Operation Manual
18
A sealed system must only be filled by a competent person using an approved filling
loop connected between the mains water supply pipe and the central heating return
pipe. Once filled the loop should be disconnected and left adjacent to the boiler.
Antifreeze/Inhibitor
The sealed CH circuit should, at all times be filled with the correct concentration of a
suitable antifreeze/inhibitor. Marco recommend Fernox Alphi
11
at a concentration
of
at least 25%. This will provide protection
on
the CH CIRCUIT ONLY down to
-11
deg Celsius and sufficient protection from corrosion.
Expansion Vessel
The following table gives the maximum system volume that the integral 7 litre
expansion vessel can sustain.
Vessel charge/initial
system
pressure
(bar)
0.5 1 1.5
Total
water
content
of
CH
system
(litres)
83
64
44
If the total water content exceeds that shown, an additional expansion vessel must
be fitted and connected to the heating system primary return pipe as close as
possible to the appliance. If an extra vessel is required, ensure that the total
capacity
of
both vessels is adequate. If the pressure display on the boiler control
panel indicates 2.2 bar
or
greater when the appliance is at maximum temperature
with all radiators
in
circulation an extra expansion vessel is required.
Pressure Relief Valve
A pressure relief valve set 3 bar (43.5psi)
is
fitted and a discharge pipe
is
routed to the
outside
of
the appliance. This discharge pipe should be extended to terminate safely
away from the appliance to a point where a discharge would not cause damage to
persons or property but would
be
detected. The pipe should
be
able to withstand
boiling water, be a minimum
of
15mm
in
diameter, and not include any upward pipe
runs or horizontal runs prone to freezing.
4.7
DOMESTIC
WATER
SYSTEM
Check that mains supply pressure is within the prescribed range
of
0.2 - 1
Obar.
If it
exceeds this limit, a pressure reducing valve should be fitted to the mains supply
before the inlet connection.
The final 1 000 mm
of
the mains supply pipe to the boiler and the hot water outlet
must be
in
15mm copper.