Water Treatment And Quality Control - Mitsubishi Electric PEFY-WL06NMAU-A Installation Manual

• 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. 7.2.4] when connecting the water supply.
[Fig. 7.2.4] (P.6)
A Indoor unit
B Water pipe: From HBC unit
C Water pipe: To HBC unit
D Strainer (40 mesh or more) (field supply)
E Shut off valve (field supply)
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.

7.3. 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 air
conditioner, 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 (mS/m)
conductivity (25°C) [77°F]
(µ s/cm)
(25°C) [77°F]
Chloride
(mg Cl-/ℓ)
ion
Stand-
Sulfate ion (mg SO4
ard
items
Acid consumption (pH4.8)
(mg CaCO
Total
(mg CaCO
hardness
Calcium
(mg CaCO
hardness
Ionic silica (mg SiO
(mg Fe/ℓ)
Iron
(mg Cu/ℓ)
Copper
Sulfide ion
(mg S
Refer- Ammonium
(mg NH
ence ion
items
Residual
(mg Cl/ℓ) 0.25 or less 0.3 or less
chlorine
Free car-
(mg CO
bon dioxide
Ryzner stability inde
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.
14
Low to mid-range tem-
Tendency
perature water system
Recirculat-
ing water Make-up Corro-
[20<T<60°C] water sive
[68<T<140°F]
〇
7.0–8.0 7.0–8.0
30 or less 30 or less
〇
[300 or less] [300 or less]
〇
50 or less 50 or less
/ℓ)
〇
2- 50 or less 50 or less
50 or less 50 or less
/ℓ)
3
/ℓ)
70 or less 70 or less
3
/ℓ)
50 or less 50 or less
3
/ℓ)
30 or less 30 or less
2
〇
1.0 or less 0.3 or less
〇
1.0 or less 0.1 or less
not to be not to be
/ℓ) 〇
2-
detected detected
/ℓ)
〇
+ 0.3 or less 0.1 or less
4
〇
/ℓ) 〇
0.4 or less 4.0 or less
2
〇
6.0–7.0 –
4 When replacing a previously installed air conditioning device (even when only
the heat exchanger is being replaced), first 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.
Scale-
form-
ing
〇
〇
〇
〇
〇
〇
〇
〇