If your installation requires a water heater with a 17-inch diameter, verify the exact product dimensions before buying: none of the supplied product details confirms a 17-inch diameter. The five options below offer compact storage, point-of-use, or tankless designs, but they are not interchangeable. The GE and ThermoMate models are 18-gallon tanks; the Rheem and WINTEMP are tankless; and the immersion heater is portable. Compare the tank’s complete dimensions and the available installation space, including clearance for plumbing and service.
| Product | Type | Best suited for | Dimension information provided |
|---|---|---|---|
| GE Appliances 18 Gallon | Storage tank | Small spaces needing stored hot water | No dimensions provided |
| Rheem 18kW | Tankless | On-demand hot water with digital control | No dimensions provided |
| ThermoMate 18 Gallon | Point-of-use storage tank | Nearby sinks or a small hot-water demand | 25.5-inch low-profile height listed |
| Portable immersion heater | Submersible portable heater | Heating water in a container | No dimensions provided |
| WINTEMP 18kW | Tankless | Continuous-flow household use where electrical service allows | 11.1 × 19.2 × 4 inches listed |
GE Appliances 18-Gallon Electric Water Heater
Best for: Buyers looking for a compact storage-tank option to serve one hookup or a small home, condo, or apartment. Its 18-gallon capacity provides stored hot water, while the adjustable thermostat lets the user set the temperature.
The listed features describe a 120-volt unit with standard 3/4-inch NPT water connections. GE says it can connect to an existing 120-volt supply and existing plumbing, making it a candidate for limited spaces such as a kitchen, bathroom, laundry room, cabin, garage, or shed. The stated installation flexibility is useful when a full-size water heater is impractical.
Why it was selected: It combines an 18-gallon tank with a compact-use positioning and 120-volt connection details. That makes it relevant for buyers comparing small electric storage heaters rather than portable heaters or tankless units.
Limitation: The supplied information gives no physical dimensions, so it does not confirm a 17-inch diameter. Check the manufacturer’s dimensional drawing and required clearances before choosing it for a measured opening.
Rheem 18kW Tankless Electric Water Heater
Best for: Buyers who prefer an on-demand tankless design with a digital temperature display instead of a storage tank. This 18kW model has external digital thermostatic control and an LED display, with the listed control accuracy of plus or minus one degree.
Rheem describes the unit as self-modulating, meaning it adjusts power to meet hot-water demand. The listed maximum flow rate is up to 4.4 gallons per minute. Its two copper immersion heating elements are described as durable and field-serviceable.
Why it was selected: It provides a tankless alternative for shoppers comparing electric water-heater types for a space-constrained installation. A tankless unit may have a different shape and mounting arrangement from a cylindrical tank, so its full product dimensions should be checked against the available space.
Limitation: The supplied details do not state the unit’s dimensions or required electrical circuit specifications. Do not assume it will fit a 17-inch opening or that an existing electrical service can support it; confirm installation requirements first.
ThermoMate 18-Gallon Point-of-Use Heater
Best for: Buyers who need stored hot water close to a sink, washing appliance, or other point of use. ThermoMate lists an 18-gallon capacity, a 120-volt, 1,500-watt rating, and a built-in adjustable thermostat. The factory setting is 125°F, and the stated adjustment range is 90°F to 150°F.
The product is described as a 25.5-inch low-profile tank that can be installed independently or used as a booster in line with a larger hot-water source. Listed settings include kitchens and bathrooms, as well as RVs, boats, cabins, campers, garages, barns, shops, and salons. Its Incoloy-800 heating element is identified in the product information.
Why it was selected: It is one of the clearest options in this group for a compact point-of-use tank, and its listed height helps buyers begin a space check.
Limitation: The 25.5-inch figure is the height, not the diameter. The listing describes it as hard-wired, so buyers should confirm the required electrical installation and full dimensions before purchase.
Portable 2000W Immersion Water Heater
Best for: People who need to heat water in a bucket or other suitable container rather than install a household water heater. This portable immersion heater is rated at 2,000 watts and 110–125 volts. Its listed features include a 304 stainless-steel guard and an LCD thermometer.
The product information says it can heat up to five gallons of water in minutes, though actual heating time depends on the amount and starting temperature of the water. It is intended for water only. The instructions specify that the heater must be fully immersed before it is connected to power.
Why it was selected: It is the most portable option in the list and may suit occasional, container-based hot-water needs when a permanently installed tank or tankless heater is not the intended solution.
Limitation: This is not a replacement for a plumbed residential water heater and does not meet the usual need for a heater with a defined 17-inch diameter. Follow the product’s operating instructions and do not heat liquids other than water.
WINTEMP 18kW Wi-Fi Tankless Heater
Best for: Buyers seeking a tankless heater for showers and household use who can meet its stated electrical requirements. The listed dimensions are 11.1 inches wide, 19.2 inches high, and 4 inches deep, with 3/4-inch NPT water connections. The maximum listed hot-water output is 4.3 gallons per minute.
