Thomas & Betts DV Series Operating And Maintenance

C E R T I F I E D
Applies to: Model Series DV
TABLE OF CONTENTS
INDOOR OR OUTDOOR, GAS, DIRECT-FIRED, MAKEUP AIR/
HEATING SYSTEMS
(Specifications subject to change without notice.)
Operation/Maintenance/Service
Form RZ-NA 441-OMS
Page
MAINTENANCE
SECTION ...................... 2-4
Configuration ................................. 2
Maintenance Schedule ................... 2
1A. Blower Bearings .............................. 3
1B. Blower Belts ................................... 3
2. Filters ................................................. 3
3. Manifold Gas Pressure ...................... 3
4. Air Pressure ....................................... 4
5. Circuit Indicator Board (check lights) 4
6. Main Burner and Pilot Assembly ...... 4
OPERATION/SERVICE
SECTION ................... 5-15
Controls - Location ....................... 5
7. Electronic Circuit Board with
Diagnostic Lights.............................. 5
References: Installation Manual, Form RZ 441
Page
8. Temperature Limit Safety Controls... 5
•Manual Reset Limit Control ........... 5
•Emergency Cut Off Limit Control .. 6
9. Air Pressure Switches ........................ 6
•Low Air Flow Switch ...................... 6
•High Air Flow Switch ...................... 6
•Bypass Damper (Optional) Air
Flow Switches ................................ 6
10. Ignition System ................................ 6
11. Gas Train Including Direct-Fired
Burner, Gas Control Systems, Manifold Arrangements and Gas
Pressure Switches ............................. 7
•Direct-Fired Burner ........................ 7
•Makeup Air Gas Control Systems .. 7
•Electronic Modulation Gas Control Options AG30, AG31, AG32,
AG33, AG35, AG36 ...................... 7
•Electronic Modulation Gas Control
Option AG37 ................................. 7
12. Outside Air Ambient Cutoff ............ 8
13. Door Switch ..................................... 9
14. Inlet Air Controls ............................ 9
15. Dirty Filter Switch ......................... 10
16. Photoelectric Smoke Detector ....... 10
17. Firestat ........................................... 10
18. Freezestat ....................................... 10
19. Troubleshooting ............................. 11
Index ................................................... 12
Replacement Parts Manual, Form RZ 741
Page
•Manifold Arrangements ................. 8
•Gas Pressure Switches .................... 8
•Air Flow Dampers ........................... 9
•Damper Motor ................................. 9
•Potentiometer .................................. 9
•Pressure Null Switch ....................... 9
•Photohelic Pressure Switch ........... 10
Chart 1 - General Troubleshooting Guide (Check the diagnostic lights on the circuit board)
FOR YOUR SAFETY
WARNING: The use and storage of gasoline or other flammable vapors and liquids in the vicinity of this appliance is hazardous.
If you smell gas:
1. Open windows.
2. Don't touch electrical switches.
4. Immediately call your gas supplier.
WARNING: Improper installation, adjustment, alteration, service, or maintenance can cause property damage, injury or death. Read the installation, operation, and maintenance instructions thoroughly before installing or servicing this equipment.
KEEP THIS BOOKLET
FOR MAINTENANCE AND
SERVICE REFERENCE.
Operating/Maintenance/Service Instructions
The information in this manual applies to Model Series DV, di­rect-fired heating/makeup air systems. As with any gas burning equipment, regular maintenance procedures are required to en­sure continued safety, reliability and efficiency of the installa­tion.
If service is required, this system should be serviced only by a qualified service person. Service information in this booklet is intended as a guideline for a qualified gas-fired equipment ser­vice person.
Mfg No. 161442
Page 1
DANGER: The gas burner in this direct gas-fired system is designed and equipped to provide safe and economically controlled complete combustion. However, if the installation does not permit the burner to receive the proper supply of combustion air, complete combustion may not occur. The result is incomplete combustion which produces carbon monoxide, a poisonous gas that can cause death.
Always comply with the combustion air requirements in the installation codes and operating instructions. The amount of air over the burner must be within the specified range. The burner profile plates are set at the factory to match CFM requirements. Do not adjust the burner profile plates without contacting the factory. FAILURE TO PROVIDE PROPER COMBUSTION AIR CAN RESULT IN A HEALTH HAZARD WHICH CAN CAUSE PROPERTY DAMAGE, SERIOUS INJURY, AND/OR DEATH. Direct­fired installations should provide for air changes as required by the applicable installation codes.
Maintenance Section
This direct-fired makeup air system is designed to require only a minimum amount of maintenance. Some maintenance procedures outlined in this Section require inspection only and some require action. Frequency requirements of each maintenance procedure are listed in the Maintenance Schedule. Depending on the environment and the number of operating hours, more frequent inspec­tion and/or cleaning may be required to certain components.
Although maintenance requirements are minimal, the routine maintenance pro­cedures in this Section are necessary to ensure safe, reliable, and/or efficient operation. The paragraphs which follow discuss the components and systems that require routine inspection/maintenance. At the beginning of each paragraph, there is a code indicating why that maintenance procedure is necessary. The legend for that code is shown below.
Maintenance Codes
Reason for Maintenance
S = Safety (to avoid personal injury and/or property damage)
R = Continued Reliability
E = Efficient Operation
WARNING: Disconnect all power to the system before doing any maintenance. Failure to do so may cause electrical shock, personal injury, or death.
Maintenance Schedule
See Chart
Quarterly
Semi-Annually
Annually
Lubricate bearings, Paragraph 1
Check the filters, Paragraph 2
 
Check air pressure sensing tubes,
Paragraph 4
Check blower belts, Paragraph 1
Verify gas pressures, Paragraph 3
 
Clean air pressure sensing tubes,
Paragraph 4
Check indicator lights, Paragraph
5
Check main burner and pilot
assembly, Paragraph 6
Discharge Air
Optional Return Air
Outside Air
Page 2
Figure 1 - System
Configuration
Blower Section
Burner/Control Section
Location of Optional Filter Cabinet (not shown)
Screened Inlet Base
R
1. Drive Components
The blower, motor and drive components are located in the blower cabinet at the top of the system. Systems with horizontal discharge have a cabinet with eight removable door panels. Systems with vertical discharge have a cabinet with six removable door panels. Remove the panels required to access the components being serviced.
