Im getting air in system but cant figure out why

[fireman2203]

Hello chaps this is my first post so i would like to say hello first then if possible pick your brains as to why i have this problem.

I keep getting air in my radiators and can sometimes hear it near the pump as well. I can only assume its being drawn down the vent pipe but i increased the depth of the header tank and then the heated water started to flow slowly out of the vent into the tank so i assume the water level in the expansion pipe is correct. All the radiators work fine and the system heats up nice and quickly but im finding im bleeding the 2 rads about every 6 weeks or so!!
Is there any thing else i can check or is there measurements i can make to try and find the cause. The pump is set to number 2 and if i increase it to 3 then again water flows out the expansion pipe into the header tank

Regards

Chris

 

[Softus]

Your system is in an advanced state of corrosion. The air in the radiators is not air, but a by-product of the reaction between the iron in your radiators and the oxygen in the water.

This is a common scenario and you should be able to find lots of topics covering the remedy.

 

[Mr Smyth]

'advanced state of corrosion'..... that sounds scary, Softus.

Could just be that your cold feed is partially blocked. Try placing a magnet next to the copper pipe where the vent and feed join the system. Copper is not magnetic.

Could be that pump speed is set too high. Has the pump been changed lately?

I could go on and on and on

Do the match test when you bleed a rad to rule out H in system. I'll let you work out that one for yourself.

The problem does need sorting out as air in your system will eventually lead to an advanced state of corrosion, but I doubt your there yet.

Mr Smyth

 

[fireman2203]

well the system was updated about 2 years ago so the radiators and the copper tank and pump were all new then. Its got corrosion inhibitor in it and the water looks clean still so im doubtful about the corrosion issue. The header tank filler works fine and like i said water comes out the vent pipe when the pump runs at number 3 speed (runs at number 2 when normal) so i assume thats not blocked. As ive just bled the system again i cant test for H so i will report back then

Question: does the expansion pipe have to be on the return side of flow side of the system. Mines on the return side just before the pump if thats correct?

 

[doitall]

Hang on, edit.

No the vent should be on the flow.

The order should be boiler flow, expansion, cold feed, pump, motorised valve.

 

[fireman2203]

Ahhhhh maybe we have found the reason then when it was upgraded the flow was put on the wrong side of the pump???

 

[doitall]

Ahhhhh maybe we have found the reason then when it was upgraded the flow was put on the wrong side of the pump???

Can you do a drawing or post a pic.

you can email it to me if you don't know how to stick it on the site.

My e is in my profile.

 

[fireman2203]

yes ill take a few pics asap and get them posted with some form of markings with flow and return on it on it.

 

[fireman2203]

Cant post pictures i dont know why it wont let me

 

[Softus]

...and nor will I, unless you say what you've done and what happens in response.

 

[fireman2203]

I click on the Img* icon and all it does is put this [/img] into the box. I dont see an option to brows to the photo i want to upload. Am i doing something wrong?

 

[Softus]

Am i doing something wrong?

Yes - you weren't to know it but the Img button is next to useless.

The instructions for posting an image are here:
http://www.diynot.com/forums/faq.php#23

I use Imageshack most of the time, and the only other thing you need to know is that you place

after it.

 

[fireman2203]

Hopefully you can make head or tail of this photo. I had to do it at work so no decent software to write on it with only microsoft paint hence the air spray writing

Bit small i think so heres another link
http://img267.imageshack.us/img267/2007/picture2withwriting8hh.jpg

 

[doitall]

Thats fine, other than I don't like pumps going downhill.

The pipe you have mark return is in fact the flow.

 

[fireman2203]

isnt return the water going into the pump then and flow the water comming out?