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CHILLER
SERVICE
All service work
performed on the refrigeration system should be done by licensed and trained
refrigeration service technicians only.
Troubleshooting the
chiller:
The chiller cycles on and off quite frequently.
- Verify the load on the chiller. If the chiller is sized too large, it
will cool the fluid too rapidly.
- Check the differential setting in the digital controller "d1 and d2"
are the differential settings for Set-points 1 and 2 respectively. If the
application temperature is not really sensitive, perhaps setting the
differential higher will alleviate the problem.
- Check the flow rate of the fluid passing through the chiller. If the
flow is too low the chiller may short cycle.
- Verify that the unit is not cycling from any of the safety devices,
such as flow switch or low pressure safety switch. If it is, determine the
cause (dirty filter, low refrigerant...)
The chiller heat exchanger is freezing up.
- Check the settings in the digital controller "ST1 and ST2". These are
the set-points for the compressor(s) to turn on. If the settings are below
55 deg F, it is strongly recommended that a mixture of propylene glycol be
used with the water to lower the freezing point of the water.
- Check the water flow rate through the chiller. The absolute minimum
water flow rate is 1.8 GPM per ton of heat exchanger. Example: A 5 ton
chiller with 1 heat exchanger has a minimum water flow rate of 9 GPM. A 10
ton Heat chiller with 2 (five ton) heat exchangers has a minimum flow rate
of 9 gpm divided across each heat exchanger or 18 gpm at the outlet of the
chiller. The optimum GPM per heat exchanger per ton is 2.4 GPM. This will
give the best performance rate and allow for a 10 deg delta or change in
water temperature across the heat exchanger.
- Check for flashing in the sight glass. Is the unit low on refrigerant?
- Check for a clogged strainer or heat exchanger.
- Check for proper pump operation and/or rotation.
- Is there air in the water circuit?
- Is the condenser clean?
- Are there any restriction in the refrigerant lines?
The suction lines and/or the compressor is frosting up.
- Sometimes, this can be normal, depending on the application.
Oftentimes, it is a lack of refrigerant or lack of airflow across the
condenser.
- Check for any restrictions in the refrigerant lines.
- Verify the controller settings are within the design parameters of the
chiller. If this chiller was designed for 60 deg fluid and is being used
to cool to 40 deg fluid, it is being used outside it's design parameters.
- If equipped with a hot gas bypass, is the device operating properly?
Is the hot gas solenoid opening.
- Is there a de-superheating valve? Is the solenoid valve staying open?
Any
questions for Professor C not addressed, request an answer here!
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