Set Up

• 1). Check the area where the back boiler will sit; the floor needs to be level and solid, and it needs easy access to the pipe work for the radiators and hot water heater, as well as to an outside wall for the flue.
  
  
• 2). Mix and pour concrete on the floor if needed, and check with a level. Leave to cure overnight or longer.
  
  
• 3). Move the back boiler into place, leaving access to attach the pipes and flue at the rear; you’ll need help to move it. Measure to be sure that the back boiler is at least 4 inches from the wall.
  
  
• 4). Examine the four points where pipes will attach. One point will be for the central heating return, a second for the gravity return, both at the lower end of the back boiler, and a pipe to the first radiator in the system and another to the hot water tank, both close to the top of the back boiler.
  
  

The Flue

• 1). Dry fit the interior flue pipe to the rear of the back boiler to mark where you need to drill through the wall. Mark the circle for the flue pipe and cut through the drywall with a jigsaw before removing the insulation. Mark a circle on the outside wall where the flue pipe will emerge. Drill small holes through the exterior wall to mark the circle.
  
  
• 2). Cut out the circle on the outside of the house, using a jigsaw. Fit the heat sleeve (intended to prevent any danger of fire) on the flue and insert the flue through the wall. Attach the flue to the back boiler with screws.
  
  
• 3). Attach the T from the flue so that the closed end is at the bottom; it can be opened for cleaning. Attach sections of the flue pipe, attaching them to the wall with rigid hangers from the flue kit. Ensure that the flue is 4 inches from the wall and extends 4 inches above the top of the roofline.
  
  

Attaching The Pipes

• 1). Turn off the water and make sure all the pipes are drained.
  
  
• 2). Attach the pipe from the first radiatior in the system to the back of the back boiler in the designated place (it will be at the top right as you face the front of the boiler) by using a wrench on the bolt; ensure that it runs at a 45-degree angle from the boiler before reaching the radiator.
  
  
• 3). Attach the gravity feed pipe (it should attach at the top left, as seen from the front) in the same manner as the radiator pipe; this will run to the hot water tank, which must be higher than the back boiler.
  
  
• 4). Attach the gravity return pipe at the bottom right of the back boiler, and then the central heat return at the remaining point, being certain that there’s a drain cock at the lowest point of the pipe before it reaches the back boiler.
  
  
• 5). Turn the water back on and allow the tanks to fill before starting a fire in the boiler.