Back Boiler - back or back and sides?

[BarneyMc]

I have an open fire with back boiler and just want to know if the boiler is located just along the back wall of the fire or does it also come along the side walls?

I have fire bricks to place inside the fireplace but don't want to block the heat if the boiler is located along the side walls of the fire (as well as the back).

 

[W200]

The water in the back boiler fills BOTH the back and side walls.
Regards.

 

[fmc]

w is correct for the most part but depends on the age of the boiler some of the older dauntless boilers had a kind of clay fire sides but 90% of back boilers are all round. tap the abck and sides and they should all sound metally then you;ll know.