Sterling SDRIOM-2 User Manual

FOR YOUR SAFETY

If you smell gas:

1. Open Windows

2. Don’t touch electrical switches.

3. Extinguish any open flame.

4. Immediately call your gas supplier.

ATTENTION: READ THIS MANUAL AND ALL LABELS ATTACHED TO THE UNIT CAREFULLY
BEFORE ATTEMPTING TO INSTALL, OPERATE OR SERVICE THIS UNIT! CHECK UNIT RATING
PLATE FOR TYPE OF GAS AND ELECTRICAL SPECIFICATIONS AND MAKE CERTAIN THAT THESE
AGREE WITH THOSE AT POINT OF INSTALLATION. RETAIN FOR FUTURE REFERENCE.

HVAC PRODUCTS

FOR YOUR SAFETY
The use and storage of gasoline or other flammable vapors and liquids in open containers
in the vicinity of this appliance is hazardous.

INSTALLATION, OPERATION AND MAINTENANCE MANUAL FOR

SDR MODEL DIRECT GAS-FIRED HEATERS

WARNING: Improper installation, adjustment, alteration, service or maintenance can cause
property damage, injury or death. Read the installation, operating and maintenance
instructions thoroughly before installing or servicing this equipment.

WARNING: Install, operate and maintain unit in accordance with manufacturer’s
instructions to avoid exposure to fuel substances or substances for incomplete combustion
which can cause death or serious illness. The state of California has determined that these
substances may cause cancer, birth defects, or other reproductive harm.

lINSTALLER’S RESPONSIBILITY

Installer Please Note: This equipment has been test fired and inspected. It has been shipped free
from defects from our factory. However, during shipment and installation, problems such as loose
wires, leaks or loose fasteners may occur. It is the installer’s responsibility to inspect and

correct any problems that may be found.

4830 TRANSPORT DRIVE, DALLAS,TX 75247

PHONE: [phone] FAX: [phone] www.sterlinghvac.com

SDRIOM-2

PN# 94.2000.03

P

POST AND MAINTAIN THESE INSTRUCTIONS IN LEGIBLE CONDITION

c

2

SECTION II - GENERAL INFORMATION

I.As is the case with any fine piece of equipment, care must

be taken to provide the proper attention to the operation
and maintenance details of this machine.

This manual of instructions has been prepared in order for
you to become well-acquainted with those details, and in
doing so, you will be able to give your Direct Gas-Fired
System the care and attention which any piece of
equipment needs and deserves.

Table Of Contents

Section I: Forward and Table of Contents........................ 2

Section II: General Information........................................... 2

Section III: Installation............................................................ 3

Section IV: Pre Start-Up........................................................ 5

Section V: Unit Start-Up........................................................ 5

Section VI: Unit Shut Down.................................................. 6

Section VII: Troubleshooting Guide..................................... 7

Section VIII: Maintenance Schedule and

Lubrication Requirements............................ 13

Section IX: Maxon NP-I Airflo® Burners........................ 16

Section X: Maxitrol Valve Adjustments and

Preliminary Circuit Analysis............................17

Section XI: Replacement Parts........................................... 19

Section XII: Recirculation.................................................... 20

SECTION I - FORWARD

A. Purpose

The purpose of this manual is to present a guide for proper
installation, maintenance, and operation of the Direct Gas­Fired System, and supplement, but not to replace, the
services of qualified field service personnel to supervise the
initial start-up and adjustment of the unit. Persons without
previous experience with commercial and industrial heating
equipment should not attempt the initial adjustment and
checkout procedure which is essential before such
installations may be considered ready for operation. This
manual should be made readily available to all operating
personnel as an aid in troubleshooting and proper
maintenance.

B. Shipping

Direct Gas-Fired units are shipped completely assembled
where shipping limitations allow. Optional inlet hoods
or other large accessories are assembled and shipped
mounted and wired whenever possible within limitations of
shipping and handling. Any optional accessories shipped
separately are shipped as assembled sections.

