The BTXL-100 Cyclone Xi™

The BTXL-100 Commercial Gas Water Heater is a light-duty, Power Direct Vent, fully condensing commercial gas water heater. Utilizing an internal helical heat exchanger allows the BTXL-100 Cyclone Xi achieves 96% thermal efficiency and is Energy Star Qualified.

Many of the BTXL-100 features include:

  • 75-gallon tank
  • 100,000 BTU input per Hour
  • Recovery capacity at a 100-degree rise is 115 Gallons Per Hour
  • 25” tall x 27.75” diameter.
  • The AO Smith BTXL-100 Commercial Gas Water Heater is available in either Natural Gas or Propane.
  • Spiral Heat Exchanger, which is positioned in the center of the tank, keeps hot combustion gases in the tank longer to lengthen the water heating time and even heat distribution.
  • Advanced Diagnostics with large LCD Display. It utilizes a Central Control Board (CCB) to set, monitor and regulate all functions of the water heater.
  • Temperature control up to 181 degrees F.
  • iCOMM Compatible: Can be monitored from remote locations.
  • The top inlet and outlet connections are ¾” NPT.
  • The side inlet and outlet connections are ¾” NPT.
  • The Gas inlet is ½” NPT.
  • Standard model certified for 10,100’ elevation.
  • Maximum Hydrostatic Working Pressure: 150 psi
  • Power Direct Vent designed for Combined Vertical and Horizontal runs terminating through outside wall, using Schedule 40 PVC, CPVC, ABS or Polypropylene pipe.
  • Blue Diamond Glass Coating with CoreGard Anode Rods, provide Superior Corrosion Resistance. CoreGard anode rods have a stainless steel core that extends the life of the anode rod.
  • Ultra-low NOx burner complies with SCAQMD Rule 1146.2 and complies with the Low-NOx emission requirements of less than 40 ng/J.
  • CSA Certified and ASME Rated T&P Valve
  • Meets the Thermal Efficiency and standby loss requirements of the ASHRAE/lENSA 90.1 code.
  • 3-Year Limited Tank and 1-Year Limited Parts Warranty

Sequence of Operation of the AO Smith BTXL-100 Cyclone Xi Commercial Gas Water Heaters

Cyclone MXI cutaway image

First, a quick note on how the AO Smith BTXL-100 Commercial Gas Water Heater achieves the remarkable Thermal Efficiency of 96%. By utilizing a Top Fired Ultra-Low NOx pre-mix burner and a Helical Heat Exchanger which is strategically positioned in the center of the Water Heater Tank, the swirling hot gases are forced thru the Heat Exchanger and radiate heat the surrounding water. The Spiral Heat Exchanger keeps the hot combustion gases in the tank longer which creates a longer heat transfer cycle.

The brain of the AO Smith BTXL-100 Commercial Gas Water Heater is the Central Control Board (CCB). This on board computer, controls the sequence of operation and allows the user, via the large LCD display, to enter the water’s set point, and establish the water’s differential temperature, which we will explain in a moment. Once a call for heat has been initiated the Central Control Board (CCB) regulates and monitors the water heater’s functions. It also alerts the user to any Fault that may have occurred during the firing sequence.

  • The Set Point is the desired water temperature for your customer’s application.
  • The Differential Water Temperature is the number of degrees the water temperature is allowed to drop before the next heating cycle is initiated.

Both the Set Point and the Differential are entered into the CCB via the LCD display.

Sequence of Operation of the AO Smith Cyclone Xi Commercial Gas Water Heaters.

  • Step 1. The CCB monitors two Temperature Probes to determine existing water temperature and compares that finding to the Set Point and the Differential. If the water temperature has reached the differential setting, a heating cycle will be initiated. Once the Set Point water temperature has been reached the heating cycle is terminated. But before the heating cycle is initiated, the position of 4 pressure switches will be checked by the CCB.

