after a few days checked to see if had gone down-it had not so i assume i do not have a leak, also checked what i could see of all the rad pipework coming up out of the floors and could not see anything.
The system was power flushed a few months ago and a magnaclean installed directly after the pump. this involved shortening the feed and vent pipe by 2" to make it fit so i am wondering if it could be drawing air in via the vent?
Can anyone help me find the cause of this and how to go about fixing it?
I want to fit a new header tank next week with closed fitting lid so i might raise it a foot or so and the feed and vent pipe if that might be the cause.
Could i block off the vent and run it under supervision for an hour to see if it stops the air?, failing this i am all out of ideas.
 
I forgot to mention, the cold feed and vent are on the same run, ie the feed tees off and vent continues up a couple of feet before bending over in to the header tank.
The system pump is also set to med so is it worth trying it on low the see if it stops the air and might prove air is coming in down the vent?
 
this is absolute nonsense - basically the short peiece of pipe between your vent pipe and cold feed should be 150mm in length MIN. and then after your cold feed the pump should come nearby (so the system is under mostly positive pressure). the vent tee should be before the cold feed tee also.

why are you changing the f & e cistern??

is the pump after the cold feed connection? is tyhe vent before the cold feed connection? where do you keep getting air ? at 1 particaulr radiator or at more than 1?


a magnaclean (imo) should be installed close to the boiler, not just after the pump).




to prevent pumping over: the vent should hae a minimum of 450 mm ry head, and the pump should e 1/3 of the pump head below the f & e cistern water level
 
thanks for the response. i am changing the header tank as it does not have a lid and has part of the rim split.
i will get a diagram of my system and post it, the magnaclean could not be fitted anywhere else due the boilers position in the downstairs loo and the fact the pipework goes strait in to the ceiling so not a lot of access.
The air collects in the magnaclean and 2 upstairs rads.
The magnaclean instructions say it can be fitted in this position although i have always thought it looked odd considering the y valve sits directly below that ie pump, magnaclen, y valve all withing a couple of feet. The plumber who did the job said it was ok but to be honest i am not too sure.
I am proficient enough to remove it and put it back to as was if it sounds like a problem?
Many thanks for your help!
 
I found an old pic (as i am at work and cannot take another right now). i have crossed out some old text and things that have been removed but it should make some sense.
Is it worth removing it and putting it back to how it was?


http://www.diynot.com/network/zooankski/albums/


I would like to just say that i have installed no part of the system-all original and magnaclean fitted by a heating engineer so i just assumed he was right.
bottom line is i need some thoughts on the air problem. I guess i have not used the heating that much since it was done 2 months ago so could it still be from that point in time?
Also one other bit of info-when the system was drained (before he flushed it) i asked for one of the living room rads down stairs to be removed. he cut the pipes below the rad and capped them. not sure if this could have any thing to do with it?
 
can't really see anything wrong with that install.

did you have air problems before the plumber came ?
 
i thought that the cold feed and open vent should be joined into the system on the suction side of the pump and within 150mm of each other max and not min :?:
 
yes they should ideally, and in 22mm pipe. and then the pump shortly after the cold feed connection.
 
Not sure either, thats a perfectly normal position for a magnaclean bearing in mind it must be after the vent pipe :roll:
 

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