Grant Aerona 3 HPID10R32, Instructions Manual, Page: 16 / 100

Section 3: Installation Information Page 16
3.11 BEFORE YOU COMMISSION
3.11.1 FLUSHING AND CORROSION PROTECTION
To avoid the danger of dirt and foreign matter entering the heat
pump the complete heating system should be thoroughly flushed
out – both before the heat pump is operated and then again after
the system has been heated and is still hot.
This is especially important where the heat pump is installed as
a replacement for a boiler on an existing system. In this case the
system should be first flushed hot, before the old boiler is removed
and replaced by the heat pump.
For optimum performance after installation, this heat pump and
the central heating system must be flushed in accordance with the
guidelines given in BS 7593 ‘Treatment of water in domestic hot
water central heating systems’.
This must involve the use of a proprietary cleaner, such as Sentinel
X300 or X400, or Fernox Restorer.
After flushing, a suitable thermal fluid should be used, such as
Grant HPC thermal fluid (Grant UK product code: INHIB03),
specifically designed for use in air source heat pump installations.
This provides long term protection against corrosion and scale as
well as the risk of the freezing in the external section of the heating
system (i.e. the flexible hoses, condenser and circulating pump
within the heat pump casing) in the event of power failure during
winter months.
In order to avoid bacterial growth, due to the lower system
operating temperatures in heat pump systems, a suitable biocide
should be used in conjunction with the thermal fluid.
As Grant HPC thermal fluid already contains a biocide, no
separate biocide is required.
The thermal fluid, and separate biocide when required, should be
added to the system water when finally filling the heating system.
The level of frost protection depends on the percentage
concentration of thermal fluid used.
Grant recommends using a thermal fluid concentration to give a
MINIMUM level of frost protection of -10°C, and down to lower
temperatures than this where local conditions are more severe.
With Grant HPC fluid, to ensure good corrosion protection, a
concentration of 25% by volume is recommended. This provides
antifreeze protection to -12°C. Refer to Table 3-3 below for details
of concentration v antifreeze protection.
Table 3-3: Antifreeze protection levels using Grant HPC fluid
% Grant HPC
by volume
20 25 30 35 40 45
Freeze point
°C
-10 -12 -15 -20 -25 -30
IMPORTANT: Mixtures with a concentration of more than 70%
by volume of Grant HPC in water are NOT recommended
because the physical properties i.e. heat transfer, are no
longer sufficient.
Always follow the manufacturers instructions on the correct use of
thermal fluids and biocides.
Failure to implement the guidelines outlined in Section 3.11.1
for fully flushing the system and using a suitable thermal fluid to
provide adequate protection against corrosion, scale, bacterial
growth and freezing will invalidate the heat pump product
guarantee.
Table 3-4: Antifreeze concentration
% Monoethylene glycol inhibitor 20% 25% 30% 35% 40% 45%
Freezing temperature* -10°C -12°C -15°C -20°C -25°C -30°C
Correction
factor
Capacity 0.995 0.990 0.985 0.980 0.975 0.970
Power absorbed 0.990 0.989 0.984 0.982 0.975 0.968
Pressure drop 1.051 1.060 1.065 1.071 1.077 1.080
* The temperature values are indicative. Always refer to the temperatures given for the specified product used.
For details of how to access the parameter settings, refer to Section 9.3.
Grant Engineering (UK) Limited strongly recommends that a
Grant Mag One in-line magnetic filter/s (or equivalent*) is fitted
in the heating system pipework. This should be installed and
regularly serviced in accordance with the filter manufacturer’s
instructions.
* As measured by gauss. The Mag One magnetic filter has a gauss
measurement of 12000.
3.11.2 ANTI-FREEZE FUNCTION SETTING
This function is factory set to ON, i.e. DIP SW1 is set to ON (up
position).
With the frost protection function set to ON, it will operate as
described in Sections 8.4.1, 8.4.2 and 8.4.3.
This function is not required if ethylene glycol is used in the heating
system water to prevent freezing.
If a suitable concentration of ethylene glycol (heating system
antifreeze) is used in the system water. Refer to Tables 3-2 & 3-3
for suitable antifreeze concentrations or follow the manufacturer’s
instructions supplied with the antifreeze.
If not required, frost protection function can be disabled as follows:
• Remove the wiring cover at the right hand end of the heat
pump. Refer to Figure 6-1.
• Set DIP SW1 to OFF (down position). Refer to Figure 3-6.
• Replace the wiring cover and secure in place with the screws
provided.
Terminal PCB
ON 1
OFF
DIP SW. position
2 3 4 5 6 7 8
Figure 3-6:
Anti-freeze function setting
! NOTE !
When using thermal fluids and biocides, ensure that the
volume of any volumisers, buffers and thermal stores
are taken into account, in addition to the heating system
pipework, when determining how much is required to
correctly dose the system.
! NOTE !
Dip switch positions:
Up:
ON
Down: OFF
Refer to Sections 8.4.1, 8.4.2 and 8.4.3.