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Table of Contents
Related Manuals for McQuay SuperMod IM-685-1
Summary of Contents for McQuay SuperMod IM-685-1
- Page 1 Installation and Maintenance Manual IM-685-1 Group: Applied Systems Part Number: IM685 Date: June 2001 SuperMod Forced Draft Gas Fired Furnace on McQuay Applied Rooftop Systems HT***A* with RM7895A Flame Safeguard © 2001 McQuay International IM 685-1...
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Page 2: Table Of Contents
When writing to McQuay for service or replacement parts, refer to the model number of the unit as stamped on the serial plate, attached to the unit. If there is an in-warranty failure, state the date of installation of the unit and the date of failure along with an explanation of the malfunctions and the description of the replacement parts required. -
Page 3: General
This forced draft gas burner is specifically designed for use combustion air adjustments were compensated to result in with the furnace on McQuay applied rooftop heating and air proper settings at the higher altitude. This checkout nor- conditioning units which are for outdoor installation only. -
Page 4: Wind Deflector
Figure 1. Flue Box Electrical The McQuay burner receives its electrical power from the main unit control panel. No additional power wiring must be routed to the burner. The sequencing of the burner is also controlled through this panel and therefore is factory wired. -
Page 5: Valve And Regulator Venting
Valve & Regulator Venting Remove all burrs and obstructions from pipe. Do not bend Valve diaphragm vents, pressure regulator vents, and pres- pipe; use elbows or other pipe fittings to properly locate sure switch vents are located in the outdoor burner vestibule pipe. -
Page 6: Gas Piping Routing Into Unit
Gas Piping Routing Into Unit Through-The-Curb Piping (Models 020-140) On-The-Roof Piping (Models 020-140) 1. Remove bottom access panel (5). See Figure 3c. 1. Remove knockout (1) at corner of burner vestibule door 2. Remove knockout (4) and make an opening (6) through and saw out corner of door. -
Page 7: Gas Piping (Models 150-200)
Gas Piping (Models 150 thru 200) is accessible from outside the unit, that valve must be relocated The gas piping cannot be routed up to the burner from or an additional valve added. In locating such a valve, it is to within the curb on Models 150 through 200. -
Page 8: Start-Up & Operating Procedures
It is highly recommended that the system must be set to call for heating and must he used to initial start-up and future service be performed by McQuay control the amount of heating. Set the control system to call certified technicians who are familiar with the hazards of for heat so MCB-B011 energizes Relay R20. -
Page 9: Preliminary "Dry" Run
5. Check voltage. With burner switch S3 at AUTO, measure the burner. These problems could include linkages dis- voltage across burner control box terminals 2 and NB. If turbed during shipment, etc. it is not between 114 and 126 volts, check the voltage and Flame Start-up tapping connections to the supplying transformer at the 1. -
Page 10: Combustion Tests
Combustion Tests Cycle the Unit These tests should be run when the furnace is at normal oper- Cycle the unit through several start-ups with the temperature ating temperature (after the furnace has been running 10 to 15 controls calling for first minimum rates and finally maxi- minutes), and should be run at several firing rates including mum rates. -
Page 11: Typical Sequence Of Operation
Typical Sequence of Operation 'MADE'. If (LS1) is not 'MADE' the combination gas control start valves (GV1) will not open and the burner will go out When the rooftop unit is energized 120 volt power is sup- on safety lockout. plied to the system on/off switch (S1), to burner on/off switch (S3) and 24 volts to the (BO#11) contacts on the main After completion of the 60 second prepurge period there will... -
Page 12: Typical Burner Control Box
Flame Safeguard Normal Start-up: Prepurge: Upon a call for heat the prepurge period will begin. If the air switch does not detect fan operation in the See manufacturer's bulletin for more detailed information on first 10 seconds into the prepurge period a recycle to the flame safeguard RM7895A. -
Page 13: Service
