

Model ST
Packaged Steam Fired Water Heater
Utilizes Steam to Heat Domestic Water, Semi-Instantaneous or Storage Type Heaters
The Model ST is a fully packaged steam fired water heater designed to be a reliable and long lasting source for hot water. Each component is carefully selected to ensure performance in even the most demanding application. Whether you are heating potable water in a commercial building or process water in an industrial application, you can select a Hubbell Model ST to do the job. When you specify and install a Hubbell ST model water heater you will have confidence in knowing that the owner will be provided with a quality product that is a long lasting and trouble-free source for hot water.

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Reliable
- Only high grade materials used in construction to ensure long operating life
- Hydrastone cement lining provides superior protection and tank longevity
- Heavy duty construction withstands demanding commercial/industrial use
Packaged System
- Factory supplied with all steam controls saving time and money during installation
- All steam operating controls are factory sized and selected to ensure reliable operation
Versatile
- Full range of styles, sizes, and optional features to meet your exact heating needs
Steam Component General Configuration
The steam control valve maintains accurate water temperature in a steam fired water heater by regulating the flow of steam through the heating coil.
There are four types of steam control valves available for use on a steam fired storage water heater.

Self Operating
The valve design includes a bulb and capillary assembly charged with a thermally responsive vapor. The expansion/contraction of the vapor acts upon the valve bellows in order to control the flow of steam throught the valve. No external power source is required for operation.Pneumatically Operated
In this configuration the building air supply feeds a factory installed temperature controller which operates the steam control valve. The temperature controller sends a precise air signal to the steam control valve which adjusts the flow of steam into the heating coil. The temperature controller is fully adjustable from 50-250°F and requires 20 psi air at a maximum consumption of 0.5 SCFM.Pilot Operated
A pilot operated control valve is the most widely used type of valve for standard water heating applications. In this type of valve, a temperature pilot device utilizes steam to operate the main valve. No external power source is required other than steam. This is a highly dependable temperature control system which is suitable for most commercial and industrial applications. As an option, this valve may include a pressure reducing pilot which limits the steam pressure to a predetermined maximum.Electronic Operated
This control valve is similar to a pneumatically operated system, except in this case the temperature controller is a PID digital display electronic temperature controller which outputs a 4-20mA signal to a compact motor mounted on the steam control valve in order to proportionally control the flow of steam to the heating coil. The temperature controller displays set point as well as actual water temperature and is available with an RS486 communications port for remote control.
Model ST Storage Type Standard Equipment
Vessel Construction
- All welded carbon steel vessel designed and built in strict accordance with the ASME Code Section VIII and stamped, certified and registered with the National Board of Boiler and Pressure Vessel Inspectors
- All internal tank surfaces are lined with a minimum of 5/8" thick Hydrastone cement for superior protection and tank longevity
- Designed for 125 psi working pressure and hydrostatically tested
Steam Operating Controls
- Steam operating controls are factory selected, sized, piped and tested to ensure reliable operation
- All steam components are factory plumbed with schedule 40 black iron pipe and ready for steam and condensate connections
- High quality cast iron pilot operated steam control valve modulates the flow of steam through the heating coil to provide accurate water temperature control
- Cast iron Y strainer with 20 mesh screen protects the steam controls and coil from dirt and debris in the steam supply
- Thermostatic drip trap removes condensate from the steam supply line
- Heavy duty cast iron float and thermostatic main condensate trap for optimum efficiency
- Brass vacuum breaker and dial steam pressure gauge
Steam Heating Coil
- A high quality factory installed 2 pass U-Tube heating coil constructed from 18 gauge 3/4" O.D. single wall copper tubing designed for a maximum working pressure of 150 psi
- All wetted parts are non-ferrous for maximum longevity
- Heavy duty fabricated steel head with threaded NPT steam and condensate connections
- Copper lined tube sheet
- Reference Heating Coils for detailed heating coil construction features
General
- Heavy duty 3" thick fiberglass insulation covers 100% of the pressure vessel for maximum operating efficiency and minimal stand-by heat loss
- Heavy gauge painted galvanized steel protective outer jacket
- Heavy duty integrally welded steel supports for floor mounting
- Full five (5) year Non Pro-Rated tank warranty and a one (1) year steam component warranty
- ASME rated combination T&P relief valve set at the tank working pressure and 210°F
Outline Dimensions
Model ST (Vertical)

