< water source solution >

< Water Source Solution >

Updated by:Yap Boon ThiamTechnical EngineerEmail: [email protected]: 20/6/2012

mailto:[email protected]

Contents

1. Introduction What is WSS? Advantages Product Line Up

2. Installation

3. Piping Sizing

4. Troubleshooting

What is WSS?

Expansion Device

Compressor

Finned Tube Heat

ExchangerTube In

Tube Heat Exchanger

Water Inlet

Water Outlet

HP SwitchLP Switch

What is WSS?

Advantages

1. Space Saving The system utilizes space-saving concepts that are interconnected by way of water loop-rather than ductwork. Improved energy efficiency for lower operating

costs.

Lower maintenance costs.

Quiet, comfortable performance.

Advantages

2. Zoned Comfort & Control• Equipped with individual room sensor and temperature

controller.

• Can be monitored and controlled centrally by using HydroIntel.

Advantages

3. Lower Maintenance Cost• Designed with easier accessibility, especially compressor, blower and control section.

• Removable top & side panel greatly reduce the time for maintenance work.

Advantages

4. Coupling Versatility

Left or right return piping and various ducting discharge configuration (horizontal unit) has contributed in towards optimizing job layouts with minimum ductwork and piping.

Easier, lower initial installation & expansion cost.

Advantages

5. Installation Flexibility

The split configuration allows to:

Install the units at the most convenient position.

Fit the unit with reduction of space utilization due to size compactness.

Advantages

5. Protection

Hi-Low Pressure Switch

Pressure Switch psi

Hi Open 426

Close 350

LowOpen 18

Close 28

Product Line Up

‘000Btu/h

08 10 13 15 16 20 25 28 30 40 50 60 65 70

AWSS A

AWH C/CR

Cooling Only Heatpump

< Installation>

Installation

1. Installation Clearance

Install the unit at the shortest path to the coupling fan coil unit.

There should be sufficient space for piping connection, service & maintenance.

Installation

2. Hanging Method

• This unit will be mounted on the ceiling by the support of four threaded rods.

• Ensure that the supports are strong enough and properly anchored to withstand the weight of the unit.

• Use isolator rubber (natural rubber) with hardness of 35º for better noise and vibration control.

• Do not locate the drainage system at any point

above the drain connection.

Installation

3. Refrigerant Piping

Do not use copper tube less than 0.8mm

Long piping cause the capacity and compressor reliability dropped.

Model WSS10A WSS15A WSS20A WSS25A WSS30A WSS40A WSS50A WSS60A

Max Length, m 12 35

Max Elevation 5 10

Max No of Bends 10

Liquid Valve Size 1/4 3/8 1/2

Gas Valve Size 3/8 1/2 5/8 3/4

Installation

4. Additional Charge

Pre charged for standard piping up to 7.6m

For additional piping, refer table below.

Model Gram/MeterWSS10A

23WSS15AWSS20AWSS25A 57

WSS30A41WSS40A

WSS50AWSS60A 77

Installation

5. Water Piping

Install a 40-60 mesh strainer to ensure water quality is good.

Air vents must be installed at the highest position while a drainage system at the lowest position of the water circuit.

Installation

6. Electrical Wiring

Model WSS10A WSS15A WSS20A WSS25A WSS30A WSS40A WSS50A WSS60A

Power Supply (V/Ph/Hz) 220-240V / 1Ph / 50Hz 380-415V / 3Ph / 50Hz

Recommended Fuse 10 15 25 10 15

Supply Cable Size 1.5 2.5 4.0 3.0

No of Cables (DOL/ with Controller) 3 3 /5

Interconnection Cable Size 1.5 2.5 4.0 2.5

No of Cables (DOL/ with Controller) 3 6 /4

< Piping Sizing >

Loop Water Flow

1.Determine System Flow Rate

- DON’T sum up directly the total nominal water flow of each WSS unit.

- Total system design flow rate is determined by the performance of the water cooler, where most of them are evaporative type and is very much dependent on the entering air wet bulb temperature.

- Lower flow rate are preferred in area with lower wet bulb temperatures. In more humid areas, a higher water flow rate will supply a higher water temperature to water source units, but with a lower differential.

Loop Water Flow

2.Determine WSS Unit Flow Rate

- Total Cooling load must be known.

- Diversity Effect must be considered. This is to prevent over sizing water cooler.

- Recommended diversity factor;

- 85% for system up to 40 tons

- 80% for system between 40 and 60 tons

- 75% for system greater than 60 tons

- System diversity will only affect the range of the water cooler.

Diversity Factor, D = Block Load / Σ(Peak Load)

Loop Water Flow

2.Determine WSS Unit Flow Rate

- By using diversity factor, D, the average range of the water source units, Rp :

where typical value of range are between 5C to 8C or equally 9F to 14.4F.

