INDIRECT FIRED, SEMI-INSTANTANEOUS STEAM & BOILER WATER HEATER. Compact Design. High Recovery. Energy Efficient. Stainless Alloy Construction

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Norma Robertson
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1 INDIRECT FIRED, SEMI-INSTANTANEOUS STEAM & BOILER WATER HEATER Compact Design High Recovery Energy Efficient Stainless Alloy Construction Factory Packaged Integral Safety System ASME Constructed & Stamped

DHT VTSI & VSI SERIES The DHT VTSI & VSI series of semi-instantaneous water heaters is the engineered solution where high recovery capacity is required and space is at a premium.

Designed for continuous high peak loads, the VTSI & VSI series are ideal for high demand applications such as hospitals or dormitories.

VTSI & VSI units are supplied as a complete packaged system with components engineered to specific application requirements.

Semi-instantaneous operation provides high output by channeling the incoming cold water directly over the tubes of the heat exchanger in a controlled manner maximizing the heat transfer rates when

Velocity of water and pressure drop are controlled by changing water flow directly across the heat exchanger, which increases heat transfer and inhibits scale formation.

2 DHT VTSI & VSI SERIES The DHT VTSI & VSI series of semi-instantaneous water heaters is the engineered solution where high recovery capacity is required and space is at a premium. The DHT VTSI & VSI series are constructed of stainless steel pipe and other non-ferrous materials to insure long leak-free operation. Designed for continuous high peak loads, the VTSI & VSI series are ideal for high demand applications such as hospitals or dormitories. Units are custom engineered using steam, boiler water or HTHW as the heating medium. VTSI & VSI units are supplied as a complete packaged system with components engineered to specific application requirements. The user simply connects domestic water to the supply and return connections in the field. Use the DHT selection tables to select the correct size and match components for peak performance. Semi-instantaneous operation provides high output by channeling the incoming cold water directly over the tubes of the heat exchanger in a controlled manner maximizing the heat transfer rates when compared to conventional stratified heat exchanger convection systems. Water is heated to the desired outlet temperature via the control valve as it exits the VTSI or VSI outlet. Velocity of water and pressure drop are controlled by changing water flow directly across the heat exchanger, which increases heat transfer and inhibits scale formation. High gain response is achieved by locating the temperature sensing probe in the outlet flow of water exiting the system thereby eliminating any stagnation zones which cause false readings. DHT water heater systems are the perfect choice where high capacity is required and space is limited. The vertical configuration requires less than four square feet of floor space and the tube bundle can be removed straight out or downward from the bottom of the unit. No overhead space or extra clearances are required for service or maintenance. Horizontal configurations, with rack-mounted stands, are also available making the DHT VTSI & VSI series a perfect fit in any mechanical room. APPLICATIONS Commercial VTSI & VSI series capacity ranges are well suited for meeting the large hot water demands of hotels, apartment buildings, military barracks and hospitals. Typically utilized in facilities with a central heating energy source, the units are perfect choices for installation in smaller satellite equipment rooms. Units may be piped in parallel or series to provide additional capacity or emergency backup. Institutional - VTSI & VSI series are widely used in facilities that exhibit high demand loads at varying intervals throughout the day. Dormitories, schools and correctional complexes exhibit strong sudden demands that are difficult for conventional convection heaters to sustain. Smaller units may be combined with storage tanks to ease the energy source requirements during minimal use periods. Industrial - VTSI & VSI series are used for high demand process applications that require a continuous flow of hot water. Other uses such as equipment food service wash down and cafeteria needs are also served by this versatile system. Construction DHT fabricates most units specifically to customer requirements. Stock systems are available for quick or emergency needs. All materials used in the construction of VTSI & VSI series systems are copper alloy or 316 stainless steel to assure long life and rust free domestic water. Each unit is fabricated by skilled technicians certified to ASME Sect IX, inspected, and stamped in accordance to ASME Sect VIII requirements. Working pressures up to 300 psig are available. The heat exchanger section is fabricated from copper, copper nickel or double wall tubes as well as 316 stainless steel for deionized water heating. Each heat transfer bundle is engineered to provide proper velocity and pressure drops while providing optimal heat transfer. The DHT VTSI & VSI series will provide exceptional long life, dependability and ease of maintenance. Seismic rated construction is available to meet IBC and other codes. Water Heater Control Panel STANDARD FEATURES Microprocessor Based Two Line Alpha-Numeric 40 Character LCD Display 3 Function Keys Isolated 24VDC Sensor Power 4/20MA 1 Analog Input 8 Digital Inputs 1 Analog Output 4 Relay Outputs 5 AMP. Fully User Programmable in English Pop Up Alarm Screens P.I.D. Setpoint Control RS485 MODBUS Data Port Compatible with BMS/BAS INPUT Temperature Set Point High Limit Temperature Set Points OUTPUT Power Normal High Temperature Alarm 2