Shipments are made F.O.B. Dallas,Texas by flatbed truck
or LTL shipment. The unit is securely strapped, tied, and
blocked to prevent shipping damage. All shipments are
checked by an inspector before they are accepted by the
carrier. Parts that are shipped unmounted are noted
on the bill of lading. These parts, where feasible, are
packaged and shipped with the units. Upon receipt of
shipment, all units should be checked against the bill of
lading to insure all items have been received. All equipment
(and any optional accessories) should be checked carefully
for physical damage in the presence of the carrier’s
representative. If parts are missing or damage has occurred,
a claim should be filed immediately with the carrier.

All Direct Gas-Fired units are given a minimum 140 point
operations test and control circuit checkout before ship­ment. Copies of the wiring diagram, piping diagram and bill
of material are included with each unit shipped.
If correspondence with the factory is necessary, please
provide the unit model and serial number.

C. Optional Factory Service

Periodic service on any piece of mechanical equipment
is necessary for efficient operation. A nationwide service
support network is available to provide quick and dependable
servicing of make-up air, heating, ventilating, or air handling
types of equipment. The factory also offers start-up service
which includes the presence of a service engineer to
supervise the initial start-up and adjustment of the equipment
and provide instructions for the owner’s maintenance
personnel on proper operations and maintenance. Consult
factory for quotations on periodic or start-up service.

3

This equipment must be installed and wired in accordance
with regulations of the National Board of Fire Under­writers, National Electrical Code, and local governing bodies.
The following recommendations are not intended to
supplant any requirements of federal, state, or local codes
having jurisdiction. Authorities having jurisdiction should be
consulted before installations are made. Local codes may
require additional safety controls and/or interlocks.

All installations in airplane hangers must be in accordance
with current ANSI/NFPA No. 409. All installations in public
garages must be in accordance with the current Standard
for Parking Garages, NFPA No. 88A, or the Standard for
Repair Garages, NFPA No. 88B, and with CAN/CGA B149
Installation Codes.

CAUTION: Do not install heating system in
corrosive or flammable atmospheres! Premature
failure of, or severe damage to the unit will result!

CAUTION: Heating system must not be installed
in locations where air for combustion would contain
chlorinated, halogenated or acidic vapors. If located
in such an environment, premature failure of the
unit will occur!

A. Handling the Equipment

The Direct Gas-Fired unit has been designed for rigging
and handling through the use of special lifting lugs installed
on the ends of each unit. As explained previously, the basic
unit is designed for shipping in one piece where shipping
limitations allow. Some optional accessories may require
field mounting.

When unloading and setting the unit, use the lifting lugs
provided or move the equipment on rollers. Hooks, jacks
or chains must not be used around the casing, main control
panel or exterior mounted controls.

During transit, unloading and setting of the unit, bolts and
nuts may have become loosened, particularly in the pillow
block ball bearing assemblies in the fan section. It is
recommended that all nuts and set screws be tightened.
Turn fan shaft by hand to make certain that blower does
not rub against blower housing, and that bearing set screws
are tight.

Open the cover on the electrical control box located on
the unit. Inspect all wire terminals and wiring terminations
to ensure that all connections are tight.

If this unit is not installed immediately, cover all openings
that might be exposed to the weather. Rotate fan monthly.

B. Locating the Unit

Prior to locating the unit, authorities having jurisdiction
should be consulted before installations are made. Approval
permits should be checked against the unit received.

Recirculation of room air is not permitted. All air must be
ducted from the outdoors.

If in doubt regarding the application of this appliance,
consult the factory.

Locate the unit exactly level. Special attention should be
given to the duct, electrical, and fuel connection points.
Install duct work with adequate flexible connections to
isolate vibrations from the duct work. All duct work should
have taped or caulked seams. Duct work should be
properly sized so as not to inhibit airflow. This information
should be cross-checked with the position of support
beams and stand pipes to insure that clearance dimensions
coincide with those of the unit. The minimum clearance to
combustible material must be maintained as listed in Table 1.