Model STH (Horizontal)

Overall Dimensions, Models ST and STH
Actual Storage Capacity (Gallons) | Overall Dimensions (Inches) | Storage Tank | Nominal Storage Capacity (Gallons) | Inlet Outlet Sizing (NPT) | Approx. Shipping Weight (Lbs.) | ||||
---|---|---|---|---|---|---|---|---|---|
Vertical | Horizontal | ||||||||
Diameter "A" | Height "B" | Length "C" | Width "D" | Height "E" | Diameter x Length | ||||
80* | 26 | 65 | 60 | 26 | 32 | 22 x 54 | 90 | 1.5 | 700 |
120* | 28 | 75 | 68 | 28 | 34 | 24 x 64 | 140 | 1.5 | 900 |
150* | 30 | 79 | 72 | 30 | 36 | 26 x 68 | 170 | 1.5 | 1100 |
175 | 36 | 73 | 67 | 36 | 44 | 30 x 63 | 195 | 1.5 | 1500 |
200 | 36 | 82 | 76 | 36 | 44 | 30 x 72 | 220 | 1.5 | 1700 |
225 | 36 | 89 | 83 | 36 | 44 | 30 x 79 | 245 | 1.5 | 1750 |
250 | 42 | 74 | 68 | 42 | 50 | 36 x 64 | 285 | 1.5 | 1850 |
275 | 42 | 80 | 74 | 42 | 50 | 36 x 70 | 310 | 1.5 | 2000 |
300 | 42 | 88 | 82 | 42 | 50 | 36 x 78 | 345 | 1.5 | 2180 |
325 | 42 | 92 | 86 | 42 | 50 | 36 x 82 | 360 | 1.5 | 2300 |
350 | 42 | 94 | 88 | 42 | 50 | 36 x 84 | 370 | 1.5 | 2500 |
375 | 48 | 81 | 75 | 48 | 56 | 42 x 71 | 425 | 1.5 | 2600 |
400 | 48 | 85 | 79 | 48 | 56 | 42 x 75 | 450 | 1.5 | 2700 |
425 | 48 | 88 | 82 | 48 | 56 | 42 x 78 | 470 | 1.5 | 2900 |
450 | 48 | 93 | 87 | 48 | 56 | 42 x 83 | 500 | 1.5 | 3000 |
475 | 54 | 79 | 73 | 54 | 62 | 48 x 69 | 540 | 2 | 3100 |
500 | 54 | 82 | 76 | 54 | 62 | 48 x 72 | 565 | 2 | 3225 |
525 | 54 | 85 | 79 | 54 | 62 | 48 x 75 | 590 | 2 | 3350 |
550 | 54 | 89 | 83 | 54 | 62 | 48 x 79 | 620 | 2 | 3400 |
575 | 54 | 93 | 87 | 54 | 62 | 48 x 83 | 650 | 2 | 3500 |
600 | 54 | 95 | 89 | 54 | 62 | 48 x 85 | 665 | 2 | 3650 |
700 | 54 | 107 | 101 | 54 | 62 | 48 x 97 | 755 | 2 | 4000 |
800 | 54 | 119 | 113 | 54 | 62 | 48 x 109 | 850 | 2 | 4300 |
900 | 54 | 132 | 126 | 54 | 62 | 48 x 122 | 940 | 2 | 4800 |
1000 | 54 | 145 | 139 | 54 | 62 | 48 x 135 | 1060 | 2 | 5200 |
1250 | 60 | 149 | 143 | 60 | 68 | 54 x 139 | 1380 | 2 | 5600 |
1500 | 60 | 174 | 168 | 60 | 68 | 54 x 164 | 1625 | 2 | 6000 |
1750 | 66 | 168 | 162 | 66 | 74 | 60 x 158 | 1935 | 3 | 7400 |
2000 | 66 | 185 | 179 | 66 | 74 | 60 x 175 | 2145 | 3 | 8100 |
2500 | 78 | 169 | 163 | 78 | 86 | 72 x 159 | 2800 | 3 | 8200 |
3000 | 78 | 197 | 191 | 78 | 86 | 72 x 187 | 3300 | 3 | 8300 |
3500 | 90 | 174 | 168 | 90 | 98 | 84 x 164 | 3935 | 6 FLG. | 8900 |
4000 | 90 | 195 | 189 | 90 | 98 | 84 x 185 | 4440 | 6 FLG. | 9800 |
4500 | N/A | N/A | 168 | 102 | 108 | 96 x 160 | 5015 | 6 FLG. | 10700 |
5000 | N/A | N/A | 183 | 102 | 108 | 96 x 175 | 5485 | 6 FLG. | 11600 |
All dimensions are approximate and subject to change. Please reference the submittal drawing for actual dimensions. The tank selections above are shown for convenience. A full selection of storage capacities is available.
* 80, 120, and 150 gallon tanks do not come equipped with a manway.
