Vent pipe missing on cold water pipe

I have an open-vent central heating system with a mid-position valve for heating up the hot water. I've noticed that there isn't a vent pipe on the cold water pipe for any expansion of water.

A plumber who recently installed our boiler said that we didn't need the cold feed pipe - is this correct? The service manual seems to say that we do need it. If you could give me any advice on this it would be really appreciated.

Responses from some of our very best tradespeople:

"You can't actually rid of the pipe but if it's at least 22mm in diameter it can be converted into a combined fill & expansion pipe."

Lewis Howard, C&J Heating and Plumbing Ltd.
C&J Heating and Plumbing Ltd. is a family owned plumbing & heating company based in Stevenage and its team has over 25 years experience in the plumbing field. Lewis and the team are Gas Safe registered and do all aspects of plumbing & heating in the domestic & commercial sector; including installation, maintenance & servicing. They are also Worcester Bosch Accredited Installers which means they offer up to 5 years warranty & service packages on all Worcester Bosch products they install.