Mitsubishi Electric CITY MULTI PLFY-WL-NEMU-E Serie Manual De Instalación página 8

4. Connecting water pipes
■ Connection of HBC (Indoor unit without valve)
* PLFY-WL·NEMU-E Series has no valve.
A
B
C
D D
A To outdoor unit
B End connection (brazing)
C HBC controller
D Indoor unit (without valve)
Note:
*1. Connection of multiple indoor units with one connection (or joint pipe)
• Total capacity of connectable indoor units: Less than 80
• Number of connectable indoor units: Maximum 3 Sets
• Selection of water piping
Select the size according to the total capacity of indoor units to be installed
downstream.
• Please group units that operate on 1 branch.
11. Please refer to the [Fig. 4-4] when connecting the water supply.
B
A
C
12. Install a shut off valve and strainer in a place that is easy to operate and makes
maintenance work easy.
13. Apply insulation to the indoor unit pipework, strainer, shut off valve, and pressure
reducing valve.
14. Please do not use a corrosion inhibitor in the water system.
en
6
Water pipework is
E
screw connections
D D D
F
*1
E Twinning pipe (fi eld supply)
F Up to three units for 1 branch hole;
total capacity: below 80 (but in
same mode, cooling/heating)
Fig. 4-3
D
E A Indoor unit
B Water pipe: Inlet
C Water pipe: Outlet
D Strainer (40 mesh or more)
(fi eld supply)
E Shut off valve
E
(fi eld supply)
Fig. 4-4
4.3. Water treatment and quality control
To preserve water quality, use the closed type of water circuit. When the circulating
water quality is poor, the water heat exchanger can develop scales, leading to a
reduction in heat-exchange power and possible corrosion. Pay careful attention to
water processing and water quality control when installing the water circulation system.
• Removing of foreign objects or impurities within the pipes.
During installation, make sure that foreign objects, such as welding fragments,
sealant particles, or rust, do not enter the pipes.
• Water Quality Processing
1 Depending on the quality of the cold-temperature water used in the airconditioner,
D
the copper piping of the heat exchanger may corrode.
Regular water quality processing is recommended.
If a water supply tank is installed, keep air contact to a minimum, and keep the
level of dissolved oxygen in the water no higher than 1mg/ℓ.
2 Water quality standard
Items
pH (25°C) [77°F]
Electric conductivity
Chloride ion
Sulfate ion
Acid consumption (pH4.8)
Total hardness
Calcium hardness
Ionic silica
Iron
Copper
Sulfi de ion
Ammonium ion
Residual chlorine
Free carbon dioxide
Ryznar stability index
Reference : Guideline of Water Quality for Refrigeration and Air Conditioning
Equipment. (JRA GL02E-1994)
3 Consult with a specialist about water quality control methods and calculations
before using anti-corrosive solutions.
4 When replacing a previously installed air conditioning device (even when only
the heat exchanger is being replaced), fi rst conduct a water quality analysis and
check for possible corrosion.
Corrosion can occur in cold-water systems even if there has been no prior signs
of corrosion.
If the water quality level has dropped, adjust water quality before replacing the
unit.
Low to mid-range
temperature water
system
Recirculating
water Make-up
[20<T<60°C] water
[68<T<140°F]
7.0 - 8.0 7.0 - 8.0
30 or less 30 or less
(mS/m) (25°C) [77°F] [300 or [300 or
less]
(μ s/cm) (25°C) [77°F]
-
(mg Cl /ℓ) 50 or less 50 or less
2-
(mg SO /ℓ) 50 or less 50 or less
4
50 or less 50 or less
(mg CaCO /ℓ)
3
(mg CaCO /ℓ) 70 or less 70 or less
3
(mg CaCO /ℓ) 50 or less 50 or less
3
(mg SiO /ℓ) 30 or less 30 or less
2
(mg Fe/ℓ) 1.0 or less 0.3 or less
(mg Cu/ℓ) 1.0 or less 0.1 or less
(mg S 2- /ℓ) not to be not to be
detected detected
(mg NH + /ℓ) 0.3 or less 0.1 or less
4
(mg Cl/ℓ) 0.25 or less 0.3 or less
(mg CO /ℓ) 0.4 or less 4.0 or less
2
6.0 - 7.0
Tendency
Scale-
Corrosive
forming
less]
–