Baxi Boston 2 80 RS Installation And Servicing Instructions page 8

Notes for Guidance – page 8
PIPE SIZING
a) The sizes of flow and return pipes from the boiler
should be determined by normal methods according to
the requirements of the system. Normally the pump
should be set to give a 11ºC (52ºF) drop across the
system with the gas rate of the boiler adjusted to the
output required.
b) The open vent pipe must be a minimum of 22mm and
must rise continuously to above the feed tank. The flow
pipe from the boiler may form part of the open vent. No
part of the open vent should contain a valve.
c) The 15mm cold feed pipe should not include a valve
unless required by the local water authority.
DOMESTIC HOT WATER
An indirect cylinder must be used. If a self priming indirect
type is employed it must be of adequate size and applied
strictly in accordance with the cylinder manufacturers'
instructions.
FUEL ECONOMY
Better fuel economy is achieved by exercising control of the
boiler by means of a room thermostat and or a cylinder
thermostat as appropriate.
ALLOWING THE BOILER TO CYCLE ON THE BOILER
THERMOSTAT DOES NOT PRODUCE THE BEST
RESULTS. SIMILARLY FOR ECONOMY AND BOILER
PERFORMANCE THE SYSTEM SHOULD BE DESIGNED
SO THAT GRAVITY CIRCULATION IN THE HEATING
CIRCUIT DOES NOT TAKE PLACE WHEN THE PUMP IS
NOT RUNNING.
IMPORTANT: Gravity Flow and Return connections
must be taken from the same side of the boiler.
In both cases the cold feed pipe which is the neutral
point of the system is shown directly behind the pump
to avoid sub atmospheric pressure (air entrainment) in
the system.