
Model HX / TX
Tankless Electric Water Heater
Available up to 54 KW Single or Three Phase Voltages
The Hubbell model TX Tankless electric water heater is a highly reliable and easily maintained heater designed for operation in a commercial or industrial application. The Hubbell TX Tankless heater is compact, extremely efficient, takes up minimal space and reduces operating costs. Hubbell's vast experience, meticulous engineering and advanced technology ensure that you can rely on the model TX for your water heating needs in even the most demanding and critical applications. The Hubbell Tankless is the right choice for your water heating requirements, as you will be providing your customer with a quality product that is long lasting, trouble-free and energy efficient.
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Heavy Duty Construction
- Constructed with high grade materials to ensure long operating life
- Simple to specify and easy to install and operate
- Factory packaged heater provides trouble-free installation and operation
Reliability
- Engineered for your specific application to ensure reliable operation
- Wide selection of sizes to meet the needs of even the most demanding application
High Efficiency
- On demand heating eliminates costly and cumbersome storage tanks
- Instantaneous design reduces stand-by heat loss and signifcantly lowers operating costs compared to traditional storage systems
The Hubbell Model HX / TX electric tankless water heater contains high powered heating elements that heat water only when there is demand for hot water. When hot water is needed, a built in flow sensor measures the exact flow rate, and that data combined with temperature readings at the heater's inlet and outlet are processed by the elctronic temperature controller. This data is continuously transmitted to the temperature controller, which constantly calculates the precise amount of power (kW) needed to achieve the desired temperature. A zero cross over firing signal is sent to the fast acting triacs in order to modulate the heating elements to the precise level needed to meet demand. The Hubbell tankless heater uses only as much power as is needed, while delivering accurate and consistent hot water temperature.
Heater Overview
Model HX/TX Water Heater Specifications
TX: 3/4" Push Fit
HX: 1" Push Fit
TX: 0.2 GPM Min, 8.0 GPM Max
HX: 0.5 GPM Min, 40 GPM Max
General Specifications
A sophisticated electronic temperature controller with LED digital display provides the user interface. The temperature controller processes all flow and temperature data and calculates the precise amount of power needed to meet demand.
Operator Control Capabilities | ||
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Power Limiting: | Allows the operator to reduce the power consumption by any percentage to provide installation and operational flexibility and savings. |
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Diagnostics: | Display inlet and outlet temperatures, flow rate and error codes to assist in troubleshooting. |
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Cost Calculator: | Determine the exact cost of operating the heater. Input your cost per KW·Hr and the controller displays total KW·HRs consumed, total cost of operation, and total hot water usage (shown in gallons or liters). |
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Temperature Control: | Set the digital display to the desired water temperature in °F or °C. Fully adjustable in 1° increments from 32-194°F (0-90°C). A user adjustable +/- 3° calibration feature provides additional control for superior accuracy. |
Each heating element is switched on/off using a fast acting solid state triac with zero cross over firing control. This switching schema provides full modulation of each heating element, ensuring that the precise amount of heat is added to meet demand. To improve operating efficiency and component longevity, each triac is mounted to a heat sink located on the incoming supply piping so that heat generated by the triac during the switching process is dissipated into the water.
All Hubbell tankless water heaters, including all 3 phase models, are engineered to operate as a balanced load and operate at 0.999 Power Factor. All Hubbell 3 phase models are designed for 3 wire (3 live, 1 ground) and 4 wire power systems and draw equal current across all conductors to maintain the power integrity of the users electrical system. Hubbell does not recommend the use of heaters that operate as an unbalanced load, as is common with staged heaters designed for star systems (3 live, 1 neutral, 1 ground) that require use of the neutral leg. All load switching in Hubbell tankless models is performed as zero cross over, eliminating phase angle firing interference and associated EMI issues.
The Hubbell tankless control schema ensures that usage is equalized across all heating circuits. To achieve this, once the controller has calculated the precise amount of kW required, all circuits are energized in a staggered fashion such that each circuit is proportionally and independently energized and then time staggered between circuits. This Full Resource Staging Schema reduces EMI output, increases component longevity, and provides highly accurate and consistent hot water temperatures. For three phase models, all circuits are fully modulated and synchronized to operate as a balanced load.
Remote Control:Ability to remotely enable or inhibit the heating operation of the unit using one of the following two methods:
1. Customer supplied 24VDC signal is user configured for either Inhibit Mode or Normal Operation Mode.
2. Customer supplied volt free contact is user configured for either Inhibit Mode or Normal Operation Mode.
Priority Control: An integrated SPDT potential free dry contact (NO/NC 10A @ 240VAC) energizes when the unit is heating and de-energizes when not heating. This feature is useful when it is desirable to give the water heater priority over another electrical load to ensure that both are not operational at the same time.
