Maintenance Of Plate-Type/Brazed Plate Heat Exchanger; Variable Water Flow Rate - Daikin VRV W T Serie Manual De Instalación

4 .4 .3 Maintenance of plate-type/brazed plate
heat exchanger
CAUTION
A brazed plate-type heat exchanger is used for this unit.
Because its structure is different from a conventional type
heat exchanger, it must be handled in a different manner.
When designing the equipment
1 Install a strainer (standard accessory) at the water inlet side
adjacent to the outside unit in order to prevent any foreign
materials such as dust, sand, etc. from entering.
2 Depending on the water quality, scale may stick to the plate-
type heat exchanger. In order to remove scale, it is necessary
to use chemicals to clean it at regular intervals. To this end,
install a gate valve in the water piping. Set up a piping
connection port on the piping between this gate valve and the
outside unit for cleaning by chemicals.
3 For the purpose of cleaning and water drain-off from the outside
unit (water draining during a long period of non-use in winter,
draining upon starting of season-off), install an "air discharge
valve" and a "water draining plug" at the inlet/outlet ports of
water piping. In addition, install an "automatic air discharging
valve" at the top of riser piping or at the top of a portion where
air tends to stay.
4 Independent of the piping inlet of the outside unit, install a
cleanable strainer at a portion close to the pump piping inlet.
5 Carry out complete cooling/thermal insulation of water piping
and outside dehumidification. If complete cooling or thermal
insulation has not been carried out, any damage may be
caused during severe winter due to freezing, in addition to
thermal loss.
6 When you stop operation during night or winter, it is necessary
to take measures to prevent water-related circuits from natural
freezing in the area the ambient temperature drops below 32°F
(0°C) (by water drain off, keeping the circulation pump running,
warming up by a heater, etc.) Freezing of water related circuits
may result in any damage to the plate-type heat exchanger.
Therefore, take appropriate measures depending on the
circumstances of use.
Before starting a test run
1 Before starting a test run, please make sure that the piping
work has been carried out in a proper manner. Especially, make
sure that the strainer, air discharge valve, automatic water
supply valve, expansion tank and cistern are positioned at their
places correctly.
2 After water has been completely filled in, first run the pump
only, and then make sure that no air has been caught in the
water circulation system and that the water flow rate is correct.
If any air has been caught or the flow rate is not enough, the
plate-type heat exchanger may freeze. Measure any water
pressure loss before and after the outside unit and make sure
that the flow rate is as designed. In case of any abnormality,
stop the test run immediately and carry out trouble shooting to
resolve the trouble.
3 Following the installation manual, carry out a test run of the
outside unit.
4 After the test run has been completed, inspect the strainer at
the inlet piping of the outside unit. Clean it if it is dirty.
RWEQ96~432TATJU + RWEQ96~432TAYDU
VRV W T-Series water-cooled system air conditioner
4P484115-1A – 2017.10
d
c
b e
a
g
h
i
a
Water inlet piping
b Strainer (accessory)
c Air discharge valve (for joint use with cleaning port)
d Cleaning device
e Strainer for pump (field supply)
f Automatic air discharge valve
g Water outlet piping
h Joint use with water draining plug
i Plate-type heat exchanger
4 .4 .4

Variable water flow rate

The RWEQ96~144TA* models are equipped with the logic to
operate with a variable water flow rate function.
a
b
c
a Constant flow
b Flow regulating valve (field supply)
c Inverter pump (field supply)
A system can either be configured as a constant flow system (a), a
variable flow system with valve (b) or a variable flow system with a
pump (c).
▪ Constant flow system (a): the variable water flow rate function is
not used.
▪ A pressure independent flow regulating valve (b): the valve
controls the flow rate of a centralized inverter pump through the
unit.
▪ Inverter pump (c): the pump directly controls the water flow rate
through the unit.
To activate the variable flow system, change field setting [2-24] to
the applicable value. See "7.2 Making field settings" on page
NOTE
Make sure that all field supplied equipment for variable
flow rate can be switched off together with the outside unit.
This is required when cleaning the plate heat exchanger.
NOTE
▪ Make sure that all field supplied equipment for variable
flow rate meet the minimum hydronic and electric
specifications. Failure to do so can result in inefficient
operation or even breakdown of the system.
▪ The outside unit is equipped to deliver variable flow
signal to one hydronic pump. Hence it is recommended
to install only one hydronic pump per single module of
the system.
Size the valve (b) or pump (c) in accordance with the maximum
required flow rate A, calculated by the installer of the hydronic
system (with respect to the operation range of the outside unit). The
typical operation range of the flow rate of the valve/pump is 50% (B)
to 100% (A).
4 Preparation
f
34.
Installation manual
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