Service & Troubleshooting - Modine HSB Serie Mode D'emploi

SERVICE & TROUBLESHOOTING
WARNING
When servicing or repairing this equipment, use only factory-
approved service replacement parts. A complete replacement
parts list may be obtained by contacting Modine Manufacturing
Company. Refer to the rating plate on the unit for complete unit
substitution of parts or controls not approved by the factory will
be at the owner's risk.
Table 15.1
Troubleshooting
Fails to Maintain Temperature
1. Undersized unit heater, boiler, pump or piping.
2. Excessive exhaust air (exhaust fans may have been
added since heating installed).
3. Unit heater operating at lower speed when sized to
operate at high speed.
4. Unit heater mounted too high — heated air not delivered
to floor level.
5. Thermostat — improper location or setting, or not
functioning.
6. Dirty or clogged condenser.
Unit Blows Cold Air
1. Manual shut-off valve closed.
2. Insufficient steam pressure of lack of hot water.
3. Aquastat not functioning.
4. Improper venting.
5. Steam trap not functioning.
6. Drip leg too short (steam system).
7. Return line plugged (steam system).
8. Pump undersized or not operating (hot water system).
Does Not Operate When Heat Needed
1. Defective motor or electrical connections.
2. Thermostat, aquastat or pressure limit control not
functioning.
Fails to Deliver Heat to Floor
1. Units mounted too high.
2. Operating on low speed.
3. Final air temperature too high.
4. Louvers not adjusted properly.
5. Wrong type of diffuser (on verticals).
6. Undersized unit heater (insufficient air delivery).
7. Wrong type of unit (may require vertical delivery).
8. Cross ventilation or drafts.
9. Obstructions to air flow.
Noisy Unit
1. Loose bolts or screws.
2. Fan blade bent, out of balance.
3. Dirt accumulation on fan blades.
4. Fan hub or blade rivets loose.
5. Motor shaft thrust bearing worn.
6. Motor mounting bent, fan not positioned properly in venturi.
7. Unit mounted too rigidly, transmits vibration noise.
8. Conduit too rigid, transmits vibration noise.
9. BX cable touching unit heater, chatters as casing vibrates.
CAUTION
Do not reuse any electrical component which has been wet.
Such component must be replaced.
IMPORTANT
To check most of the Possible Remedies in the troubleshooting
guide listed in Table 15.1, refer to the applicable sections of
the manual.
Unit Leaks
1. Loose connection.
2. Internal corrosion.
Employees Complain of Hot Blast
1. Air stream aimed directly at employees.
2. Louvers not adjusted properly.
3. Wrong type of diffuser (on verticals).
4. Excessive final air temperature.
Unit Operates Too Long
1. Thermostat installed on cold wall or otherwise improperly
located.
2. Heavy exhaust fan load. (May have been increased since
heating system was laid out).
3. Aquastat or pressure limit control not functioning properly.
4. Unit is undersized.
Frequent Motor Failure
1. Voltage fluctuations too high or too low.
2. Excessive or insufficient lubrication.
3. Wiring to motor undersized.
4. Improper electrical connections.
5. Motor operating in too high air temperature.
6. Restricted air flow through unit due to clogged condenser,
closed louvers, too much duct work connected to unit.
7. Fan out of balance.
8. Unbalanced voltage on 3φ power.
Premature Failure
1. Severe internal corrosion due to condition of boiler water.
Condenser Failure
1. Severe internal corrosion from feedwater.
2. Type of boiler treatment.
3. Entrained air causing water hammer.
4. Too much outdoor air portion in freezing temperatures.
5. Continuous operation above 150 PSI (375°F)(steam
systems).
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