3 Sizing DHT Semi-Instantaneous Water Heater To size DHT Semi-Instantaneous Water Heater you must determine the total water flow rate. First you have to determine total fixture units for all fixtures by using hot water demand in fixture units tables, then determine the demand GPM of hot water from the chart below. HOT WATER FLOW RATE CURVE SEE ENLARGED DETAIL ON CHART AT RIGHT FIXTURE UNITS RESTAURANTS HOSPITALS, NURSING HOMES, NURSES RESIDENCE, APT. HOUSES, HOTELS & MOTELS OFFICE BUILDINGS AND HIGH SCHOOLS FIXTURE UNITS HOT WATER DEMAND IN FIXTURE UNITS (140 F WATER) Sizing: Determine the total fixture units for all fixtures by using the above table. Determine the required GPM from the above Hot water flow rate curve. Select the model of the water heater from Water heater selection chart according to the calculated GPM and the given steam pressure or boiler water temperature. EXAMPLE: Apartment building has 20 apartments: Bathtubs 1.5 x 20 = 30 Dishwashers 1.5 x 20 = 30 Kitchen Sinks 0.75 x 20 = 15 Total 75 Demand from the curve above (Green color): 30 GPM If steam pressure supplied to the Building 5 psig, the unit model is VTSIS24HB8A2-4-30, or VSISB8A (USING CHARTS FOR TEMPERATURE RISE ON PAGES 5 & 7. FOR BOILER WATER USE CHART ON PAGE 8) 3

4 DHT VTSI (TANK) SERIES DHT VTSI Series Semi-Instantaneous Water Heater Overall Dimensions Heating Source: STEAM WATER OUTLET INSULATION & JACKETING WATER SOLENOID T & P VALVE PROBE & WELL STEAM INLET THERMOMETER AQUASTAT CONTROL BOX STEAM STRAINER PILOT PRESSURE GAUGE WATER INLET B A CONTROL VALVE DRIP STRAINER DRIP TRAP CONDENSATE E C RECIRCULATING PUMP CONDENSATE STRAINER MAIN TRAP F D RECIRCULATION VTSIS18HB6A2-X-XX VTSIS24HB8A2-X-XX VTSIS30HB10A2-X-XX VTSIS30HB12A2-X-XX NOTE: Above dimensions are company s standard model. For customers who wish to have a custom build, please consult with the engineering department. (Steam pilot shown, pneumatic and electric control available). 4

5 DHT VTSI (Tank) Series Semi-Instantaneous Water Heater Selection Chart GPM GPM Heating Medium (Steam) Temperature Rise From 40 o -140 o F Steam Inlet Pressure (PSI) Pressure in lines / Pressure in heat exchanger 5/2 10/5 15/10 25/15 50/25 VTSIS18HB6A VTSIS18HB6A VTSIS18HB6A VTSIS18HB6A VTSIS18HB6A VTSIS24HB6A VTSIS24HB6A VTSIS24HB6A VTSIS24HB8A VTSIS18HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB12A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A Heating Medium (Steam) Temperature Rise From 40 o -120 o F Steam Inlet Pressure (PSI) Pressure in lines / Pressure in heat exchanger 5/2 10/5 15/10 25/15 50/25 VTSIS18HB6A VTSIS18HB6A VTSIS18HB6A VTSIS18HB6A VTSIS18HB6A VTSIS24HB6A VTSIS24HB6A VTSIS24HB8A VTSIS24HB6A VTSIS18HB6A VTSIS24HB8A VTSIS24HB6A VTSIS24HB6A VTSIS24HB6A VTSIS24HB6A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS24HB8A VTSIS30HB10A VTSIS30HB8A VTSIS30HB8A VTSIS30HB8A VTSIS24HB8A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB12A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB12A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB10A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A VTSIS30HB12A NOTE: For performance rating greater or less then the table provided above, please consult with company s engineering department for further details. For performance rating for units with double wall tubes please consult with company s engineering department. 5

