Modine Manufacturing HD Installation And Service Manual - page 16
16
SERVICE INSTRUCTIONS – GENERAL
General Maintenance
The unit and venting system must be checked once a year by
a qualified service technician.
Only people trained and familiar with the operation of unit
heaters and their controls should service this equipment.
Before any service, BE SURE TO TURN OFF GAS AT THE
MANUAL SHUT-OFF VALVE AHEAD OF THE
COMBINATION GAS CONTROL AND TURN OFF ALL
ELECTRIC POWER TO THE HEATER.
1. Service air moving components annually.
a.
Check fan for fit on motor shaft and for damage to
blades.
2. Keep unit free from dust, dirt, grease, and foreign matter,
paying particular attention to:
a.
Combustion air inlets.
b.
Burners and burner orifices. Turn off gas ahead of the
combination gas control and shut off electric power to
the heater. Remove the access panel, open the union
on the gas line, and disconnect the igniter and sensor
wires. Remove the screws that attach the burner tray
to the header plate and remove the burner tray and
manifold assembly from the heater. Carefully clean the
burners with a wire brush or other suitable means.
Replace any damaged or deteriorating burners or
orifices. Install the burner assembly back on to the
header making certain that all screws, pipes and
electrical connections are tight.
CAUTION: Be careful when handling the igniter.
1. Inspect the flame sensor and igniter for
deterioration and/or cracks.
2. Verify that the burners are touching each other at
the carryover points. This will ensure flame
carryover from burner to burner.
c.
Clean exterior of heat exchanger tubes.
d.
Fan blade.
3. Check wiring for possible loose connections.
4. Controls – See control instruction sheets furnished
separately with the unit heater.
5. Power exhaust assembly – The power exhaust motor
bearings have been lubricated for long life and do not
require additional lubrication. In dirty atmosphere, it may be
desirable to clean the motor and blower housing and blow
out the cooling air passages of the motor with compressed
air.
SERVICE INSTRUCTIONS –
SAFETY DEVICES
Limit Control (Overheat Switch)
The limit control, mounted in airstream (on access side), will
shut off the gas supply to the burners in the event of
overheating. It is a single pole, single throw switch. The
contacts open to shut the electric gas valve off in the event the
unit should overheat. This limit control should operate only
when something is seriously wrong with the unit. Anytime this
control operates, correct the difficulty immediately or serious
damage may result. If the limit control cuts off the gas supply
during normal operation:
1. Make certain the deflector blades are open and that there
are not any obstructions in the air inlet or outlet.
2. Check actual input to unit against rated input.
3. Check to be sure motor is operating.
4. Check that fan is not loose on motor shaft.
5. Check fan speed against speed on motor nameplate.
6. Check to make sure the venting system is not damaged or
blocked. Also check to be sure unit is venting normally and
that there is not negative pressure in the building adversely
affecting draft.
7. Clean heat exchanger tubes inside and out if necessary.
8. If items 1-7 do not solve the problem, check limit control
and replace if necessary. To remove control, first remove
access door then remove screws holding control to header.
IMPORTANT NOTE:
The limit control (overheat switch) on this unit heater will
shut off the gas should excessive discharge temperatures
occur. Do not attempt to control the fan with the limit
control. Any change in wiring to attempt to control the fan
with the limit control will result in hazardous conditions
and void the warranty.
Flame Rollout Switch (or Switches)
The switch (switches), mounted on a bracket above the
burners, will shut off the gas supply to the burners in the event
of flame rollout. They are a single pole, single throw, manual
reset switch. Anytime this control operates, correct the
difficulty immediately or serious damage may result.
1. Make sure louvers in casing are not restricted.
2. Make sure power exhaust is operating properly.
3. Make sure vent is not blocked.
4. Clean inside of heat exchanger tubes.
5. Make sure area around orifices is clear.
Pressure Switch
The pressure switch (located behind the access panel) will
shut off the gas supply to the burners in the event of a problem
with the venting system. It is a single pole, single throw switch
that is normally open. The contacts close as the power
exhauster develops the necessary pressure in the vent system
to discharge the flue gases. If it is suspected the pressure
switch is not closing or if the switch may be opening under
normal conditions;
1. Check the vent system and remove any obstructions in the
vent.
2. Check the rubber tube behind the access panel, make sure
it is securely connected to the pressure switch and the
power exhauster housing.
CAUTION
SERVICING OR REPAIRING THIS EQUIPMENT MUST BE
PERFORMED BY A QUALIFIED SERVICE AGENCY.
Use only Modine approved service replacement parts. A
replacement parts list can be found on page 18 of this manual or
obtained by contacting Modine Manufacturing Company, Buena
Vista, VA. Refer to the rating plate on the unit for complete unit
model number, serial number and company address. Any
substitution of parts or controls not approved by Modine will be
at the owners risk.
Do not use this appliance if any part has been under water.
Immediately call a qualified service technician to inspect the
appliance and replace any gas control which has been under
water.
Should overheating occur, or the gas supply fail to shut off,
shut off the manual gas valve to the appliance before
shutting off the electrical supply.
!