Outline Dimensions
8-27 KW Models (2 and 3 element)

Model Selection Selection Chart | ||||||||||||||||
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0.2 - 8.0 GPM | 0.4 - 40.0 GPM | |||||||||||||||
Base Model No. | KW | 3 Phase Voltages | 1 Phase Voltages | Base Model No. | KW | 3 Phase Voltages | 1 Phase Voltages | |||||||||
208V | 240V | 480V | 600V | 208V | 240V | 208V | 240V | 480V | 600V | 208V | 240V | |||||
TX008 | 8 | ![]() |
HX008 | 8 | ![]() |
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TX011 | 11 | ![]() |
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HX011 | 11 | ![]() |
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TX012 | 12 | ![]() |
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HX012 | 12 | ![]() |
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TX014 | 14 | ![]() |
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HX014 | 14 | ![]() |
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TX016 | 16 | ![]() |
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HX016 | 16 | ![]() |
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TX018 | 18 | ![]() |
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HX018 | 18 | ![]() |
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TX020 | 20 | ![]() |
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HX020 | 20 | ![]() |
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TX021 | 21 | ![]() |
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HX021 | 21 | ![]() |
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TX024 | 24 | ![]() |
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HX024 | 24 | ![]() |
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TX027 | 27 | ![]() |
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HX027 | 27 | ![]() |
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24-54 KW Models (6 Element)

Model Selection Chart | ||||||||||||||||
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0.2 - 8.0 GPM | 0.4 - 40.0 GPM | |||||||||||||||
Base Model No. | KW | 3 Phase Voltages | 1 Phase Voltages | Base Model No. | KW | 3 Phase Voltages | 1 Phase Voltages | |||||||||
208V | 240V | 480V | 600V | 208V | 240V | 208V | 240V | 480V | 600V | 208V | 240V | |||||
TX024 | 24 | ![]() |
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HX024 | 24 | ![]() |
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TX031 | 31 | ![]() |
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HX031 | 31 | ![]() |
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TX033 | 33 | ![]() |
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HX033 | 33 | ![]() |
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TX036 | 36 | ![]() |
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HX036 | 36 | ![]() |
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TX040 | 40 | ![]() |
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HX040 | 40 | ![]() |
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TX042 | 42 | ![]() |
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HX042 | 42 | ![]() |
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TX048 | 48 | ![]() |
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HX048 | 48 | ![]() |
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TX054 | 54 | ![]() |
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HX054 | 54 | ![]() |
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Heating Capacity and Amperage Chart
KW Rating | Heating Capability in GPM at oF Temperature Rise (°FΔT) | MAX Amps (at 100% heater output) | ||||||||||||||
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20° ΔT |
30° ΔT |
40° ΔT |
60° ΔT |
70° ΔT |
80° ΔT |
100° ΔT |
110° ΔT |
120° ΔT |
140° ΔT |
3 Phase Voltages | 1 Phase Voltages | |||||
208V | 240V | 480V | 600V | 208V | 240V | |||||||||||
8 | 2.73 | 1.82 | 1.36 | 0.91 | 0.78 | 0.68 | 0.55 | 0.50 | 0.45 | 0.39 | - | - | - | - | 38 | - |
11 | 3.75 | 2.50 | 1.88 | 1.25 | 1.07 | 0.94 | 0.75 | 0.68 | 0.63 | 0.54 | 31 | - | - | - | - | 46 |
