Air lock i think

[Johntheo5]

Thanks when i tested with a magent it only seemed to stick / get attracted to the pipes very close the separator? so if i cut close to the separator then how do i clear it out as wouldnt i just dislodge anything and 'move it further around system, or if that is the purpose should i then had some sentinal x400 or something to 'clean' system

Looking at my pipe work and tracking the pipes down from loft it appears to be like this, does this look correct and the red circle is that where you on about cutting it? and a very stupid question what 'gap' should there be between the pipes for a compression connector to fit.

View attachment 339833

Thats where I would cut them but first,
can you measure the distance indicated, basically this must take up the full length of the coupling, when the two pipe ends bottom out inside the coupling there is only ~ 3 to 5 mm distance between them so thats all you should shorten the pipe by, if cutting the vertical part as well then probably no need to cut any more out of the piece indicated, you will soon know when the cuts are made and pipe removed.

 

[scotthud]

I will when i get home, isn't that the feed to the boiler? as the one on top is upto the F&E feed vent pipe and then the next one is to the F&E outlet and the one below your arrow is to the pump ( or is that just a picture to show where to measure )

 

[Johntheo5]

Yes, you are correct, its the one you say, that may be a bit trickier, take a few measurements anyway.

 

[scotthud]

Yes, you are correct, its the one you say, that may be a bit trickier, take a few measurements anyway.

When you say trickier in what sense, as the cold feed comes straight down the wall into the bend - air separator, so could i not cut the pipe slightly above the bend ? Then as you say if its blocked further up the pipe i can cut the section out? my only worry is how to clean the separator though?

or i found another post on here, where they have used a 3 way air separator instead of a four and it looks like they have the cold feed and pump pipes connected together but im unsure how i would mange all that in such a tight space and without the ability or equipment to solder? and im im a novice with plumbing plus this would mean cutting all the pipes buying a new separator and connectors/pipe

 

[Johntheo5]

You might be able to clear it with that one cut on the vertical that you suggest, just try it, if you are thinking of installing a new separator, forget it, you might be able to modify it to the very best system (IMO) that was installed in my house 54 years ago, from new, no separator, its a combined cold feed and vent like shown below, some rads are over 40 years old.
You would throw away the separator, bring the boiler flow pipe directly to the pump inlet, T in the vent directly to this pipe and T in the cold feed to the vent pipe, if the cold feed is blocked, tee it in up as high as possible or just underneath or at the F&E like mine.

 

[scotthud]

Here's a simplified version of what you're trying to do ...
It was thought you had a blockage in the pipe from the F&E tank ... the top up pipe ... by applying mains water into the system with an hose pipe and blocking the vent pipe A it will force water thro to B and into the tank.

View attachment 339720

Update, got home, put 22mm push blank on Pipe (A) (Feed Vent) connected downstairs rad to hose and outside tap, ive turned water on and waited nothing for about 10 mins the F&E was not getting any water to it, then i started down stairs and bled each individual radiator in turn loads of air came out of everyone and they filled up with water AND the same happened upstairs, once i had bled them all i went back into loft and the F&E started back filling from the outlet pipe (B) in the diagram above. Ive disconnected hose unhooked the ballcock and opened the vent on the fill valve, im going to leave it for an hour or two whilst im out coaching kids football and then, see whats what when i get back.

Any suggestions and how to proceed next? Thanks

 

[Johntheo5]

If nothing happened after 10 minutes then either the tap was only cracked open to fill the system and was compressing the air in the rads but not sufficient to push water through the cold feed which could be still practically blocked but hopefully not. To prove it, fill the F&E cistern, turn off the ballcock filling, open a rad drain or drains down stairs, if the cold feed is reasonably clear then the cistern level should start falling failing rapidly to keep up with the draining. If it doesn't try back filling again and let it overflow but not over the top of the cistern, it might clear it eventually.

 

[kidgreen61]

You have a blockage somewhere, almost certainly around the area near where cold feed joins the system, or in the air separater.

 

[Ray1000]

10 mins might be expected with 15 radiators and the mains only cracked open … I imagine there’ll still be a bit of air to come out of the radiators after it’s been stood a while …

 

[Ray1000]

You would throw away the separator ...

I don't think I've seen a separator until now ... is it normal to have one?
Is the "auto vent" on ours in place of a separator?

 

[scotthud]

10 mins might be expected with 15 radiators and the mains only cracked open … I imagine there’ll still be a bit of air to come out of the radiators after it’s been stood a while …

Yeah i hadnt opened the outside tap fully as i wanted to also check for leaks, i havent had time to check it last night or this morning but a lot of air did come out of the system whilst backfilling it yesterday, ill go around al lthe radiators again when i get home and bleed them, after should i turn the heating / hot water on and see what happens as well

 

[Johntheo5]

If you are happy that the F&E cistern was refilling at a reasonable rate while backfilling then the blockage should be at least be reduced enough to allow normal operation of the circulating pump as it requires a (net) positive suction head which is supplied from the water level in the cistern.

When you do fire up the system, post a close up photo of the pump and its LEDs, we can then see its exact model, mode & setting and can then calculate the exact flow rate, (if not displayed on the pump), from the pump curves and the power W, with both CH&HW on, with CH only on & with HW only on, which will tell a lot.

 

[scotthud]

If you are happy that the F&E cistern was refilling at a reasonable rate while backfilling then the blockage should be at least be reduced enough to allow normal operation of the circulating pump as it requires a (net) positive suction head which is supplied from the water level in the cistern.

When you do fire up the system, post a close up photo of the pump and its LEDs, we can then see its exact model, mode & setting and can then calculate the exact flow rate, (if not displayed on the pump), from the pump curves and the power W, with both CH&HW on, with CH only on & with HW only on, which will tell a lot.

will do and thanks everyone for the help so far it is really appreciated and its helped me feel a lot more confident going forward with issues like this, hopefully this will have sorted it out short term, will know more this evening.

 

[Johntheo5]

I don't think I've seen a separator until now ... is it normal to have one?
Is the "auto vent" on ours in place of a separator?


View attachment 339893

Here is the (now) normal set up, its a VCP system, from the boiler flow pipe, you have Vent, Cold feed, (no more than 150mm from vent) and Pump, this particular one still gave pump over problems and air ingress, probably, IMO, not helped by the cold feed being too close to the pump suction, problem was "cured" by cutting off the cold feed at the T (below) and it was then Teed into the vent pipe up near the F&E cistern, a manual vent was installed, on the cut off stub piece, it would possibly have worked as well if just teed into vent at this lower level.

 

[scotthud]

Went around bled all rads water coming out of them all, I've put heating and water on heard a few gurgling noises but don't appear to be getting heat to radiators? Here's a close up of pump, I did notice boiler fired up for a bit then went back to pilot setting as well?