Specifications

2 IM 685-2
General
Warranty Exclusion .......................................................... 3
Ventilation and Flue Pipe Requirements .......................... 3
Factory Mounting............................................................. 3
Factory Checkout ............................................................. 3
Installation
General ............................................................................. 3
Flue Box ........................................................................... 3
Wind Deflector ................................................................. 4
Electrical........................................................................... 4
Gas Pressure Requirements.............................................. 4
Gas Piping ........................................................................ 4
Valve and Regulator Venting............................................ 5
Normally Open Vent Valve .............................................. 5
Gas Piping Routing into Unit........................................... 6
On-the-Roof Piping (Models 020-140) ........................ 6
Through-the-Curb Piping (Models 020-140)................ 6
Typical Piping Connections .......................................... 6
Gas Piping (Models 150-200)....................................... 7
Gas Piping Within the Vestibule................................... 7
Field Gas Piping Required............................................ 7
Condensate Drain.......................................................... 7
Vestibule (Models 150-200) ......................................... 7
Start-Up & Operating Procedures
Start-Up Responsibility .................................................... 8
Start-Up Procedure........................................................... 8
Before Start-Up ................................................................ 8
About This Burner............................................................ 8
Prepurge is Low-High-Low .......................................... 8
Low Fire Start............................................................... 8
“Pilot” is Main Flame Modulated Down
to Pilot Rate ................................................................ 8
Set Control System to Enable Heating ......................... 8
Start-Up Preliminary ........................................................ 8
Preliminary “Dry” Run..................................................... 9
Flame Start-Up ................................................................. 9
Modulate Firing Rate ....................................................... 9
Combustion Tests ........................................................... 10
Cycle the Unit................................................................. 10
Record Data.................................................................... 10
References
Typical Sequence of Operation .......................................11
Flame Safeguard
Keyboard Display Module..............................................12
Operation.........................................................................12
Normal Start-Up..............................................................12
Service
General............................................................................13
Gun Assembly.................................................................13
Gun Assembly Removal and Installation .......................13
Flame Rod Adjustment ...................................................13
Flame Rod Installation....................................................13
Ignition Electrode Adjustment........................................13
Air & Gas Adjustments...................................................14
Gas Supply Pressure .......................................................14
High Pressure Regulator .................................................14
Gas Adjustment...............................................................14
Air Adjustments ..............................................................14
Air and Gas Control Linkage..........................................14
Actuator Crankarm..........................................................15
Switch Adjustments ........................................................15
Altitude Considerations ..................................................15
Gas Valve Pressure Regulator Adjustment .....................16
Adjustment Procedure for Parallel Valves ......................16
Check Manifold Pressure at Minimum Rate...................16
Combustion Testing ........................................................17
Verify Input Rate.............................................................17
Check CO
2
, CO and Stack Temperature .........................17
Cleaning Heat Exchanger (Models 032-200) .................17
Cleaning Heat Exchanger (Models 020-025) .................18
Leakage Symptoms.........................................................18
Checking for Leaks .........................................................18
Causes of Failures ...........................................................18
Replacing Heat Exchanger..............................................19
Furnace Condensation ....................................................19
Rear Inspection Cover.....................................................19
Combination Fan and Limit Control...............................20
Maintenance
Monthly, Twice Yearly, Yearly........................................20
Flame Safeguard
Characteristic and Operation...........................................20
Troubleshooting Chart .................................................22
Typical Parts List - 60 Hz..............................................27
Capacities & Adjustments Table ................................ 28
Performance & Service History.................................. 29
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. Parts are warranted for ninety (90) days
unless covered by original unit warranty.
SERVICED BY:
TELEPHONE NO: INSTALLATION DATE:
Installer: Leave this manual with owner. It is to be posted and maintained in legible condition.
Table of Contents
McQuay Model Designation
Furnace
Model
20 25 32 40 50 64 65 79 80 100 110 140 150 200
Output
Capacity
(MBh)
200 250 320 400 500 640 650 790 800 1000 1100 1400 1500 2000