Altec AIR MHT Series, Owner'S Manual

Page: 5 / 22

5
DRYER CONTROLS
1. ON/OFF Switch – Turns the refrigerant compressor and dryer ON.
2. Dryer ON Light – Indicates the air dryer is turned on and operating. Integrated into ON/OFF Switch
3. Refrigerant Suction Pressure Gauge - Displays refrigeration system low side (Evaporator) pressure.
(Installed on UA75/MHT40 and above)
4. Refrigerant Discharge Pressure Gauge - Displays refrigeration system high side pressure. (Installed on
UA400/MHT200 and above)
5. Inlet Compressed Air Temperature Gauge - Displays air temperature for the compressed air source
(Installed on UA1600 and above)
6. Dewpoint Temperature Gauge - Displays outlet dewpoint to ensure dryer is performing correctly.
(Installed on UA20 to UA55, and MHT25)
7. Hot Gas Bypass Valve (HGBV) – Prevents compressed air freeze ups by controlling the evaporator
pressure.
8. Temperature Expansion Valve (TXV) - Metering device between the liquid refrigerant line to the
evaporator. (Installed on UA400/MHT200 and above)
9. High Pressure Shutdown w/manual reset - Shuts down dryer in the event of overload conditions
(Installed on UA150/MHT100 and above)
10. Low Pressure Shutdown - Shuts down the dryer in the event of low ambient temps or if there is a
refrigerant leak in the system
. (
Installed on UA200A-3/MHT130A-3 & UA250-2/MHT150A-2 and
above
)
11. Fan Cycling Switch(s) - Cycles condenser fan(s) ON and OFF during periods of low ambient
temperatures. (Installed on UA400 and above).
12. Programmable Electronic Auto-Drain Valve – Automatically controls the draining of liquid condensate
removed by the dryer.
13. Compressor Internal Overload. - Shuts down the refrigerant compressor if amp draw/heat is to high.
14. Control Fuses - Shuts down the dryer in the event of high amp draw on the control circuit.
Dryer Model Refrigerant Normal
SUCTION PSIG
Dew point Temp
UA20 to UA150 R134A 25 to 35 PSIG 33 to 39 F
Normal
DISCHARGE PSIG
75-120 PSIG
UA200 to UA2000 R404A 69 to 85 PSIG 135 to 275 PSIG 33 to 39 F
MHT25 to MHT100 R134A 25 to 35 PSIG 75-120 PSIG 33 to 39 F
MHT130 to MHT200 R404A 69 to 85 PSIG 135 to 275 PSIG 33 to 39 F
ON-OFF SWITCH
W/DRYER ON LIGHT
DANGER
Only qualified and licensed refrigeration service persons should attempt to work on the air dryer.