Do I need to add a vent?

[F1yTrap]

I have replaced my poorly installed gravity system with a new Y Plan fully pumped system.

The Problem: When the HW system is on it is quite noisy, with the sound of water rushing around the pipes. I am assuming that this is caused by trapped air.

I think my layout is wrong and I need to add a vent pipe to the 28mm tank inlet running to the CH expansion/feed tank in the loft.

Here is what I have currently with the proposed pipe (in orange).

Is this correct?

Untitled

• F1yTrap
• 6 Mar 2011
• 1

[Edit] The initial image in the post was wrong, the CH upstairs now runs direct to the boiler rather than teeing into the HW return. Don't think that affects this post 's problem though.

 

[misterdubya]

Put an auto air vent or manual type.

Dont run the open vent from there.

Mr. W.

 

[greemyamochop]

Open vent needs to be between the boiler and the pump so dont move it

Manual air bleed might sort it out

 

[F1yTrap]

Ok cheers, glad I came here before putting in the extra vent into the loft!

Screwfix have a 15mm bottle air vent (http://www.screwfix.com/prods/97868/Plumbing/Brassware/Bottle-Air-Vent-15mm#). So if I replace the top most 28mm compression elbow with a 28mm 28mm 15mm reducing tee, and run a short bit of 15mm this bottle vent should that sort it?

 

[Stamina]

Ok cheers, glad I came here before putting in the extra vent into the loft!

Screwfix have a 15mm bottle air vent (http://www.screwfix.com/prods/97868/Plumbing/Brassware/Bottle-Air-Vent-15mm#). So if I replace the top most 28mm compression elbow with a 28mm 28mm 15mm reducing tee, and run a short bit of 15mm this bottle vent should that sort it?

yes

 

[bengasman]

Once the air is out of the system, there should be no need for a vent. If there is, you have another problem and letting the air out is only solving the symptoms, not the actual problem.

 

[F1yTrap]

Once the air is out of the system, there should be no need for a vent. If there is, you have another problem and letting the air out is only solving the symptoms, not the actual problem.

Don't think there is a problem. The air in the system has been there since since I filled it for the first time. It doesn't seem to be working its way out.

Please correct me if I'm wrong, but I was expecting the air to eventually work its way out, if it can get to the boiler then it should work its way back up the feed/vent or into the rads. Its just not making it back to the boiler. Does that sound sensible?

 

[F1yTrap]

Manual air bleed might sort it out

How do I do a manual bleed? I have a compression fitting on the last elbow before the cylinder inlet, is it a case of cracking the nut loose so the air can find its way out? Please advise.

 

[bengasman]

In theory, you are right. In reality, many open vent systems do not what they should do.
OV is great from a business point of view, but I wouldn't have one in my own house.
I suspect your system suffers from corrosion and as a result draws air in.

If it is purely a matter of one time air not coming out, the easiest way to solve it would be to undo a compression joint at the top of the dhw loop just enough to let the air out after the system has been off for an hour.