Cyclone® MXi Modulating

Modulating burner advances the cyclone® to higher levels of efficiency.
Unit of Measure



N/A A. O. Smith®


N/A Liquid Propane Gas Natural Gas

Input Power

N/A 199900 BTU/hr58 kW

Thermal Efficiency

N/A 97 %

Approximate Capacity

N/A 100 U.S. gal379 L100 gal

Size of Gas Connection

N/A 3/4 in. NPT

Standard Shipping Weight

N/A 523 lb237 kg

ASME Shipping Weight

N/A 553 lb251 kg

Minimum Gas Supply Pressure

N/A For Liquid Propane Gas: 2.12 kPaFor Natural Gas: 1.10 kPaFor Liquid Propane Gas: 8.5 inWcFor Natural Gas: 4.4 inWc

Maximum Gas Supply Pressure

N/A 14 inWc3.49 kPa

Number of Installed Elbows

N/A 1 2 3 4 5 6

Industry Standards

N/A ANSI Z-21.10.3 - CSA 4.3 ASHRAE/IESNA 90.1 ASME Certified ASME Optional NSF


N/A Recovery capacities are based on AHRI rated thermal efficiencies.

Maximum Recovery (ºF)

Recovery at 30 ºF Temperature Rise

N/A 783 gal/h

Recovery at 40 ºF Temperature Rise

N/A 588 gal/h

Recovery at 50 ºF Temperature Rise

N/A 470 gal/h

Recovery at 60 ºF Temperature Rise

N/A 392 gal/h

Recovery at 70 ºF Temperature Rise

N/A 336 gal/h

Recovery at 80 ºF Temperature Rise

N/A 294 gal/h

Recovery at 90 ºF Temperature Rise

N/A 261 gal/h

Recovery at 100 ºF Temperature Rise

N/A 235 gal/h

Recovery at 110 ºF Temperature Rise

N/A 214 gal/h

Recovery at 120 ºF Temperature Rise

N/A 196 gal/h

Recovery at 130 ºF Temperature Rise

N/A 181 gal/h

Recovery at 140 ºF Temperature Rise

N/A 168 gal/h

Maximum Recovery (ºC)

Recovery at 17 ºC Temperature Rise

N/A 2965 L/h

Recovery at 22 ºC Temperature Rise

N/A 2224 L/h

Recovery at 28 ºC Temperature Rise

N/A 1779 L/h

Recovery at 33 ºC Temperature Rise

N/A 1483 L/h

Recovery at 39 ºC Temperature Rise

N/A 1271 L/h

Recovery at 44 ºC Temperature Rise

N/A 1112 L/h

Recovery at 50 ºC Temperature Rise

N/A 988 L/h

Recovery at 56 ºC Temperature Rise

N/A 890 L/h

Recovery at 61 ºC Temperature Rise

N/A 809 L/h

Recovery at 67 ºC Temperature Rise

N/A 741 L/h

Recovery at 72 ºC Temperature Rise

N/A 684 L/h

Recovery at 78 ºC Temperature Rise

N/A 635 L/h



Schematic Drawing for Cyclone® MXi Commercial Gas Water Heaters (BTH-120(A) to BTH-250(A))

