boiler move with gravity hot water and back boiler

[Scotty 890]

Hi all...I need a bit of advice on a central heating job..the job is for a relitive who gave me a call wondering if I could move an oil boiler from the utility room of his house to the corner of the garden he wanted to buy a new condensing oil boiler that can be fitted externally for this..I thought this would be a straight forward job but when I went to look at it I realised that the flow to the hot water was separate and on a gravity circuit..and now I'm worried if I fit the pump at the boiler will it pump water out the vent and into the f and e tank..I thought I could seal the system but realised there is a back boiler in the house and this is not a solution to the problem..I will add some pictures to try show what a mean one being the way the system is currently and one of my proposed way to plumb and a couple from the house...excuse the quick drawings any advice would be greatly appreciated..Scotty

 

[Scotty 890]

This is the current way of the system

 

[Scotty 890]

This is my proposed way of plumbing any advice?

 

[flameport]

there is a back boiler in the house

Where and why - diagrams do not show this.

 

[Scotty 890]

Hi flameport thanks for reply here is the drawing with the back boiler..hopefully you will be able to make it out not very neat..the hot water heats from the back boiler in gravity and drops from the attic to feed cylinder..there is a pipe stat on the return to the back boiler at the coil of the cylinder this then brings on the pump to heat the radiators..I would just like to leave this side of the system as is if possible maybe just stop end the feed as I will have a new feed to the heating system or just leave it connected As long as it won't Circulate the f and e..thanks

 

[Elkato531]

Diagram of proposed system is standard s plan but the feed and vent connections are the wrong way round. Should be Boiler-vent-feed-pump. Vent and feed no more than 150mm apart.

 

[Scotty 890]

Thanks for reply elkato531 sorry didnt realise I had drawing them wrong way round..I am fine with the oil boiler side of the heating system the problem is because it is a duel system will plumbing like this affect the back boiler plumbing in anyway..I just want to make sure if I leave the back boiler plumbing as is it will still work and no circulation of the f and e tank will happen because the pump will now be on the flow..thanks