On outdoor curb mounted installations, flash and seal roof
curb to prevent leakage. The cross section of factory
provided curb is formed to accept wood nailing strip and
insulation provided by others.

C. Location of Accessories

Where applicable, standard or optional accessories will
be placed inside the fan section of the unit for shipment,
and must be removed and installed by the mechanical or
electrical contractor.

Field provided discharge or inlet dampers must be
equipped with an end switch and interlocked to insure
maximum design opening before starting and running
circuits may be energized.

Field constructed intake accessories should be properly
designed to minimize the entry of rain and snow.

Adequate building relief must be provided, so as to not
over-pressurize the building, when the heater is operating

at
its rated capacity. This can be accomplished by taking into
account, through standard engineering methods, the struc­ture’s designed infiltration rate, by providing properly sized
relief openings, by interlocking a powered exhaust system,
or by a combination of these methods.

SECTION III - INSTALLATION

Table 1

Minimum clearance to combustible material and access

clearance (consult local codes and regulations)

Clearances to Combustible Material

Vertical Units Horizontal Units
Front* 36 inches 36 inches
Rear 6 inches 6 inches
Right 6 inches 6 inches
Left 6 inches 6 inches
Top 12 inches 12 inches
Floor Zero 6 inches

* Consider control side as front of unit.

4

D. Electrical Connections

NOTE: Before installing any wiring, check the unit
rating plate for supply power rating.

All electrical connections and wiring must conform to the
current edition of:ANSI/NFPA No. 70 National Electrical
Code and applicable state and local codes.

Entry location for all field-installed and control wiring is
located beside the control panel.

If optional disconnect is not furnished with heater, the
field provided disconnect must be of the proper size and
voltage. Refer to unit nameplate for minimum circuit
ampacity and voltage. The disconnect must be installed
in accordance with Article 430 of the current edition of
ANSI/NFPA No. 70 National Electrical Code.

Check the supply voltage before energizing the unit. The
maximum voltage variation unbalance must not exceed 2%.

NOTE: Should any original wire supplied with the
heater have to be replaced, it must be replaced
with wiring material having a temperature rating of
at least 105° C.

E. Field Piping

All gas piping must be in accordance with the requirements
outlined in the National Fuel Gas Code - ANSI Z223.1. It
is required that a ground union be installed adjacent to the
manifold for easy servicing. A drip leg and/or filter should
be provided upstream of the unit’s inlet gas connection. A
shut-off must be located external of the unit’s enclosure.
The location of this valve must comply with all local codes.
A 1/8 inch N.P.T. test gauge connection must be installed
immediately upstream of the gas supply connection to the
unit.

Refer to the heaters rating plate for determining the
minimum gas supply pressure for obtaining the maximum
gas capacity for which this heater is specified.

The gas line should be supported so that no strain is
placed on the unit. Pipe compounds, which are not
soluble to liquid petroleum gases, should be used on
threaded joints.

The appliance and its individual shutoff valve must be
disconnected from the gas supply piping system during
any pressure testing of that system at test pressures in
excess of 1/2 PSIG.

The appliance must be isolated from the gas supply piping
system by closing its individual manual shutoff valve during
any pressure testing of the gas supply piping system at test
pressure equal to or less than 1/2 PSIG.

Correctly sized piping must be run to the unit. Please note
that gas line pressure must be as shown on rating plate
when unit is operating at full input.

F. Field Wiring and Remote Control Installation

1. Connect the power lines to the line side of the main

disconnect switch.

2. Mount and wire remote control panel, thermostats,

temperature sensors, and any other field installed
controls as indicated on the unit control wiring diagram.

3. Connect the wires to the appropriate field wiring

terminals as indicated on the unit control wiring diagram.

4. If the optional low-temperature limit was not an integral

part of the heater, the factory recommends that a low­temperature limit control be installed in areas where
freeze protection is needed in the event of burner shut­down.