6 DHT VSI (VERTICAL) SERIES DHT VSI Series Semi-Instantaneous Water Heater Selection Chart Heating Source: STEAM TEMPERATURE TRANSMITTER OR PROBE CHECK VALVE PUMP BALL VALVE DOMESTIC WATER OUTLET T & P RELIEF VALVE THERMOMETER WATER SOLENOID VALVE CONTROL PANEL INSULATION & JACKET I/P TRANSDUCER SHUTOFF SOLENOID VALVE STEAM CONTROL VALVE STEAM STRAINER DOMESTIC WATER INLET CONDENSATE STRAINER DRIP LEG THERMODYNAMIC TRAP WITH STRAINER CONDENSATE L MAIN F & T TRAP Vertical Stand Configuration DHT WATER HEATER SYSTEM DIMENSIONS (inches) (Vertical Configuration) DHT Model Number OH OL H L VSISB6A2-X-XX VSISB8A2-X-XX VSISB10A2-X-XX VSISB12A2-X-XX Width (not shown) NOTE: Above dimensions are company's standard models. For customers who wish to have a custom build, please consult with the DHT Engineering Department. (Pneumatic control shown, pilot, and electric available) 6

7 DHT VSI (Vertical) Series Semi-Instantaneous Water Heater Selection Chart VSISB6A VSISB6A VSISB6A VSISB6A VSISB6A VSISB6A VSIS6A VSISB6A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB8A VSISB10A VSISB10A VSISB10A VSISB10A VSISB10A VSISB10A VSISB10A VSISB10A VSISB10A VSISB10A VSISB12A VSISB10A VSISB10A VSISB10A VSISB10A VSISB12A VSISB12A VSISB12A VSISB12A VSISB12A VSISB12A VSISB12A VSISB12A VSISB12A VSISB12A VSISB 6A VSISB 6A VSISB 6A VSISB 6A VSISB 6A VSISB 6A VSISB 6A VSISB 8A VSISB 6A VSISB 6A VSISB 8A VSISB 6A VSISB 6A VSISB 6A VSISB 6A VSISB 8A VSISB 8A VSISB 8A VSISB 8A VSISB 8A VSISB 8A VSISB 8A VSISB 8A VSISB 8A VSISB 8A VSISB 10A VSISB 8A VSISB 8A VSISB 8A VSIS 8A VSISB 10A VSISB 10A VSISB 10A VSISB 10A VSISB 10A VSISB 12A VSISB 10A VSISB 10A VSISB 10A VSISB 10A VSISB 12A VSISB 10A VSISB 10A VSISB 10A VSISB 10A VSISB 12A VSISB 12A VSISB 12A VSISB 12A VSISB 12A NOTE: For performance rating greater or less then the table provided above, please consult with company s engineering department for further details. For performance rating for units with double wall tubes please consult with company s engineering department. 7

8 DHT VSI (VERTICAL) SERIES DHT VSI Series Semi-Instantaneous Water Heater Selection Chart Heating Source: BOILER WATER TEMPERATURE TRANSMITTER OR PROBE CHECK VALVE DOMESTIC WATER OUTLET T & P RELIEF VALVE THERMOMETER WATER SOLENOID VALVE OH BALL VALVE I/P TRANSDUCER SHUTOFF SOLENOID VALVE PUMP DOMESTIC WATER INLET CONTROL PANEL INSULATION & JACKET TWO OR THREE WAY WATER CONTROL VALVE H BOILER OR HTHW OUTLET BOILER OR HTHW INLET L OL Vertical Stand Configuration DHT WATER HEATER SYSTEM DIMENSIONS (inches) (Vertical Configuration) DHT Model Number OH OL H L VSISW6A2-X-XX VSISW8A2-X-XX VSISW10A2-X-XX VSISW12A2-X-XX Width (not shown) NOTE: Above dimensions are company's standard models. For customers who wish to have a custom build, please consult with the DHT Engineering Department. (Pneumatic control shown, pilot, and electric available) 8

DHT VSI Series Semi-Instantaneous Water Heater Selection Chart Heating Source: BOILER WATER VSIW6A2-2.5-40 VSIW8A2-4-36 VSIW8A2-2.5-36 VSIW8A2-2.

9 DHT VSI Series Semi-Instantaneous Water Heater Selection Chart Heating Source: BOILER WATER VSIW6A VSIW8A VSIW8A VSIW8A VSIW10A VSIW10A VSIW10A VSIW10A VSIW10A VSIW10A VSIW12A VSIW12A VSIW6A VSIW6A VSIW8A VSIW8A VSIW8A VSIW10A VSIW10A VSIW10A VSIW10A VSIW10A VSIW10A VSIW10A VSIW8A VSIW10A VSIW10A VSIW10A VSIW10A VSIW12A VSIW12A VSIW12A VSIW12A VSIW12A VSIW14A VSIW6A VSIW8A VSIW8A VSIW10A VSIW10A VSIW10A VSIW10A VSIW10A VSIW12A VSIW12A VSIW12A , ,000 1,000,000 1,250,000 1,500,000 2,000,000 2,500,000 3,000,000 3,500,000 4,000,000 5,000,000 NOTE: For performance rating greater or less then the table provided above, please consult with company s engineering department for further details. For performance rating for units with double wall tubes please consult with company s engineering department. 9

Double-Wall Tube Bundles for Water Heaters Meets Uniform Plumbing Code requirements for heating potable water. Prevents cross-contamination.