Dimension A

N/A 3 in7.62 cm

Dimension B

N/A 27.75 in70.5 cm

Dimension C

N/A 6.3 in16 cm

Dimension D

N/A 56.38 in143.2 cm

Dimension E

N/A 76 in193.04 cm

Dimension F

N/A 75.75 in192.4 cm

Dimension G

N/A 11.25 in28.6 cm

Dimension H

N/A 64 in162.6 cm

Dimension I

N/A 70 in177.8 cm

Dimension J

N/A 18.25 in46.36 cm

Electrical Characteristics

AC Voltage

N/A 120 V


N/A 60 Hz


N/A 5 A

3" Vent Pipe

One 90º Elbows for Maximum 3" Vent Pipe

N/A 45 ft13.7 m

Two 90º Elbows for Maximum 3" Vent Pipe

N/A 40 ft12.2 m

Three 90º Elbows for Maximum 3" Vent Pipe

N/A 35 ft10.7 m

Four 90º Elbows for Maximum 3" Vent Pipe

N/A 30 ft9.1 m

4" Vent Pipe

One 90º Elbows for Maximum 4" Vent Pipe

N/A 115 ft35 m

Two 90º Elbows for Maximum 4" Vent Pipe

N/A 110 ft33.5 m

Three 90º Elbows for Maximum 4" Vent Pipe

N/A 105 ft32 m

Four 90º Elbows for Maximum 4" Vent Pipe

N/A 100 ft30.5 m

Five 90º Elbows for Maximum 4" Vent Pipe

N/A 95 ft29 m

Six 90º Elbows for Maximum 4" Vent Pipe

N/A 90 ft27.4 m

Optional Kits

Optional Kits

  • Optional Concentric Vent Kits
    • BTH-120 - 250 vent kit p/n 9006328005
    • BTH-300 - 500 vent kit p/n 9006144005
  • Optional Low Profile Termination Vent Kits
    • 3" Flush Mount Vent Kit p/n 9008933005 4" Flush Mount Vent Kit p/n 9008934005 6" Flush Mount Kit p/n 9008935005
    • Optional Condensate Neutralization Kits BTH-120-199 kit p/n 9007959005 BTH-250-500 kit p/n 9007960005



N/A The full line of A. O. Smith Cyclone® Mxi condensing water heaters has been designed to provide years of dependable service and feature industry leading technology. Models are available from 120000 to 500000 Btu/h and all deliver thermal efficiencies of 95 % and higher. The unique helical coil heat exchanger limits weld joints for optimal service life while maximizing heat transfer.

Cyclone is the industry leader in high efficiency commercial water heating with over a quarter million Cyclone®s sold since 1996. The current Mxi modulating models adjust firing rate to the specific demand further increasing efficiency and money savings.

Intelligent Control System with Lcd Display
  • Exclusive A. O. Smith designed control system.
  • Provides detailed water heater status information.
  • Precise temperature control adjustable from 90 to 180 degrees.
  • Built-in diagnostics.
  • Run history information.
  • Cyclone water heaters are compatible with the iCOMM™ remote monitoring system.
Submerged Combustion Chamber, with Helical Heat Exchanger Coil
  • Positioned in center of tank, surrounded by water to virtually eliminate radiant heat loss from chamber.
  • Direct spark ignition.
  • Spiral heat exchanger keeps hot burner gases swirling, uses centrifugal force to maximize efficiency of heat transfer to water in tank.
  • Spiral heat exchanger reduces lime scale from forming on water-side surfaces, which maintains energy efficiency over time.
Powered Anodes Standard on All Models
  • Provides long-lasting tank protection in varying water conditions.
  • Powered anodes are non-sacrificial.
  • Automatically adjusts output needed to properly protect the tank.
Permaglas® Ultra Coat™ Glass Lining
  • Glass coating is applied using a liquid slush coating technique to ensure uniform coating.
  • Heat exchanger coil is glassed both externally and internally for optimum protection.
Mechanical Venting Versatility
  • Conventional power venting or direct venting.
  • Vents vertically or through a sidewall.
  • Front located exhaust and condensate connections allow for easy install and access.
  • Vents with low cost PVC Schedule 40 intake and exhaust pipe. Approved for optional CPVC Schedule 40, Polypropylene and AL29-4C stainless steel vent materials.
  • Direct-vent intake and exhaust pipe can terminate separately outside building or through single opening, using concentric vent assembly.
  • Canadian installations require ULC S636 PVC/CPVC, ULC S636 Polypropylene and AL29-4C stainless steel pipe for intake and exhaust.
High Efficiency Modulating Pre-Mix Powered Burner
  • Down-fired pre-mix burner provides optimum efficiency and quiet operation.
  • Top-mounted burner position prevents condensation from affecting burner operation.
Space-Saving Design for Installation Flexibility
  • Reduced footprint, ease of service, protection from water damage in case of flooding.
  • Easy-to-remove top cover for convenient access to serviceable parts.
  • 0" installation clearances on sides and rear, 1-1/2" installation clearance on top.
  • Handhole cleanout allows easy access to tank interior for cleaning.
  • 0" clearance to combustibles, approved for installation on combustible floors.

Testing and Certifications

Testing and Certifications

N/A Codes and Standards
  • CSA® certified and ASME rated T&P relief valve
  • Maximum hydrostatic working pressure: 160 PSI
  • All models are design certified by Underwriters Laboratories (UL), Inc., to ANSI Z21.10.3 - CSA® 4.3 Standards
  • Meets the thermal efficiency and standby loss requirements of the U.S. Department of Energy and current edition ASHRAE/IESNA 90.1
  • Design-certified by Underwriters Laboratories to NSF standard 5 for 180 ºF (62 ºC) water
  • Complies with SCAQMD Rule 1146.2 and other Air Quality Management Districts with similar requirements for low-NOx emissions
  • ASME tank construction optional on 120-500 model sizes



  • 3-Year Limited Warranty.
  • Optional 5-Year Extended Tank Warranty.