Baxi LUNA HT 1.450 Installation And Servicing Instructions page 19

Concentric Vent Support
All venting must be fixed every 3.28 ft (1.0 m) using steel strapping or equivalent.
Fig. 7
A: Steel strapping or equivalent
Note:
Ensure that the vent is sloped towards the boiler of approximately 0.39 in for every 3.28 ft (1.0 cm for every 1.0 m).
For horizontal flues a minor deviation from the horizontal is allowable, provided it results in a downward slope
towards the boiler.
Additional flue components are available as follows:
• 3.28 ft / 1.0 m flue
• 90° bend
• 45° bend
Vertical flue terminal assembly Refer to the separate installation instructions supplied with the assembly.
WARNING
If an extra 90° bend is used, this reduces the maximum flue length by 3.28 ft / 1.0 m.
Each 45° bend used reduces the maximum flue length by 1.64 ft / 0.5 m.
Under no circumstances must the flue length (including allowances for extra bends) exceed 32.80 ft / 10.0 metres.
1. Locate the flue elbow on the adaptor at the top of the boiler. Set the elbow to the required orientation (rear, right or
left).
2. Measure the distance from the outside wall face to the elbow (Fig. 5). This dimension will be known as 'X'.
3. To dimension 'X' add "Y" + 1.97 in (50.0 mm). This is the total dimension of the ducts.
4. Taking the air duct, mark the above dimension. Measure the length of waste material, and transfer the dimension to
the flue duct.
5. Remove the waste from both ducts (flue and air ducts). Ensure that the cut ends are square and free from burrs.
6. Insert the flue duct into the air duct and pass them through the hole in the wall
WARNING
• Check all measurements before cutting. Clearance to combustible materials when using a concentric vent
system is zero.
• After installing ducts make sure that there is no recirculation of combustion by using a regularly calibrated
analyzer.
• Ensure a minimum downward slope of 0.39 in for every 3.28 ft of duct length toward the boiler, at least 2° (figure
5.1).
• Ensure that the terminal is positioned with the slots to the bottom (figure 5.1).
INSTALLATION AND SERVICING INSTRUCTIONS
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7110242.02 - en