Gun Assembly be concentric with the hole it passes through, not be shorted The McQuay gas burner gun assembly is easily removable out against the disc, the 0.75 inch long end tip will point and includes the ignition electrode assembly, the flame rod toward the 0.086 inch diameter alignment hole, and the end... -
Page 14: Air & Gas Adjustments
Air and Gas Adjustments Air Adjustments The burner has been adjusted and tested at the factory with Airflow and the resultant combustion characteristics have been preset and tested at the factory and no further adjust- accurate instruments. There should not be a need to readjust the burner after the unit has been installed. -
Page 15: Actuator Crankarm
Grasp the rod and while applying some thrust to the rod in Actuator Crankarm the direction of the actuator to take up any free play, and The actuator crankarm should not require adjustment. The with the bracket in alignment with the linkages that connect radius indicated by "G"... -
Page 16: Gas Valve Pressure Regulator Adjustment
Gas Valve Pressure Regulator Adjustment While the burner is operating and only one combination gas control is open, increase the firing rate of the burner. As the The high turndown burner uses combination gas controls to firing rate is increased the manifold pressure will be rela- provide redundant on-off gas control and pressure regulation. -
Page 17: Combustion Testing
Figure 12a Figure 12b Generally a valve will he found that has an effect, and very little adjustment will cause a reduction in the minimum rate manifold pressure. Reduce the pressure adjustment of that dominant valve by slowly rotating the adjuster CCW until 300º... -
Page 18: Cleaning Heat Exchanger (Models 020-025)
Models 020 thru 025 (see Figure 14) 2. Low CO Readings - Low CO readings that cannot be 1. To gain access to the inside of the combustion chamber, corrected can be caused by air leaking into the heat detach the burner from the furnace and set it on the floor exchanger and diluting the flue gas. -
Page 19: Replacing A Heat Exchanger
3. Excessive Condensation - Applications which will pro- A modulating burner will produce more condensate than an duce condensation require an all stainless steel heat on-off burner. As the firing rate of the burner is reduced the exchanger that is resistant to the effects of this condensa- flue gas temperature will he reduced, and if it is reduced below its dew point condensate will be produced. -
Page 20: Rear Cleanout Port
Figure15b. Condensate Drain Retrofit Kit upper end of the copper tube (2). Bend the end of the spout out from the casing panel slightly so the tube can be slipped into position. 3. The copper tube runs vertically down the side of the unit and extends approximately 2 inches below the bottom of 2.75* the unit base frame. -
Page 21: Maintenance
Maintenance Yearly Preventative maintenance is the best way to avoid unneces- sary expense and inconvenience. The system should be 1. Gas Train - Check all valves, piping, and connections for inspected at regular intervals by a qualified service techni- leakage. Remove burner gun assembly. Inspect, and if cian. -
Page 22: Troubleshooting Chart
Troubleshooting Chart Some of the steps listed in this troubleshooting chart will be The RM7895A flame safeguard is equipped with five LEDs unnecessary if a Keyboard Display Module is used, as that to aid in the diagnosis of burner operation and problems. In module will pinpoint many problems. - Page 23 BURNER MOTOR RUNS, FLAME IGNITES... 3.1 Burner motor starts, a nor- a. The flame is momentarily proving itself to the flame safeguard. It must be proven at the end of the 10 second trial for ignition mal prepurge cycle occurs, period.
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Page 24: Typical Parts List -60 Hz
Typical Parts List -60 Hz MCQUAY VENDOR USED ON QTY. VENDOR DESCRIPTION PART NO. PART NO. MODELS HT *** 0342492-00 Emerson 4526 020 — 080 Burner Fan: Motor 1/4 hp, 3450 rpm 0322486-00 Emerson 100 — 150 Motor 1/2 hp, 3450 rpm... -
Page 25: Capacities & Adjustments Table
Capacities and Adjustments IM 685-1... -
Page 26: Performance & Service History
Performance & Service History Table 6. IM 685-1... - Page 27 Notes: IM 685-1...
- Page 28 13600 Industrial Park Boulevard, P.O. Box 1551, Minneapolis, MN 55440 USA (612) 553-5330 IM 685-1...
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