Original: $500.30
-70%$500.30
$150.09The Story
Rinnai / Grundfos GTK03U Pump Kit — Smart Recirculation with Circ-Logic™
The GTK03U Pump Kit enables hot water recirculation using Rinnai’s Circ-Logic™ technology on tankless water heaters lacking built-in pumps. It includes a Grundfos 15-55 pump with an internal check valve, prewired conduit, and flange kit, allowing you to enjoy “instant hot water” without needing a dedicated return line.
Key Features & Benefits
- Enables Circ-Logic™ recirculation on compatible Rinnai models (VC, KB, Sensei)
- Includes Grundfos 15-55 pump with internal check valve
- Pre-wired conduit with 4A fuse for plug-in setup
- Flange / union kit for ¾″ piping connections
- Stainless-steel pump housing resists corrosion
- Reduces water waste — hot water delivered faster to fixtures
Applications
- Tankless water heaters without built-in recirculation pumps
- Retrofit installations using Circ-Logic™ mode
- Crossover loops or dedicated return loops where allowed
- Homes seeking to reduce wait time and wasted water
Specifications
| Model / SKU | GTK03U Pump Kit |
| Pump Type | Grundfos 15-55 with check valve |
| Flow Rating | 20 GPM (nominal) |
| Head Rating | 17 ft (5 m) |
| Max Liquid Temp | 150 °F (65 °C) |
| Max System Pressure | 145 PSI |
| Voltage / Frequency | 115 V, 60 Hz |
| Max Current | 0.75 A |
| Connection Size | ¾″ flange / union |
| Weight (pump + flange kit) | ~8.6 lbs (4 kg) |
| Included Kit Items | Pump + internal check valve, 6 ft BX conduit prewired (with 4A fuse), Circ-Logic manual |
Common Questions
Q: Which Rinnai heaters support this kit?
A: Compatible with many VC, KB, and Sensei series models using Circ-Logic mode.
Q: Do I need a return line?
A: The kit is meant for use in systems with dedicated return lines where possible. Some configurations may be limited by code or manufacturer rules.
Q: Can it be used outdoors?
A: The pump is intended for indoor installation per manufacturer guidelines.
Q: Is installation difficult?
A: An authorized technician should handle gas, water, and electrical connections for safe and code-compliant installation.
With the GTK03U pump kit, your tankless setup gains responsive hot water delivery, better efficiency, and compatibility with Rinnai’s Circ-Logic platform.
If you are installing a GTK03U Kit on one of the following tankless water heater models, follow the instructions in Section 2 in the install Manual:
RU199i/e
RU180i/e
RU160i/e
RU130i/e
CU199i/e
CU160i/e
If you are installing a GTK03U Kit on one of the following models, follow the instructions in Section 3 in the install Manual:
RLX94i
RL75i/e (VC models)
RL94i/e (VC models)
RU98i/RUC98i and RU98e (KB models)
RU80i/RUC80i and RU80e (KB models)
Details & Craftsmanship
Every detail has been carefully considered to bring you the perfect product.
Details & Craftsmanship
Every detail has been carefully considered to bring you the perfect product.
Details & Craftsmanship
Every detail has been carefully considered to bring you the perfect product.
Description
Rinnai / Grundfos GTK03U Pump Kit — Smart Recirculation with Circ-Logic™
The GTK03U Pump Kit enables hot water recirculation using Rinnai’s Circ-Logic™ technology on tankless water heaters lacking built-in pumps. It includes a Grundfos 15-55 pump with an internal check valve, prewired conduit, and flange kit, allowing you to enjoy “instant hot water” without needing a dedicated return line.
Key Features & Benefits
- Enables Circ-Logic™ recirculation on compatible Rinnai models (VC, KB, Sensei)
- Includes Grundfos 15-55 pump with internal check valve
- Pre-wired conduit with 4A fuse for plug-in setup
- Flange / union kit for ¾″ piping connections
- Stainless-steel pump housing resists corrosion
- Reduces water waste — hot water delivered faster to fixtures
Applications
- Tankless water heaters without built-in recirculation pumps
- Retrofit installations using Circ-Logic™ mode
- Crossover loops or dedicated return loops where allowed
- Homes seeking to reduce wait time and wasted water
Specifications
| Model / SKU | GTK03U Pump Kit |
| Pump Type | Grundfos 15-55 with check valve |
| Flow Rating | 20 GPM (nominal) |
| Head Rating | 17 ft (5 m) |
| Max Liquid Temp | 150 °F (65 °C) |
| Max System Pressure | 145 PSI |
| Voltage / Frequency | 115 V, 60 Hz |
| Max Current | 0.75 A |
| Connection Size | ¾″ flange / union |
| Weight (pump + flange kit) | ~8.6 lbs (4 kg) |
| Included Kit Items | Pump + internal check valve, 6 ft BX conduit prewired (with 4A fuse), Circ-Logic manual |
Common Questions
Q: Which Rinnai heaters support this kit?
A: Compatible with many VC, KB, and Sensei series models using Circ-Logic mode.
Q: Do I need a return line?
A: The kit is meant for use in systems with dedicated return lines where possible. Some configurations may be limited by code or manufacturer rules.
Q: Can it be used outdoors?
A: The pump is intended for indoor installation per manufacturer guidelines.
Q: Is installation difficult?
A: An authorized technician should handle gas, water, and electrical connections for safe and code-compliant installation.
With the GTK03U pump kit, your tankless setup gains responsive hot water delivery, better efficiency, and compatibility with Rinnai’s Circ-Logic platform.
If you are installing a GTK03U Kit on one of the following tankless water heater models, follow the instructions in Section 2 in the install Manual:
RU199i/e
RU180i/e
RU160i/e
RU130i/e
CU199i/e
CU160i/e
If you are installing a GTK03U Kit on one of the following models, follow the instructions in Section 3 in the install Manual:
RLX94i
RL75i/e (VC models)
RL94i/e (VC models)
RU98i/RUC98i and RU98e (KB models)
RU80i/RUC80i and RU80e (KB models)