1A. Blower Bearings
All blowers are Class I with pillow block bearings. Clean the fitting and add type NLG-2 or -2 standard grade grease. Add grease with a handgun until a slight bead of grease forms at the seal. Be careful not to unseat the seal by over lubricating.
NOTE: If unusual environmental conditions exist (temperatures below
o
F or above 200oF; moisture; or contaminants) more frequent lubri-
32 cation is required.
excessive motor and blower bearing wear. If adjustment is required, adjust belt tension by means of the adjusting screw on the motor base until the belt can be depressed 1/2" to 3/4" (Figure 2). Tighten the lock nut on the adjusting screw. Be sure the belt is aligned in the pulleys.
Figure 2 ­Belt Tension
3/4 (19mm)
CAUTION: If the blower is unused for more than three months, the bearings should be purged with new grease prior to startup.
Recommended Bearing Lubrication Schedule in Months
Bearing Bore Diameter (Inches)
RPM
1/2 >1 to >1-1/2 to
to 1 1-1/2 1-15/16
to 500 6 6 6 501 - 1000 6 6 6 1001 - 1500 5 5 5 1501 - 2000 5 4 5
1B. Blower Belts
Check belts for proper tension and wear. Adjust belt tension as needed. Replace worn belts. Proper belt tension is important to the long life of the belt and motor. A loose belt will cause wear and slippage. Too much tension will cause
3. Manifold Gas Pressure
S
Semiannually, check the gas pressure to the burner and to the pilot. Measure both manifold pressure and pilot supply pressure with the blower in operation. Refer to Figure 3 for pressure tap locations. Verify against pressures listed on the rating plate.
R E
If the system includes filters, check the filters quarterly. Filters could be either in the optional inlet base or in an optional filter cabinet.
If the filters are in the perimeter of the inlet base; they are two-inch permanent filters. Remove and clean the filters as needed.
If the filters are in a filter cabinet (the filter cabinet is always between the inlet base and the burner/control section), remove the filter cabinet door panels to access the V-bank filter rack. Filters may be either 2" disposable, 1" or 2" permanent, or 1" or 2" disposable pleated. Clean or replace as needed.
Size 109 112 115 118 122 125
16" x 16" 4 4 - - 16 16
16" x 20" 4466- -
16" x 25" - - 6688
2. Filters
Sizes and Quantity of Filters in the Filter Cabinet
( same for all types of filters)
Figure 3 - Location of pressure taps for measuring burner and pilot gas pressure. Measure with blower operating.
Gas
Supply
Pilot Manifold
Valve
Inlet Pressure Tap
Pilot Regulator
Valve
Pilot Solenoid Valve
Pilot Pressure Tap
Regulator
Manifold Pressure Tap
Page 3
S
4. Air Pressure
Profile plate sensing tubes should be checked quarterly and cleaned no less than semiannually. If the sensing tubes become even partially blocked, false pressure readings may be relayed. To clean, remove the screened end caps. Clean the screens and the tubes, if necessary. Re­place the cleaned end caps. Check the pressure differential across the profile plate using a slope gauge. Air pressure differential should be between -.5" and -.7" w.c.
To attach the slope gauge, open the control compartment door panel. Just below the junction box, locate the tubing connections. Remove the cap at each connection and attach the slope gauge using two field­supplied 1/4" x 1/8" female NPT barbed tubing connections. For in­structions on measuring air pressure, see Service Section, Paragraph 9.
5. Circuit Indicator Board (check
R
lights)
The circuit indicator board is located in the control compartment elec­trical box (See Figure 7). Check operation of all indicator lights by switching lights that are not lit with one that is currently lit. Replace all burned out indicator bulbs (P/N 125189).
Figure 4 - Circuit Indicator Board, P/N 151263
Check bulbs not lit with other bulbs; replace any burned out bulbs
Row of Bulbs
Figure 5 - Burner End Plate showing Hot Surface Ignitor
Burner End Plate
Flame Sensor
Ignitor
If air pressure does not unplug burner orifices or pilot tube, drill burner orifices with a Size #50 drill and/or pilot tube with a Size #55 drill.
WARNING: Do not enlarge burner ports or performance may be drastically affected.
Inspect the upstream and downstream sides of the mixing plates. Remove any accumulation of scale or foreign material with a wire brush. If any mixing plate fasteners are loose or missing, tighten or replace. Always use zinc plated or stainless fasteners.
If any cracks are present, replace that mixing plate. Because of the effect of flame temperature on the metal, fasteners may be difficult to remove. Be careful not to damage the gaskets that go between the mixing plates and the burner body. The gaskets are designed to overlap approximately 1/16" for tight air seal.
5) Follow Steps in reverse order to re-install the pilot assembly. Close all panels and check for proper operation.
6. Main Burner and Pilot Assembly
S
For the most part, the burner and pilot are self cleaning. However, if the application is extremely dirty or dusty, cleaning of the burner and pilot may be necessary. Inspect the burner annually. Follow these instruc­tions. If it is necessary to replace any parts, use only factory-autho­rized replacements.
1) Turn off the gas and power supply to the system.
2) Remove the door panels in the burner/control cabinet (four or six depending on whether or not the system has return air). Locate the pilot.
3) Disconnect the two ignition wires (male and female quick connec­tions) and disconnect the flame sensor lead at the burner. Remove the set screw located in the ignitor tube (set screw holds the brass bushing in place). Carefully remove the brass bushing and the igni­tor.
Check the hot surface ignitor for cracks or unusual deterioration.
Check the flame rod for integrity. Replace the flame rod (P/N 131188) and/or the hot surface ignitor (P/N 121865) if not in good condition.
4) Clean the burner and pilot by back-flushing, using high pressure air (40-80 lbs). Continue until dust particles are completely expelled from both the upstream and downstream sides of the burner.
CAUTION: Wear eye protection while pressure cleaning and drilling.
Figure 6 - Illustration of the first Burner Section
Mixing Plate
Full length of the burner is made up of a series of 6" or 12" burner sections in a linear or oval configuration
Burner
WARNING: Burner profile plates are factory set to match CFM requirements.
Do not adjust profile plates without contacting your Sales Representative for technical assistance.
Page 4
Operation/Service Section
Controls - Location, Operation, and Service
To service this system, it is necessary to understand the normal operation of the controls and the function of the diagnostic circuit board. Refer to the electrical box drawing in Figure 7 and to the individual illustrations to identify and locate each of the controls. The wiring diagrams for this unit are located in the main electrical box.
