Rinnai Circ-Logic - User Manual

For SENSEI™ and non-SENSEI™ Tankless Water Heaters

Summary

About Rinnai Circ-Logic

How This Manual is Organized

Details the manual's sections and appendix, covering kit contents, installation for SENSEI and non-SENSEI models, operation, and system drawings.

Disclaimers

States the document is a guide, not a replacement for professional engineering, and stresses compliance with local codes.

Kit Contents

Lists the components included in the Grundfos GTK03U Kit for Rinnai Circ-Logic installation.

Pipe Length

Specifies the equivalent pipe length for the Grundfos GTK03U using 3/4 in. piping at 120°F.

Installation Guidelines for All Models

Outlines general installation requirements, necessary skills for licensed professionals, and pump operating limits.

SENSEI Installation

Wiring the Pump to the Water Heater

Provides step-by-step instructions and a wiring diagram for connecting the GTK03U pump to SENSEI™ tankless water heaters.

Parameter Settings

Explains how to adjust parameter settings on the water heater controller for recirculation modes (Economy/Comfort).

Non-SENSEI Installation

Wiring the Pump to the Water Heater

Details the wiring process for installing the GTK03U pump on non-SENSEI™ models, including rerouting power cords.

Operating the Pump

How It Works

Explains how the pump operates based on Rinnai temperature settings and modes, including typical ON intervals.

Troubleshooting

Provides guidance on troubleshooting pump operation issues, including manual shaft rotation and system pressure equalization.

Appendix - System Drawings

SENSEI and Non-SENSEI Recirculation Using One Tankless Water Heater

Illustrates the system configuration for recirculating hot water with one tankless heater for SENSEI™ and non-SENSEI™ models.

SENSEI Recirculation Using Two Tankless Water Heaters

Presents a system drawing for recirculating hot water with two tankless water heaters for SENSEI™ models.

Non-SENSEI Recirculation Using Two Tankless Water Heaters

Shows the system layout for recirculating hot water with two tankless water heaters for non-SENSEI™ models.

Overview

1. Function Description
2. Important Technical Specifications
3. Usage Features
4. Maintenance Features

The Rinnai Circ-Logic with Grundfos GTK03 Kit is an external pump system designed to enable recirculation functionality with Rinnai SENSEI™ and non-SENSEI™ tankless water heaters. This kit allows users to implement Rinnai's Circ-Logic technology, which optimizes hot water availability while minimizing energy consumption by circulating water only when needed, aligning with user hot water usage patterns.

Function Description:

The primary function of the Grundfos GTK03U Kit is to facilitate the recirculation of hot water in a dedicated return line system. When integrated with a compatible Rinnai tankless water heater, the GTK03U pump works in conjunction with the water heater's Circ-Logic technology. This system ensures that hot water is readily available at fixtures without the typical wait time associated with drawing cold water from the main line. The Circ-Logic system can operate in two modes: Comfort Mode and Economy Mode. Comfort Mode cycles the pump more frequently, maintaining a higher loop temperature for quicker hot water delivery, albeit with increased energy use. Economy Mode cycles the pump less often, consuming less energy while still maintaining the circulation loop temperature. The pump is controlled by the tankless water heater, which monitors water temperature via inlet and outlet thermistors. Recirculation is initiated when the water heater is turned on, and the pump cycles based on the temperature setting and the selected operating mode. The system stops circulating when the return water temperature reaches approximately 15°F (8.3°C) below the set temperature, or if an abnormal temperature (diagnostic code 51) is detected by the inlet thermistor, in which case the pump will turn off.

Important Technical Specifications:

• Pump Model: Grundfos 15-55 pump with an internal check valve.
• Electrical Connection: Pre-wired with a 6 ft. (2 m) BX conduit, including an in-line 4 amp glass fuse.
• Maximum Operating Pressure: 145 PSI.
• Water Temperature Range: Designed to circulate water from 36°F to 150°F.
• Pipe Length Capability: Up to 200 ft. (61 m) equivalent pipe length using 3/4 inch (19 mm) piping at 120°F. This equivalent length includes supply piping, return piping, and fittings, requiring calculation by the installer.
• Operating Voltage: The proper operating voltage and other electrical information are found on the nameplate attached to the top of the motor.
• Compatibility: Compatible with Rinnai SENSEI™ series (RU199i/e, RU180i/e, RU160i/e, RU130i/e, CU199i/e, CU160i/e) and non-SENSEI™ series (RLX94i, RL75i/e, RL94i/e, RU98i/RUC98i, RU98e, RU80i/RUC80i, RU80e) tankless water heaters.
• Installation Environment: Intended for indoor installations only.

Usage Features:

• Circ-Logic Technology: Provides on-demand hot water without waiting, reducing water waste.
• Two Operating Modes:
  • Comfort Mode: Prioritizes immediate hot water availability by cycling the pump more frequently, maintaining higher loop temperatures.
  • Economy Mode: Prioritizes energy efficiency by cycling the pump less often, while still maintaining the circulation loop temperature.
• Parameter Settings: Users can select the recirculation settings (No Recirculation or Recirculation (Dedicated)) and the operating mode (Economy or Comfort) directly from the tankless water heater's controller. For SENSEI™ models, this involves pressing an "A" button and using up/down arrows to navigate settings, then the "On/Off" button to change selections. For non-SENSEI™ models, dip switches (SW2, switch 4 and 8) are used to configure these settings.
• Automatic Operation: Once configured, the pump operates automatically based on the chosen mode and temperature settings, cycling on and off at calculated intervals to maintain the desired loop temperature.
• System Integration: Seamlessly integrates with Rinnai tankless water heaters, utilizing their internal controls and thermistors for efficient operation.
• Dedicated Return Line: Designed for systems with a dedicated return line, ensuring optimal performance of the recirculation system.

Maintenance Features:

• Pre-Installation Cleaning: The system should be thoroughly cleaned and flushed prior to pump installation to prevent dirt and sediment accumulation.
• Proper Pump Placement: The pump should not be installed at the lowest point of the system where dirt and sediment naturally collect.
• Air Vent Installation: An air vent should be installed at the high point(s) of the system to remove accumulated air, which can affect pump performance.
• Terminal Box Orientation: The terminal box should be located to one side of the pump with the conduit entry down to prevent water ingress.
• Motor Shaft Orientation: The pump must be installed with the motor shaft positioned horizontally; vertical shaft orientation or shaft falling below the horizontal plane is unacceptable.
• Isolation Valves: It is recommended to install isolation valves on each side of the pump to facilitate maintenance or replacement without draining the entire system.
• Troubleshooting Stalled Pump: If the pump does not run, the shaft may be manually rotated to free it. This involves switching off the electrical supply, closing isolation valves, removing the large screw on the nameplate, inserting a flat blade screwdriver into the shaft end, gently turning until free, then replacing the plug and opening valves before restarting.
• Electrical Safety: Always disconnect the power supply to the tankless water heater before servicing the pump or making any electrical connections, as the pump's power source is from the water heater.
• Grounding: The tankless water heater must be electrically grounded, and the GTK03U pump's ground wire should be connected to the body of the tankless water heater.

Rinnai Circ-Logic Specifications