An electric tankless heater can supply hot water to an outdoor shower, but the right choice depends on more than the unit’s maximum flow rate. Cold incoming water can sharply reduce how much warm water an electric model can deliver, and these heaters need the right electrical circuit and a protected installation location. The picks below range from compact point-of-use units to a higher-power model, plus one propane option designed for outdoor installation. Check the flow and installation requirements against your shower setup before you buy.
Table of Contents
Quick Comparison
| Product | Power or fuel | Listed flow | Best fit | Outdoor shower consideration |
|---|---|---|---|---|
| Westinghouse 11kW Electric Tankless Water Heater | 11kW, 240V | Up to 2.6 GPM; varies with inlet temperature | A compact, controllable point-of-use setup | Install in a suitable protected location; confirm available flow for your water temperature. |
| Rinnai V53DeP Propane Tankless Water Heater | Propane | 5.3 GPM | Shoppers open to an outdoor propane heater | Designed for outdoor installation, but it is not electric. |
| NOVIEEX 18kW Electric Tankless Water Heater | 18kW, 240V, 75A maximum current | Up to 4.9 GPM listed | Higher-power electric setups with suitable service | Confirm the actual temperature rise and installation location; listed maximum flow is not a shower-flow guarantee. |
| CAMPLUX 6kW Electric Tankless Water Heater | 6kW, 240V | Up to 1.5 GPM listed | Low-flow or small point-of-use needs | Its listed 50°F rise at 1.0 GPM may be limiting for a full shower, especially with cold inlet water. |
| Ranein 8kW Electric Tankless Water Heater | 8kW, 240V | Up to 1.9 GPM listed | A modest-flow point-of-use installation | Check whether its output can meet your shower’s temperature and flow needs. |
Our Picks: Best Electric Tankless Water Heaters For Outdoor Shower reviews
1. Westinghouse 11kW: Smart Controls in a Compact Unit
This 11kW, 240V electric heater is a compact point-of-use option with a digital display and Wi-Fi control. You can set the temperature from 86°F to 140°F in 1°F steps, and the listing says it works with Alexa and Google Home. Its small wall-mounted body may be easier to place near the plumbing than a bulky tank, provided the location meets electrical and moisture-protection requirements.
For shower use, pay close attention to the flow figures: the listing gives up to 2.6 GPM with 77°F incoming water and a 104°F output, but only 1.4 GPM with 57°F incoming water at that same output. That difference matters for an outdoor shower, where the supply line may be cold. The heater needs at least 0.5 GPM to start, and it requires a hardwired 240V, 46A connection. Have an electrician confirm your panel and circuit can support it.
Compared with the smaller 6kW and 8kW picks, this model offers more listed output and more temperature-control features. It is not described as weatherproof or outdoor-rated, so plan on installing it in an appropriate protected space and running plumbing to the shower.
Pros:
- Temperature setting adjusts in 1°F increments.
- Wi-Fi app control and compatibility with Alexa and Google Home.
- Compact design with copper heating elements.
- Listed flow figures show how inlet temperature affects output.
Cons:
- Requires a dedicated 240V, 46A hardwired installation.
- Available shower flow can drop considerably with colder incoming water.
Verdict: Choose the Westinghouse if you want a compact, connected electric heater and your electrical service and expected shower flow suit its temperature-dependent output.
2. Rinnai V53DeP: Outdoor Propane Alternative, Not Electric
This Rinnai is the one product in this roundup specifically described as an outdoor unit, but it runs on propane rather than electricity. Its listed 5.3 GPM flow is higher than the electric models here, making it worth considering if you want a dedicated outdoor heater and are willing to use gas. The compact wall-mounted design is intended for outdoor installation.
That higher flow does not make it a match for every setup. You will need a suitable propane supply and professional installation, and the product listing recommends a qualified technician. Its fuel type also means it does not meet a strict electric-only requirement. The warranty information in the listing varies by section, so confirm the current terms with the manufacturer before purchasing.
Compared with the electric options, this is the clearest fit for placing the heater outdoors, while the electric models are better considered for protected installation near the shower’s plumbing. If you do not already have propane service or do not want a gas appliance, look at the electric picks instead.
Pros:
- Designed for outdoor installation.
- Listed 5.3 GPM flow rate.
- Propane operation avoids the high-amperage electrical requirements of the larger electric picks.
- Compact wall-mounted format.
Cons:
- Uses propane, so it is not an electric tankless heater.
- Professional installation is recommended.
Verdict: Consider the Rinnai only if you are open to propane and want an outdoor-designed unit; for an electric-only purchase, skip it.
