RH SERIES—HIGH TEMPERATURE
2.14 TROUBLESHOOTING
IMPORTANT
Before starting maintenance activity or repair on the dryer, the main power switch and ON/
OFF switch must be turned OFF. Also, the compressed air must be vented from the system and the inlet and outlet valves must be closed. The dryer has to be isolated completely.
SECTION 2
PROBLEM
Dryer-on light is lit but refrigerant compressor is not operating cont.
POSSIBLE CAUSE
Refrigeration unit is not operating
REPAIR
Check refrigeration compressor
The refrigerant high pressure protection has tripped
The refrigerant safety high pressure switch has tripped
Excessive ambient temperature
Excessive temperature on crankcase of compressor
Excessive compressed air inlet temperature
Ensure that dryer inlet conditions are within the recommended range.
Designed conditions and correction factors are described in product literature.
Allow time for the compressor to cool down
Reason may be a possible incorrect adjustment or shortage of refrigerant
Be sure that dryer inlet conditions are within the specified range.
COMMENTS
Several factors may cause compressor failure.
A qualified refrigeration contractor should check all electrical and refrigerant control
The dryer is protected against a very high refrigerant pressure. It will trip in case the condenser efficiency is reduced
Manually reset the switch (green button)
A high ambient temperature may cause the refrigerant system to operate at higher than normal pressures.
Results will be a higher than normal evaporator temperature.
Important: there should be adequate air circulation around the dryer, and proper ventilation in the equipment room is a must to achieve a low enough ambient temperature
Compressor is protected against too high a temperature of the crankcase by a thermal switch called “klixon”
Klixon can be located internally to refrigerant compressor or under the protective cover on the top of the compressor
The dryer is designed for working within calculated maximum conditions.
Should these conditions change, the dryer can be overloaded, the dew point will go up and protecting devices can switch off
32
SECTION 2 RH SERIES—HIGH TEMPERATURE
PROBLEM
Dryer-on light is lit but refrigerant compressor is not operating
Dryer-ON light is lit but refrigerant compressor does not run
Dryer-on light is lit but fan does not come ON
Dryer on light is lit but fan motor of aftercooler does not run
When compressor starts, it vibrates a lot and makes mechanical noise
POSSIBLE CAUSE
Too much air flow
Faulty electrical wiring
One electrical protection has tripped
Compressor is sucking liquid refrigerant at start up.
REPAIR
Clogged condenser fins Clear fins of all obstructions
Check actual flow through the dryer
Inspect the circuit
Reset the protection or replace the blown fuse
Fan has to run if refrigerant high pressure has reached upper set point
Inlet air temperature may be too low
Check the compressed air flows through the dryer. Check to make sure that the fan blades are free to rotate.
Increase the inlet air temperature
Be sure that pre-heating period of minimum 4 hours has elapsed for dryers equipped with crankcase heater (all models equal to and larger than 250CFM)
COMMENTS
The clogged fins in the condenser will restrict the air passage and reduce the refrigeration capacity, causing high temperature in the evaporator.
Air condensers should be periodically checked and cleaned.
This dryer is designed for a maximum air flow. If too much air is pumped into the dryer, water removal capacity decreases, resulting in liquid carryover downstream. Check the rated output of the air compressor and make sure that it matches the dryer capacity.
The compressor-on light should be wired into the refrigerant compressor circuit.
Refer to the electrical and wiring diagram for proper connections.
The dryer is protected by a fuse and/ or overload relay that can trip.
Reset or replace blown fuse once, but do not insist if it trips again. Instead have a qualified refrigerant technician check the complete dryer thoroughly.
Fan is automatically turned ON/OFF in order to keep the refrigerant pressure to a minimum value. The fans might stop if the pressure setting is incorrect
The fan motor of the aftercooler is designed to run if the inlet air temperature is equal or greater then 95F. In case it is less then that temperature then the fan motor of the aftercooler does not start to run.
Refrigerant may move between the receiver when refrigerant compressor is stopped and not heated, especially if it has been non-operational for a long time
This migration may cause liquid shock in valves specially on dryers containing more refrigerant
33
RH SERIES—HIGH TEMPERATURE
PROBLEM
Water in system
SECTION 2
POSSIBLE CAUSE
Inlet and outlet connections are reversed
Drain system is clogged or inoperative
Bypass system is open
Free moisture remains in pipe lines
Excessive free moisture
Excessive compressed air inlet temperature
REPAIR
Check inlet and outlet connections
Restore free flow of water condensate.
Check water evacuation points and connections.
Check the valves
Blow out the system
Check the separator and drain system ahead of the dryer
Be sure that the dryer is working well within the maximum operating conditions
COMMENTS
This dryer is designed for air flow in one direction only.
Inlet and outlet directions are identified on the dryer and cannot be interchanged.
The attached drain may be timer and solenoid valve type or pneumatically assisted.
