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2.7. Buffer tank
The water system does not force the use of the buffer tank, but in the following cases, the system shall set
additional buffer tank to prevent the unit from frequent starting and stopping and to prevent the damage to the
compressor and the increase of the running cost, and at the same time, it will solve the problem of severe temperature
fluctuation of the water system, which may obtain good stability of the air-conditioning system.
a. When the capacity of the water system is less than the minimum water capacity
b. When the control accuracy of the water temperature is high
c. When load between the main machine and the terminal does not match
The volume of the buffer tank is the minimum water capacity (required capacity) – pipeline's water capacity –
terminal's water capacity.
The recommended values for minimum water capacity or required capacity are:
Application
Scenario
Air Conditioner
Process
Note: The above calculation method is applicable to the case whose requirements for the water's temperature
fluctuation is not high. If the site's requirements for the water's temperature fluctuation is high, please contact the
personnel of the York office.
The recommended installation position of the buffer tank is the backwater side of the unit. Please refer to the
following installation method.
2.8. Expansion tank
The air-conditioning water system must be installed with the expansion tank, which has certain volume, in order to
adapt to the volume change of system's water (expanding with heat and contracting with cold) caused by the change of
the water temperature, for purpose of preventing the water system's frost crack and the phenomenon that the pressure of
water pump's suction inlet is not stable; at the same time, it can be used as system's water supply and gas exhaust.
In mechanical circulation system, the expansion pipe of the expansion tank shall be connected to the pipeline in
front of the water pump's inlet, in order to be treated as the constant pressure point of the system; The circulating pipe
shall be connected to the horizontal backwater pipe whose distance to the system's constant pressure point is not less
than 1.5~3m.
For the volume calculation of the expansion pot/expansion tank, it shall refer to the following formula.
Vp=α×△ t×Vs
Vp---the effective volume of the expansion tank (the volume of water in the height difference between the signal
pipe and the overflow pipe), m
α----the volume expansion coefficient of water, α =0.0006/°C
△ t ----maximum change value of the water temperature,°C
Vs----the water capacity within the system (including the total water storage capacity of the system's pipeline and
3
equipment), m
Caution:
Considering that it shall perform anti-freezing measures in winter, the expansion tank needs to be insulated.
2.9. Water flow switch
The water flow switch shall be installed in the mixed water outlet pipe section of the same communication network
(see "Installation Diagram of Water System") , in order to realize shut-off protection for the unit. The plant equips the
cooling-water & chilled-water flow switch for the water system's main pipe in the control module package, and, on the
site, the selection shall be made according to the pipe diameter and flow rate of the main water pipe, and the
Cooke Industries - Phone: +64 9 579 2185
Minimum capacity (L/kW)
3.5
6.5
3
Email: sales@cookeindustries.co.nz
Installation Requirements
Recommended
capacity
(L/kW)
5.5~8.5
7.5~12
17
Web: www.cookeindustries.co.nz
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