If you want a tankless water heater with a reserve tank, note that none of the five products below includes a built-in reserve tank. They are tankless heaters that provide hot water on demand; a separate storage or buffer tank may be needed to create reserve capacity. The Rheem is a higher-flow electric option, the GASLAND is a whole-house natural-gas model, and the CAMPLUX is designed for outdoor propane use. The smaller ORBEK and Jflapil models suit more limited electric applications.
| Product | Best suited for | Key listed detail |
|---|---|---|
| Rheem 18kW | Electric home use | Up to 4.4 GPM |
| GASLAND Gasmart E | Whole-house natural gas | Up to 7.6 GPM stated in title |
| CAMPLUX BW528 | Outdoor propane use | 5.28 GPM stated in title |
| ORBEK 14kW | Limited electric hot-water demand | Up to 3.38 GPM |
| Jflapil 3000W | Single sink or low-flow use | 110V, 3000W |
Rheem 18kW Electric Tankless Water Heater
Best for: Households seeking an electric tankless unit with a higher stated flow rate than the smaller electric models in this selection. The product information lists flow up to 4.4 gallons per minute (GPM), an external digital thermostat with LED display, and temperature accuracy of plus or minus one degree.
The self-modulating feature adjusts power to meet hot-water demand. Its copper immersion heating elements are described as durable and field-serviceable. These features make the Rheem a practical option to compare when you want on-demand electric heating and serviceable heating components.
Reserve-tank note: This is a tankless heater, not a model with an integrated reserve tank. The listed information does not specify what separate tank or configuration would be compatible. Limitation: Its advertised flow rate does not by itself establish performance for every home; incoming water temperature and simultaneous demand matter.
GASLAND Gasmart E Natural Gas Heater
Best for: Buyers looking for a natural-gas, indoor, whole-house tankless heater. The product title identifies a 199,000 BTU unit with up to 7.6 GPM and describes it as a residential on-demand heater. Those figures make it the highest stated flow option among these products, although the supplied feature details do not provide additional operating specifications.
Choose this model if your home uses natural gas and you want to investigate a tankless system intended for whole-house service. Its fuel type and stated capacity distinguish it from the electric units and the outdoor propane model.
Reserve-tank note: The product title describes a tankless heater, not a heater with a reserve tank. Limitation: The supplied information does not detail installation requirements, temperature rise, or performance under local conditions. Confirm the complete specifications and local code requirements before selecting it.
CAMPLUX BW528 Outdoor Propane Heater
Best for: Buyers who need an outdoor propane tankless heater for settings such as camping or other outdoor hot-water use. The product name identifies the BW528 as a 20-liter model with a stated flow of 5.28 GPM. Its propane fuel and outdoor design make it a different choice from indoor electric and natural-gas units.
Choose this if propane operation and outdoor placement fit your intended installation. Do not select it as a direct substitute for an indoor whole-house heater without confirming that its placement and use match the product instructions and your local requirements.
Reserve-tank note: The supplied product information does not describe a built-in reserve tank or a separate storage tank. Limitation: The listing information provided here does not specify temperature rise, indoor-use suitability, or reserve capacity.
ORBEK 14kW Electric Tankless Heater
Best for: Buyers comparing compact electric tankless options for several points of use, provided their electrical service can support the stated requirements. ORBEK lists a maximum flow of 3.38 GPM and says the heater can serve two to three points of use, such as a bathroom and kitchen.
The listed electrical requirements are 240 volts, a 60-amp two-pole breaker, one set of 6 AWG wires, and 1/2-inch NPT water connections. The feature information also says the household breaker panel should have at least 150 amps of total current capacity. Verify the circuit and panel requirements with a qualified electrician before purchase.
Reserve-tank note: This is an on-demand heater without a listed reserve tank. Limitation: Its electrical requirements are substantial, and the maximum flow figure should not be treated as a guarantee at every incoming water temperature or household demand level.
Jflapil 110V Under-Sink Tankless Heater
Best for: A low-flow sink or point-of-use application where a standard 110V outlet-based product is being considered. The listed specifications identify a 3000W heater with adjustable temperature from 82°F at 0.3 GPM to 131°F at 0.5 GPM. Its stated flow is much lower than the whole-house-oriented options in this group.