Figure 7 - Control Locations
Control Relays
(high ambient limit control)
Ignition Module
Outside Air Cutoff
Bypass Damper Motor
WARNING: Service work on this system should only be done by a qualified gas ser­vice person. The service information and the troubleshooting guides are intended as an aid to a qualified service person.
Time Delay
Relay
24-volt Terminals
Return
Air
Damper
Motor
Status Lights
Maxitrol Amplifier
or Signal Conditioner
Optional Dirty Filter Pressure Switch
Circuit Board
Optional Bypass Damper Pressure Switches
Service Switches
24-Volt Terminals
High
Standard Pressure
Switches
Low
Relay for
Optional 2-Speed
NOTE: Wiring diagrams for the unit are located on the inside of the electrical box door.
7. Electronic Circuit Board with Diagnostic Lights
Location: Control Compartment Electrical Box (See Figure 7)
Function: The diagnostic lights on the circuit board are designed to assist
in troubleshooting. When the system is operating properly, the lights on the circuit board are lit. If the system fails to operate properly, all lights on the circuit board up to that one that represents the component or system that has failed will be lit. For more detailed information, refer to the Trouble­shooting Guide in Paragraph 19.
8. Temperature Limit Safety Controls
Location: 1) Manual Reset Limit Switch is mounted on a 2x4
electrical box located in the blower section. To access the manual reset, remove the blower section access panel to the left of the discharge (left when facing the discharge); 2) Emergency Cutoff Limit Control is in the burner/control cabinet just above the electri­cal box.
• Manual Reset Limit Control - Blower Cabinet
Function: The
Figure 8 ­Diagnostic Circuit Board, P/N 151263
Column of 13 indicator bulbs; always replace burned out bulbs, P/N
125189.
manual reset limit is a temperature activated safety control. Re-start of the system can be done only after the limit control is cooled and the reset button is depressed.
CAUTION: If the manual reset limit activates, find and correct the cause before re-starting the system.
Service: Failure of the manual reset limit requires replacement of
the control.
Transformer
Starter Relay
Figure 9 ­Manual Reset Limit
Capillary tubing is
in a holder that
extends into the
Motor Starter
Line Voltage Terminals
Page 5
8. Temperature Limit Safety Controls (cont'd)
• Emergency Cut Off Limit Control
Function: The emergency cut off is a fus-
ible link high temperature limit which pro­vides one-time redundant protection against overheating. If the temperature sensitive limit control malfunctions, the electrically activated emergency cutoff will shutdown the system.
Service: If this limit activates, the manual
limit control has failed and must be re­placed. The cause for activating the emer­gency cut off limit control must be found and corrected before re­starting the system.
Figure 11 - ECO Limit Control, P/N 82414
Setting 305oF
9. Air Pressure Switches
Location: Control Compartment Electrical Box (See Figure 7.)
Depending on the options selected, there are two or four switches.
Figure 12 - Air Pressure Switch
Attach a slope gauge (0 to 1.0" scale) to the tubing connections in the control compartment. The two connections are located below the elec­trical control box. Remove the caps on the 1/8" NPT test connections and attach the slope gauge. (The recommended method for attaching the slope gauge is to use field-supplied 1/8" female NPT x 1/4" O.D. barbed hose connections.)
A) If the system includes an optional discharge damper, before measur-
ing burner differential air pressure, check to be sure that the damper is fully open.
B) With the blower operating, the pressure differential on the slope
gauge should read between -.5" and -.7" w.c. If the slope gauge reading is within those limits, no adjustments are necessary.
If the slope gauge reading is not within the setpoint limits of the air flow switches (.2" to .9" w.c.), and the system is operating, replace the air pressure switch(es).
If the slope gauge reading is not between -.5" and -.7" w.c., but within the setpoint limits, clean the sensing tubes (Follow the in­structions in Maintenance Section, Paragraph 4).
C) When air pressure is within the proper range, turn the disconnect
switch OFF. Disconnect the manometer and the slope gauge. Re­place the caps removed to connect the slope gauge.
Service: If the pressure check determines that an air flow switch is not
functioning properly, the switch cannot be serviced and must be re­placed with an identical replacement. Low air pressure switch is P/N 86986; high air pressure switch is P/N 86987; bypass damper switches, P/N 87249 (normally closed, set to open at .5" w.c.) or P/N 87250 (normally open, set to close at .65" w.c.).
• Low Air Flow Switch
Function: The low air flow switch is a velocity pressure switch that
monitors air flow across the burner. Until the air flow attains adequate volume for combustion, the switch remains open. When the switch recognizes adequate air volume, it closes, permitting both the pilot and burner to operate. Low pressure switch is normally open; it closes on pressure rise at .2" w.c. Do not alter or adjust setting.
• High Air Flow Switch
Function: The high air flow switch is a velocity pressure switch that
monitors air flow across the burner. If the high air flow switch senses air velocity above the prescribed limit, it will shutdown gas flow to the burner. High pressure switch is normally closed; it opens when pres­sure rises above .9" w.c. Do not alter or adjust setting.
• Bypass Damper Air Flow Switches (systems with Air Control Options AR19, AR20, AR22, AR23, AR32, AR33, AR34, AR36, or AR37)
Function: With a bypass damper, the volume of outside air supplied
to the building is adjusted by a manually set potentiometer (Option AR19 and AR22) or automatically by a pressure null switch (Option AR20 or AR23), a photohelic pressure switch (Option AR36 or AR37), or a field-supplied computer signal (Option AR33 or AR34). With Options AR19, AR20, AR33, and AR36 the supply air is varied by adjusting the position of a damper at the blower discharge. With Op­tions AR22, AR23, AR34, and AR37, a return air damper is adjusted to vary the volume of return air. The unit is arranged so that a fixed amount (20%) of the rated volume flows over the burner at a constant velocity. The remainder (80%) of the rated air volume flows either through a balancing bypass damper or a combination of bypass and return air dampers. As the supply air volume is varied by the return air or dis­charge damper, the balancing damper is adjusted to maintain the re­quired air velocity over the burner. Adjustment of the bypass damper is controlled by the bypass damper pressure switches. One pressure switch is normally closed with a setting of .5" w.c.; the other is nor­mally open with a setting of .65" w.c. balancing bypass damper.