G. Locating Temperature Controls

The room or outdoor thermostats should be mounted
where they will not be subjected to direct impact of
the heated air or radiant heat from the sun. It is also
recommended that thermostats, especially those with
mercury bulb contacts, be mounted on a vibration free
surface. Interior walls or the side of building columns away
from the heater are usually the location best suited for
mounting thermostats.

Controls with outdoor bulbs require that the outdoor bulb
be shielded from direct radiation from the sun. Unit mounted
sensors are factory located and mounted.

WARNING: Controls must be protected from
water. Do not allow water to drip on the
ignition system.

WARNING: Open all disconnect switches and
secure in that position before wiring unit. Failure
to do so may result in personal injury or death
from electrical shock.

WARNING: To avoid equipment damage or
possible personal injury, do not connect gas piping
to this unit until a supply line pressure/leak test
has been completed. Connecting the unit before
completing the pressure/leak test may damage
the unit gas valve and result in a fire hazard.

DANGER: Never use an open flame to detect
gas leaks. Explosive conditions may exist which
would result in personal injury or death.

5

SECTION IV - PRE START-UP

A. Pre Start-Up

All equipment has been factory tested, adjusted, metered
and inspected to meet conditions set at the time the order
was placed. Only minimal adjustments should be required.
All information in this service manual is typical. All products
are semi-custom and changes may occur.

Suggested Tools and Instruments

Volt/Ohm Meter Thermometer
Tachometer Ammeter
Manometer (0-10" W.C.) Microammeter
Standard Hand Tools D.C Volt Meter
Gas Pressure Gauge (0-35 lbs.)

NOTE: All servicing and adjustments of the Direct
Gas-Fired unit should be performed by a qualified
service engineer.

1. The owner’s representative or equipment operator
should be present during start-up to receive instructions
on care and adjustments of the equipment.

2. Remove all shipping blocks, brackets and bolts from
supply fan base with optional isolation base.

3. Check all wiring for loose connections and tighten if
necessary.

CAUTION: Line side of disconnect may be
energized.

4. Inspect all fan and motor bearings and lubricate if
necessary.Tighten setscrews on pulleys, bearings, and fans.

CAUTION: Do not rupture grease seals.

5. Inspect pulleys and belts for tightness, tension and
alignment. Do not over tighten belts.

6. Check set screws on all bearings, pulleys and fans for
tightness.

7. Check voltage supplied to disconnect switch. The
maximum voltage variation should not exceed ±10%.
Phase voltage unbalance must not exceed 2%.

8. Check thermostat(s) for normal operation.

9. Check that system duct work is installed and free from
obstructions.

10. Check that fans turn free in housing.

11. Check burner for proper location and alignment.

12. Check that filters and accessories are installed correctly.

13. Check that vent lines have been run to atmosphere on
indoor units. Note that some units will use vent
limiters and vent lines are not required.

14. Check that all manual gas shut-off valves are closed.

15. When failure or malfunction of this heater creates a
hazard to other fuel burning equipment, (e.g. when the
heater provides make-up air to a boiler room), the
heater is to be interlocked to open inlet air dampers
or other such devices.

16. If inlet duct is attached to the heater, a purge
timer must be provided and set to purge 4 times
the inlet duct volume.

Purge time in seconds = 4 x L x W x H x 60

SCFM
L = duct length in feet,W = duct width in feet,
H = duct height in feet, SCFM = rating plate air
throughput.

Refer to the electrical schematic for the proper
circuit placement. Purge timer P/N 65.0711.00.

6

SECTION V - UNIT START-UP

Close or replace all doors and service panels.

Turn main disconnect switch off. Verify the incoming line
voltage matches the unit nameplate rating. If the voltage is
over ±10% of nameplate rating or phase voltage unbalance
is over 2%, notify the contractor or power company.

Turn Heat OFF/ON switch to the OFF position. Turn main
disconnect switch on. Turn Fan OFF/ON switch to the
ON position. Damper opens. Blower fan turns on.

Turn Fan OFF/ON switch to OFF position and check sup­ply blower for proper rotation.

