Rise Range (°F) Base Unit Weight (lbs.) 14,000 3 (1 motor) 240 450 16 to 30 4,080 22,000 5 (1 motor) 240 750 10 to 32 4,140 30,000 10 (1 motor) 520 1,000 16 to 31 4,210 30,000 10 (1 motor) 560 1,250 17 to 39 4,420 AT-260 CFM Motor (HP) Output (MBH) Minimum Output (MBH) Maximum Temp. Rise Range (°F) Base Unit Weight (lbs.) 54,000 5 (2 motors) 600 3,000 10 to 51 11,070 61,000 7.5 (2 motors) 720 4,000 11 to 61 11,335 74,000 10 (2 motors) 720 4,000 9 to 50 11,385 AT-236 CFM Motor (HP) Output (MBH) M

/0# 1"( 1 2 ,-. /0# 3 0& 4 567& % 57 1 8 ,-409 *:" ;<" Description Part Number S-Hook 91907302 Tube/Reflector Hanger 03090100 Total Straight Length (both sides) or Length from U-Tube to U-Tube in a Double "U" Layout Typical Expansion Each Side Minimum “X” Length 0’ - 50’ ±1” (3 cm) 12” (31 cm) 51’ - 60’ ±2” (5 cm) 18” (46 cm) 61’ - 80’ ±3” (8 cm) 24” (61 cm) 81’ - 100’ ±4” (10 cm) 30" (76 cm) 101’ - 120’ ±5” (13 cm) 36" (91 cm) 121’ - 140’ ±6” (15 cm) 42" (107 cm) 141’ - 160’ ±7” (18 c

• All dimensions are subject to change without notice. • Due to height of unit, additional support is recommended on top of the unit. • Dimension "F" is flue diameter. Flue located on left side of unit for 1,000 MBH heat exchanger and smaller; flue located on right side of unit for 1,250 MBH heat exchanger and larger. • Dimensions "D" and "F" may vary depending on heat exchanger size (ex. 45 = 450 MBH heat exchanger). 2 AT-Series Heating Unit with Filtration AMMBLCGDHFFKJCONTROLPANELINSPECTIONAN

• To install the heater in accordance with the clearances to combustibles. • To furnish all needed materials not furnished as standard equipment. • To plan location of supports, vents and air intakes. • To provide access for servicing. • To provide the owner with a copy of this Installation, Operation and Service Manual. • To never use heater as support for a ladder or other access equipment and never hang or suspend anything from heater. • To ensure there is adequate air circulation around the

There is an LED light on the ignition control that flashes codes to assist in fault correction. See Page 24, Figure 13 for LED indication codes. Figure 13: LED Diagnostic Codes LED INDICATION FAULT MODE Slow Flash Normal Operation - No call for heat. Fast Flash Normal Operation - Call for heat. 2 Flashes Ignition Lockout - No flame detected. 3 Flashes Airflow Fault - Pressure switch open or closed. 4 Flashes Temperature Limit or Switch Open 5 Flashes Flame Sense Error - Gas valve not energized.

• All dimensions are subject to change without notice. • Due to height of unit, additional support is recommended on top of the unit. • Dimension "F" is flue diameter. Flue located on left side of unit for 1,000 MBH heat exchanger and smaller; flue located on right side of unit for 1,250 MBH heat exchanger and larger. • Dimensions "D" and "F" may vary depending on heat exchanger size (ex. 45 = 450 MBH heat exchanger). 5 AT-Series Estimated Shipping Weights ESTIMATED SHIPPING WEIGHTS - BURNERS (A

450 Horiz.450 Horiz.450 Horiz.450 Horiz. 450 Horiz. 450 Horiz. 450 A 6 8 68 68 0 6 0 6 2 6 2 8 B 27 8 35 8 38 8 40 8 46 8 50 8 52 8 C 53 51 63 60 66 66 71 74 77 78 80 84 82 85 D 27 46 35 54 38 60 40 64 46 69 50 74 52 79 Model t Horizontal 450 *Clearances B, C, D can be reduced by 50% for locations 25 ft (7m) or more downstream of the burner. For other mounting options and associated clearances, complete installation, operation and service criteria, please see the current issue of the VA

If any of the original wire supplied with the heater must be replaced, it must be replaced with wiring material having a temperature rating of at least 105° C and 600 volts. SECTION 10: WIRING AND ELECTRICAL INFORMATION 10.5 DAT Wiring Diagram @%')D%1" 2#3#' E &#'/+2+2&/)'/)+&#% ! % ')D ;:/D&8F):!99'9)8')D')D ')8:')D/&8:B>C9 B%C! B#C" )):7" ! )'>4 98: "%% 9 /%'1%'')D@'@'%)1/')2%)1)) !')D%9 ')D0:: B C')/! ')D%G @+&02''''8!

Burner Pressure in wc 3.2 3.4 3.7 3.7 4.0 2.7 2.7 3.3 LPG / Propane (G31) Data - Inlet Pressure 12.0 in wc Min., 14 in wc Max. Burner Pressure in wc 9.9 10.4 10.5 10.7 10.5 9.4 9.3 11.1 SECTION 16: THE ROBERTS GORDON® COMBAT® UHD-SERIES WARRANTY SECTION 16: THE ROBERTS GORDON® COMBAT® UHD-SERIES WARRANTY ROBERTS GORDON® WILL PAY FOR: Within 24 months from date of purchase by buyer or 27 months from date of shipment by Roberts-Gordon (whichever comes first), replacement parts will be provided fre

The T and Fork layouts have a tee or cross (called the "last tee" or "last cross") where the combustion gases in the system enter the tee or cross with directly opposing flow directions, which creates an added source of pressure drop in the system. This additional source of pressure drop requires some difference in how the allowed manifold length is calculated. In this case, we have to differentiate manifold tube that is located between the radiant pipe and the last tee (or cross) from manifold