Feed and Vent side by side?

[Steve Hart]

Can anyone give me a steer please on best position of the feed pipe and the Vent pipes for an open vented CH system?
I appreciate that each needs to be on the same side of the pump so as to ensure water doesn't get pumped out of the vent but is it acceptable, from a good design perspective, to have both conections side by side on either the flow or return and is an air separator advisable?
I have read lots of the postings on this site and a number of books on CH design but this point is never very clear so would appreciate your real world advice please.
Cheers

 

[mdogg53]

I found this link useful when I was chasing Air problems in my system.

http://www.fernox.com/?cccpage=air_in_CHS&sub=3

It says from left to right Boiler, Open Vent, Cold Feed, Pump. (Flow Side)

I've fitted mine not more than 4inches apart, the important thing is the order to maintain balance when the pump is switched off and prevents air being sucked in vent when starting again. At least that's how I understand it.


As for air separators i'd be interested know myself??

 

[Gas2Air]

Ideally a closed couple arrangement should be used. The open vent and cold feed no further apart than 150mm. Then the pump fitted after the cold feed connection. Any other config would result in ingress of air or pumping over. The cold feed acts a s a neutral point.

If as described above the pump will give positive pressure, if the pump is fitted for example before the cold feed, the system would be under negative pressure and thus sucking in air from micro leaks/open vent and cause corrosion/sludge/gas/air problems.

 

[Steve Hart]

Thanks guys, appreciate your advice. Thats what I will do.
Cheers