Worcester 70/90, Installation And Servicing Instructions

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Down draught conditions will adversely effect the operation of
the boiler and must be avoided. Where possible the flue should
be extended beyond the apex of the roof and should always be
taken beyond the eaves of the building. Where down-draught is
experienced a suitable anti down-draught terminal should be
fitted to the flue termination.
The natural flue draught must be checked in the flue pipe
immediately above the appliance or in the hole provided in the
flue outlet plate. The flue draught should be no less than
0.75mm W.g. and no greater than 5.1mm W.g. If a flue draught
greater than 5.1mm W.g. is experienced a draught stabiliser
should be introduced into the flue and adjusted to achieve a flue
draught within the specified range.
7.2 Low Level Discharge (See Fig. 4)
The appliance may be converted to discharge the products of
combustion at low level. For this purpose a special flueless
k i t a n d a s s o c i a t e d d u c t i n g i s a v a i l a b l e , a l l o w i n g t h e
conventional flue to be discarded. Detailed instructions for
converting the appliance to low level discharge are supplied
with the conversion kit. The 5 inch flue spigot should be
removed from the flue outlet plate, by undoing the three
retaining screws, and the hole blanked off with the plate
provided in the kit.
Note: Under no circumstances may 35 Second Gas Oil be
burned with this type of flue terminal arrangement
.
6
Fig. 4. Flue Installation (Rear Discharge).
See Fig. 5 for
flue terminating
positions.
80
min.
Flue guard
766
L
F
F
K
G
A
E
B
C.D.
H.J.
N
O
M
Minimum Distance (mm)
Terminal Position Open Low-Level
Flue Discharge
A Directly below an opening, air brick, window, etc. ............... Not allowed 600
B Horizontally to an opening, air brick, window, etc. .............. Not allowed 600
C Below a gutter or sanitary pipe ................................................ Not allowed 75
D Below eaves or a balcony.......................................................... Not allowed 600
E From vertical sanitary pipework .............................................. Not allowed 75
F From an internal or external corner......................................... Not allowed 300
G Above ground or balcony level ................................................ Not allowed 300
H From a surface facing the terminal .......................................... Not allowed 600
J From a terminal facing the terminal ........................................ Not allowed 1200
K Vertically from a terminal on the same wall .......................... Not allowed 1500
L Horizontally from a terminal on the same wall ..................... Not allowed 300
M Above an intersection with the roof ........................................ 600 Not applicable
N From a vertical structure on the side of the terminal ........... 600 Not applicable
O Above a vertical structure less than 750 mm from the
side of the terminal.....................................................................
600 Not applicable
NOTE:
The dimensions given are for general guidance only. Other surrounding buildings or objects may affect the clearance of
combustion products. An alternative flue terminal position should be sought when there is any possibility of a nuisance being
caused by inadequate dispersal of flue products.
The flue terminal must be located in a suitable position as shown, such that the products of combustion can be freely dispersed
without the possibility of the gases entering the dwelling or that of a neighbouring dwelling.
Fig. 5. Flue terminating positions for oil-fired appliances
Open
Flue
Window
Flue
Terminal