3. NOVIEEX 18kW: Higher Electrical Output for More Demanding Setups
The NOVIEEX is the highest-wattage electric model in this group at 18kW and 240V. It has an LED temperature display and a listed adjustment range of 77°F to 140°F. The maker lists a maximum flow rate of 4.9 GPM, but that number should not be treated as guaranteed hot-shower flow: the listing does not provide the inlet-water temperature conditions for that maximum.
Electrical requirements are substantial. The product information specifies a maximum current of 75A, two 40A double-pole breakers, and two sets of 8 AWG wires with grounding. Have a qualified electrician check the panel, circuit layout, and applicable requirements before buying. Its slim wall-mounted dimensions may help in a utility space, but the listing does not establish that the unit is suitable for direct exposure to outdoor weather.
Some owners describe the unit as compact and report using it in small homes or a shop. Those experiences can help set expectations for its size and general use, but they do not establish performance at a particular outdoor shower flow or water temperature. Compared with the Westinghouse, it has a higher rated power level but a more demanding electrical installation.
Pros:
- 18kW output and adjustable temperature settings.
- Slim wall-mounted design.
- LED screen displays the set temperature.
- Higher listed maximum flow than the other electric models in this roundup.
Cons:
- Requires significant electrical capacity and multiple circuits as specified by the listing.
- The listed maximum flow does not state the inlet-temperature conditions.
Verdict: The NOVIEEX is worth considering when you need a higher-power electric option and an electrician confirms your service can support it, but verify expected shower flow rather than relying on the maximum GPM claim.
4. CAMPLUX 6kW: Compact Heater for Lower-Flow Needs
This 6kW, 240V CAMPLUX is a small point-of-use heater with touch controls, a temperature display, and self-modulating power. The listing says it can provide a 50°F temperature rise at 1.0 GPM, with a maximum listed flow of 1.5 GPM. That makes the temperature-rise figure more useful than the maximum flow alone when deciding whether it can serve your shower.
At a 50°F rise, very cold supply water may still leave the outlet below a comfortable shower temperature unless you reduce the flow or the incoming water is warmer. For that reason, this model is a better match for a low-flow shower or milder conditions than for a high-flow shower supplied with cold water. Its installation requirements include a 30A circuit breaker, 10 AWG wire, hardwiring, and a 1/2-inch NPT water connection.
The compact size can suit a small protected utility area, and owners have described fitting the unit in tight spaces such as under a sink or in an RV. That does not make it an outdoor-rated appliance; check the installation instructions and local requirements for the actual location. It is the lowest-power electric pick here, which also means the least headroom for a larger shower demand.
Pros:
- Compact wall-mounted design.
- Self-modulating power and touch temperature controls.
- Clear listed temperature-rise figure at 1.0 GPM.
- Lower electrical demand than the 11kW and 18kW options.
Cons:
- A 50°F rise at 1.0 GPM may not be enough for cold inlet water and a comfortable shower.
- Limited listed flow compared with the higher-power models.
Verdict: Pick the CAMPLUX for a compact, low-flow application only after confirming that its stated temperature rise matches your water supply and shower needs.
5. Ranein 8kW: Simple Controls for a Modest Shower Flow
The Ranein is an 8kW, 240V electric unit with knob controls and an LED display. Its temperature range is listed as 86°F to 131°F, adjustable in 1°F steps, and its maximum flow is listed at 1.9 GPM. The maker describes it as suitable for one or two usage points, but for an outdoor shower, the key question is whether it can maintain your desired temperature at the flow you use.
Its smaller power draw than the 11kW and 18kW models may be easier to accommodate, though it still requires a 40A circuit breaker. The listing says the heating elements are separated from water and lists leakage and overheat protection. The compact body may work well in a utility area, but no outdoor-weather rating is provided.
Compared with the CAMPLUX, the Ranein has a higher listed maximum flow and a higher power rating. Neither figure alone guarantees an adequate shower: the listing does not give a temperature-rise value at a particular flow, so check the product documentation and your incoming water temperature before deciding.
Pros:
- LED temperature display and simple knob controls.
- Temperature adjustment in 1°F increments.
- Compact wall-mounted design.
- Listed 1.9 GPM maximum flow.
Cons:
- Requires a 40A circuit breaker.
- Temperature-rise performance at a specific shower flow is not provided in the supplied listing details.
Verdict: The Ranein is a reasonable compact option for a modest-flow shower if its actual temperature output suits your water conditions and you can provide the required circuit.
