Gravity fed system with no open vent?

[efficient]

Hi all, just viewed a proposed boiler install heat only direct swap. The system is gravity fed but has no open vent? So I presume the water expands back into the cistern. Is this common?

 

[Simon F]

common or not, you would need to fit to the manufacturers instructions.
that would mean running a new vent pipe. or fitting a sealed system instead?

 

[efficient]

Have already told the customer they need a vent pipe. I've just not seen a gravity fed system without one. Wondering has anyone else come across this?

 

[Dannypipe]

Yeah, I bet the cold feed is in 22mm? Combined feed and vent. OK if boiler manufacturer allows it in their instructions.

 

[tamz]

It will be a primatic cylinder

 

[plumber0808]

Seen this quite a bit. My house for one.
can be left like it and it will work fine as long as manufacturers allow it.

 

[efficient]

Yeah MI allows combined feed and vent. Yes it's 22mm feed.