Sensing Pressure Check: (requires a slope gauge, several feet of
1/4" O.D. tubing and two 1/4" O.D. barbed tees.)
Page 6
10. Ignition System
Location: Ignition Controller Module in the Control Compartment
Electrical Box (See Figures 7 and 13.); Ignitor and Flame Sensor on the Burner (See Figure 14.)
Figure 13 - Ignition Control Module in the Electrical Compartment, P/N 157953
Hot Surface Ignition System with Prepurge Time Delay and Flame Sensor with 100% Lockout
Function: The ignition system including the controller, the hot surface
ignitor, and the flame sensor function to ignite and prove the pilot flame. When there is a call for heat, the modular ignition controller is energized. When the controller reads 1.4 amps going to the hot surface ignitor, it opens the pilot valve for a 15-second trial for ignition. After the pilot flame rod senses pilot flame, the main gas valve is energized. If the pilot flame rod does not sense a pilot flame, the controller shuts down the pilot valve for a 10-second interpurge and then opens it again for a second ignition trial. If pilot flame is not proven on the second trial, the ignition controller locks out and must be manually reset by an interruption of the main circuit (disconnect switch).
Service: The modular ignition controller does an internal self-check
each time that it is energized and will lockout if not found to be func-
Figure 14 - Ignitor, P/N 121865, and Flame Sensor, P/N 134706, on the Burner
Sensor
Ignitor
tioning properly. If the ignition controller locks out and there is no other cause, the controller module must be replaced.
11. Gas Train Including Direct-Fired Burner, Gas Control Systems, Manifold Arrange-ments, and Gas Pressure Switches
Direct-Fired Burner
Function: The design of the direct-fired burner and the con-
trolled velocity of air at the burner ensure complete combustion through the full range of burner sizes and gas inputs as determined by the gas control system. The velocity of air is controlled by the profile plates and monitored by a standard low and high air pres­sure switch.
Service: Refer to Paragraph 6 in the Maintenance Section for
instructions on burner maintenance.
For troubleshooting guides and further explanation of Maxitrol Series 14 and 44 electronic modulation gas control systems, refer to the Maxitrol literature in the owner's envelope.
The Option AG30, AG31, AG32 and AG35 electronic modulation systems are comprised of Maxitrol Series 14 controls. Options AG30 and AG31 systems electronically maintain a constant discharge air temperature in the range of 55-90°F (55-75°F for C.G.A.). Option AG31 includes an overriding thermostat. Option AG32 system will maintain a constant discharge air temperature in the range of 80-130°F. Option AG35 maintains a discharge temperature range of 120-160°F.
Figure 15 - Components of the Gas Control System (Maxitrol Series 14) used in Gas Control Options AG30, AG31, AG32, and AG35
Amplifier,
P/N 148590
Mixing Tube
WARNING: Burner profile plates are factory set to match CFM requirements. Do not adjust profile plates without contacting your Sales Representative for technical assistance.
Makeup Air Gas Control Systems
Electronic Modulation Gas Control
Options AG30, AG31, AG32, AG33, AG35, AG36
Refer to the wiring diagrams in the main electrical box to deter­mine which controls are on the system being serviced. NOTE: All field-supplied control wiring for Maxitrol controls must not be run inside conduit with line voltage wiring. To avoid any potential electrical interference, all field-supplied wiring for Maxitrol con­trols should be shielded wiring and must be grounded at the unit only. Function: These makeup air gas control systems provide heated makeup air at a temperature controlled by a discharge air sensor. Each system is equipped with electronic modulation controls that modulate burner flame from 1/25th of full fire input to full fire.
The electronic modulating-type gas controls act in response to discharge and/or room air temperature sensors to change the gas flow rate to the burner, thus lengthening or shortening the flame. The BTU output is varied (modulated) to maintain the required discharge air temperature.
These modulating gas control options are electronic because in all cases the gas valve acts to adjust the flow of the gas to the main burner in response to DC volts emanating from an amplifier. When the DC voltage is between 0 and 5 volts, the main valve seat is closed. Low fire flow is accomplished through a mechanical bypass. The low fire flow rate is set at the factory and should not need adjustment. However, if adjustment is necessary, refer to the Maxitrol literature that is included in the heater owner's enve­lope.
All of the electronic modulating gas control burner systems in­clude low fire start. On an initial call for heat, the main burner ignites at its lowest input. During mild weather, the burner may then cycle off. Such full shutdown can be dictated by the outdoor ambient cutoff control. As the outside air temperature climbs above the setpoint of the outdoor ambient control, the burner control circuit is de-energized. When moderately cold outside air temperatures exist, the burner will modulate between low flame and high flame. Low fire start and the outdoor ambient control prevent the makeup air system from heating already warm air and providing "too much" heat to the building.
Temperature Selector
Option AG33 electronic modulation system is comprised of Maxitrol Series
44 controls. The low limit (20-60°F) and the high limit (60-140°F) for con­trol of discharge air temperature are set at the amplifier located in the control compartment. The space temperature is set at the remote selectrastat (55­90°F range) located in the space. When the temperature is below the space temperature setpoint, the control system operates the burner to automati­cally adjust the discharge air temperature within the maximum and minimum limits set on the amplifier.
Temperature
Sensor
Figure 16 - Components of the Gas Control System (Maxitrol Series 44) used in Gas Control Option AG33
Temperature Sensor, P/N 119617
Mixing Tube, P/N 90323
Option AG36 is a special application gas train that is designed for controlling
the environment of a paint booth operation. The system includes a Maxitrol A1494 amplifier, discharge air temperature sensor, dual remote discharge air temperature selector (drying selector 80-140°F and a spray selector 60­90°F), and two switches to control the operation of the modulating gas valve.
Amplifier, P/N 157915
Temperature
Selector, P/N 86990
Figure 17 - Components of the Gas Control System used in Option AG36 designed specifically for paint booths - controls are mounted on a remote console
Selector,
Amplifier,
P/N 133229
Electronic Modulation Gas Control Option AG37
Function: Control Option AG37 does not have a duct sensor or ampli­fier. Instead, a Maxitrol A200 signal conditioner is activated by a cus­tomer-supplied input signal (either 4­20 milliamps or 0-10 volt) to control the modulation of the gas valve.
