C
LEANING
For cleaning or maintenance purposes, the
fan-motor assembly can be removed from
the unit heater. The unit casing, fan, diffuser,
and coil should be cleaned thoroughly once
each year. The heating performance and air
throw depend on cleanliness of the coil and
fan blades.
When cleaning the fan-motor assembly,
wipe all excess dirt or lubricant from the
motor casing. Buildup on the motor casing
will cause it to run hot and eventually cause
inconvenience or discomfort due to random
automatic thermal overload shut down, or
could cause internal motor damage. Note:
standard unit heater motors have integral
automatic thermal overload protection.
Clean the coil by loosening dirt with a brush
on the fan side of the coil, then operate the
unit allowing the fan to blow the loosened
dirt through the unit. Use high pressure air or
steam on the coil away from the fan.
Use a damp cloth to clean the casing, fan
blades, or diffuser. If rust spots are found on
the casing, they should be cleaned and
repainted.
Tighten the fan guard, motor frame and fan
bolts. Check the fan for clearance in the
panel orifice and free rotation.
The heater system should be checked once
per year by a qualified technician. All
maintenance and service information should
be recorded.
T
ABLE
1
T
ROUBLE
-S
HOOTING
C
HART
S
YMPTOM
P
OSSIBLE
C
AUSE
C
ORRECTIVE
A
CTION
Leaking Coil
1. Frozen coil
2. Defective coil
3. Corrosion
4. Leak in joint
1. Replace coil.
2. Replace coil.
3. Replace coil.
4. Braze joint if joint is exposed where leak has
occurred.
Poor output
on steam
1. Check for air in coil
2. Lint on coil fins
1. Repair or replace thermostatic air vent.
2. Clean coil and fins. Check filter and clean.
Poor output
on steam or
hot water
1. No circulation of water through coil
2. Short cycling of motor
3. Backward rotating motor
1. Check circulation pump. Check for blocked tubes.
2. Check voltage and correct. Remove and service
motor to confirm if automatic overload needs
repair.
3. Change direction of motor rotation to by making
appropriate wiring changes as recommended by
the motor manufacturer.
Noisy or
vibrating unit
1. Damaged fan
2. Dirty fan
1. Change fan.
2. Clean fan.
Unit Heaters
Installation & Operation Manual
4
www.sigmaproducts.com Tel: (905) 453-0446 Fax: (905) 453-0675
Rev 2