Range of Water Cooler,

Rs = Twi – Two

where

Twi = entering water temperature

Two = leaving water temperature

Rp = Rs /D

Loop Water Flow

3.Determine individual unit peak cooling load

- By assuming 30% of heat rejection ratio

Substitute 1 into 2: ,

Qh = 1.3 *D* Qc

Qh = mw * Cp * (Twi – T wo)

where

mw = mass flow rate of water

Cp = water specific heat

Qh = gpm* 500* Rs

1.3 *D* Qc = 500 * gpm * Rs

1

2

Rp = 1.3 * qc / (500 * gpm)

By taking qc as individual unit peak cooling load

Loop Water Flow

Example 1

A water loop system consists of 30 units of water source heat pump units with a combined total peak loading of 450,000btu/hr. the system is served by a centrifugal water pump. Aclosed loop water cooler is used to give a leaving water temperature of 30C. the ambient air wet bulb temperature is 25C.

Determine the required total system water flow rate.From the given table, at 25C wet bulb temperature, the water flow rate is 2.36 gpm/ton.Therefore, the total system water flow rate is 2.36 gpm/ton * (450000/12000)ton = 88.5 gpm

Calculate the average range of the water source units.The system range is first calculated;Rs = 1.3 * D * Qc / gpm / 500 = 1.3 * 0.85 * 450,000 / 88.5 / 500 = 11.24 F or 6.24CRp = Rs / D = 13.22F or 7.35C

If one of the water source units has been designed to give a cooling capacity of 11,000btu/hr, calculate the water flow rate required.Rp = 1.3 * qc / (gpm *500) 13.22 = 1.3 * 11000 / (gpm *500) ; gpm = 2.16gpm

Piping Sizing

Pipe Sizing Procedure- The layout drawing should give dimensional lengths of the piping network.

- The layout must include all the floors of the building where the water-source units are installed.

- Location of water cooler, pumps and boiler must be identified.

- All fittings and accessories used in the piping installation should be clearly identified.

- Study the pipe circuit layout and do preliminary check if the circuits are balanced. Re-arrange if

necessary. Use balancing valves only if it is not possible to have balanced circuits.

- Size the pipes by using the pipe chart. The water velocity should be in the range of 2 – 9 fps, with a

recommended max friction loss of 10 ft of water per 100 ft.

- Calculate equivalent pipe length. Include the losses for all the valves and fittings used. Calculate

the total pipe friction loss by using the friction loss value from the pipe chart. Add this with the

pressure drop in heat exchangers, water cooler and boiler.

- Select a pump which will match these total system water flow rate and total head pressure.

Piping Sizing

Example 2

The water source units which serve the main building has a total installed cooling capacity of 560,000 btu/hr (peak load).

There a altogether 40 sets, with 10 sets for each of the four floors.

The water source units have been selected based upon the following conditions:

Entering air = 25C DB / 18C WB

Entering water = 32C

All the units are connected to an evaporative water cooler located on top of an adjoining service building outside of the main building.

Ambient WB = 24C

Piping Sizing

Piping Sizing

1. Calculate the total system water flow rate.

Total installed capacity = 560,000 btu/hr (46.67 tons) Therefore, the total system water flow rate @ 24C wet bulb is 2.19 gpm/ton * 46.67 tons = 102.2 gpm.

2. Calculate the range (Rs) of water cooler

For 46.67 tons, use diversity factor of 0.80. Rs = 1.3 * D * Qc / (gpm*500) = 1.3 * 0.80 * 560000 / (102.2*500) = 11.4F or 6.3C.

3. Calculate the range (Rp) of water source units.

Rp = Rs / 0.80

= 11.4 / 0.80

= 14.25F or 7.9C.

Piping Sizing

4. The unit on the 4th floor have been sized to give the following peak loads:

By using equation Rp = 1.3 * qc / (500 * gpm) , assume the total system water flow rate is distributed to all the

four floors of the main building in such manner.

Unit Btu/hr Flow Rate (gpm)

h 9800 1.79

i 9600 1.75

j 13000 2.37

k 11700 2.13

l 12500 2.28

m 12500 2.28

n 14000 2.55

o 10600 1.93

p 11000 2.01

q 12000 2.19

Total 116700 21.29

Floor Flow Rate (gpm)1 30.662 25.553 24.74 21.29

Total 102.20

Piping Sizing

Hence, we can no look into the pipe sizing all the way up to 4th floor.

Focus is given to determine the route which is having max friction loss to the water pump.

Reference is then made to pipe chart to determine a suitable pipe size.

