
Xtreme High-Input Gas Commercial Water Heaters
Available in 90 Gallon Tank-Type Models
!
550,000 BTU/Hr. thru 715,000 BTU/Hr.
Xtreme Gas Commercial Water Heaters are specifically designed to
 minimize the difficulty of replacing failed water heaters and are versatile for 
new installations. These products are designed for applications requiring 
large quantities of hot water.
Construction Features:
GX90-550 and 
GX90-640 Comply 
With SCAQMD 
Rule 11 46.2 for 
Low NOxEmissions
Small
Jacket Diameters
• Space saving tank design –
maximizes installation adaptability 
by offering models with front side 
and rear side inlet/outlet water 
connections. Short heights and 
small jacket diameters result in 
greater installation flexibility.
• Patented multi-flue tank design 
– proprietary steel formulation,
patented multi-flue design, and 
two coats of high temperature 
porcelain enamel to maximize 
 corrosion resistance result in a 
superior heat exchanger design.
• Low profile automatic flue 
damper –
low profile design minimizes overall product height. Heavy duty vent 
hood supports are designed to 
withstand rigors of installation.
• Specialized burner 
assembly –
each model features five premix 
burners mounted into a metal face 
plate and sealed with a Viton 
 gasket. Patented “quick release” 
manifold for easier service.
• Spark-To-Pilot ignition system –
Standard on all models. Provides 
reliable and energy saving ignition 
sequencing by igniting the pilot 
only when the thermostat calls 
for heat.
™
• System Sentinel 
 diagnostic system –
Our exclusive diagnostic system, 
with glowing LED lights, verifies 
system operation sequence 
by sequence.
• Full port, full flow brass drain 
valve
LED
Short Floor-to-Vent
Heights
Multiple Water 
Connection Options
(On Selected
Models)
Certifications and Ratings:
• Efficiency – these models have been tested according to ANSI test
 procedures, and exceed the thermal efficiency and standby loss 
 requirements of current ASHRAE standards (Part of the Federally 
 mandated Energy Policy Act (EPact)). Also exceeds energy efficiency 
codes of all states. 
• Safety and construction – These products are design certified by U.L.: 
a) For operation at 180°F. b) To meet all safety and construction 
 requirements of ANSI Z21.10.3-2001 c) As an automatic storage or 
 instantaneous water heater. d) As an automatic circulating tank water 
heater. e) For operation on combustible floors and in alcove installations.
CERTIFIED FOR A 150 PSI MAXIMUM WORKING PRESSURE 
(160 PSI FOR ASME MODELS).
Continued next page.

treme Gas continued.
X
DIMENSIONAL INFORMATION All Dimensions Shown in English and Metric.
WATER CONNECTIONS APPROXIMATE
MODEL FRONT REAR
NUMBER UNITS ABCDEFG SIDE SIDE STD. ASME
GX90-550(A) inches 74.5 68 30 25 10 59 12 2905 945
mm 1892 1727 768 635 254 1509 25.4 51 51 905 945
GX90-640(A) inches 74.5 68 30 25 10 59 12 2905 945
mm 1892 1727 768 635 254 1509 25.4 51 51 905 945
GX90-715(A) inches 74.5 68 30 25 10 59 12 2905 945
mm 1892 1727 768 635 254 1509 25.4 51 51 905 945
GX90-500(A) inches 74.5 68 30 25 10 59 12 2905 945
mm 1892 1727 768 635 254 1509 25.4 51 51 905 945
GX90-600(A) inches 74.5 68 30 25 10 59 12 2905 945
mm 1892 1727 768 635 254 1509 25.4 51 51 905 945
GX90-680(A) inches 74.5 68 30 25 10 59 12 2905 945
mm 1892 1727 768 635 254 1509 25.4 51 51 905 945
All Models Require a 120V Power Source. (A) Suffix Indicates ASME Tank Construction Available.
SHIPPING WEIGHT
MAXIMUM DELIVERY In U.S. Gallons and Liters. (Includes useable storage and recovery for indicated times.)
MODEL TANK CAPACITY INPUT BTU/HR. TEMP. 5 10 15 20 30 45 60 120 180 Min. to Rec. 
NUMBER 
GX90-550(A) 90 341 550,000 NAT 100°F GAL 107 152 196 241 330 463 596 1130 1663 10
GX90-640(A) 90 341 640,000 NAT 100°F GAL. 115 166 218 270 373 529 684 1304 1925 9
GX90-715(A) 90 341 715,000 NAT 100°F GAL. 121 179 236 294 410 583 756 1450 2143 8
GX90-500(A) 90 341 500,000 LP 100°F GAL. 103 144 184 225 305 427 548 1033 1518 11
L.P. 37.7°C LTR. 391 544 697 850 1156 1615 2073 3909 5744
GX90-600(A) 90 341 600,000 LP 100°F GAL. 112 160 209 257 354 499 645 1227 1809 9
L.P. 37.7°C LTR. 422 606 789 972 1340 1890 2441 4643 6845
GX90-680(A) 90 341 680,000 LP 100°F GAL. 118 173 228 283 393 558 722 1382 2041 8
L.P. 37.7°C LTR. 446 654 862 1070 1486 2110 2886 5230 7726
GALLONS
LITERS NAT. &L.P. RISE UNITS Min. Min. Min. Min. Min. Min. Min. Min. Min. Contents
37.7°C LTR. 407 575 743 911 1248 1752 2257 4276 6294
37.7°C LTR. 434 630 826 1022 1413 2000 2587 4936 7285
37.7°C LTR. 457 676 894 1113 1551 2207 2863 5487 8111
RECOVERY CAPACITIES Recovery in U.S. Gallons/Hr. (GPH) and Liters/Hr. (LPH) at Various Temperature Rises.
MODEL INPUT BTU/HR. THERMAL 40°F 50°F 60°F 70°F 80°F 90°F 100°F 110°F 120°F 130°F 140°F 
NUMBER NATURAL & L.P. EFFICIENCY UNITS
GX90-550(A) 550,000 NAT 80% GPH 1333 1067 889 762 667 593 533 485 444 410 381
LPH 5047 4037 3364 2884 2523 2243 2019 1835 1682 1553 1442
GX90-640(A) 640,000 NAT 80% GPH 1551 1241 1034 887 776 690 621 564 517 477 443
LPH 5873 4698 3915 3356 2936 2610 2349 2135 1958 1807 1678
GX90-715(A) 715,000 NAT 80% GPH 1733 1387 1156 991 867 770 693 630 578 533 495
LPH 6561 5249 4374 3749 3280 2916 2624 2386 2187 2019 1875
GX90-500(A) 500,000 LP 80% GPH 1212 970 808 693 606 539 485 441 404 373 346
L.P.
LPH 4588 3670 3059 2622 2294 2039 1835 1668 1529 1412 1311
GX90-600(A) 600,000 LP 80% GPH 1455 1164 970 831 727 647 582 529 485 448 416
L.P.
LPH 5506 4404 3670 3146 2753 2447 2202 2002 1835 1694 1573
GX90-680(A) 680,000 LP 80% GPH 1649 1319 1099 942 824 733 659 599 550 507 471
L.P.
LPH 6240 4992 4160 3565 3120 2773 2496 2269 2080 1920 1783
Recovery ratings are based on thermal efficiencies obtained in a CSA certified laboratory. Recovery rate shown on the rating 
plate (80%) Thermal Efficiency in accordance with ANSIZ21.10.3 labeling requirements. (A) indicates available ASME model.
22°C 28°C 33°C 39°C 45°C 50°C 56°C 61°C 67°C 72°C 78°C

