Condensing Boiler
8
7/5/99
Rear Outlet
Install as above but using the STRAIGHT
connector in turning box. Follow the
instructions under Right or Left outlet
,
points
1,2, 3, and, 5.
TERMINAL
Fix to the outside wall with the screws
provided. The top has no holes and is marked
'TOP'. If a guard is fitted , the terminal should
be at its centre.
PLUMBING
Prepare the flow and return pipe work on the
rear of the boiler. Note: It is important that the
joints on this pipework are leakproof as access
is very limited after fitting the boiler module.
Facing the boiler the FLOW connection is at
the bottom left and the RETURN at the top
right.
SECURING THE BOILER ON TO THE
TURNING BOX
1. Remove the two M5 screws from the turning
box, and retain.
2. Remove the boiler Top Trim by undoing the
two screws, and retain.
3. With the bottom of the boiler away from the
wall, hang the top of the back plate onto the
hanging bracket. Now, by gently lowering
the bottom of the boiler against the wall the
fan spigot should engage in the flue
connector. Observe the correct engagement
of the fan spigot into the flue.
4. Replace the two
M5 screws around the fan
that hold the turning box to the back panel.
5. Replace the decorative top trim, if required.
LOWER BOILER FIXING
The boiler is finally attached to the wall by two
screws, washers and a rawlplugs. See Fig.7.
GAS CONNECTION
The ½" BSP. gas connection point is shown in
Fig.2. A minimum of 20mb. (8in. w.g.) must be
available at the boiler inlet, with the boiler and
other connected appliances firing. Check for
gas soundness (B.S. 6891: 1988) in pipework
to boiler using a manometer. Open the gas
cock. Gas soundness within the boiler should
be checked using sense of smell and/or leak
detection fluid. Check the burner bar pressure
with a manometer connected to the control and
adjust if required with the nut beneath the
black rubber cap on the underside of the valve.
CONDENSATE CONNECTION.
The position of the plastic condensate drain
pipe is shown in Fig 2.
Where possible an internal termination of the
Condensate discharge pipework should be
used.
Installation pipework must be in plastic to a
suitable drain location with a gradient of 2.5°
(45mm/ meter run) minimum. If connected to
another drainage a trap, an air break is
required between the boiler drain and that trap.
(see Figs.13 and 14 ). Internal runs may be
in a minimum of 19mm pipe. External runs
MUST be made in a minimum of 32mm pipe,
starting inside the building, and if possible
insulated to defer problems from freezing.
The British Gas booklet "Guidance for the
installation of Domestic Condensing Boilers"
should also be referred to.
SYSTEM DESIGN
General principals
Condensing Boilers give their best
performance when the system water
temperature is as low as possible and still
achieve the desired room temperatures.
Oversized radiators make this easier to
achieve but are not essential as, even in a
standard designed installation, most of the
boilers' working hours are spent with the
system producing much less than the designed
output.
This is because the outside temperature is
often higher than the figure used for the
design, typically -1 to -2º
C.
Consequently, the standard 'Y' plan design
using 3-port flow-share valve, room thermostat
and cylinder thermostat, is a perfectly suitable
minimum.