Water Chillers and Maintenance part 2 Electric-Drive Chillers

Water Chillers and Maintenance

 part 2
Electric-Drive Chillers

Water Chillers and Maintenance

Electric-Drive Chillers:

1. Determine that the chiller full load amperes (FLA) is within 5% of design.

2. Test volts, phase-to-phase.

3. Compute voltage imbalance and determine that the maximum variation

between phases is less than 2%.

Absorption Chillers:

1. Determine that the high generator temperature is within the design range.

2. Test high/low generator solution level.

3. Determine that supply steam pressure is within 5% of design.

4. Test automatic overconcentration, dilution cycles, and dilution on

shutdown.

Water-Cooled Chillers:

1. Confirm that the cooling tower has been commissioned (see the section

“Tower Commissioning” in Chapter 15).

2. Determine the entering CDW temperature and confirm that it is within

1°F of setpoint.

3. Determine leaving CDW temperature and compare to design.

4. Determine CDW temperature range and compare to design.

Air-Cooled Chillers:

1. Determine ambient air temperature.

2. Determine chiller head pressure and compare to rated value.

Operations and Control:

1. Confirm that the chiller appears to meet load.

2. Confirm that the chiller operates without alarm conditions or safety

shutdowns.

3. Confirm that the chiller start sequence operates properly.

4. Confirm that multichiller staging sequence operates properly.

CHILLER MAINTENANCE:

When establishing a maintenance program for chillers, maintenance managers

have three options:

1. Implement the program fully in-house.

2. Outsource the entire program.

3. Use a combination of in-house and outsourced functions.

One of the most important benefits of a program that uses in-house personnel

is the institutional knowledge of those systems. Maintenance personnel who have

been working with those chiller systems for years are most likely to know what

many of the existing maintenance problems are.

Another benefit of using in-house personnel is long-term quality. Maintenance

managers and in-house personnel are better able to focus their attention and

efforts on both short- and long-term requirements, up to the expected life of the

equipment. Outsourced programs tend to have a much shorter focus, that is, the

period of the maintenance contract.

However, the cost of establishing a complete in-house program can be very

high. Managers have to arrange for the training of maintenance personnel on the

specifics of maintaining the chiller(s) installed in the facility, provide specialized

training for infrequent testing and servicing, and purchase specialized test

equipment

for many of the inspection and maintenance activities that must be

performed.

Combination of in-house and outsourced programs typically assign the routine

and preventive maintenance tasks to in-house personnel, while contracting is utilized

for specialized activities that require a higher level of expertise than is available

in-house. This approach maintains in-house personnel being actively involved

in the maintenance, while outside experts assist them by performing the more

complex and infrequent tasks. This arrangement helps preserve the institutional

knowledge and typically is the most cost-effective approach.

No matter which maintenance scheme is utilized, a preventative maintenance

program to ensure that the chiller operates reliably over its design life is required.

The majority of chiller operating problems and maintenance needs are discovered

by visual inspection and the monitoring of equipment operating parameters.

Figure 7.1 is a form that can be used to guide chiller visual inspection and to collect

operating data every 2 h during the day. These data will give a complete

“snapshot” of the running conditions of the chiller, and variations in data between

observations can be a prime indicator of operating problems.

Over the long term, these data can be used to predict maintenance requirements.

These data, along with the data collected during periodic checks and routine

maintenance

procedures, can be plotted against time so that a trend or change

in conditions can be identified. A decision on maintenance can then be made from

the trend.

Recommended preventative maintenance procedures for air-cooled electricdrive

water chillers are as follows:

Daily monitoring/visual inspection: The majority of chiller operating problems

and maintenance needs are discovered by visual inspection and

frequent monitoring of equipment operating parameters.


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