If you are searching for a small water-to-water heat pump, first note that the products listed here do not include a true water-to-water heat pump. The Rinnai is a heat-pump water heater that draws heat from ambient air; the other selected products are pumps or a tankless-heater flushing kit. The Rinnai is the closest match for efficient household hot water, while the flushing kit and utility pumps are suited to maintenance and water transfer—not heating water.
| Product | Best suited for | What it does |
|---|---|---|
| Rinnai REHP50 | Households needing stored hot water | Air-source heat-pump water heater |
| 6699 Tankless Flushing Kit | Tankless heater maintenance | Circulates cleaning solution |
| TecHome Transfer Pump | Small water-transfer jobs | Moves water; does not heat it |
| KITLUCK Transfer Pump | Portable draining and transfer | Moves water; does not heat it |
| 6699 1/6 HP Utility Pump | Clean-water draining | Submersible drainage pump |
Rinnai REHP50 Heat-Pump Water Heater
Best for: Households looking for an energy-efficient electric water heater with a storage tank. This is the most relevant product here for a buyer whose main goal is household hot water, though it is not a water-to-water model.
The REHP50 has a 50-gallon capacity, a listed 3.75 Uniform Energy Factor, and a first-hour delivery of up to 73 gallons. The product description says it uses heat from ambient air and is designed for everyday household hot-water demand. It also lists demand-response capability, which can communicate with participating local utilities to reduce energy use during peak periods.
Why it was selected: Unlike the utility pumps below, this product heats and stores domestic hot water. It is the closest fit for someone comparing small heat-pump water-heating equipment.
Consider: The listed specifications are 240V and 30A, and the product uses ambient air as its heat source. Check the installation requirements and available space before choosing it. It is not described as a water-to-water heat pump.
6699 Tankless Water Heater Flushing Kit
Best for: Owners maintaining a tankless water heater that has compatible isolation valves. This kit is a maintenance tool rather than a heat pump or a hot-water appliance.
The kit includes a 1/6 HP pump, two six-foot hoses, a three-gallon pail, adapters, washers, and a lid opener. Its instructions describe circulating a mixture of one gallon of vinegar or biodegradable cleaner and one gallon of water through a tankless heater. The cleaning solution is not included. The pump is listed at up to 1,100 gallons per hour, with a maximum delivery height of 16.5 feet and a 10-foot power cable.
Why it was selected: It is the most directly relevant accessory for buyers researching pumps around water-heating equipment. It helps with a specific maintenance task, not heating water or supplying a home.
Consider: The product description says it connects to tankless heater isolation valves. Confirm that the heater has the appropriate service connections and follow its manufacturer’s maintenance directions.
TecHome 115V Water Transfer Pump
Best for: Buyers who need a compact electric pump for transferring or draining water from tanks, rain barrels, aquariums, or similar sources. It is not a water heater or heat pump.
The TecHome pump is listed as a 115V, 1/10 HP model with a maximum flow of 330 gallons per hour and a maximum head of 40 feet. Its kit includes two six-foot suction hoses, a suction strainer, and replacement impeller parts. The listing says the strainer supports low-water suction down to 1/8 inch. A built-in waterproof on/off switch provides a direct way to start and stop the pump.
Why it was selected: Its stated uses include water heaters and water tanks, making it relevant for water-handling tasks near a heating system. The included hoses and replacement parts also distinguish it from a bare pump.
Consider: Water transfer is its function; it does not create hot water or provide space heating. Check hose connections and the pump’s operating instructions for the intended job.
KITLUCK 115V Transfer Pump
Best for: People who want a portable surface pump for water transfer or light drainage, including work with pools, rain barrels, and aquariums.
The KITLUCK is a 115V, 1/10 HP pump with a listed maximum flow of 330 gallons per hour. Its product information gives a maximum lift of 39 feet and a maximum suction lift of six feet. The package includes a six-foot suction hose and a weighted suction strainer. With the strainer attached, it is described as able to remove water down to 1/8 inch from a surface. The pump body is aluminum, with a zinc-alloy pump head and metal connector.
Why it was selected: It is a small, portable option for moving water when the buyer does not need a heater. It is better suited to transfer tasks than to heating-system circulation or domestic hot-water production.
Consider: The stated suction lift is limited to six feet. Check the required elevation, hose size, and water condition before selecting it for a particular setup.
6699 1/6 HP Submersible Utility Pump
Best for: Draining clean water from a basement, pool, tank, or similar location. It is a drainage pump, not a water-to-water heat pump.
