CH sucking air in via vent

[wadihalfa]

Hi Folks, I'm sure this question has been answered many times before but my CH system doesn't seem to be like anyone elses.
Air is being sucked into the system via the vent pipe. If you hold a glass of water over the end of it in the loft and turn the system on, the water gets sucked out of the glass.
The system is about 15 years old and I've been told by a couple of plumbers "I wouldn't have done it like that!"
Now it's winter and the heating is on more, the sound of air rushing around the system is driving me up the wall. For some reason it's a lot worse this year - ever since I cleaned the system out, not having been done for at least 13 years. Everything works fine, it's just the air that is the problem.
I've read that t-ing the feed into the vent could stop the problem. If so, looking at my photo, do I connect pipe A to pipe B, or Pipe A to pipe C.
Or if there is a better way altogether, I'd love to hear about it.
Thanking you in anticipation.
If God had intended me to be a plumber, he would have given me webbed feet!

Untitled

• wadihalfa
• 26 Oct 2010
• 1

 

[Gasguru]

Cut out the air seperator (probably full of muck). Form an "H" pattern of pipework in place of the seperator.

On the left hand branch continue up to the vent pipe.

On the right hand branch continue up to the feed pipe. On the existing feed stick on a manual vent to bleed out the air.

Wouldn't go for a combined feed and vent since the seperator could be partially blocked and not all boilers are approved for combined F&V.

 

[spraggo]

The gadget below "B" is known as an aireator, what this does is slow down the velocity of water pasing through it to enable air bubbles to escape up through the vent "B". But what is happening is that the pump attempting to pull the water down through this vent pipe rather than pulling the water around the system.
The easiest way out of this problem (other than to pipe it using the coventional way) is to remove the feed pipe "A" in the airing cupboard by blanking it off at low level and then proceed to the loft and teeing it into the expansion pipe "B" where it comes out of the bottom of the expansion tank which in effect makes the pipe "B" a dual feed and vent pipe.

 

[45yearsagasman]

This may have todays date but it is a repeat post of exactly the same problem.All the answers were given at the time so why post again? How do I know this?because I contributed to the solution of combining the feed and vent in the loft,and I remember the pic.

 

[Gasguru]

.........not all boilers are approved for combined F&V.

Check first

 

[spraggo]

This may have todays date but it is a repeat post of exactly the same problem.All the answers were given at the time so why post again? How do I know this?because I contributed to the solution of combining the feed and vent in the loft,and I remember the pic.

Clever lad.

 

[wadihalfa]

Yes, sorry this is a repeat of my old query. I was totally confused last time so I thought I'd ask again with a labelled picture. I'm a bit more clued up about the system now but still need to be spoken to like a numpty. A retired plumber mate of mine gave some advice but didn't seem completely convinced that's why I thought I'd go over it again with you guys.
I've just gone through my boilers manual but it doesn't say if its suitable for feed & vent (Worcester Danesmoor 12/14 oil).
Sorry for the duplication.

 

[spraggo]

You should not use a combined F/V if the boiler has no over heat stat, the Dansmoor has one, In fact I do not know of a gas or oil boiler that has not got one. Solid fuel boilers do not have one. If you had a solid fuel boiler then the flow and return pipes to the cylinder would be 28mm.
But your photo shows that these are 22mm.

 

[Gasguru]

There are plenty of boilers with no overheat stats.

That's beside the point; air separators are notorious for blocking up (and causing the problems highlighted) so it makes more sense to cut it out.

 

[wadihalfa]

In that case then, I think Spraggo's T-ing in the loft caper wins the cigar.
I know there are a lot of ways to skin a cat but I just want one simple answer to the problem. I'm clueless when it comes to plumbing - I can re-wire your fuse board or build you a computer but don't let me anywhere near a stilson!

If anyone thinks I'm going to wake-up cold and wet if I do the above, please speak nor or forever hold thy peace.

Thanks

 

[wadihalfa]

Gasguru, I like the sound of cutting things out but don't really understand the H pipework you refer to. Is there a diagram anywhere.
This is the problem I have. Its got to relate to my pipework not pipework in general. If any of you blokes live near Cirencester, you can have the job.

 

[Gasguru]

H pattern feed and vent

• Gasguru
• 26 Oct 2010
• 1

Form the H from a couple of 22 equal tees. Join the branches together and keep them within 150mm to equalise the pressure at the feed and vent connections. Run the feed up in 22mm for say 100mm and reduce down to the 15mm feed (less chance of the connection blocking).

 

[spraggo]

There are plenty of boilers with no overheat stats.

That's beside the point; air separators are notorious for blocking up (and causing the problems highlighted) so it makes more sense to cut it out.

I`m always willing to learn, can you name one oil boiler that does not have a over heat stat. Cheers.

 

[Gasguru]

Long since stopped working on oil...not much call for it in London

 

[spraggo]

In that case then, I think Spraggo's T-ing in the loft caper wins the cigar.
I know there are a lot of ways to skin a cat but I just want one simple answer to the problem. I'm clueless when it comes to plumbing - I can re-wire your fuse board or build you a computer but don't let me anywhere near a stilson!

If anyone thinks I'm going to wake-up cold and wet if I do the above, please speak nor or forever hold thy peace.

Thanks

I consider that I and others have given you sound advice over the last month, so I do not know why you keep wasting our time, I repeat your boiler does have a over heat stat. lol.