Ideal e type conventional flue

[Generalemail]

Hi
I wonder if anyone could advise.
I am doing a project where I would like to add an alternative external heat source into an old central heating system.
The system currently has a very old Ideal type E conventional flue boiler which uses a thermosyphon for the hot water and a pump for the heating.
As part of the project I would like to convert the system to a simple S plan pumped system.
The boiler has a 28mm common flow out at the top back of the boiler, a 28nmm return at the bottom back of the boiler and a 22 mm return at the bottom FRONT of the boiler.
The manual states that the return for the hot water (back bottom) must not be "pumped" (thermosyphon)
The other return port (front) can be pumped as should be used for heating
I wonder if could provide some general information regarding the ports of this boiler.
Would it be as issue using the heating return port (front) for heating and water?
Why can't the larger return port (back) be part of a pumped system? Lack of circulation at front of boiler/hot spot?
Thanks

 

[Exedon]

The return port that's the heating one is a spreader tube that distributes through the boiler sections.
The gravity return connection just goes into back section.
Presuming you your heating cold feed / expansion is connected to the cylinder connections you will have to alter them you can't just fully pump gravity circulators.

 

[Generalemail]

Thank you very much for your reply - much appreciated
It has clarified some of what I was thinking and also confirmed the reason for not being able to pump the thermosyphon loop.
Thanks