Timer has to be adjusted in accordance with values listed in the manual and depending on the amount of moisture in the air stream.
Solenoid valves includes a strainer that has to be periodically checked and cleaned.
Membranes of pneumatically assisted drains have to be checked or replaced every 6 months
Important: Bypass piping should be installed around the dryer so the dryer can be isolated for service without shutting down the air supply.
During dryer operation, valves must be set so all air goes into the system.
Check tightness of the bypass system
Before the dryer is placed inline, blow out all the moisture from the system and from the compressed air piping.
In some systems there may be an accumulation of free moisture in the line ahead of the dryer.
If this moisture is pumped into the dryer intermittently, the water removal capacity may not be sufficient.
A water separator has to be installed into the line before the dryer
The dryer is designed for working into calculated maximum conditions.
Should the conditions be exceeded, the dryer will be overflowed, dew point will go up and protecting devices can switch off
34
SECTION 2
PROBLEM
Water in system
High pressure drop
RH SERIES—HIGH TEMPERATURE
POSSIBLE CAUSE
Clogged condenser fins Clean fins of all obstruc-
Shortage of refrigerant
Refrigeration system is not functioning
Excessive pressure dew point
Excessive compressed air flow or too low air inlet pressure
Freeze up
REPAIR tions
Fix the leak and add a charge of refrigerant
Double check if the refrigerant compressor is running
Readjust refrigerant evaporating pressure
Check actual pressure and flow through the dryer
Ensure that the operating room temperature is above 41°F/5°C
Readjust refrigeration controls
Clogged heat exchanger Clean heat exchanger with a reverse air flow
COMMENTS
The clogged fins in the condenser will restrict air passage and reduce refrigerant capacity causing water downstream.
Fins should be periodically checked and cleaned
Loss of refrigerant will cause improper functioning.
A qualified refrigeration specialist should perform the necessary repairs, or factory should be contacted if the units is in warranty
To check if the compressor is running, check compressor-on light.
It is possible for the fan to be operating but not the compressor.
Compressor not running can be caused by several factors. A qualified refrigerant technician should check all refrigerant and electrical controls
The refrigerant pressure adjustment valve is identified by a label.
Turning the adjustment screw counterclockwise will decrease the refrigerant pressure and lower the dew point.
Adjust valves in ¼ turn increments to allow 15 minutes for pressure stabilization with full air flowing. Be sure that gauge indicates that pressure stays in green zone
This dryer is designed for a maximum air flow. If too much air is pumped into the dryer, water removal capacity may not be sufficient, resulting in liquid carryover downstream. Check the rated output of the air compressor
Frosting of the lines is an indication that controls are set too low.
Controls may be adjusted in the field by means of the hot gas bypass valve.
Turn the screw clockwise to increase refrigerant pressure setting which will increase pressure dew point.
Turn screw in ¼ turn increments until frost disappears. Allow 15 minutes for pressure stabilization with air flowing
Dryers are supposed to be used with compressed air free of any aggressive contaminants. Some contaminants and impurities may require a special heat exchanger. Contact your dealer with your application details.
35
RH SERIES—HIGH TEMPERATURE SECTION 2
PROBLEM
The unit will not run or cycles ON and OFF
POSSIBLE CAUSE
Line disconnect switch is open.
Faulty refrigerant compressor or controls
Excessive compressed air inlet temperature
Excessive ambient temperature
Clogged condenser fins
Shortage of refrigerant
REPAIR
Close the start or disconnect switch
Determine the cause and make correction
Designed conditions and correction factors as described in the product literature must be strictly followed. Ensure that the dryer is working well within the maximum conditions
Designed conditions and correction factors as described in the product literature must be strictly followed. Ensure that the dryer is working well within the maximum conditions
Clear fins of all obstructions
Fix the leak and add the appropriate amount of refrigerant into the system.
COMMENTS
If the dryer is not operating, check the disconnect switch or circuit breaker to be certain it is turned ON.
Failure of compressor to run may be caused by several factors.
A qualified refrigeration technician should check all electrical and refrigeration controls, or the factory should be contacted if the unit is under warranty
The dryer is designed for working within the calculated maximum conditions.
Should the conditions be exceed, the dryer will be overflow, dew point will go up and protecting devices can get switched off
A high ambient temperature may cause the refrigerant system to operate at higher than normal pressures.
Result will be a higher than normal evaporator temperature.
Important: there should be adequate air circulation around the dryer, and proper ventilation in the equipment room. This should guarantee a low enough ambient temperature
The clogged fins in the condenser will restrict the air passage and reduce the refrigeration capacity, causing high temperature in the evaporator.
Fins should be periodically checked and cleaned
Loss of refrigerant will cause improper functioning.
A qualified refrigeration specialist should perform the necessary repairs, or factory should be contacted if the unit is under warranty
36