Model ST Optional Equipment
Vessel
- Alternate protective lining:
Phenolic epoxy resin, Flame spray copper, Hot dip galvanizing, other - Alternate vessel construction:
Stainless Steel Type 304 or 316L, 90/10 Copper-Nickel, other - Alternate working pressure: Specify
Steam Heating Coil
- Double wall tubing with a leak detection port
- Alternate tubing material:
Stainless Steel, 90/10 Copper-Nickel, Admiralty, Other - Fabricated steam head constructed from:
Stailess Steel, Copper Alloy, Other
General
- Skid mounting on heavy duty all welded I Beam
- Type 304 stainless steel protective jacket
- Manway 12" x 16" or Inspection Opening 3" NPT
Operating Controls
- Steam controls can be factory sealed and sized, but shipped loose for in the field installation by others.
- Various steam control vavles are available to meet the specific needs of your application: Self-operated type, pneumatic operated, electronic operated, separate pressure reducing pilot type
- Single solenoid safety system closes the steam supply to the control valve should the water temperature in the tank reach the hi-limit set point. Requires 120 volt 5 amp electrical service
- A double solenoid safety system dumps over heated water in the storage tank to drain addition to closing the steam supply to the control valve. Requires 120 volt 5 amp electrical service
- Intra-tank circulation pump pacakage continuously circulates water within the tank in order to reduce stratification. All bronze fractional HP pump
- Anticipator control system forces incoming cold water over the control valve sensing bulb in order to begin heating water immediately
- Dial water thermometer and pressure gauge factory installed in the tank
- Factory wrapped and baffled steam coil with integral pump package
Please note: optional equipment may impact overall dimensions and weight. Please request submittal drawing from factory.
Model Number Designation ST
Model:
ST = Vertical
STH = Horizontal
Storage Capacity:
80-5000 Gallons
Vessel Type:
SL = Cement Lined Steel
GL = Phenolic Lined Steel
M = Galvanized Steel
CN = Solid 90/10 Copper Nickel
SS = Solid Stainless Steel
(Type 304 or 316L)

Tank:
SL = Hydrastone Cement
lined tank
SS = Solid stainless
steel tank
CN = Solid 90/10
copper-nickel tank
Coil Type:
S = Single Wall
D = Double Wall
Example:
ST600SL-1250
A vertically installed 600 gallon steam fired water heater with a cement lined steel storage tank rated to heat 1250 GPH at a 100°F temperature rise.
Downloads
Technical Documents
- Model ST Brochure PDF (3.4 MB)
- Model ST Written Spec PDF (510 KB)
- Model ST Written Spec DOC (26.0 KB)
- Model ST AIA Master Spec PDF (27.0 KB)
- Model ST AIA Master Spec DOC (41 KB)
- Model ST O&M Manual PDF (2.3 MB)
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