Plumbing a pumped back boiler...

[theflyingpig]

Hi all, I'm looking for some advice as to how to plumb a rayburn back boiler into a spare heating coil in our hot water cylinder.
The stove was previously plumbed into the old cylinder on a gravity circuit, which seemed highly inefficient. I want to add a circulating pump, triggered by a pipe stat on the flow put of back boiler.
I understand that the vent pipe back up to f&e tank in loft should come off the highest point in system, but where should feed and pump be best located?

This bad drawing is what I'm currently thinking.....

Thanks for any advice...

 

[oldbutnotdead]

Gravity flow isn't that inefficient if 28mm or larger tube has been used.
Gravity flow also has the advantage of always working even if power fails.
You can fit a loading valve (these come with a pump and thermostat and are specifically designed for your application).

 

[muggles]

If it's a solid fuel or old style pot burner Rayburn it needs to be on gravity circulation, your can't pump it

 

[theflyingpig]

If it's a solid fuel or old style pot burner Rayburn it needs to be on gravity circulation, your can't pump it

Why?

 

[muggles]

Because they're uncontrolled heat sources. In the event of a power failure or the pump breaking down the system needs to be able to continue to circulate to prevent an excessive buildup of heat. Water flashing to steam can cause a very powerful explosion

 

[oldbutnotdead]

Loading valves (some of which have an integral pump) can be used in the primary circuit from an uncontrolled heat source)- they all have some sort of thermostatic bypass to prevent the very real problem outlined by @muggles .