E
C
G
FDBA
OUTLET
FRONT SIDE
INLET
FRONT SIDE
SYSTEM
SENTINEL
T&P
treme Gas continued.
X
DIMENSIONAL DIAGRAM
CLEARANCES TO 
COMBUSTIBLES
MODEL
NUMBER UNITS SIDE REAR TOP
GX90-550 inches
mm
GX90-640 inches
mm
GX90-715 inches
mm
GX90-500 inches
mm
GX90-600 inches
mm
GX90-680 inches
mm
Allow a minimum of 18" (457mm) front clearance 
for servicing.
2.5 Amps.
4412
102 102 305
4412
102 102 305
4412
102 102 305
4412
102 102 305
4412
102 102 305
4412
102 102 305

treme Gas continued.
X
Other Features:
• Insulation – sag and moisture proof fiberglass
insulation surrounds the storage tank to 
 minimize heat loss.
• Anode rods – patented design utilizes multiple
magnesium rods to ensure long life and 
 corrosion resistance.
• Temperature and pressure relief valve –
AGA/ASME rated and factory installed.
• Hand-hole cleanout – for removal of lime/
sediment deposits.
• Manual reset high limit – all
models are factory 
equipped with a manual reset high limit to meet the 
code requirements of many states.
• Gas control system –
fully adjustable thermostat 
from 100°F to 180°F, 24 volt combination gas valve 
includes main gas pressure regulation, 
On-Off manual valve, 120/24 volt transformer, and 
high limit temperature cut-out.
• 
Round premix burners – precision burners are
formed from high chromium stainless steel.
Recommended Specifications (for trade reference only)
Water 
of __________ Btu/hr. and a recovery rate of _____________ GPH at a 100°F temperature rise when tested and 
certified at ____________ thermal efficiency. Water heater(s) shall have a storage capacity of 90 gallons. Water 
heater(s) shall have the U.L. seal of certification and supplied with a factory installed AGA/ASME rated temperature 
and pressure relief valve. Tank(s) shall be furnished with a tube bundle having a double coating of high temperature porcelain enamel and furnished with magnesium anode rods rigidly supported. Water heater(s) shall meet or 
exceed the thermal efficiency and standby loss requirements of current ASHRAE standards. Tanks shall have a 
working pressure rating of 150 psi, and shall be completely factory assembled, including a pressure regulator 
 properly adjusted for operation on ___________ gas with chromium stainless steel burners. Controls will be 
arranged for safety shutoff in event of pilot failure. Water heater(s) shall have front and rear side inlet/outlet water 
connections. Water heater(s) shall be covered by a three year limited warranty against tank leaks.
heater(s) shall be XTREME model ________________, manufactured by RHEEM-RUUD, having gas input
Add “A” for ASME construction
Water heater(s) shall be constructed in accordance with the requirements of the ASME Boiler and Pressure Vessel 
Code, Section IV Part HLW.
Limited Warranty
This product features a three year limited warranty against tank leaks. Please refer to Commercial 
Warranty Information Certificate for complete warranty information.
In keeping with its policy of continuous progress and product improvement, Rheem-Ruud reserves the right to make changes without notice.
Rheem Water Heating • 101 Bell Road, Montgomery, Alabama 36117-4305 • www.rheem.com 
Rheem Canada Ltd./Ltée • 125 Edgeware Road, Unit 1, Brampton, Ontario L6Y 0P5
P R I N T E D  IN U .S .A 0 2 / 1 0  WP F O R M  NO . R R1 02 C -1 5  Re v. 5