P/N
133230
Figure 18 - Maxitrol A200 Signal Conditioner, P/N 134170, used in Gas Control Option AG37
Page 7
11. Gas Train Including Direct-Fired Burner, Gas Control Systems, and Manifold Arrangements (cont'd)
Service - All Maxitrol Controls: Check all electrical connec-
tions. A qualified service person should refer to the Maxitrol Trouble­shooting Guides for assistance in identifying problems and determining the correct solution. None of the Maxitrol controls have field replace­able parts. All components must be replaced with identical replacement parts.
Figure 19 - Gas Manifold Control Components
Solenoid Valve
Modulating/
Regulating
Valve
Manifold Arrangements
Description: The manifold is the gas train from the gas supply con-
nection to the burner. The manifold selection ordered determines the manifold arrangement including all of the gas train components except the main control valve. Manifold arrangements are available for varying BTUH ranges and gas controls and include versions that meet FM or IRI requirements.
In addition to the Maxitrol valve and two solenoid valves, all manifold arrangements include main gas and pilot gas shut-off cocks, a pilot regulator, and a pilot solenoid valve.
The table below lists the pressure drops through the various types of manifolds by option designation (BM). To determine the required mini­mum supply pressure for natural gas, add 5.0" w.c. to the natural gas manifold pressure drop. For propane gas, add 2.0" w.c.
Manifold Pressure Drops (“ w.c.)
Manifold Opt BM62 BM63 BM64 BM65 BM67 BM68 BM53 BM66 Manifold Size 1" 3/4" 1" 1-1/4" 1-1/4" 2" 1-1/4" 2"
MBH Nat Pro Nat Pro Nat Pro Nat Pro Nat Pro Nat Pro Nat Pro Nat Pro 250 .56 .21 .66 .25 .43 .17 .22 .09 .19 .07 .07 .03 .22 .09 .07 .03 500 2.23 .85 2.65 1.01 1.74 .66 .89 .34 .76 .29 .27 .10 .89 .34 .27 .10 750 5.02 1.91 5.96 2.27 3.91 1.49 2.01 .77 1.71 .65 .61 .23 2.01 .77 .61 .23 1000 -- -- -- -- 6.95 2.65 3.58 1.36 3.04 1.16 1.09 .41 3.58 1.36 1.09 .41 1250 -- -- -- -- -- -- 5.59 2.13 4.76 1.81 1.70 .65 5.59 2.13 1.70 .65 1500 -- -- -- -- -- -- 8.05 3.07 6.85 2.61 2.44 .93 8.05 3.07 2.44 .93 1750 -- -- -- -- -- -- 10.96 4.17 9.32 3.55 3.33 1.27 10.96 4.17 3.33 1.27 2000 -- -- -- -- -- -- 14.31 5.45 12.18 4.64 4.34 1.66 14.31 5.45 4.34 1.66 2250 -- -- -- -- -- -- 18.11 6.90 15.41 5.87 5.50 2.09 18.11 6.90 5.50 2.09 2500 -- -- -- -- -- -- 22.36 8.52 19.02 7.25 6.79 2.59 22.36 8.52 6.79 2.59 2750 -- -- -- -- -- -- -- -- -- -- 8.21 3.13 -- -- 8.21 3.13 3000 -- -- -- -- -- -- -- -- -- -- 9.77 3.72 -- -- 9.77 3.72
Gas Pressure Switches
If the gas train includes either or both high and low gas pressure switches, the switches monitor gas pressure downstream from the safety valves.
If the gas pressure in a system equipped with a high gas pressure switch (Op­tion BP2) exceeds the setpoint, the switch will open the electrical circuit to the burner, stopping all gas flow. The high gas pressure switch is a manu­ally reset device.
A low gas pressure switch (Option BP3) will shutoff the gas flow if the gas pressure drops below the setpoint of the low pressure switch. The low gas pressure switch will automatically reset when the gas pressure rises above the setpoint.
(NOTE: Both high and low gas pres­sure switches incorporate a vent limiting device and do not require venting to the outdoors when used in an application installed indoors.)
Page 8
Figure 20 - Gas Pressure Switches
Low, P/N 93850
(automatic)
High, P/N 93849
(manual reset)
Pilot Valve
Pilot Regulator
12. Outside Air Cutoff Control (Option BN2; required on C.G.A.-certified units)
Location: The control is in the electrical box (See Figure 7.); the sensor is in the air inlet.
Function: After sensing pilot flame, the burner ignites at its lowest input rate. The "amount of heat" required to reach the de­sired discharge temperature also depends on the temperature of the incoming outside air. The outside air control is factory set at 60°F (adjustable 25-250°F). The burner reacts differently depending on the entering air tem­perature and the setting on the outside air control. The burner --
• may not ignite (pilot valve will not open);
If the actual temperature of the outside air is above the setpoint on the outside air control, the burner will not ignite.
• may modulate to satisfy discharge setting;
• may shutdown; or
Figure 21 ­Outside Air Cutoff Control
Burner shutdown or modulating operation will depend on the tem­perature rise between the outside air and the discharge air setting.
• may remain on continuous low fire. If the outside air control is set too high, the burner will continuously
burn on low fire as long as the control switch is set to "winter".
When the outside air control is set properly for the climate, the system blower will continue to provide the required makeup air (ventilation) at the ambient outdoor temperature (burner not operating) even when the control switch is set to "winter".
Service: If the control does not function properly, replace it with an identical switch.
13. Door Switch (Option BX1; required on
C.G.A.-certified units)
Location: The control is installed on an over­head door opening to control the operation of the heater to coincide with the opening and clos­ing of the door. Function: The function of the switch is to ener­gize and interlock the heating unit when an out­side overhead door reaches approximately 80% of full open travel. The switch will de-energize the furnace when the overhead door closes ap­proximately 20%. The complete switch includes a limit switch electrically wired to the heater and a roller yoke for mechanical activation by a field-supplied trigger on the overhead door.
Figure 22 ­Door Switch, P/N 124253
14. Inlet Air Controls
WARNING: Burner profile plates are factory set to match CFM requirements. Do not adjust profile plates without contacting your Sales Representative for technical assistance.
Description: The system is equipped with one of the 11 types of
inlet air control arrangements listed below. All systems provide a con­stant flow of outside air across the burner at the required air volume (CFM).