The unit has a digital display that can switch between Celsius and Fahrenheit, a wall-mounted design, and listed safety features including dry-burn and overheating protection. The product information also claims IPX4 waterproofing and ETL certification.
Reserve-tank note: This product heats on demand and does not have a listed reserve tank. Limitation: Its stated flow of 0.3 to 0.5 GPM makes it better suited to a limited point-of-use demand than multiple simultaneous fixtures.
Buying Guide: How to Choose a Tankless Heater With Reserve Capacity
Does a tankless heater include a reserve tank?
Not necessarily. “Tankless” means the heater warms water as it flows through the unit rather than storing a tankful for later use. The products reviewed here are listed as tankless units, and none is described as including a reserve tank. If stored hot water is a requirement, look for a product explicitly sold with a storage tank or ask a qualified installer about a compatible separate tank arrangement.
A separate tank can change how a system is designed, connected, and controlled. Do not assume that any storage tank can be attached to any tankless heater. Confirm the intended configuration, controls, and installation instructions with the manufacturer or a qualified plumbing professional.
How much hot-water flow do you need?
Estimate which fixtures may run at the same time, then compare that demand with a heater’s stated flow under the temperature conditions in your home. A listed maximum GPM is not a universal measure of how many showers or faucets a unit can support. Incoming water temperature, desired output temperature, and simultaneous use all affect the result.
- For a limited sink application, the Jflapil’s listed 0.3–0.5 GPM range is the most clearly point-of-use-oriented option here.
- For electric models with higher stated flow, compare the ORBEK at up to 3.38 GPM with the Rheem at up to 4.4 GPM.
- For gas options, the GASLAND title states up to 7.6 GPM, while the CAMPLUX title states 5.28 GPM. Their different fuels and intended settings matter as much as the flow figures.
Should you choose electric, natural gas, or propane?
Start with the fuel and utilities available at the installation location. Electric tankless models may require dedicated electrical capacity; the ORBEK listing, for example, specifies a 240V circuit and a 60-amp two-pole breaker. Natural-gas equipment requires an appropriate gas supply and installation arrangement. The CAMPLUX is identified as an outdoor propane unit, which makes it a different type of solution from a permanently installed indoor heater.
Have electrical and gas requirements verified before buying. A heater’s advertised flow does not confirm that your home’s panel, wiring, gas supply, venting, or plumbing is suitable.
When is a reserve tank useful?
A reserve tank may be worth investigating when you need stored hot water, want a buffer for short periods of high demand, or are planning a particular system layout. However, the right capacity and configuration depend on the home and the heater. The product information supplied for these five models does not specify compatible tank sizes or control arrangements.
Ask an installer to evaluate the whole system rather than selecting a tank based on volume alone. Include demand patterns, available space, piping, energy source, and the manufacturer’s approved installation approach in the discussion.
What should you verify before ordering?
- Whether the heater is for indoor or outdoor installation.
- Fuel type, voltage, breaker, wiring, and connection requirements.
- Flow capacity under the temperature conditions expected at your home.
- Whether a reserve or buffer tank is included, required, or supported.
- Local plumbing, electrical, gas, and building-code requirements.
- Complete manufacturer specifications, especially when the product summary does not provide installation details.
Frequently Asked Questions
Is a tankless water heater with a reserve tank truly tankless?
The heater itself may be tankless while a separate storage or buffer tank is added to the system. The products reviewed above do not list an included reserve tank, so confirm the intended configuration before purchasing.
Which product listed here has the highest stated flow rate?
The GASLAND product title states up to 7.6 GPM. That figure does not guarantee a particular flow at every incoming water temperature or installation condition.
Which option is intended for an outdoor propane setup?
The CAMPLUX BW528 is identified as an outdoor propane camping water heater. Check the product instructions and local requirements for the planned use and placement.
Can the Jflapil 110V heater supply a whole house?
The listed temperature range corresponds to 0.3–0.5 GPM, so its stated capacity is better suited to a limited point-of-use application than broad household demand.
What electrical service does the ORBEK require?
The listed requirements are 240V, a 60-amp two-pole breaker, one set of 6 AWG wires, and at least 150 amps of total household breaker-panel capacity. Have an electrician verify suitability.
Should I buy a separate reserve tank for one of these heaters?
Do not assume compatibility. Ask the manufacturer or a qualified installer to confirm whether a separate tank is supported and what system configuration is appropriate.