12 | 4.09 | 2.73 | 2.05 | 1.36 | 1.17 | 1.02 | 0.82 | 0.74 | 0.68 | 0.58 | 33 | - | - | - | 58 | - |
14 | 4.78 | 3.18 | 2.39 | 1.59 | 1.36 | 1.19 | 0.96 | 0.87 | 0.80 | 0.68 | - | 34 | - | - | 67 | 58 |
16 | 5.46 | 3.64 | 2.73 | 1.82 | 1.56 | 1.36 | 1.09 | 0.99 | 0.91 | 0.78 | 44 | 39 | - | - | 77 | 67 |
18 | 6.14 | 4.09 | 3.07 | 2.05 | 1.75 | 1.54 | 1.23 | 1.12 | 1.02 | 0.88 | 50 | - | 22 | - | 87 | 75 |
20 | 6.82 | 4.55 | 3.41 | 2.27 | 1.95 | 1.71 | 1.36 | 1.24 | 1.14 | 0.97 | 56 | - | - | - | 96 | - |
21 | 7.17 | 4.78 | 3.58 | 2.39 | 2.05 | 1.79 | 1.43 | 1.30 | 1.19 | 1.02 | - | 51 | 25 | 20 | - | 88 |
24 | 8.19 | 5.46 | 4.09 | 2.73 | 2.34 | 2.05 | 1.64 | 1.49 | 1.36 | 1.17 | 67 | 58 | 29 | 23 | 115 | 100 |
27 | 9.21 | 6.14 | 4.61 | 3.07 | 2.63 | 2.30 | 1.84 | 1.67 | 1.54 | 1.32 | - | 65 | 33 | 26 | - | 113 |
31 | 10.58 | 7.05 | 5.29 | 3.53 | 3.02 | 2.64 | 2.12 | 1.92 | 1.76 | 1.51 | 86 | - | - | - | 149 | - |
33 | 11.26 | 7.51 | 5.63 | 3.75 | 3.22 | 2.81 | 2.25 | 2.05 | 1.88 | 1.61 | - | 79 | - | - | - | 138 |
36 | 12.28 | 8.19 | 6.14 | 4.09 | 3.51 | 3.07 | 2.46 | 2.23 | 2.05 | 1.75 | 100 | - | 43 | - | 173 | - |
40 | 13.65 | 9.10 | 6.82 | 4.55 | 3.90 | 3.41 | 2.73 | 2.48 | 2.27 | 1.95 | 111 | - | - | - | 192 | - |
42 | 14.33 | 9.55 | 7.17 | 4.78 | 4.09 | 3.58 | 2.87 | 2.61 | 2.39 | 2.05 | - | 101 | 51 | 41 | - | 175 |
48 | 16.38 | 10.92 | 8.19 | 5.46 | 4.68 | 4.09 | 3.28 | 2.98 | 2.73 | 2.34 | 133 | 116 | 58 | 46 | 230 | 200 |
54 | 18.42 | 12.28 | 9.21 | 6.14 | 5.26 | 4.61 | 3.68 | 3.35 | 3.07 | 2.63 | - | 130 | 65 | 52 | - | 225 |
Unshaded flows specify Base Model TX, shaded flows must specify Base Model HX due to high flow rate.
Alternate voltages including 277, 380, 415, 440 and 575 volt available. Please contact us directly for exact KW availability in these voltages.
Optional Equipment
- High flow construction specify model HX for up to 40 GPM flow (min 0.5 GPM actuation)
- Type 316L stainless steel heating chamber for added corrosion resistance
- Special construction features
- Inlet and Outlet Valve assembly simplifies installation and includes unions, shut offs, check valve, drain ports and pressure relief valve
- Heating chamber built to ASME Section VIII and "UM" stamped
- Remote Control Display allows the heater to be installed in a remote location. The 3" x 5" NEMA 4 display enclosure can be located up to 250' from the heater and gives the operator full remote control and monitoring capabilities
- NEMA 4x construction when heater is located in a wet environment. Overall dimensions 24" x 20" x 6"
- Additional heater control features to meet UL834 Electric Boiler requirements
- Factory supplied manifold single point connection for redundancy and high demand applications
- An ASSE 1070 code compliant Thermostatic mixing valve to increase the amount of hot water available. Valve is 1/2" (-UT) size and adjustable from 80-120°F. Typically used when supplying hot water to multiple lavs from a single water heater.
Please note: optional equipment may impact overall dimensions and weight. Please request submittal drawing from factory.
Model Number Designation HX and TX
Model:
TX = 8 GPM Max
HX = 40 GPM Max
KW Rating:
8 thru 54 KW
(008 - 054)

Number of
Heating Elements:
2
3
6
Voltage/Phase/Hz:
RS = 208-1-60
R = 208-3-60
S = 240-1-60
T = 240-3-60
T3 = 380-3-50/60
T7 = 415-3-50/60
T5 = 440-3-60
T4 = 480-3-60
T6 = 600-3-60
Example:
TX024-3T4
A Hubbell tankless electric water heater rated at 24 KW with 3 heating elements and powered with 480 volt, three phase, 60 Hz.
Downloads
Revit Files
- Model HX 2-3 Revit ZIP (959 KB)
- Model HX 6 Revit ZIP (1.3 MB)
- Model TX 2-3 Revit ZIP (1.1 MB)
- Model TX 6 Revit ZIP (1.5 MB)
Technical Documents
- Model HX / TX Brochure PDF (2.4 MB)
- Model HX / TX Written Spec PDF (571 KB)
- Model HX / TX Written Spec DOC (25.5 KB)
- Model HX / TX AIA Master Spec PDF (106 KB)
- Model HX / TX AIA Master Spec DOC (15.0 KB)
- Model HX / TX O&M Manual PDF (2.5 MB)
- Tankless Low Lead Certificate PDF (546 KB)
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