Open coal fire back boiler

Lancashire-lad

Hi when I removed the back coal saver I can now see the mental back boiler. I could not see the back boiler when I put the coal saver in place last year .

Do I recover the metal back boiler in fire cement or is their something better.

The fire cement at the bottom of the photo is where I block off the hole under the back boil

To stop it drawings to much. Because the Stove in the backroom gives us enough hot water. When both fire are on. The water gets far to hot.

Because both fire are connected to the hot waters tank upstairs.

Thanks