Vapor Power / HSI Electric Boilers and Heaters

HSI Electric Boiler

HSI BBJ Electrode Boiler

HSI RCH Electric Heaters

HSI Electric Boilers and Heaters

Key Features of Vapor Power HSI Electric Boilers and Heaters

Help solve the Energy Problem by coupling an electric boiler with fossil-fueled boilers and using available power!

With the electric boiler set at a slightly higher pressure than parallel fossil-fueled boilers, sensing plant demand, and limited to a maximum plant demand set point, competitively priced AVAILABLE POWER can be consumed to effect a flat demand curve.


HSI Electric Boiler

Vapor Power HSI Electric Boiler

  • Resistance Type (208 - 600 V)
  • Steam (up to 2500 psig and 4320 KW /14,700 lbs/hr)
  • Hot Water (up to 415 psig and 4320 kW)
  • Thermal Fluid Heaters & Steam Super Heaters (up to 1200° F and 2000 psig)
  • Electrode Steam Boilers 3000-34,000KW/ 10,000-113,000PPH/ 100-500PSI
  • Electrode Hot Water Boilers 3000-34,000KW/ 10,000-113,000MBH

HSI ‘Resisto-Flo’ Hot Water Boilers are designed to provide fast,efficient and economical hot water for heating through the use of electric resistance elements. The boiler controls automatically energize/de-energize steps of elements to maintain the desired water temperature. All HSI Hot Water Boilers utilize ASME pressure vessels (Section IV up to 160 psi; Section VIII above 160 psi) and all electrical components are UL listed and are wired in accordance with the current National Electrical Code requirements.

Each boiler is insulated with 3-1/2" fiberglass secured to the vessel, and is housed in an enameled heavy-gauge sheet metal cabinet mounted on a full-size structural steel base. All HSI ‘Resisto-Flo’ boilers utilize 70 wpsi Incoloy-sheathed elements configured in conservatively-sized circuits to allow for overvoltage conditions as great as 10% without adversely affecting the integrity of circuit components.

How Steam is Generated by the High Voltage “JET FLO®” Electrode Steam Boiler

Water from the lower part of the boiler shell is pumped by the internal circulation pump (3) to the nozzle header (19) and flows by gravity through the jets to strike the electrode (18), thus creating a path for the electrical current. As the unevaporated portion of the water flows from electrode (18) to the counter electrode (20), a second path for current is created. Primary voltage connections are made directly to the electrode terminals (12), often eliminating the need for a step-down transformer. At max rated conductivity, approximately 3% of the flowing water is evaporated.

Regulation of the boiler output is accomplished by varying the circulating pump (3) speed, which regulates the amount of water reaching the nozzle header. The pump speed is controlled by the boiler pressure and load control system via a VFD, either to hold the steam pressure constant or to stay within an adjustable KW limit.

Regulation is stepless between no-load and full-load, so that the boiler output is finitely responsive to demand variation. No load to full load regulation can be accomplished in as little as 5 seconds, although normally this is stretched out to 20-30 seconds.

NOTE: To generate hot water, HSI offers a steam boiler/heat exchanger system consisting of a steam-to-water converter attached directly to the boiler; outputs available range up to 170,000 MBTU/Hr. The advantages of this system is that the condensate from the heat exchanger flows by gravity back to the boiler eliminating the need for a condensate return/deaerator system, which also improves the system efficiency.


With the electric boiler set at a slightly higher pressure than parallel fossilfueled boilers, sensing plant demand, and limited to a maximum plant demand set point, competitively priced AVAILABLE POWER can be consumed to effect a flat demand curve.

By using a 2-element control system, the electric boiler would either generate as much steam as allowed by the demand control system or, when steam demand is below what the electric boiler is allowed to generate, be limited by the steam pressure control to a preset steam pressure.

Features and Advantages

  • Power factor correction because of a unity power factor contribution to the plant electrical load.
  • Reliable source of steam for areas affected by oil and/or gas shortages, or where coal is either low grade or not available.
  • Lower capital investment as compared to oil-fired (75% of installation cost) or coal-fired (10% of installation cost).
  • Eliminates need for special boiler room, fuel handling and storage equipment, air handling equipment, preheaters and/or economizers, stacks, flues and emission control equipment, ash handling and disposal facilities, combustion safety systems, noise abatement equipment, plus space and installation costs associated with aforementioned equipment.
  • Electric boilers in most states are classified as “unfired steam generators” and as such do not require full operator attendance, thus enabling substantial labor savings.

General Specifications

The HSI High Voltage “Jet Flo” Electrode Steam Boiler consists of a fiberglass-insulated pressure vessel constructed in compliance with Section I of the ASME Code. The vessel, registered with the National Board and furnished with a manufacturer’s Data Report, is fully enclosed in 18 gauge enameled steel panels secured to the boiler by supports welded to the vessel.

All necessary trim and controls are included to provide a complete packaged boiler designed in accordance with ASME, ANSI, NEC, state and local codes. The majority of controls are contained in a Factory-wired floor-standing Nema 12 control cabinet. The basic control system shall incorporate a PLC and HMI, and shall be wired with 16 gauge color-coded stranded copper wire.

Reference Data

  • 10KW = 1.02 BHP = 34 Lbs. Stm/Hr = 34,120 BTU/hr
  • 1 Gal Water at 62° F = 8.34 Lbs.
  • 1 Cu Ft Water at 62° F = 62.4 Lbs.
  • 1 Cu Ft = 7.48 Gal
  • 1 Ft Water = 0.435 psi
  • KW = GPH x T (°F)/410 = LPH x T (°C)/862
  • Amps (3ph) = Watts/(Volts x 1.73)
  • Enthalpy of water = Temp (°F) -32 BTU/LB

Saturated Steam: Pressure vs Temperature

0 psig = 0 KPa = 212°F
8 psig = 55 KPa = 235°F
15 psig = 103 KPa = 250°F
30 psig = 207 KPa = 274°F
50 psig = 345 KPa = 298°F
80 psig = 552 KPa = 324°F
100 psig = 690 KPa = 338°F
125 psig = 862 KPa = 353°F
150 psig = 1034 KPa = 366°F
200 psig = 1379 KPa = 388°F
225 psig = 1551 KPa = 397°F
250 psig = 1724 KPa = 406°F
300 psig = 2068 KPa = 422°F
350 psig = 2413 KPa = 436°F