Refer to the wiring diagrams in the main electrical box to determine which controls are on the system being serviced.
zz
zOption AR1 - a constant supply of 100% makeup air
zz zz
zOption AR19 - 100% outside makeup air with variable supply air
zz
volume (CFM). The discharge damper controlling the variable air sup­ply is controlled by a manually set remote potentiometer and can be varied from 100% to 20% of total rated air flow (CFM). In response to changes in the discharge damper setting, the bypass damper balances the volume of air so that the required fixed amount of air volume flows over the burner.
zz
zOption AR20- 100% outside makeup air with variable supply air
zz
volume (CFM). The discharge damper controlling the variable air sup­ply is automatically controlled by a building pressure sensor and can be varied from 100% to 20% of total rated air flow (CFM). In response to changes in the discharge damper setting, the bypass damper balances the volume of air so that the required fixed amount of air volume flows over the burner.
zz
zOption AR22 - a combination of outside makeup air and bypass
zz
return air including modulating return air and bypass air dampers. The volume of outside air is regulated by a remotely located, manually set potentiometer.
zz
zOption AR23 - a combination of outside makeup air and bypass
zz
return air including modulating return air and bypass air dampers. The volume of outside air is regulated automatically by a remotely located building pressure sensor.
zz
zOption AR32 - a combination of outside makeup air and bypass
zz
return air including a two-position actuator. The two position actuator
changes the position of the damper to provide either 100% outside air or 20% outside/80% return air. Control is from a SPDT toggle switch mounted on a 4x4 box (or if ordered, the switch is mounted on a remote console).
zz
zOption AR33 - 100% outside makeup air with variable supply air
zz
volume (CFM). The discharge damper controlling the variable air sup­ply is automatically controlled by a 0-10 VCD or 4-20 milliamp signal. In response to changes in the discharge damper setting, the bypass damper balances the volume of air so that the required fixed amount of air volume flows over the burner.
zz
zOption AR34 - a combination of outside makeup air and bypass
zz
return air including modulating return air and bypass air dampers. The volume of outside air is regulated by a 0-10 VCD or 4-20 milliamp signal.
zz
zOption AR35 - a constant supply of 100% makeup air to the unit but
zz
including a two-position inlet shutoff damper that closes the dampers when the system is not operating. The damper attaches to the duct flange of the optional inlet base (used only with the optional inlet base that has three closed sides and a duct connection for outside air).
zz
zOption AR36 - 100% outside makeup air with variable supply air
zz
volume (CFM). The discharge damper controlling the variable air sup­ply is automatically controlled by a remotely located photohelic pres­sure sensor. In response to changes in the discharge damper setting, the bypass damper balances the volume of air so that the required fixed amount of air volume flows over the burner.
zz
zOption AR37 - a combination of outside makeup air and bypass
zz
return air including modulating return air and bypass air dampers. The volume of outside air is regulated by a remotely located photohelic pressure sensor.
Air Flow Dampers
Function: Dampers operate in response to controls to provide the
rated flow of makeup air to the building.
Service: Clean dampers of dust or dirt.
Damper Motor
Function: The damper motor automatically ac­tuates the return air, bypass, and/or discharge dampers in response to an electrical control de­vice. The damper motor is direct-coupled to the dampers so there is no damper linkage to ad­just. Service: There is no service required on these motors other than external cleaning. If the mo­tors need replaced, replace with an identical damper motor.
Potentiometer
Function: The potentiometer is a manually set
switch that operates either the discharge damper (Option AR19) or the return air damper (Op­tion AR22) providing a mixture of return and outside air. It is a remotely located switch that requires manual adjustment.
Figure 23 ­Damper Motor
Figure 24 ­Potentiometer, P/N 16110
Service: If the potentiometer does not func-
tion properly, replace it with an identical switch.
Pressure Null Switch (automatic building pressure sensor)
Description/Function:
The pressure null switch is a diaphragm operated differ­ential pressure switch used in makeup air applications to automatically control
Figure 25 ­Pressure Null Switch (building pressure sensor), P/N 88052
Page 9
14. Inlet Air Controls (cont'd)
Pressure Null Switch (cont'd)
building pressure. It maintains a selected positive or negative pressure setpoint by changing the amount of outside air being introduced to the building through modulating outside air damper. As more pressure is required in the building, the pressure null switch activates the damper motor driving the outside air damper towards the full open position (causing the bypass return air damper to go toward the closed posi­tion). Conversely, as less pressure is required, the switch drives the outside air damper in the opposite direction.
Service: Clean the tubing and the screened ends of the pressure tap
vents. Be sure that the switch is installed with the diaphragm in a vertical plane and that the pressure taps are sheltered from the wind. For further service, follow the manufacturer's instructions included with the switch.
Photohelic Pressure Switch (automatic building pressure sensor)
Description/Function: The
photohelic pressure switch is a phototransister relay operated positive pressure switch used in makeup air applications to automatically control building pressure. It maintains a selected positive pressure setpoint by changing the amount of outside air being introduced to the building through a modulating outside air damper. As more pressure is required in the building, the switch activates the damper motor driving the outside air damper towards the full open position (causing the bypass return air damper to go toward the closed position). Con­versely, as less pressure is required, the switch drives the outside air damper in the opposite direction.
Service: Clean the tubing and the screened ends of the pressure tap
vents.
If the interior of the switch is protected from dust, dirt, corrosive gases and fluids, years of trouble-free service may be expected. Zero adjust­ment should be checked and reset occasionally to maintain accuracy; follow the manufacturer's instructions included with the switch.
There are no field-repairable parts in this switch. If the switch should require repair, contact either the system or the switch manufacturer concerning switch replacement or repair.
Figure 26 ­Photohelic Pressure Sensor, P/N 159893
15. Dirty Filter Switch
Location: Switch is located in the
main electrical box (See Figure 7); sensor tubes run to either side of the filter rack; indicator light is on the remote console.
Function: The dirty filter
switch is a pressure switch that activates an indicator light on the remote console when the filters need cleaned or replaced (See Ser­vice Section, Paragraph 2). This
Figure 27 - Dirty Filter Pressure Switch, P/N 105507
switch is only on systems with an optional console that includes a dirty filter light. The pressure switch is set during installation so that the light will be activated at approximately 50% filter blockage. Contacts should close at .17 to 5.0" w.c. ± .05" w.c.
