7. SYSTEM DESIGN GUIDE
DATA G10
HEAT SOURCE UNITS
2 - 396
WY
7. SYSTEM DESIGN GUIDE
7-1. Designing of water circuit system
E.H
S.T
T
T
C.T.P
C.T
P
3-way valve
1) Example of basic water circuit
Example of basic water circuit for water heat source CITY MULTI
The water circuit of the water heat source CITY MULTI
connects the heat source unit with the cooling tow-
er/auxiliary heat source/heat storage tank/circulation
pump with a single system water piping as shown in the
figure below. The selector valve automatically controls
to circulate water toward the cooling tower in the cooling
season, while toward the heat storage tank in the heat-
ing season. If the circulation water temperature is kept
in a range of 10~45°C[50~113°F]* regardless of the
building load, the water heat source CITY MULTI can
be operated for either cooling or heating. Therefore in
the summer when only cooling load exists, the tempera-
ture rise of circulation water will be suppressed by oper-
ating the cooling tower. While in the winter when heat-
ing load increases, the temperature of circulation water
may be dropped below 10°C[50°F]. Under such situa-
tion, the circulation water will be heated with the auxili-
ary heat source if it drops below a certain temperature.
When the thermal balance between cooling and heating
operation is in a correct proportion, the operation of the
auxiliary heat source and cooling tower is not required.
In order to control the above thermal balance properly
and use thermal energy effectively, utilizing of heat stor-
age tanks, and night-time discounted electric power as
a auxiliary heat source will be economical.
Meantime as this system uses plural sets of heat source
unit equipped with water heat exchangers, water quality
control is important. Therefore it is recommended to use
closed type cooling towers as much as possible to pre-
vent the circulation water from being contaminated.
When open type cooling towers are used, it is essential
to provide proper maintenance control such as that to
install water treatment system to prevent troubles
caused by contaminated circulation water.
S.T
: Heating tank
(Heat storage tank)
C.T
: Cooling tower
C.T.P
: Cooling water pump
P
: Circulation water pump
T
:
Thermostat
for
water
E.H
: Electric heater
: Heat source unit for cooling
operation
: Heat source unit for heating
operation
The indoor unit and refrigerant piping system are excluded in this figure.
