Always getting air lock when refilling system

[markyhud]

I have drained and refilled my system a few times (with some cracking advice off here) and each time I still end with an air lock. After draining down I re-open the valve in the f&e tank in the loft, let it fill and then start bleeding downstairs rads first to encourage filling. Once all the downstairs is done I move upstairs and again bleed each rad in turn I then bleed the screw on the pump and finally the vent in the airing cupboard next to the coil. I then have the boiler set at 0 and turn on hot water for a few seconds, go upstairs and bleed the pipework again. I repeat this a few times and then turn on the hot water and turn the boiler up. I then switch off the hot water and then turn on the central heating by itself. I work round each rad and bleed any air.
After all this I still end up with air in the pipework and coil. Grrrrrr!!!
As the system is initially refilling should I leave the vent open next to the coil to encourage filling of the airing cupboard pipework?
I was thinking of partially draining it down (via lowest rad) and then using cold mains water and refill from the bottom up. I am hoping this would fill the pipework and coil and push any air up into the tank in the loft. Is this feasible?

 

[mountainman]

My advice would be to stop draining and refilling the system.
I believe that there is a support group for OCDDD.
(obsessive compulsive draining down disorder)

 

[markyhud]

My advice would be to stop draining and refilling the system.
I believe that there is a support group for OCDDD.
(obsessive compulsive draining down disorder)

Very good mate. I'll have to get that CCTV taken out of this house!!
On another note could it be the F&E tank being too full. Can this have an effect on air? How full should it be?

 

[mountainman]

One third full is about right.
Why do you keep draining the system???

 

[markyhud]

I don't keep draining it to be honest. I've done it a couple of times over the past few years. I recently asked on these forums which is the best cleaner to use as it has never been cleaned in it's 14 year life. Had settled on fernox f3 but just not had time to drain it down and add it. I looked in the loft the other day and the water in the f&e tank was brown!! Today i've drained it down and cleaned this tank out. It was full of orange/brown/rusty water at the bottom. So I think this might possibly be causing the gassing and the kettling noise. I still haven't added the cleaner as I haven't got round to buying it. Anyway I was very careful when refilling but it still gurgles through the pipework and coil when the hot water is first turned on

 

[Ch4 plumbing]

Have you got any of these on the F/R to the cylinder? If not cut one into the return pipe and that will help get rid of air at that point.

 

[markyhud]

Yeah this is where I am having to bleed air from probably once a week.

The hot water seems to gurgle when first turned on but this has possibly been caused by the rusty water in the header tank. Now I've cleaned that out I'm hoping the noise settles but immediately after re-filling and carefully bleeding it's gurgling again at the airing cupboard.
What effect if any does it have if the header tank is too full?

What about blasting the air out by attaching cold water mains to the lowest drain point?

 

[diamondgas]

In my experience you'll always have a settling period where the air will find its way to somewhere or tother and stay there! How do you know you have airlocks?

"Rusty water in the header tank!" .... That's something to raise the 'something dodgy there' eyebrow Is the system 'pumping over'? Water warm/hot in the header tank at anytime?

 

[markyhud]

The house was newly built 14 years ago and the CH hasn't had much TLC until the last few years. In fact I've only paid attention to the F&E tank today. It was manky!!!! And I did notice afterwards that the pump was pumping over via the vent pipe when it was set to speed 3. At setting 2 (where I normally have it) it is fine but I did notice the level was quite high. In fact the L shaped piece of the overflow is submerged in the water.
I tend to vent/bleed the system and then within a few weeks it becomes noisy again. However today it started gurgling immediately after refilling so I think I may be doing something incorrect when refilling and trapping air somewhere.
Basically I've got 2 issues
1. Long term air/gas that needs occasionally venting and is noisy
2. Problems re-filling the system without getting air trapped.

 

[diamondgas]

The house was newly built 14 years ago and the CH hasn't had much TLC until the last few years. I've I by really paid attention to the F&E tank today. It was manky!!!! And I did notice afterwards that the pump was pumping over via the vent pipe when it was set to speed 3. At setting 2 (where I normally have it) it is fine but I did notice the level was quite high. In fact the L shaped piece of the overflow is submerged in the water.
I tend to vent/bleed the system and then within a few weeks it becomes noisy again. However today it started gurgling immediately after refilling so I think I may be doing something incorrect when refilling.

'L' shaped pipe sounds like a bylaw kit! Only necessary on a domestic feed tank I believe? ... however pumping over is a serious problem ... clearing air depends on the pipework configuration and pump position ... Check for pumping over on water only, heating only and then both on together! If it occurs on any I'd advise you get a decent plumber in who knows how to overcome the issues...!

Continual venting may be an indication of 'active corrosion'/pumping over or 'surging' occuring ... IMO