Service: Clean the sensor tubes. If the dirty filter indicator system still
does not function properly, check the setting of the switch. With clean filters in place, blower doors closed, and blower in operation, decrease the pressure setting by adjusting the set screw on the switch clockwise until the filter light is energized or screw is bottomed out. At that point, adjust the set screw three full turns counterclockwise or until the screw is top ended.
If it is determined that the switch needs replacing, use an identical switch. When a new switch is installed, it must be manually set; follow the instructions above.
16. Photoelectric Smoke Detector (Option SA1)
Location: Field-mounted in the discharge ductwork.
Function: The detector will shut down the system if smoke is detected in the dis­charge ductwork.
Service: Clean the external surface. Check the wiring and connections.
Figure 28 - Photoelectric Smoke Detector (cover removed), P/N 159553, used with sampling tube, P/N 159714
17. Firestat (Option BD5)
Location: Field-mounted on the dis­charge ductwork so that the sensor extends into the duct. This control requires manual reset so should be mounted in an accessible location.
Function: The firestat will shut down the system if the temperature in the ductwork reaches 200°F. The switch must be manually reset.
Service: Clean the external surface. Check the wiring and connections.
Figure 29 ­Firestat, P/N 42782
18. Freezestat (Option BE2)
Location: The control is in the blower section electrical box; the sensing bulb is field-mounted in the discharge duct.
Function: The freezestat will shut down the system if the discharge temperature falls below the setpoint. The switch is automatic and will startup the heater when the temperature reaches the setpoint.
Service: Clean the external surface. Check the wiring and connections.
Figure 30 - Freezestat Controller, P/N 126170
REFERENCE: For service and troubleshooting information on the electrical controls, refer to the
manufacturer's literature covering that component. Component literature is included in the literature
Refer to Paragraph 19 for unit troubleshooting.
Page 10
envelope shipped with the system.
19. Troubleshooting
Chart 1 - General Troubleshooting Guide (Check the diagnostic lights on the circuit board)
Symptom or Problem Cause and Remedy
Disconnect switch is closed, but
1.
Disconnect switch is closed, but
2.
Disconnect closed, blower switch in test position, 1. Freezestat option not ordered - verify order/wiring diagram.
3. "firestat"
Disconnect closed, blower switch in test position, "firestat" and 1. End switch on damper motor not closed. - check end switch wiring.
4. "free ze stat"
and the blower motor is not operating. 3. Damper motor miswired - rew ire damp er motor per wiring diagram.
Disconnect closed, blower switch in test position, 1. Blower motor not wired correctly - check wiring diagram on motor.
5. "firestat", "freezestat"
lights are lit, but t he blower motor is not operating. 3. Faulty blower mot or relay - rep lace relay .
Disconnect closed; blower switch in test position;
6. "free ze stat"
blower motor is operating; but t he "low air light" is not lit. 3. Faulty low air switch - replace pressure switch (P/N 86986).
Disconnect closed; blower switch in test position; 1. High air switch open - verify p ressure drop at burner.
7. "firestat", "freezestat", "starter energized" air"
but t he
Disconnect closed; blower switch in test position;
8. "free ze stat", "starter energiz ed", "l ow air" and "high air"
are lit; but the
Disconnect closed; blower s wit ch in test p osition; 1. Indicator light is burned out - rep lace bulb (P/N 125189).
9. "firestat", "freezestat", "starter energized", "low air", "high air"
but t he
10. "firestat", "freezestat", "starter energized", "low air", "high air", "limit control normal" cutoff normal " pressure n ormal"
11. "firestat", "freezestat", "starter energized", "low air", "high air", "li mit controls normal", "ambient (outside air) cutoff normal"
but t he
12.
posit ion; control s wit ch is in "winter" p osition; cause then rep lace ECO .
"control power", "high gas normal"; "low gas normal"; "firestat normal"; "system switch energize d"; "starter energized"
ignitor is not becoming energized or beginning to glow. 4. Faulty low stage relay - replace relay.
13. Disconnect closed; blower and burner switches in run 1. Ignitor not reaching 1.4A threshold - check voltage and position; control switch is in "winter" position;
high gas normal; "low gas normal "; "fi restat normal"; "system switch energized"; "starter energized" and "freezestat normal"
lights are lit; ignitor glowing but (thus the pilot valve) is not energized.
light is lit, but
lights are lit, but
and
lights are lit and the blower motor is operating; 3. High air switch option not ordered - verify order/wiring diagram.
"high air light"
"limit control normal"
and
"limit control normal"
"ambient (outsi de air) cutoff normal"
Disconnect closed; blower s wit ch in test p osition; 1. Indicator light is burned out - rep lace bulb (P/N 125189).
lights are lit; but the
Disconnect closed; blower s wit ch in test p osition; 1. Indicator light is burned out - replace bulb (P /N 125189).
and
"high gas pressure normal"
Disconnect closed; blower and burner switches in run 1. Lack of power at L1 on ignition module - ECO blown, find
and
"freezestat normal"
"free ze stat"
and
"starter energized"
is
light is
"low gas pressure normal"
"control power"
"firestat normal"
light is not lit 2. Freezest at relay cont acts are open - checking setting on cont rol.
"starter energized"
"starter energized"
lights are lit and t he 2. Indicator light is burned out - replace bulb (P/N 125189).
lit. 4. Faulty high air switch - rep lace pressure switch (P/N 86987).
not
light is not lit. 3. Faulty manual limit cont rol (s) - rep lace limit cont rol.
lights are lit; 3. High ambient control contacts open - check setting on control.
and
"ambient (outsi de air)
"low gas
lit. 5. Faulty gas p ressure switch - rep lace gas p ressure swit ch.
not
light is
lights are lit; but thermostat sett ing.
"pilot valve normal"
light is not lit. 1. Fuses are missing or blown in disconnect switch - replace fus es.
2. T ransformer not wired according to diagram - check wiring.
3. Secondary 8A fuse (on transformer) is missing or blown - replace fuse.
4. Indicator light is burned out - rep lace bulb (P/N 125189).
light is not lit. 1. See causes and remedies for Problem 1 above.