What do I mean by “Position”? Pressure switches come in either a normally open or normally closed position. All pressure switches have a diaphragm that either opens or closes an electrical switch when the activation pressure is met. So if you have a Normally Open pressure switch when the activation pressure is applied, the pressure switch will close. So let’s take a look at the 4 pressure switches the Central Control Board checks in order.

  • Step 2. Low Gas Pressure Switch

The Low Gas Pressure Switch, which is Normally Open, is the first pressure switch the CCB checks. When the minimum gas pressure is applied this switch closes. The minimum gas pressure for a particular model of AO Smith commercial gas water heater is listed on the data plate. If the gas pressure drops below the minimum listed gas pressure, a Low Pressure Gas Error Message will appear on the LCD screen. If the actual gas pressure is correct you may need to replace the pressure switch. This switch should remain closed for the life of the heater. The next pressure switch to be checked by the CCB is the:

  • Step 3. Blocked Inlet Switch

The Blocked Inlet Switch is Normally Closed that will open if the negative pressure in the inlet pipe is too high.  The next pressure switch to be checked is the:

  • Step 4: Blocked Exhaust Pressure Switch

The Blocked Exhaust Pressure Switch is Normally Closed that will open only if the positive pressure in the exhaust pipe is too high.
Note: All 3 of these Pressure Switches should stay closed.
The next and final pressure switch is the:

  • Step 5: Blower Prover Pressure Switch

The Blower Prover Pressure Switch is Normally Open until it senses increased air pressure from the blower housing. Once power is supplied to the blower, you will see a symbol of a fan blade on the LCD screen. If the switch closes you will see a check mark which “proves” the blower is working. Note: If the CCB senses the Blower Prover Switch is Closed before the blower is powered up, you will receive a Blower Prover Failure Message on the LCD display. If the Blower Prover Switch remains in the Open position, the LCD screen will display a “Blower Prover Open” message. You will probably need to replace the pressure switch.

  • Step 6. Hot Surface Igniter

If the Low Gas Pressure Switch, the Blocked Inlet Pressure switch, the Blocked Exhaust pressure switch and the Blower Prover Pressure Switch all close, the next step is to power the Hot Surface Igniter. As current is supplied to the Hot Surface Igniter, you will see a lightning bolt on the LCD display. If the igniter is good you will have an amp draw of approximately 2 amps or higher and a check mark will appear next to the lightning bolt. If all the above steps are successful, the next step is…

  • Step 7. Opening the Gas Valve

Displayed on the LCD will be a gas valve symbol which will turn from the off position to the on position. The Flame Sensor must detect ignition within 3 seconds or the gas valve will close and the blower motor will continue to run for 30 seconds to purge any unburnt gases. If this continues for 3 cycles, then you will have displayed an Ignition Failure Message.

You now have Air, Fuel and Spark and the initiation of the heating cycle of the water heater. The Heating Cycle will continue until the Set Point has been reached, then the blower will run for 30 seconds to purge any unburnt gases and the unit will shut off. 

AO Smith has created excellent resources including a 15-minute video on the sequence of operation and a 20-minute video showing how to use the control display. We’ve provided those here for your convenience. View videos below.
(Videos provided by: http://university.hotwater.com/commercial/xi/)

Sequence of Operations

Control Display

To Order a Natural Gas AO Smith BTXL-100 Water Heater

To Order a Propane AO Smith BTXL-100 Water Heater

Includes Free Standard Shipping! (On Water Heaters shipped within the Mainland Continental United States)

To View or purchase all our AO Smith Commercial Electric Water Heaters, AO Smith Commercial Gas Water Heaters or Rheem Commercial Electric Water Heaters or Rheem Commercial Gas Water Heaters, please visit Wallingford Sales or the Water Heater Store.

I wish you much success!
“Keeping you in hot water…so you stay out of hot water!”
Doug Wallingford
Wallingford Sales
Water Heater Store