15
For long term protection against
corrosion and scale, after flushing, it is
recommended that an inhibitor such as
Betzdearborn’s Sentinel X100 or Fernox
MB-1 is dosed in accordance with the
guidelines given in BS 7593:2006.
Failure to implement these
guidelines will invalidate the
guarantee.
4.8 Heating System Design
Considerations
To achieve the maximum efficiency
possible from the Grant VORTEX Eco
boiler, the heating system should be
designed to the following parameters:
Radiators:
• Flow temperature 70°C
• Return temperature 50°C
• Differential 20°C
Underfloor:
• Flow temperature 50°C
• Return temperature 40°C
• Differential 10°C
Size radiators with a mean water
temperature of 60°C.
Design system controls with
programmable room thermostats or
use weather compensating controls
to maintain return temperatures below
55°C.
4.11 Sealed Systems
If plastic pipe is to be used, the installer
must check with the plastic pipe
manufacturer that the pipe to be used
is suitable for the temperature and
pressures concerned.
Plastic pipe must be Class S to BS
7291-1: 2010.
4.12 Underfloor Pipework
Plastic pipe may be used on Underfloor
systems where the plastic pipe is fitted
after the thermostatic mixing valve.
Copper tube must be used for at least
the first metre of flow and return primary
pipework between the boiler and the
underfloor mixing/blending valves.
The use of a pipe thermostat is
recommended to control the return
temperature when using weather
compensating controls.
Refer to Section 2.5 for the size and
type of the connections and Section 5
for the position of the connections.
4.9 Underfloor Heating
Systems
In underfloor systems it is essential
that the return temperature must be
maintained above 40°C to prevent
internal corrosion of the boiler water
jacket.
4.10 Pipework Materials
Grant boilers are compatible with both
copper and plastic pipe. Where plastic
pipe is used it must be of the oxygen
barrier type and be of the correct class
(to BS 7291-1: 2010) for the application
concerned.
!
NOTE
We recommend that both antifreeze
and corrosion inhibitor be used in
the primary water system.
!
NOTE
The boiler should not be allowed to
operate with return temperatures of
less than 40°C when the system is
up to operating temperature.
!
WARNING
The first metre of pipework
connected to both the heating flow
and return connections of the boiler
must be made in copper on all types
of system - sealed or open-vented.
!
WARNING
The system must incorporate a low
pressure switch to shut off power to
the boiler if the system pressure
drops below 0.2 bar. A suitable low
pressure switch kit is available to
purchase from Grant UK (product
code: MPCBS63).
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