10 Double-Wall Tube Bundles for Water Heaters Meets Uniform Plumbing Code requirements for heating potable water. Prevents cross-contamination. Easy Inspections and low maintenance Fully visible, 360 vented leak detection between tubesheets. Bolting and gaskets for potable water and heating medium are completely independent. Individual tube access for easy maintenance. Optional: Tubesheet contacting potable water is solid 304 stainless steel Used to upgrade present single-wall tube bundles Available semi-instantaneous water heaters and exchangers with copper or cupro-nickel tubes and carbon steel or stainless steel tube sheets (Up to 400 PSIG with. cupro-nickel tubes) Double Wall Protection Performance Tube failure can be caused by corrosion, erosion, and vibration, and can result in the contamination of the domestic water system to be contaminated by a heating medium such as steam, hydronic water, glycol solution, etc. There is no practical way to have the heating medium sterile or free from harmful treatment compounds or corrosion by-products. A low pressure heating medium circuit does not ensure contamination protection of indirect, single-wall water heaters. Whether they are shell and tube, shell and coil, plate and frame, or any other type, all consist of relatively thin wall heat transfer surface separating the heating medium from the domestic water system. Therefore, the potential for cross contamination is real and in some instances contamination has occured. Several states and cities are now insisting on double-wall vented construction in all indirect type domestic water heaters. Plumbing codes have also been re-written to include double-wall protection. DHT has developed the most practical, state-of-the-art double tube wall heaters to preclude any possibility of contaminating the domestic water system. The heat transfer surface is 5/8 O.D. x.04 thick inner wall and 3/4 O.D. x.04 outer wall SB-75 or SB-111 copper tubing. The.04 dimensions are actual net tube wall thicknesses which equal.08 thickness of total wall separation. This is more than twice the thickness of many single wall water heater products. Both inside and outside tube surfaces are smooth (prime) with no fins or surface irregularities to promote scale formation or corrosion attack. Double-wall tubing has a similar overall heat conductivity as a single wall tube of equivalent wall thickness. The heat transfer capabilities were determined by actual tests. Each tube has multiple parallel and continuous vent paths. 10

11 DHT VTSI & VSI SERIES Stainless Steel Semi-Instantaneous Steam-Water Heating Systems DHT stainless steel semi-instantaneous water heater system is a very efficient, high quality and high capacity system for use with steam, boiler water, or high temperature water as a heating medium. DHT steam-water heater system has a small compact size and a wide range of capacities that are designed for many standard hot water applications. DHT s compact design makes it an ideal replacement unit where space is at a premium. Also the compact design and size reduces the installation time to the minimum. The customers only need to provide the connection line for cold and hot water, steam, condensate and electricity to service. DHT s stainless steel semi-instantaneous water heater system provides both designer flexibility and space saving design. Standard DHT Stainless Steel Semi-Instantaneous Water Heater System Material of Construction Coil Material: Standard Copper Optional Cupro-Nickel Optional Stainless Steel Optional Double Wall Copper or Cupro-Nickel Shell High Alloy Stainless Steel Piping Copper, Brass Insulation Fiberglass Protection Jacket Gauge Steel/Vinyl Support Skid Carbon Steel OPTIONAL: 1. Electric Control Box 2. Recirculator Package 3. Double Solenoid Safety System Standard DHT Stainless Steel Steam or Boiler Water Heater System Package Includes: Compact Design A.S.M.E.CODE Construction (225 PSIG of water pressure at 300 ) High Alloy Stainless Steel Tanks/Shells High Alloy Stainless Steel Threaded Connections (domestic water only) Fiberglass Insulation 20 Gauge Steel Jacket Carbon Steel Support Base A.S.M.E Relief Valve-Pressure and Temperature Temperature gage Pressure Gauge Drain Valve Solenoid Safety System Temperature Control Valve (self conatined or pneumatic) Steam, Condensate Strainers (steam only) F&T Traps (steam only) 3-Way - Optional Control Valve with Safety Solenoid Drip Strainer 11