NOTE: To change rotation of the blower, simply
interchange any two (2) of the line leads of the
motor starter for three (3) phase motors. Refer to
motor nameplate for reversing single (1) phase
motors.

Turn Fan OFF/ON switch to the ON position. Check for
proper blower rpm. Check that all motor amp draws do
not exceed nameplate ratings, and the overload relay is set
to the motor nameplate amperage.

Check dampers for proper operation. Be sure they operate
freely, and the linkage does not bind.

Make sure all manual gas shut-off valves are in the closed
position.

Turn Heat OFF/ON switch to the ON position. Blower
fan will run.

Turn Fan and Heat OFF/ON switches to OFF position.

Setting Burner

NOTE: To adjust gas pressure on supply lines where
a regulator has been installed (to reduce the inlet
pressure to 1/2 PSIG or less), remove dust cap of main
gas regulator and turn adjusting screw clockwise to
increase pressure, or counter-clockwise to decrease
pressure.

Set all thermostats to call for heat. Set inlet ductstat (if
applicable) above outside air temperature.

Connect a DC microammeter between the SENSE terminal
and the flame rod sensing wire.

Turn Fan and Heat OFF/ON switches to ON position.

Open inlet manual gas shut-off valve slowly. Reset high and
(if applicable) low gas pressure switches. Check main gas
line for leaks using soap solution.

Unit will run for 5 seconds before ignition trial.

NOTE: 3 OR 4 TRIALS MAY BE NEEDED TO
PURGE AIR FROM GAS LINE.

United Technologies Electronic Controls Spark Ignitor

Watch microammeter carefully. The reading should be at
least 5.0 microamps. If the reading is too low, slowly turn
the low-fire adjustment on the modulating valve in or out
until satisfactory readings are obtained. When adjusting
low fire, there should be a continuous flame along the
entire burner length without any blowout spots.

Refer to Maxitrol Valve Adjustment instructions
in Section IX for setting high and low fire gas
pressure settings.

When the flame is adjusted, shut the unit off by turning the
Fan and Heat switches to OFF.

Setting Main Flame

Install manometer at test port on the last tee of the burner
manifold or modulating valve.

Slowly open all manual gas shut-off valves.

Restart unit. After main gas valves open and burner lights
check gas lines for leaks.

Adjust high gas pressure reading (from manometer) to
match firing rate shown on unit nameplate.

Adjust the high and low fire setting according to the
Maxitrol Valve Adjustment instructions in Section IX. The
high fire setting must not exceed the pressure stated on
the rating plate.

When adjusting low fire, there should be a continuous flame
along the entire burner length without any blow out spots.

Main flame is now set. Recheck the microamp signal on the
ignition control throughout the full burner input range. Re­check low fire setting. Cycle unit 2 or 3 times to insure
good ignition.

Safety Controls Check

A. High Temperature Limit and Firestats – These limit

controls are not adjustable and are checked by the
factory. Reset the red button(s) to be sure they are
ready for operation. Contact the factory if these switch­es fail to reset.

B. Ignition Control - Operate unit in Heat mode. After

flame has been established, close last manual gas valve
before main burner. The ignition control must trip out
within 15 seconds. Reset the ignition control by turning
the HEAT switch to the OFF position.

7

SECTION VI - UNIT SHUTDOWN

C. Gas Pressure Switches - Operate unit in Heat mode.

The low pressure switch will trip out and must be reset
before resuming operation when the inlet gas valve is
turned off during operation.The high pressure switch
may be checked out by reducing the setting of its trip
point below unit operating pressure. It should then trip
out and shut off the burner. Return the adjustment to
its original setting and reset to resume operation.

When checking operation of gas pressure switches on
systems without pilot the heat switch will have to be
turned off for approximately five seconds to reset the
ignition control.

D. Air Pressure Switches - The high air pressure switch is

checked by removing the sensing tube from the enter­ing air side of the burner. Switch operation will shut
off the burner. Recycle is automatic when the sensing
tube is replaced.The low air pressure switch is checked
by removing the sensing tube from the leaving air side
of the burner. Switch operation will shut off the burner.
Recycle is automatic when the sensing tube is replaced.

