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Products Hot-Pak®


Semi-Instantaneous Hot Water Heater

In most commercial and industrial facilities, hot water isn’t something people can wait for – they need it now! That’s why you need a Thrush Hot Pak®, our state-of-the-art semi-instantaneous water heating system that provides an uninterrupted supply of hot water without the need of a storage tank. 

Instant hot water is a necessity for hospitals, universities, hotels, and countless commercial and industrial facilities. Thrush Hot-Pak® is a pre-engineered system that provides the continuous supply of hot water you need without the expense of large storage tanks. The compact, state-of-the-art water heater is available in:

  • Single or double-wall designs
  • Horizontal or vertical designs
  • Control Panel options

Combined with duplex stainless steel or premium copper-nickel construction, the Hot-Pak® system provides superior corrosion resistance, better temperature control, and higher energy efficiency.

Hot-Pak® Selector 3D Models & 2D Drawings

Why choose Hot-Pak® 

The space-saving vertical 24” to 30” square footprint of our Hot-Pak® along with our horizontal designs make it ideal for tight installations.

From Problem to Solution

Fluctuations in temperature may cause serious issues – and bulky storage tanks may not be an option.
A well-controlled hot water supply with consistent flow rates is challenging and costly with standard storage tank systems. Fluctuations in circulating hot water temperature are common and can cause serious repercussions for sensitive downstream operations. 

Improper temperature control can lead to: 

  • Mineral buildup and corrosion 
  • Downstream issues in operations requiring instant hot water
  • Eyewash and safety shower delays which could be in violation of Health & Safety regulations  
  • Wasted energy 

To maintain a smooth downstream operation, with instant hot water consistently available at the flow rates you require, engineers choose the famous Thrush Hot-Pak®.

The Hot-Pak® Solution

We designed our Hot-Pak® water heating technology to eliminate the need for storage tanks and provide instant hot water with rigorous temperature control. Designed in accordance with ASME requirements, the Thrush Hot-Pak® is ideal for hospitals, hotels, correctional facilities, universities, and industrial applications – anywhere instant hot water is needed. The Thrush Hot-Pak® features several competitive advantages:

  • Adaptable to tight spaces using sleek, space-saving vertical and horizontal design options
  • Manufactured with superior materials:
    • 316/Duplex stainless-steel shell combats the damaging effects of chlorine and provides strong resistance against chloride stress cracking
    • Premium Copper-nickel provides superior resistance against corrosion
  • 6 port leak detection on double wall models allows for leak detection before the liquid can cross-contaminate
  • 3-speed circulator for adjustment to the proper de-stratification and anticipation level
  • Superior safety with a vacuum breaker to break the vacuum formed on the steam side and an ASME standard relief valve to provide instant safety action against high-pressure buildup

The Thrush Hot-Pak® maintains the thermal quality of fluid, provides height and diameter selection flexibility, and rigid safety control to ensure safe operation.

Hot-Pak® Anatomy

Here is a look at the prominent features which make the Hot-Pak® the best semi-instantaneous water heater for commercial and industrial operation. Apart from the standard features, Thrush provides a list of optional features to accommodate the individual needs of every application. These additional features further improve the quality of the system in specific circumstances.

1. Water Outlet 

2. High-Temperature Limit Aqua-Stat

3. ASME T&P Relief Valve

4. Temperate Gauge

5. High-Temperature Safety Solenoid Purge Valve

6. Insulated Shell with Sheet Metal Jacket

7. Control Panel

8. 3 Speed Wet Rotor Circulator

9. Isolation High-Temperature Solenoid Valves (2)

10. Drain

11. Water Inlet

12. Captive Tubesheet Mounting

13. Steam Pressure Gauge

14. Vacuum Breaker

15. Steam Inlet

16. Condensate Drain

17. Support Stand and Base


Standard Features

  • Steam-to-water design
  • ASME Sec. VIII Div. 1 construction
  • Shell Insulation and Jacket
  • Copper tubing (single or double wall)
  • Naval brass tube sheet
  • Brass tube bundle supports
  • Brass baffles
  • Duplex/316 stainless steel shell with anticipation plate
  • Copper Piped High-Efficiency Circulator with isolation valves
  • T&P relief valve
  • High-Temperature Safety Solenoid Purge Valve
  • Water Temperature Gauge
  • Vacuum breaker
  • Support stand and base
  • UL listed control panel – provides single-point power supply
  • Steam pressure gauge
  • Captive tubesheet mounting – allows removal of bonnet without disrupting the domestic water system seals
  • 6 port leak detection on double wall tube sheets – allows for easier identification of leaky tube location

Optional Features

  • Premium Cupronickel Shell
  • Electronic control
  • Steam control valve, temperature probe, and safety solenoid shut-off on steam pilot (valve sized Y-strainer included)
  • F&T steam trap with strainer
  • Stand height to accommodate tube bundle replacement or condensate drain height
  • Water to Water units available
  • Custom engineered models for special applications
  • Horizontal design

Safety First

Thrush has incorporated two safety features in our Hot-Pak® system, making it a top choice for end users. The T&P relief valve is installed on the water-side of the heater to prevent overheated water and pressure, the high-temperature solenoid valve is electrically actuated to dump overheated water if the temperature inside the shell exceeds a predetermined set point on the temperature aquastat.

Looking for a Custom Solution?

At Thrush, we can provide you with customized solutions to tackle the specific challenges you are facing. Our engineers have decades of experience and can adapt our models to produce the flow, temperature, or output you need. We can even provide a custom paint job.

When a dealer rep asks, we say yes. For the University of Illinois, we were excited to help infuse their Hot-Pak® products with a little bit of school spirit by supplying all of their Hot-Pak® products painted in their school colors. Whether a custom paint job or custom design, Thrush’s problem-solving spirit is fueled by meeting our customer’s needs, resulting in solutions that keep customers coming back to Thrush time and time again.

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765-472-3351 340 W 8th Street, Peru, IN 46970