Baxi Boston 2 80 OF Installation And Servicing Instructions page 4

Water Circulation Systems - Page 4
(see page 8)
The appliances are only suitable for connection to a cistern
supply and can be used with:-
1) Open vented pumped domestic hot water and pumped
central heating systems.
2) Gravity flow domestic hot water and pumped central
heating systems.
(a) With 28mm pipes the minimum circulating head
for gravity domestic hot water should not be less
than 1m (3ft 3in) measured vertically from the flow
connection on the boiler to the flow connection on
the cylinder. At this head, the maximum horizontal
distance measured along the run of the pipe
should not exceed 3m (10ft). Greater horizontal
distances and smaller pipe sizes are acceptable
with suitably increased heads. Allowances must
be made for pipe bends where necessary.
(b) If the above conditions are not easily met then
pumped primaries should be used.
(c) Gravity flow and return pipes should be laid to
maximum fall to avoid air locks.
The following points are of particular importance:
1) THE WATER SPREADER MUST BE FITTED TO THE
PUMPED RETURN CONNECTION ON ALL
SYSTEMS.
2) The appliances must not be used on sealed systems.
3) The system must be designed to avoid reverse
circulation.
4) The static head must not exceed 30m (100ft) of water.
5) The boilers must only be used with an indirect cylinder
when domestic hot water is required.
6) Drain points should be fitted at the lowest points in the
system.
7) The system must be designed such that gravity
circulation in the heating system does not take place
when the pump is not running.
8) In systems using non-metallic pipework it is necessary
to use copper pipe for the boiler Flow and Return. The
copper must extend at least 1 metre from the boiler and
include any branches.
GAS SUPPLY
The gas connection is located at the bottom left hand side of
the appliance and is Rc ½ ( ½ in B.S.P.T. internal). Ensure
that the pipework from the meter to the appliance is of
adequate size. Do not use pipes of a smaller size than the
appliance gas connection.
ELECTRICAL SUPPLY
External wiring must be correctly earthed and polarised and
in accordance with I.E.E. Regulations.
For wiring instructions see 'Electrical Connections'.
Treatment of Water Circulating Systems
For optimum performance after installation, this boiler and its
associated central heating system must be flushed in
accordance with the guidelines given in BS7593:1992
"Treatment of water in domestic hot water central heating
systems".
This must involve the use of a proprietry cleanser, such as
BetzDearborn's Sentinel X300 or X400, or Fernox's
Superfloc. Full instructions are supplied with the products but
for immediate information please contact BetzDearborn on
0151 420 9563, or Fernox on 01799 550811.
For long term protection against corrosion and scale, after
flushing it is recommended that an inhibitor such as
BetzDearborn's Sentinel X100, or Fernox's MB-1 or Copal is
dosed in accordance with the guidelines given in
BS7593:1992.
Failure to flush and add inhibitor to the system may
invalidate the appliance warranty.
APPLIANCE DETAILS (all models)
HEIGHT
WIDTH
FORWARD PROJECTION
FROM THE WALL
BOILER TAPPINGS
ELECTRICAL SUPPLY
GAS CONNECTION
MAX. WORKING HEAD
THERMOCOUPLE OUTPUT
HYDRAULIC RESISTANCE CHARTS
900mm (35 ½ in)
395mm (15 ½ in)
535mm (21 in).
4 x Rp1 (1 in BSP internal) and
1 x Rp ¾ ( ¾ in BSP internal)
230V~50Hz - 3 amp fuse
RC ½ ( ½ in BSPT internal)
30m (100ft)
10 - 15mv