When checking operation of air pressure switches on
systems without pilot the heat switch will have to be
turned off approximately five seconds to reset the igni­tion control.

E. Temperature Controls – These controls are checked by

adjusting control settings to a lower temperature setting
while the unit is operating on high fire and observing
cutoff. The controls should be reset to settings shown
below:

Suggested Control Settings

TC-01 Room Thermostat ................... Customer Discretion

TC-03 On-Off Inlet Ductstat ............................................65°F

TC-08 Freeze Thermostat .................................. 3 min.,...45°F

PS-04 Low Gas Pressure Switch ................................1.0”w.c

PS-07 High Gas Pressure Switch............125% of firing rate

TC-09 Night Set Back Room .................Customer Discretion

TC-52 Remote Temperature Selector .... Customer Discretion

FL-02 High Temperature Limit (manual) ........ Not adjustable

RE-26 High Limit Discharge Ductstat ................................ 95°F

RE-26 Low Limit Discharge Ductstat ................................ 55°F

PS-12 Clogged Filter Switch ....... Adjust to Field Conditions

PS-13 Building Pressure Switch .. Adjust to Field Conditions

A. Extended Shutdown -

1. Set the Heat OFF/ON switch to the OFF, then turn the
Fan switch to the OFF position.

2. Close all manual gas valves.

3. Open the main electrical disconnect switch.

B. Emergency Shutdown ONLY -

1. Open the main electrical disconnect switch.

2. Close all manual gas valves.

1. Low or no voltage.

2. Fuse(s) blown.

3. Customer interlock not closed
or connected.

4. Fan Off-On switch in Off position.

5. Time clock, night setback thermo­stat or field installed controls
open.

6. Freeze protection tripped.

7. Damper motor not operating, or
its end switch not making.

8. Overload protection on motor
starter tripped.

9. Belts loose or broken

10. Bearings seized.

11. Motor may be burned or incor­rectly wired.

12. Motor overheating.

1. Heat Off-On switch in Off
position.

2. Burner enable relay open
(if applicable).

3. Outside air temperature higher
than On-Off inlet ductstat
(if applicable).

4. Field purge timer open
(if applicable).

1. Manual gas shut-off valve closed.

2. Inlet gas pressure lower than
required gas pressure.

3. Type of gas (Natural, LP) supplied
different from factory required
type.

4. Auxiliary switch on starter not
closed.

5. Air flow switches not closing.

6. High temperature limit switch
open.

7. High or low gas pressure switches
open (if applicable).

8. Main gas valve relay open.

8

SECTION VII – TROUBLESHOOTING

Symptom

Cause

Remedy

A. If blower does not operate.

B. If there is no voltage at ignition

control.

C. Burner does not light after 5 sec-

onds pre purge of flame safeguard
relay and there is voltage at igni­tion control.

1. Check power source.

2. Check and replace.

3. Close or connect customer
interlock.

4. Switch to On position.

5. Check time clock, night setback
thermostat and field installed
controls for proper settings.

6. Reset freeze stat by interrupting
power. Check for proper setting
and burner operation.

7. Check for power at damper motor
and that end switch has been wired
correctly to the N.O. (normally
open) contact. Check that the
linkage is clear and not binding.

8. Push reset button on starter and
check amps.

9. Turn power off and check belts.

10. Check and replace.

11. Turn power off and check motor
and wiring.

12. Check burner firing rate.

1. Switch to On position.

2. Check for power and replace if
necessary.

3. Lower On-Off inlet ductstat
setting.

4. Check for power and replace if
necessary.

1. Slowly open valve.

2. Increase gas pressure.

3. Replace with factory required
type of gas.

4. Check for power and replace if
necessary.

5. Adjust the air flow and external
static pressure to match rating
plate.

6. Correct problem. Reset by pushing
down the reset button.

7. Correct problem. Reset both
switches.

8. Check for power and replace if
necessary.

System without Pilot