How to Choose an Electric Tankless Water Heater for an Outdoor Shower
Estimate the temperature rise you need
Temperature rise is the difference between the incoming water temperature and the temperature you want at the shower. For example, if your supply water is cold, the heater must raise it more than it would in a warm climate. A unit’s maximum GPM does not tell you by itself how much hot water it can deliver at your desired temperature. Look for flow information tied to an inlet temperature and target output, then compare it with your shower’s expected flow.
Match the heater to your shower flow
Showerheads use different amounts of water, and a higher-flow shower needs more heating capacity. If a listing gives only a maximum flow rate without the water temperature conditions, treat that number as a limit—not a promise of comfortable hot-shower flow. For a low-flow outdoor shower, a smaller unit may work in suitable conditions; for colder water or more flow, a higher-power model may be needed. Confirm performance with the manufacturer’s sizing information before buying.
Check the electrical service first
These heaters can draw a large amount of power. The models here range from 6kW to 18kW, with requirements such as a 30A breaker, a 40A breaker, a 46A connection, or the NOVIEEX’s specified dual-breaker arrangement. Those details are model-specific. Ask a qualified electrician to check your panel, wiring, breaker capacity, and local requirements before you purchase or install a unit.
Plan for a protected installation location
An outdoor shower does not mean the heater itself should be mounted where it is exposed to rain or spray. The electric models in this roundup are not identified as outdoor-rated. Check the installation manual for approved locations and required clearances, and plan for a dry, protected mounting spot with plumbing routed to the shower. An electrician can advise on required disconnects and ground-fault protection under local rules.
Consider winterizing and freezing conditions
Outdoor shower plumbing and a water heater can be at risk in freezing weather. Before choosing a location, consider how you will drain or protect the water lines and follow the heater maker’s instructions for cold-weather shutdown and storage. Do not assume a compact electric unit can safely remain outdoors through freezing temperatures simply because the shower is seasonal.
Choose controls and connections that fit your setup
Digital controls can make it easier to set a target temperature, while Wi-Fi features may be useful if you want remote adjustment. Also check the plumbing connections: the listed models use different connection details, including 1/2-inch and 3/4-inch NPT. Confirm that your plumbing layout and fittings match the specific unit, and use a qualified installer if the connections or electrical work are unfamiliar.
Decide whether propane is an option
If mounting the heater outdoors is a priority, the Rinnai V53DeP is the only product here described as designed for outdoor installation—but it uses propane. A propane model may suit a property with an appropriate fuel supply and professional installation. If you want electric only, focus on an electric unit installed in a suitable protected location rather than treating the Rinnai as an electric alternative.
Frequently Asked Questions
Can I install an electric tankless water heater outside?
Do not assume these models can be exposed to outdoor weather. The supplied product details do not identify the electric units as outdoor-rated. Check the installation manual and local code, and plan for a protected location unless the manufacturer explicitly approves another setup.
Which electric heater is best for an outdoor shower?
There is no single best choice for every shower. The Westinghouse provides flow information at two inlet temperatures, while the NOVIEEX has the highest listed power but also the most demanding electrical requirements. Compare temperature rise, actual shower flow, and available electrical service before choosing.
Will a 6kW heater provide a comfortable outdoor shower?
It depends on the incoming water temperature and shower flow. The CAMPLUX listing states a 50°F temperature rise at 1.0 GPM. If your water is colder or your shower uses more water, that output may not reach your preferred temperature.
Does a higher GPM rating mean more hot shower water?
Not necessarily. GPM should be considered alongside the heater’s temperature rise and the incoming water temperature. A maximum-flow figure without those conditions may not describe how much comfortably warm water the heater can provide.
Can I use a regular outdoor showerhead with these heaters?
Only if the heater can maintain the desired outlet temperature at the showerhead’s flow rate. Check the showerhead flow and compare it with the heater’s temperature-dependent capacity. A lower-flow showerhead may help when heating capacity is limited.
Is the Rinnai V53DeP an electric water heater?
No. It is a propane tankless water heater. It is included as an outdoor-installation alternative for shoppers who are open to gas, not as an electric pick.
Do I need an electrician to install one?
Professional help is strongly advisable for these hardwired, high-power appliances. The correct circuit, wiring, protection, and installation location depend on the model and your home’s electrical system. Have a qualified electrician verify the requirements before purchase and installation.
Final Recommendation
For an electric outdoor-shower setup, start by matching the heater’s temperature rise and flow to your water supply and showerhead, then confirm that your electrical panel can support the required circuit. The Westinghouse 11kW is a useful option when its listed temperature-dependent flow fits your needs and you value precise controls. The NOVIEEX offers higher listed power but calls for a substantial electrical installation. If you specifically want a heater designed to sit outdoors, the Rinnai is the relevant alternative here—but it runs on propane, not electricity.
