Maximum Flue Length - Concentric; Maximum Flue Length - Twin-Pipe; Air Restriction Plate - Lochinvar LBF81 Installation, Commissioning & Maintenance Instructions

9.5

MAXIMUM FLUE LENGTH - CONCENTRIC

When using the concentric flue system the maximum flue length for all models is 3 metres for horizontal
termination and 2 metres for vertical termination. For each 45° bend, 0.5 metres should be deducted from the
total length. For each 90° bend 1.0 metre should be deducted from the total length.
NOTE: The maximum flue run includes the length of the terminal.
9.6 MAXIMUM FLUE LENGTH – TWIN-PIPE
When using the twin-pipe flue system, the maximum flue length is 6 metres for both the inlet and exhaust pipe. For
each 45° bend, 0.5 metres should be deducted from the total length. For each 90° bend 1.0 metre should be
deducted from the total length.
NOTE: This is the maximum length for each pipe and not an aggregate for the two, for example a 3 metre
inlet cannot be combined with a 9 metre exhaust.
9.6.1

AIR RESTRICTION PLATE

The following restriction plate should be inserted if required:

LBF151/171 No Restriction Plate required.

LBF221 Ø 52mm Restriction Plate required.

LBF301 Ø 52mm Restriction Plate required if air and exhaust ducts less than 3m (no restriction plate is
needed for ducts over 3m).

LBF401 No Restriction Plate required.
The air restriction plates are supplied with the twin-pipe flue system and should be fitted as shown in Figure 8.10..
FIGURE 8.10
Item Description
1 Air Duct Transition Piece
2 Gaskets from Kit and Blank Plate
3 Restriction Plate
POSITION OF AIR RESTRICTION PLATE
30