2. Op tional control relay or door switch contacts are open - to test , jump terminals 3 to 4 or 1 to 2.
3. Firestat opt ion not ordered - verify order/wiring diagram.
4. Firestat manual reset tripped - reset firestat control.
3. Indicator bulb is burned out - rep lace bulb (P/N 125189).
light is not lit 2. Faulty damp er relay - replace relay .
2. Faulty motor start er - rep lace (check coil firs t).
"firestat"
and
"low
"firestat"
light is
lights are lit; 4. High gas pressure switch contacts open - check gas p ressure.
lit. 5. M anual reset on switch tripp ed - reset p ressure switch manual reset.
not
"control power",
light
, 1. Low air switch open - verify p ressure drop at burner.
2. Indicator light is burned out - rep lace bulb (P/N 125189).
, 1. Indicator light is burned out - replace bulb (P/N 125189).
2. T rip p ed manual reset limit control(s) - reset manual cont rol.
2. High ambient control op tion not ordered - verify order/wiring diagram.
lit.
not
2. Low gas pressure switch option not ordered - verify order/wiring diagram.
3. Low gas pressure switch contacts op en - check setting on control.
4. Low gas pressure switch contacts op en - check gas pressure.
2. High gas pressure switch op tion not ordered - verify order/wiring diagram.
3. High gas pressure switch contacts open - check setting on control.
6. Faulty gas p ressure switch - rep lace gas p ressure swit ch.
2. Faulty burner enable relay - rep lace relay .
3. Low stage relay cont act s are not closed - check air cont roller or
5. Faulty hot surface ignitor - check cont inuity at the ignition module and circuit board. If reading is greater than 5-6 ohms, replace ignitor.
6. Faulty ignition module - replace entire module.
current to ignitor.
2. Faulty hot surface ignitor - check cont inuity , replace ignitor.
3. Faulty ignition module - replace entire module.
Page 11
19. Troubleshooting (cont'd)
Chart 1 (cont'd) - General Troubleshooting Guide (Check the diagnostic lights)
Symptom or Problem (cont'd) Cause and Remedy (cont'd)
14. Disconnect closed; blower and burner switches in run position; control 1. Air in pilot gas line - bleed pilot line. switch is in "wint er" p os ition;
gas normal"; "firestat normal"; "system switch energize d"; "starter energized" and "freezestat normal"
1.4A and has opened the pilot valve bringing on the light; but t he p ilot flame is not present . (Aft er two t rials the unit will go into safety lockout requiring cycling of the main disconnect switch.)
15. Disconnect closed; blower and burner switches in run position; 1. M icroamp signal on flame rod is inadequate - check position and
control switch is in "winter" p osition; all status light s are lit condition of flame rod and signal (minimum 0.5 microamps required.)
"main valve normal" light. The pilot flame is present 2. Grounding for unit or flame rod inadequate - check ground path.
except
and stable, but the (low stage portion or) main gas valve will not 3. Fault y main gas valve - replace main gas valve.
open, or rap id cycling of the main valve is occurring. 4. Faulty ignition module - rep lace ignition module.
16. Disconnect closed; blower and burner switches in run position; 1. Faulty main gas valve - replace main gas valve.
cont rol swit ch is in "winter" posit ion; all s tatus lights are lit; the 2. Inadequate timing on high fire time delay relay - adjust setting.
pilot flame and low fire on the main burner are p resent and st able, 3. Faulty high fire t ime delay relay - replace t ime delay relay .
but the unit will not p rogress t o a high fire condit ion. 4. High st age relay contacts are not closed - check control setting.
"control power", high gas normal; "l ow
lights are lit; ignitor has reached 4. Faulty ignition module - rep lace entire module.
"pilot valve normal"
2. Inadequate pilot gas pressure - verify pilot gas pressure (3.5" w.c.)
3. Faulty p ilot valve - rep lace pilot solenoid valve.
5. Inadequate main gas pressure - verify main burner pressure.
5. Inadequate main gas pressure - verify main burner gas pressure.
6. Faulty high stage relay - replace relay.
7. Faulty ignition module - rep lace entire module.
FOR SERVICE OR REPAIR, FOLLOW THESE STEPS IN ORDER:
FIRST: Contact the Installer
Name ___________________________________________________________________________
Address ___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Phone ___________________________________________________________________________
SECOND: Contact the nearest distributor (See Yellow Pages). If no listing,
contact Authorized Factory Representative, 1-800-695-1901 (Press 1).
®
THIRD: Contact REZNOR
150 McKinley Avenue
Mercer, PA 16137
Phone: (724) 662-4400
Model No. _____________________________________________
Unit Serial No. _____________________________________________
Date of Installation _____________________________________________
Index .................................................. Page
Air Pressure ............................................. 4
Air Pressure Switches ............................... 6
Blower Bearings ....................................... 3
Circuit Indicator Board ............................ 4
Control Locations .................................... 5
Damper Motor ........................................ 9
Direct-Fired Burner ................................. 7
Dirty Filter Switch ................................ 10
Drive Components ................................. 3
Electronic Circuit Board with
Diagnostic Lights ................................. 5
Emergency Cut Off .................................. 6
/Thomas & Betts Corporation
Index .................................................. Page
Filters ....................................................... 3
Firestat .................................................... 10
Freezestat ............................................... 10
Gas Control Systems ............................... 7
Gas Pressure ............................................ 3
Gas Pressure Switches .............................. 8
Inlet Air Controls ..................................... 9
Limit Control ........................................... 5
Main Burner ............................................. 4
Maintenance Schedule ............................. 2
Maintenance Section ......................... 2-4
Maintenance/Service Access .................... 2
Index .................................................. Page
Manifold Arrangements ........................... 8
Operation/Service Section .............. 5-12
Outside Air Cutoff Control ..................... 8
Photoelectric Smoke Detector ................ 10
Photohelic Pressure Sensor ..................... 10
Pilot Assembly ........................................ 4
Potentiometer ........................................... 9
Pressure Null Switch ............................... 9
Sensing Pressure Check ........................... 6
Troubleshooting ..................................... 11
Wiring Diagram ......................... In the main
electrical box on the unit
Page 12
©2001 Thomas & Betts Corporation, All rights reserved. Printed in the U.S.A. MANUFACTURER OF HEATING, COOLING, AND VENTILATING SYSTEMS
Trademark Note: Reznor® is registered in the United States and other countries. (800) 695-1901; www.ReznorOnLine.com 8/01 YL Form 441OMS (Version .1)
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