Mitsubishi Electric PURY-WP-YJM-A Data Book page 202

3. Piping Design
5. Leakproof the water pipework, valves and drain pipework. Leakproof all the way to, and include pipe ends so that condensation
cannot enter the insulated pipework.
6. Apply caulking around the ends of the insulation to prevent condensation getting between the pipework and insulation.
7. Add a drain valve so that the unit and pipework can be drained.
8. Ensure there are no gaps in the pipework insulation. Insulate the pipework right up to the unit.
9. Ensure that the gradient of the drain pan pipework is such that discharge can only flow out.
10. HBC water pipe connection sizes and pipe sizes.
Water inlet
Indoor unit
To outdoor unit
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 units
• 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 figure below when connecting the water supply.
HBC controller
12. Use formula 0.1 ≤ 0.01 + 0.01 × A ≤ 0.16 for the supply pressure range to be used.
(A: Head pressure (m) between the HBC and the highest indoor unit)
If the supply pressure is greater than 0.16 MPa, use a pressure reducing valve to keep the pressure within the range.
If the head pressure is unknown, set it to 0.16 MPa.
13. Install a shut off valve and strainer in a place that is easy to operate and makes maintenance work easy.
14. Apply insulation to the indoor unit pipework, strainer, shut off valve, and pressure reducing valve.
15. Please do not use a corrosion inhibitor in the water system.
16. When installing the HBC unit in an environment which may drop below 0°C, please add antifreeze (Propylene Glycol only) to
the circulating water. For the brine selection, refer to 6-5. "Correction by brine concentration" in chapter "Outdoor Unit".
3-2-3-3 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 scale, 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
Depending on the quality of the cold-temperature water used in the airconditioner, 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.
Connection size
Water outlet Water out
Rc 3/4 Rc 3/4
I.D. 20 mm
screw screw
End connection (brazing)
HBC controller
Water pipework is screw
connections
Indoor Indoor Indoor
unit unit unit
Water pipe
Strainer
Pressure reducing valve
SYSTEM DESIGN
Pipe size
Water return
I.D. 20 mm
Twinning pipe (field supply)
Indoor Indoor
unit unit
Up to three units for 1 branch hole;
total capacity: below 80
(but in same mode, cooling/heating)
Shut off valve
Indoor
unit
*1
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