This submersible model has a 1/6 HP motor with thermal overload protection and a listed maximum pumping rate of 1,100 gallons per hour. The product description says it can lower the water level to 1/12 inch and has a screened inlet to keep large solids out. It includes adapters for a 3/4-inch garden hose and a one-inch PVC lay-flat hose.
Why it was selected: It offers a practical small-pump option for clean-water removal and includes adapters for two hose types. This makes it useful for drainage around household equipment, though it does not circulate or heat water in a heating system.
Consider: The listing says it is not suitable for dirty water or expandable hoses. Choose another type of pump if the water contains debris or sediment.
Buying Guide: Choosing Equipment for a Small Water-Heating System
Do you need a heat pump, a water heater, or a transfer pump?
These terms describe different equipment. A heat pump moves heat from a source to water or a building. A heat-pump water heater uses heat from its surrounding air to warm stored domestic water. A transfer or submersible utility pump moves water but does not heat it. A flushing pump circulates cleaning solution through equipment for maintenance.
The listed Rinnai is an air-source heat-pump water heater, not a water-to-water heat pump. The other products are pumps for transferring, draining, or cleaning. If you specifically need a water-to-water system, look for equipment whose product documentation identifies a water source and a water-heating or hydronic output. Do not treat a general-purpose utility pump as a substitute.
What does “small” mean for your application?
For a household water heater, capacity and first-hour delivery matter more than the word “small” alone. The Rinnai listing specifies a 50-gallon tank and up to 73 gallons of first-hour delivery. Compare those figures with the household’s hot-water demand and the available installation area.
For a utility pump, consider flow rate, lift, suction, and hose connections. The TecHome and KITLUCK models are listed at up to 330 gallons per hour. The submersible 6699 model is listed at up to 1,100 gallons per hour. These figures describe water movement, not heating capacity or energy efficiency for producing hot water.
Which power and installation details should you check?
Match the equipment to the available electrical supply and installation requirements. The Rinnai listing specifies 240V and 30A, while the portable transfer pumps listed here operate on 115V. Verify the manufacturer’s electrical instructions and local requirements before installation. A tank-style heat-pump water heater also needs suitable space for its equipment and air source.
For utility pumps, confirm whether the design is submersible or surface-mounted, what hose adapters are included, and how high or far the water must be moved. The maximum head, suction lift, and flow rate are separate limits. Real-world flow can vary with hose length, elevation, and setup; do not assume the maximum listed rate will apply to every job.
When is a flushing kit the right choice?
Choose a flushing kit only when the task is maintenance of a compatible tankless water heater. The 6699 kit includes a pump, hoses, pail, and adapters, and its description specifies a cleaning-solution procedure. It is not a device for delivering hot water to fixtures or circulating water as part of a heat-pump heating system.
Before purchasing a kit, check the heater’s instructions for the recommended cleaning method, connection type, and cleaning agent. The listed kit does not include vinegar or biodegradable cleaner. Do not assume a maintenance accessory is compatible with a particular heater unless its instructions confirm it.
How should you compare pump limitations?
- Clean water: The 6699 1/6 HP pump is explicitly described as unsuitable for dirty water. Its screened inlet is meant to block larger solids, not make it a sewage pump.
- Low-water removal: TecHome and KITLUCK list removal down to 1/8 inch under specified conditions. The 6699 submersible pump lists 1/12 inch.
- Hose fit: Compare included adapters with the hose you plan to use. A listed connector size does not establish that every hose type is appropriate.
- Operating location: A submersible pump and a surface transfer pump have different placement requirements. Follow the product instructions rather than using them interchangeably.
- Heating function: None of the listed utility pumps is described as a heat pump. Use a product specifically designed for heating if your goal is to produce hot water.
Frequently Asked Questions
Is the Rinnai REHP50 a water-to-water heat pump?
No. Its listing describes an electric heat-pump water heater that extracts heat from ambient air. It is the closest listed product for household hot water, but it is not identified as a water-to-water model.
Can a utility transfer pump heat water?
No. The KITLUCK, TecHome, and 6699 utility pumps move or drain water. Their listed features do not include heating water.
Which listed product is intended for tankless water-heater maintenance?
The 6699 Tankless Water Heater Flushing Kit is described for cleaning a tankless heater using a circulated solution. Check the heater’s instructions and connections before use.
Which option has the highest listed flow rate?
The 6699 1/6 HP submersible pump is listed at up to 1,100 gallons per hour. That is a water-transfer specification, not a measure of hot-water production.
What should I buy if I specifically need a small water-to-water heat pump?
None of the listed products is identified as a water-to-water heat pump. Search for a unit whose manufacturer documentation explicitly specifies water as the heat source and describes the intended heating application, capacity, and installation requirements.