Formula To Calculate The Expansion Vessel Pre-Pressure; To Check The Water Volume And Flow Rate - Daikin EWYA004D2V3P Installer's Reference Manual

8.1.2 Formula to calculate the expansion vessel pre-pressure

8.1.3 To check the water volume and flow rate

EWAA004~008D + EWYA004~008D
Packaged air-cooled water chillers
and packaged air to water heat pumps
4P688013-1B – 2022.09
▪ Air vents. Provide air vents at all high points of the system, which must also be
easily accessible for servicing.
The outdoor unit has an automatic air purge valve.
The external backup heater kit (option) has an automatic air purge valve.
Check that the automatic air purge valves are NOT tightened too much, so that
the automatic release of air from the water circuit is possible.
▪ Zn-coated parts. NEVER use zinc coated parts in the water circuit. Because the
internal water circuit of the unit uses copper piping, excessive corrosion may
occur.
▪ Non-brass metallic piping. When using non-brass metallic piping, insulate the
brass and non-brass properly so that they do NOT make contact with each other.
This to prevent galvanic corrosion.
▪ Valve – Change‑over time. When using a 2-way valve or a 3-way valve in the
water circuit, the maximum change-over time of the valve must be 60 seconds.
▪ Filter. It is strongly recommended to install an additional filter on the heating
water circuit. Especially to remove metallic particles from foul heating piping, it is
recommended to use a magnetic or cyclone filter, which can remove small
particles. Small particles may damage the unit and will NOT be removed by the
standard filter of the heat pump system.
▪ Thermostatic mixing valves. In accordance with the applicable legislation, it may
be necessary to install thermostatic mixing valves.
▪ Hygienic measures. The installation must be in compliance with the applicable
legislation and may require additional hygienic installation measures.
The pre-pressure (Pg) of the vessel depends on the installation height difference
(H):
Pg=0.3+(H/10) (bar)
The outdoor unit has an expansion vessel of 7 litre with a factory-set pre-pressure
of 1 bar.
To make sure that the unit operates properly:
▪ You MUST check the minimum and maximum water volume.
▪ You might need to adjust the pre-pressure of the expansion vessel.
Minimum water volume
Check that the total water volume in the installation is higher than the minimum
water volume, the internal water volume of the outdoor unit NOT included:
If...
Cooling operation
Heating/defrost operation and the external
backup heater kit is...
8 Piping installation
|
Then the minimum water volume
is...
15 l
Installer reference guide
61