The best LP tankless water heater depends on how many fixtures need hot water at once and whether the unit will be installed indoors or outdoors. The Ranein 4.3 GPM model suits smaller homes, while the APUS 6.8 GPM model and Ranein 8.5 GPM model target higher demand. For an outdoor installation, consider the Rheem 7.0 GPM unit.
| Product | Best For | Key Capacity |
|---|---|---|
| Ranein 4.3 GPM | Smaller homes and preset controls | 100,000 BTU |
| APUS 4.42 GPM | Multiple fixtures and low-flow starts | 95,000 BTU |
| Ranein 8.5 GPM | Large homes with higher demand | 190,000 BTU |
| APUS 6.8 GPM | Whole-home flow with booster pump | 140,000 BTU |
| Rheem 7.0 GPM | Outdoor installation | 160,000 BTU |
Ranein 4.3 GPM Indoor Propane Water Heater
Best for: Smaller households that want preset operating modes and a stated capacity for several water points. The unit is rated at 100,000 BTU and 4.3 GPM, with the product listing describing support for three to four water points.
Four modes cover seasonal, kitchen, bathtub, and shower use. The adjustable temperature range is 95°F to 155°F, and the listing notes a high-temperature lock. Anti-freeze protection and an LED display are also listed.
Consideration: This is an indoor model, so choose it only if the planned installation suits an indoor unit and its venting requirements. Its stated flow is lower than the larger-capacity options below.
APUS 4.42 GPM Indoor Propane Heater
Best for: Buyers who want a lower flow activation threshold and temperature control for multiple fixtures. This 95,000 BTU model lists a 4.42 GPM flow rate and a 0.66 GPM low-flow start. The product description says it can serve two showers and one sink at the same time.
Its temperature range is 95°F to 140°F, and the listing specifies temperature control within ±1°F. Listed construction and efficiency features include an oxygen-free copper heat exchanger, segmented combustion, up to 98% thermal efficiency, and a 0.81 UEF.
Consideration: The maximum temperature setting is lower than the Ranein 4.3 GPM model’s stated upper limit. Confirm that the 95,000 BTU capacity fits the home’s demand.
Ranein 8.5 GPM High-Flow Indoor Heater
Best for: Larger homes where several fixtures may need hot water at once. The listing gives this indoor unit an 8.5 GPM flow rate and 190,000 BTU output, and describes it as suitable for four to six water points.
The unit is wall-mounted and listed at 24.25 by 15.08 by 8.07 inches. Its fan can adjust to changes in external wind pressure and water temperature, according to the product information. Standard 3/4-inch NPT water inlet fittings are specified.
Consideration: Its higher stated capacity does not guarantee a particular flow at every temperature rise. Check household demand and installation requirements before choosing it.
APUS 6.8 GPM Heater With Booster Pump
Best for: Homes seeking higher flow and listed circulation features. This 140,000 BTU indoor model includes a built-in booster pump, with a stated maximum flow of 6.8 GPM. The manufacturer says it can support two showers and two sinks at once.
The listing describes a zero-cold-water circulation feature, Wi-Fi app control, anti-freeze protection, and a temperature range of 95°F to 140°F. It connects to standard 120V AC power. The heat exchanger is described as oxygen-free copper.
Consideration: Unlike a unit that relies only on gas, this model requires an electrical connection. Check whether the listed 120V power supply and circulation features suit the installation.
Rheem 7.0 GPM Outdoor Liquid Propane Heater
Best for: Buyers who specifically need an outdoor-mounted LP model. Rheem lists a 7.0 GPM flow rate at a 35°F temperature rise and 160,000 BTU per hour. The product description identifies it for residential whole-house use and says the output can serve two to three simultaneous showers.
This non-condensing unit has a stated 0.82 UEF. Its outdoor installation eliminates the need for indoor venting, and the listing describes a metal cabinet and wall mounting by a qualified installer.
Consideration: This model is designed for outdoor installation, not as a substitute for an indoor heater. Its stated flow is tied to a 35°F temperature rise, so compare that figure with local water conditions and expected use.
Buying Guide: How To Choose An LP Tankless Water Heater
How much flow does your household need?
List the fixtures likely to run together, such as showers, sinks, or a bathtub. Compare that demand with each product’s stated GPM and the conditions attached to the figure. The Ranein 4.3 GPM model targets more modest demand, while the 6.8, 7.0, and 8.5 GPM options advertise higher flow. Actual delivered flow can depend on temperature rise and installation conditions.
Should you choose an indoor or outdoor model?
Match the heater’s installation type to the available location. The four Ranein and APUS products here are listed as indoor models; the Rheem is designed for outdoor installation. Indoor gas appliances require appropriate venting and installation planning. Follow the product instructions and local code, and use a qualified installer where needed.
Which controls and features matter?
Preset modes can simplify everyday operation, while a stated low-flow start may matter when a fixture uses little water. Consider whether you want a temperature lock, LED display, app control, anti-freeze protection, or a circulation feature. Compare these functions against your actual use rather than treating feature count as a substitute for capacity.
What should you verify before buying?
Check propane supply requirements, BTU capacity, water connections, electrical needs, installation type, and venting details in the current product documentation. Verify that the unit’s rated flow matches your simultaneous fixture demand. A higher GPM number alone does not show how much hot water it will deliver under every temperature condition.
Frequently Asked Questions
What does LP mean on a tankless water heater?
LP means liquid propane. Confirm that the heater is specified for propane rather than assuming that a natural-gas model can use LP.
Can a tankless propane heater serve multiple fixtures?
Yes, if its capacity can meet the combined demand. Compare the product’s GPM rating and stated fixture guidance with the fixtures that may run simultaneously.
Do indoor propane tankless heaters need venting?
Indoor gas models require suitable venting and installation planning. Check the manufacturer’s instructions and applicable local requirements before installation.
Does a tankless heater need electricity?
Some models require an electrical connection for features or operation. The APUS 6.8 GPM listing specifies standard 120V AC; verify power requirements for any model you consider.
Is a higher GPM rating always better?
No. Choose a flow capacity that matches household demand and local temperature conditions. A larger rating may be unnecessary for a smaller home, while a lower rating may not serve several fixtures at once.