YORK ® AIR-CONDITIONING PRODUCTS
Minimum system water volume Warm water system
To allow the Chiller or Heat Pump to operate smoothly at low load
capacities sufficient thermal storage is required in the primary water
circuit to give at least 5 minutes operation when the machine is not
running. This will ensure that the equipment will not continuously stop
and start at low load conditions and consequantly cause undue wear on
the compressor. The leaving water temperature from a Heat Recovery Chiller or a Heat
Pump is normally between 45°C and 60°C depending on the refrigerant
that the machine is charged with. For Heat Pumps more heating
capacity and higher operating efficiency is available with lower leaving
water temperatures. Water temperatures of 45°C to 50°C are quite
adequate for the selection of heating coils in Air Handling Units and Fan
Coils.
The following formula will satisfy the toral required thermal storage
volume:
V =
Refrigerant to water condensers are limited in the volume of water
that can be passed through them and it is necessary that this limitation
is considered during the system design process. This may result in a
larger water temperature differences than those used in a normal Boiler
fed low temperature hot water system. The water temperature can be
increased from a Boiler but measures must be taken to ensure that the
return water to the Chiller or Heat pump cannot ever exceed 60°C.
(N x 60 x Z)
4.18 x dt
V = Total system water content (Litres)(4.18 x dt)
N = Capacity of the Chillers first capacity step (kW)(4.18 x dt)
Z = Minimum allowable running time (minimum 5 min.)
dt = Temp. difference at the minimum partload condition
V = 35.88 x S x Q
Chiller condenser connection
S = Minimum capacity step (at lowest operating ambient)
Q = Full capacity at nominal conditions
Chiller cooler connection
Victaulic or Flanged
Connection
CONDENSER
Pressure Tapping
Victaulic or Flanged
Connection
COOLER
Flow Switch
Pressure Tapping
Drain Connection
Flow Switch
Isolating Valve
Maintenance
Bypass
Drain Connection
Water Out
Maintenance
Bypass
Air Vent
Isolating Valve Double Regulation
Valve with Pressure
Tapping
Air Vent Strainer
Double Regulation
Valve with Pressure
Tapping
Water In
Water Out
Water In
Strainer
Chiller condenser water systems
In order to ensure a trouble-free operation of the cooling water pump
during startup of the system, the entire cooling water piping should be
as far as possible below the operating level of an open circuit cooling
tower. This prevents emptying of the cooling water lines in the cooling
tower trough.
To ensure satisfactory pump operation at start-up and to prevent
overflowing of the Cooling Tower sump all condenser piping, and as
much tower piping as possible, should be installed below the operating
level of the tower. If multiple towers are used on a common system
equalising lines should be installed between the sumps of the separate
Cooling Towers to ensure balanced water level in all the towers. If more
than one inlet connection is required to a tower balancing valves should
be installed to give the required flow to each circuit.
If multiple cooling towers are used in a common cooling water circuit,
compensation pipes must be installed between the cooling tower tanks
in order to keep the cooling water in all cooling towers at the same
level. If more than one water entry into the cooling tower is required,
install throttle valves to balance the flow between circuits. Check that
the pressure of the spray nozzles and the pressure of the make-up
water are not exceeded.
Check that the maximum spray water and make-up water pressures are
not exceeded.
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