Open vented heating issue

[sitja]

Hi i was looking at a ch system today, its fed from tank in attic and using old potterton primaf boiler, problem is... it has no vent pipe over the f&e tank... and the feed from the tank is only 15mm. I will try attach a sketch now too..

Untitled

• sitja
• 21 Jun 2012
• 1

 

[Boilerman2]

Looks a typical Irish installation, so whats the problem?

 

[sitja]

but there is no vent pipe??

 

[buck51]

why was you looking at it???
Does it work or not?

 

[dcawkwell]

The vent pipe really is completely unnecessary.
Some will say it is there to stop freezing.
But any expansion will come back up he feed pipe anyway.
I think building regulations allow no vent pipe if the system is
under a certain size and you have a 22mm feed pipe.
I never have anything to do with vented normally as I only
install modern sealed systems.

 

[sitja]

System was drained to make some changes and wondering will this affect filling back up.. yes but its only 15mm for cold feed..

 

[Tibbot]

Are you sure it's not a F&E tank with a NRV feeding a sealed system. These were a popular method in Eire due to water regulations excluding any mains connection other than to the drinking tap. Primas with sealed kits were used instead of Potterton system boilers as those required a filling loop.

 

[sitja]

No the sketch is all thats in the heating system.

 

[Tibbot]

It should fill, just might be some time before all the air is cleared.

 

[sitja]

What about expansion.. like is this system ok to use..

 

[Tibbot]

Expansion occurs up the feed pipe even with a vent pipe installed. The vent is for safety. Ideally combined F&V, like yours, s/be 22mm.

 

[sitja]

Yes but being half inch does this make it unsafe.. as its accessible should i change cold feed to 22mm.

 

[Terry lambert]

Yes, 22 is the minimum for combined feed and vent

 

[martineire]

Is there a NRV on the 15mm feed, and a expansion vessel on the system somewhere making it a semi-sealed system

 

[sitja]

Nope no vessel or non return. I can see all pipework its all exposed, the sketch is the layout of the pipework and how it is.

I assume no one came across this before.. but its weird that the first post or so, say whats wrong with it???