Spring into Hot Water: 20 Best 20 Gallon Water Heaters for Reliable Home Heating

A 20-gallon water heater provides a practical balance of capacity and efficiency for many homes and applications. This guide evaluates the most reliable 20-gallon water heaters available in the market, comparing their energy efficiency, durability, and value to help you make an informed choice.

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Reviews

Richmond 6EP20-1 20 Gallon Electric Water Heater

This Rheem water heater packs 2,000 watts of heating power into a space-efficient design that fits easily in tight spots. At just 69 pounds, it’s surprisingly light for its capacity. The automatic thermostat helps keep your water temperature consistent, while the over-temperature protector adds an important layer of safety. Overall, it’s a reliable 20-gallon option that’s built to last.

SEAWARD S1900 20-Gallon Marine Water Heater

This reliable marine water heater serves up 20 gallons of hot water for boats, leveraging both dockside 120V power and engine heat for operation. The stainless steel case and aluminum tank construction make it a solid choice for marine environments, though adding a magnesium anode helps extend the tank’s lifespan against corrosion. The front-mounted heat exchanger keeps installation straightforward, making it a practical upgrade for any boat’s hot water needs.

Attwood HF2000 20 Gallon Water Heater

This compact water heater packs a powerful punch, efficiently maintaining 20 gallons of hot water for on-demand use. The double-walled front heat exchanger keeps things safe while the welded aluminum tank ensures lasting performance. With straightforward installation and reliable UL approval, it’s a solid choice for marine or RV applications.

Raritan 172002 20-Gallon Water Heater

This reliable 20-gallon water heater keeps boaters warm with its efficient heating system, whether you’re out on the water or docked at your marina. The solid foam insulation keeps your water hot, and the built-in engine heat exchanger warms your tanks quickly when you’re underway. With adjustable thermostats and proven Raritan durability, this heater has been keeping boats stocked with hot water since 1986.

Raritan 20-Gallon Hot Water Heater

Built for longevity with a 75 PSI safety valve and dense foam insulation, this 20-gallon heater offers reliable hot water for both galley and shower. The round tank design handles more pressure than conventional cubes, while the compact footprint keeps your engine room spacious. The adjustable thermostat lets you fine-tune the water temperature between 110° and 160° F, automatically shutting off at 190° F for peace of mind.

Raritan 20-Gallon Water Heater

This 20-gallon water heater maintains consistent temperature with its dense foam insulation, which retains heat better than traditional fiberglass tanks. The temperature and pressure relief valve operates at 75 psi for added safety. Its cylindrical design withstands higher pressure than a cube-shaped alternative, making it a reliable addition to any setup.

American PMDH-20 Water Heater Tank

This pump tank stores 20 gallons of water and maintains 25 PSI pressure, helping your dishwasher, washing machine, and showers run smoothly. It runs for at least a minute each cycle, as pump manufacturers recommend, and reduces the number of cycles throughout the day to help prolong pump life.

GE 18 Gallon Side Port Lowboy Electric Water Heater

At just 18 gallons, this water heater doesn’t tower over your space like some electric models do, making it perfect for bathrooms or laundry rooms where height is limited. While it’s not the biggest heater you can get, the two powerful 5500W elements mean it’ll have your shower or laundry done in no time. Setting up is a breeze too – it uses standard connections for both water and electricity, so hooking it up should be pretty straightforward.

SEAWARD Marine Water Heater

This reliable marine water heater efficiently delivers hot water thanks to its robust aluminum construction and powerful 1500-watt heating element. The durable marine-grade stainless steel exterior jacket protects the unit during harsh ocean conditions, while the convenient horizontal design saves valuable space in tight installations. The safety features, including the pressure relief valve and easy-to-use controls, provide peace of mind during even the most challenging sea conditions.

Raritan 20-Gallon Water Heater

This reliable water heater has earned solid praise from its users who’ve put it to work on everything from sailboats to personal yachts. The dense foam insulation keeps the water hot, and the cleverly coiled heat exchanger provides instant hot water without taking up much space. The compact design fits snugly in tight engine rooms, and the straightforward installation makes it a practical choice for both new installations and replacements.

Rheem EGSP20 Electric Water Heater

The Rheem EGSP20 packs impressive features into its efficient design, from its durable porcelain-enamel lining to its smart temperature control system. With commercial-grade reliability and energy-saving insulation, it delivers hot water with minimal maintenance, though some users have noted the occasional reliability issues with the REVIT model.

Seaward Marine Water Heater

This marine-grade water heater delivers consistent hot water in any weather, thanks to its robust aluminum construction and marine-stainless steel exterior. The welded mounting brackets and double-wall heat exchanger ensure durability in harsh conditions, while the space-saving horizontal design and 120V power make it a practical addition to any boat or marine installation.

Rheem PROE20 1 RH Pou Electric Water Heater

This compact water heater delivers on-demand hot water for small spaces or point-of-use applications. With a 19.9-gallon tank and 2,000-Watt heating element, it provides plenty of hot water for single applications like sink faucets or_shop tools. The Rheem PROE20 mounts easily on walls and includes essential safety features like temperature and pressure relief valves. While some users appreciate its quiet operation in workshops, others find it noisy in residential settings. Overall, it’s a practical solution for homes or businesses where space is limited and consistent hot water is needed.