Closed System Piping Flow Graph

Piping Sizing

Each of the WSS has fittings as shown below:

The water pump has been installed as shown below:

Piping Sizing

Water pipe connection to the evaporative water cooler as shown below :

Piping Sizing

SectionFlow Rate Pipe Dia Velocity Friction Loss Pipe Length Fitting Equipvalent Length & Quantity

Total Equipvalent

Length

Total Friction Loss

gpm in fps ft/100ft m ft Elbow 90 Tee-Thru Gate/Auto Strainer ft ft

WC-P 102.2 3 4.4 2.50 6 19.68 Qty 1 1 62.88 1.57ft 3.2 40

P-a 102.2 3 4.4 2.50 2 6.56Qty 1 1

17.26 0.43ft 7.5 3.2

a-WC 102.2 3 4.4 2.50 10 32.8Qty 1 1

43.5 1.09ft 7.5 3.2

a-b 102.2 3 4.4 2.50 16 52.48Qty 2

67.48 1.69ft 7.5

b-c 102.2 3 4.4 2.50 40 131.2Qty 2

146.2 3.66ft 7.5

c-d 102.2 3 4.4 2.50 60 196.8Qty 2

211.8 5.30ft 7.5

d-e 102.2 3 4.4 2.50 4 13.12Qty 2

27.12 0.68ft 7

e-f 71.54 2.5 4.6 3.50 6 19.68Qty 2

30.88 1.08ft 5.6

f-g 45.99 2 4.3 3.70 6 19.68Qty 2

29.08 1.08ft 4.7

g-h 21.29 1.5 3.3 3.00 14 45.92Qty 4 2

69.32 2.08ft 4 3.7

h-i 19.5 1.25 4.2 5.80 8 26.24Qty 2

31.44 1.82ft 2.6

i-j 17.75 1.25 3.6 4.80 8 26.24Qty 2

31.44 1.51ft 2.6

j-k 15.38 1.25 3.3 3.60 8 26.24Qty 2

30.84 1.11ft 2.3

k-l 13.24 1.25 2.9 3.00 28 91.84Qty 2 2

104.64 3.14ft 3.3 3.1

l-m 10.96 1 3.8 7.50 10 32.8Qty 2

36.2 2.72ft 1.7

m-n 8.68 1 3.3 5.00 10 32.8Qty 2

37.4 1.87ft 2.3

n-o 6.13 0.75 3.5 8.50 20 65.6Qty 2 2

72.4 6.15ft 2 1.4

o-p 4.19 0.75 2.5 4.20 10 32.8Qty 2

36.6 1.54ft 1.9

p-q 2.19 0.5 2.3 5.00 14 45.93Qty 2 4 3

55.23 2.76ft 1.6 1 0.7

41.26Pressure drop across WSS at point 'q' 2.75Pressure drop acrosss the water cooler 7.5

Total 51.5115% safety factor 59.24

Fitting Loses

Valve Loses

< Troubleshooting>

Troubleshooting

1.Unit cannot Start

Power supply plug disconnected.

Circuit breaker or fuse tripped / blown.

Wiring connection.

2. Neither Fan Coil Unit & Compressor Run

The fuse may be blown or circuit breaker opened.

Check electrical circuit or motor winding for shorts or grounds. Investigate for possible over loading. Replace fuse if necessary.

Check wiring connections. It might be caused by loose wire. Replace or tighten.

Control system may be faulty.

Troubleshooting

3. Compressor does not Operate

Check capacitor if available. Replace capacitor if faulty.

Check wiring connection. Wire connections might be loose. Replace or tighten.

The high pressure switch may tripped due to: No or insufficient water flows into and leaves heat exchanger. May be clogged. Water entering temperature higher than the maximum operating conditions. Not enough air flow into fan coil unit. May be due to dirty filter or block by object, cardboard Unit over-charged. Release some of the refrigerant charge.

The compressor internal/external overload protection is opened. If the compressor body is extremely hot, the overload will not reset until it cooled down.

The compressor winding may be grounded to the compressor shell. If so, replace the compressor.

Troubleshooting

4. Insufficient Cooling

Power supply plug disconnected.

Check controller temperature setting.

Filter may be clogged. Check and clean the filter.

Check capillary tube for possible restriction of refrigerant flow. Replace capillary tube.

The reversing valve may be defective (valve position is not shifted properly), creating a bypass of refrigerant. Check the reversing valve coil connection.

Check for restriction of air and water flow.

Refrigerant leakage. Check all piping bends and connection for leakage. Repair the leakage area or replace with new piping.

Window or door wide open.

Unit may be under-sized.

Troubleshooting

5. Insufficient Water Flow through Heat Exchanger

Valves are not opened fully.

Circulating water pump is faulty.

Water pipes or strainers are clogged.

6. Noisy Operation

Check for loose bolts or screws & ensure rubber isolators are used for installation.

Check for water balance to unit for proper water flow rate.

Check for tubing touching compressor or other surface. Readjust tubing by bending it slightly.

Fan (fan coil unit) knocking / hitting on its housing.

May be due to worn compressor bearing.

< FAQ>

FAQ

1. How to judge water capacity in the system if water pressure meter is not available?

Measure the pressure drop across the inlet & outlet tube. The nominal flow rate can be estimated from table below.

FAQ

2. Minimum & maximum recommended water flow rate? It is advisable to maintain within 10% of the nominal water flow rate so that the temperature diffrential wouldn’t too great.

3. Minimum & maximum water entering temperature?

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