WINTEMP says the unit adjusts power according to incoming water temperature, water flow, and the selected temperature. Its product information recommends a 150-amp household service and specifies a maximum current of 75 amps, two 40-amp double-pole breakers, and 2 × 8/2 AWG wiring. It advises consulting a qualified electrician before purchase.
Why it was selected: Unlike the other products here, this listing provides the unit’s width, height, and depth, which can help with an initial space comparison. It is a wall-mounted-style tankless alternative rather than a cylindrical 18-gallon tank.
Limitation: Its stated width is 11.1 inches, not a 17-inch diameter, and the listed electrical requirements may be a major installation constraint. Confirm the exact mounting and clearance requirements as well as the home’s electrical capacity.
Buying Guide: How to Choose a Heater for a 17-Inch Space
Does “17 inches” mean diameter, width, or clearance?
Measure the space and identify exactly what the 17-inch limit describes. A cylindrical tank’s diameter is different from its height, while a tankless unit is generally described by width, height, and depth. Also measure the usable opening and account for plumbing connections, electrical access, mounting, and any manufacturer-required service clearances. Product images are not a reliable way to determine fit.
For the products in this list, only the WINTEMP listing provides three external dimensions: 11.1 × 19.2 × 4 inches. The ThermoMate listing provides a 25.5-inch height but not its diameter. The other supplied descriptions do not give overall dimensions. Ask the seller or manufacturer for a dimensional drawing when the fit is close.
Should you choose a storage tank or tankless heater?
A storage tank holds a set amount of heated water. The GE and ThermoMate models each list an 18-gallon capacity, making them more relevant when stored hot water is part of the requirement. A tankless heater warms water as it flows through the unit and does not store a stated tank volume. The Rheem and WINTEMP models are 18kW tankless options.
Do not compare tank capacity and tankless flow rate as if they were equivalent measures. Consider how many fixtures may need hot water at once, the incoming water temperature, and the expected flow. A product’s maximum flow figure does not by itself guarantee a particular temperature at every fixture.
What electrical requirements should you check?
Match the unit to the home’s voltage, wiring, breaker capacity, and available service. The GE listing describes a 120-volt connection. ThermoMate specifies 120 volts and 1,500 watts and describes the unit as hard-wired. The WINTEMP listing gives detailed high-amperage requirements and recommends qualified electrician consultation. The Rheem information provided here does not specify its circuit requirements.
Never assume that two heaters with the same kilowatt rating have identical installation needs. Consult the current manufacturer instructions and a qualified electrician where required. A unit that fits physically may still be unsuitable for the home’s electrical system.
Is a portable immersion heater suitable for a home installation?
No. The immersion heater listed here is designed to heat water in a container, not to connect to household plumbing as a conventional water heater. It may suit occasional portable use, but it is not comparable to an 18-gallon storage tank or an installed tankless system. Use it only as directed, including fully immersing the heating element before connecting power.
What should you confirm before ordering?
- Dimensions: Get the complete width, height, depth, or diameter—not just a low-profile height or a product photo.
- Clearance: Check room for water connections, wiring, access, and service.
- Water demand: Compare tank capacity or tankless flow to the intended fixtures and use.
- Installation type: Determine whether the unit is a storage tank, tankless heater, point-of-use booster, or portable immersion heater.
- Utilities: Confirm voltage, breaker, wiring, plumbing connections, and any requirements in the manufacturer’s installation documentation.
- Use location: Check whether the product is intended for the planned residential or other application.
Frequently Asked Questions
Which product listed here is confirmed to have a 17-inch diameter?
None of the supplied product descriptions confirms a 17-inch diameter. The WINTEMP listing gives width, height, and depth, while the ThermoMate listing gives a height. Check the manufacturer’s dimensional drawing for any model being considered.
Is the ThermoMate heater 17 inches in diameter?
The supplied listing does not state its diameter. It describes the heater as 25.5 inches tall. That height cannot be used to confirm the diameter or whether the unit fits a 17-inch opening.
Which listed products are storage-tank water heaters?
The GE Appliances and ThermoMate products are listed as 18-gallon electric storage-tank heaters. The Rheem and WINTEMP models are tankless, and the immersion heater is portable.
Can an 18kW tankless heater run on a standard 120-volt outlet?
Do not assume that it can. The WINTEMP listing specifies 240 volts and substantial circuit requirements. The supplied Rheem details do not state its electrical specifications, so consult its installation documentation before planning a circuit.
What is the best choice for a small sink or point-of-use location?
The ThermoMate is specifically described as a point-of-use 18-gallon heater and can also be used as a booster, according to its listed features. Confirm its full dimensions, hard-wiring needs, and fit before buying.