Armstrong Flo-Rite-Temp® Pre-Piped Water Heater Package is a factory-assembled solution designed for non-recirculated and recirculated hot water systems. It includes a shell-and-tube heat exchanger and an integral control valve for precise water heating and system temperature control. The feed-forward design instantly determines downstream hot water demand and directs cold water through the heat exchanger. Water is heated with constant-pressure steam to temperatures above Legionella survival limits, then proportionally mixed with cold water to achieve the exact set temperature.

The Flo-Rite-Temp Pre-Piped Water Heater Package is available in 4 standard sizes with single-wall or double-wall heat exchangers. Each package offers parallel/standby options and can be customized to specific application requirements. Pre-piped packages come equipped with thermal loops, thermometers, check valves, isolation valves, and gauges. Connections should only be made to the package, and all connection points are clearly tagged with the appropriate utility connection.

Feed-Forward Technology Advantages

Flo-Rite-Temp feed-forward instantaneous steam/water heaters offer a simple yet time-proven alternative to traditional feedback instantaneous, semi-instantaneous, and tank-type steam-heating methods. By eliminating the temperature-sensing feedback element and relying upon the actual hot water system demand requirement, feed-forward systems respond rapidly and are extremely accurate.

• Constant Steam Pressure: The constant, non-modulating steam pressure within the shell eliminates cycling wear and tear, ensures positive condensate evacuation, and avoids water hammer damage.
• No Thermal Lag: The system demand or flow feed-forward activation eliminates the requirement for a steam control valve or thermostatic control device, delivering a consistent outlet temperature (+/-4°F of set-point) with no thermal lag.
• Failure Safe: The Flo-Rite-Temp is extremely safe because the mixing unit will position to cold water flow upon failure of the primary operating component.
• Legionella Risk Reduction: With no water storage requirement, Flo-Rite-Temp water heaters are a sensible selection as a component of a broader system design initiative for Legionella risk reduction.
• Ease of Maintenance: Accessible "non-helical" admiralty brass straight tubes inside the carbon steel shell allow for mechanical cleaning and visual inspection.

DANGER

No water heater will work satisfactorily if improperly installed and operated. Read all instructions carefully before installing this unit. FAILURE TO ADHERE TO THESE INSTRUCTIONS COULD RESULT IN SERIOUS BODILY INJURY OR PROPERTY DAMAGE.

Single Wall Instantaneous Water Heater

Model	Connections (1, 2, 3)	Weight (lb/kg)
415	1" NPT, 3/4" NPT, 2" NPT	133 / 60
535	1-1/2" NPT, 1" NPT, 2-1/2" NPT	235 / 107
665	2" NPT*, 1-1/4" NPT, 3" NPT	358 / 162
8120	3" NPT*, 2" NPT, 4" 150# ANSI	585 / 265

*665 and 8120 connections for water inlet and outlet are on opposite sides of the valve body.

INFO

Units are NSF-61 certified. Reusable insulation wraps are available.

Double Wall Instantaneous Water Heater

The DW (double wall) version of the Armstrong Flo-Rite-Temp instantaneous water heater uses a double-walled tube to provide positive separation of the steam and water in the heat exchanger. The area between the walls of the tubes vents to atmosphere so you can detect tube failure without cross-contaminating either the steam or water.

Model	Connections (1, 2, 3)	Tube Bundle Removable	Weight (lb/kg)
415DW	1" NPT, 3/4" NPT, 2" NPT	75" (1905 mm)	199 / 90
535DW	1-1/2" NPT, 1" NPT, 2-1/2" NPT	75" (1905 mm)	270 / 122
665DW	2" NPT*, 1-1/4" NPT, 3" NPT	87" (2210 mm)	444 / 201
8120DW	3" NPT*, 2" NPT, 4" 150# ANSI	75" (1905 mm)	665 / 302

Stainless Steel (SS) Instantaneous Water Heater

The Flo-Rite-Temp® SS is a compact, steam-to-water, instantaneous water heater with all wetted metal parts of type 316 stainless steel. It is well-suited for heating corrosive liquids, such as demineralized, deionized, or reverse osmosis water.

• Heavy-duty 5/8” tubes of 16 gauge 316L stainless steel ensure long life.
• Control valve is mounted integral to the heat exchanger, eliminating intermediate piping leaks.

Installation Guidelines

Heater Installation

Steam Piping Installation

1. Install the Flo-Rite-Temp® with adequate room to allow for tube bundle removal when cleaning is required.
2. If 2-15 psig of steam is available, a pressure reducing valve is NOT required. If a PRV is required, an Armstrong Inverted Bucket Steam Trap is recommended to drain condensate at the inlet.
3. An Armstrong Y-strainer should be installed before the PRV to reduce dirt fouling.
4. A steam safety relief valve should be used prior to the heat exchanger if the maximum steam pressure could exceed the minimum water pressure in the tubes, or if it could exceed 150 psig.
5. Install a vacuum breaker in the piping between the heat exchanger drain connection and the steam trap to prevent improper draining.

Water Piping Installation

1. The hot and cold pipe should drop a minimum of 18" immediately out of the water heater. These loops act as a thermal check valve or heat trap to prevent the conduction of heat through the water during inactive times.
2. Isolation valves and hose connections added to both the inlet and outlet water supplies will allow for Clean-In-Place equipment to be utilized.
3. Use pipe unions on both the water inlet and outlet to allow ease of mixing valve removal and tube bundle cleaning.

TIP

Expansion tanks should be used in on/off demand applications where there is a short duration of time from high flow to no flow of water (e.g., a shut-off time of 10 seconds or less).

Clean-In-Place (CIP) Operating Instructions

When there is a noticeable drop in the Flo-Rite-Temp’s hot water capacity, temperature, or an increased water pressure drop across the unit, tube bundle scale removal should be considered using a commercially available product like RITE-Qwik.

1. Shut off the steam supply valve to the Flo-Rite-Temp.
2. While the water pressure is still ON and the steam is OFF, run the Flo-Rite-Temp for 10 minutes or until the outside of the unit is cool to the touch.
3. Connect the Clean-in-Place return and discharge hoses to the designated cleaning connections.
4. Circulate the cleaning solution through the Flo-Rite-Temp. Do not exceed a maximum circulation time of 3 hours.
5. After cleaning, flush the unit thoroughly with water before reintroducing steam.