12 DHT VTSI & VSI SERIES (PIPING LAYOUTS) Steam Water Heater Single Unit Hot Water Out Recirculation Steam Supply T / To Drain Cold Water In Condensate Return Condensate to Gravity Free Drain or to Pump to Lift P Drain Steam Water Heater Dual Unit T / P T / P 12

13 Steam Water Heater Single Unit with Storage Tank Hot Water Supply To Drain Hot Water Out Condensate Return Condensate to Gravity Free Drain or to Pump to Lift Steam Supply P T Drain / To Drain Recirculation Cold Water In Hot Water Return Storage Tank Boiler Water Heater Single Unit Hot water Outlet To Drain Recirculation Boiler Water Supply T / Cold Water In Boiler Water Return Drain 13

14 Specifications for DHT Water Heater Each heater shall be capable of being disassembled and the heat exchanger section removed for inspection and service without breaking water connections. The bolting between the steam bonnet, tube sheet and shell flange shall be independent of each gasket to allow inspection and replacement of either gasket without disturbing the other gaskets. Each heater shall have easy access to the individual tubes without moving the heater from its installed position. Steam to Water Furnish and install where shown on the plans water heater(s), Model Number, manufactured by Diversified Heat Transfer, Inc. Each heater shall be factory assembled package rated to heat.gpm of water from F to _ F and control the outlet within 4 F of the selected temperature, when supplied with psig saturated steam before the control valve. The domestic water pressure drop through the heater shall not exceed psig. Each heater shall be constructed and stamped in accordance with Section VIII of the ASME Code for a working pressure of 150 psig. Inspection form U -1 shall be furnished. Each packaged heater shall consist of the following components completely factory assembled so that the contractor need only connect to service. 1. Water heater with stainless steel shell and heat exchanger wrapper, copper or Cu-Ni tubes, non ferrous or carbon steel with non-ferros liner tube sheet and baffles, carbon steel steam chamber, steel vertical support skids and lifting lug. 2. Steam strainer. 3. Temperature control valve ( pilot operated or air operated). 4. Condensate strainer. 5. Main steam trap. 6. Auxiliary steam trap. 7. Water thermometer and steam pressure gauge. Thermometer installed with separable thermowell. 8. ASME pressure relief valve for domestic water. 9. Insulation: 1-1/2 fiberglass covered with a galvanized steel or plastic gasket. 10. Bronze circulator 115 volt/60 cycle/single phase, wired for continuous operation. (Optional Yes, No) 11. Component piping. 12. Solenoid Safety System ( Single, Double) 13. Electric Control Box (Optional Yes, No) 14. Installation and operating instructions. The manufacturer shall assume the operational responsibility for all components of the package. Water to Water Furnish and install where shown on the plans water heater(s), Model Number, manufactured by Diversified Heat Transfer, Inc. Each heater shall be factory assembled package rated to heat.gpm of water from F to _ F and control the outlet within 4 F of the selected temperature, when supplied with boiler water. The domestic water pressure drop through the heater shall not exceed psig. Each heater shall be constructed and stamped in accordance with Section VIII Inspection form U -1 shall be furnished. of the ASME Code for a working pressure of 150 psig. Each packaged heater shall consist of the following components completely factory assembled so that the contractor need only connect to service. 1. Water heater with stainless steel shell and heat exchanger wrapper, copper or Cu-Ni tubes, non ferrous or carbon steel with non-ferros liner tube sheet and baffles, carbon steel steam chamber, steel vertical support skids and lifting lug. 2. Temperature control valve ( pilot operated or air operated). 3. Water thermometer and steam boiler water pressure gauge. Thermometer installed with separable thermowell. 4. ASME pressure relief valve for domestic water. 5. Insulation: 1-1/2 fiberglass covered with a galvanized steel or plastic jacket. 6. Bronze circulator volt/60 cycle/single phase, wired for continuous operation. (Optional Yes, No) 7. Component piping. 8. Solenoid Safety System ( Single, Double) 9. Electric Control Box (Optional Yes, No) 10. Installation and operating instructions. The manufacturer shall assume the operational responsibility for all components of the package. INDIRECT FIRED SEMI-INSTANTANEOUS STEAM & WATER HEATER Manufacturers and Designers Since Tel: Pub DHT03R1 12/15

Packaged Semi-Instantaneous Steam Fired Water Heater

MODEL STX Packaged Semi-Instantaneous Steam Fired Water Heater Shell and Tube Style Heater Features Reliable Only high grade materials used in construction to ensure long operating life Heat exchange pressure