AO Smith DEL-20S Commercial Electric Water Heater

This 20-gallon AO Smith water heater delivers commercial-grade performance with its glass-lined tank and durable construction. The lowboy design keeps it compact while the dual-element system ensures consistent water temperatures. The temperature control range goes from 110° to 170°F, giving you plenty of flexibility for different water heating needs.

Kuuma 11871 20 Gal. Water Heater

A 20-gallon marine water heater that fits the bill for providing hot water on boats. The aluminum unit measures a practical 16x16x34 inches and packs 1500 watts of heating power. While the front heat exchanger and bracket system are nice touches, the repeated damage reports raise some red flags about the product’s durability.

Marathon 20 Gallon Electric Water Heater

This Rheem Marathon water heater combines a durable fiberglass tank with a plastic body for lasting performance without the maintenance of traditional steel tanks. The 50-gallon capacity model offers efficient 21-gallon-per-hour recovery and comes with a lifetime leak warranty. While some customers report minor installation challenges like wobbling due to its lightweight design, many appreciate the reduced maintenance compared to conventional heaters.

AO Smith EJCT-20 20-Gallon Compact Electric Water Heater

This compact electric water heater doesn’t compromise on performance despite its small footprint – with a 19-gallon tank and 2500-watt heating element, it delivers hot water efficiently enough for a family home. The durable blue diamond glass lining and reliable single-element design have earned it a solid reputation among homeowners who appreciate its quiet operation and energy-efficient R8 insulation. While occasional shipping mishaps have popped up in reviews, most customers find this A. O. Smith heater to be a dependable upgrade for their hot water needs.

Isotemp 20 Gal. Marine Water Heater

This marine-grade water heater packs a powerful 750 watts into its 16-inch diameter tank, delivering plenty of hot water for your boat or RV. The clever design keeps the heating element in the cold water zone for even temperature distribution, while the included temperature mixing valve prevents scalding at the tap. At just 64 pounds, it’s a surprisingly lightweight addition to your plumbing system.

AO Smith EJCS-20 ProMax Water Heater

Compact enough for under-counter installation, this 19-gallon electric water heater delivers fast recovery with its 2500-watt element. Users appreciate its slim profile and convenient top and side connection ports, though some note the wire nut connection space is tight. The blue diamond glass-lined tank and reliable Dr. Diamond heating elements have earned consistent praise from customers who appreciate the consistent hot water and efficient performance.

GE 20-Pint Electric Water Heater

This compact electric water heater lives up to its space-saving promise, fitting effortlessly into tight quarters like bathrooms and laundry rooms. Its 18-gallon capacity delivers on-demand hot water, perfect for short showers or small household needs. The simple 120-volt installation makes it a practical choice for both new installations and water heater upgrades.

Buyer’s Guide

A 20-gallon water heater provides moderate hot water capacity for households with 2-3 bathrooms. When selecting a 20-gallon water heater, consider these factors to find the right fit for your home.

Size and Capacity

While the tank size is fixed at 20 gallons, check the model’s recovery rate - the number of gallons heated per hour. A typical 20-gallon unit has a recovery rate of 2-3 gallons per minute, suitable for standard household needs.

Energy Efficiency

Look for an energy-efficient model with a high Energy Factor (EF) rating. Consider the heating method: tankless heaters offer better efficiency but higher upfront costs. Check for ENERGY STAR certification to ensure optimal energy performance.

Installation and Location

Measure your available space to confirm the water heater will fit. Consider the floor load capacity and accessibility for maintenance. Some models are designed for wall-mounting to save floor space.

Additional Features

Consider features like thermostats with temperature controls, electronic ignition for natural gas models, and temperature sensors. Some units offer digital displays for easier monitoring of water temperature and usage.

FAQ

Do 20-gallon water heaters provide enough hot water for my needs?

A 20-gallon water heater typically provides 12-15 minutes of showering, which may be sufficient for small households or for spot heating needs. For household size estimates, each member requires about 1.5 - 2 gallons per daily shower.

These heaters are ideal for single occupants, couples, or small families with moderate usage. If more than 2 people will be showering daily or if you need multiple hot water appliances running simultaneously, consider a larger capacity model.

What is the difference between gas and electric 20-gallon water heaters?

Gas water heaters generally heat water faster than electric models and are more cost-effective for large homes. They require a nearby gas line and vent for exhaust. Installation costs about $1,000 - $1,500.

Electric models are more energy-efficient, cheaper to install (around $700 - $900), and require only a standard electrical outlet. They heat water through electric resistance elements and provide reliable performance in any home with adequate electrical capacity.

How long do 20-gallon water heaters typically last?

With regular maintenance, a 20-gallon water heater typically lasts 8-12 years. Factors affecting longevity include usage frequency, water quality, and maintenance practices. Replace sacrificial anodes annually to prevent corrosion and check for leaks at least twice yearly.

The tank will eventually develop sediment buildup and small leaks, which can significantly reduce heating efficiency. Monitor temperature fluctuations and sediment levels to determine when replacement is necessary.

Are 20-gallon water heaters suitable for whole house heating?

While a 20-gallon tank can supply hot water for an entire home, it is insufficient for whole-house heating. Most homes require at least two 20-gallon units to maintain consistent hot water pressure and supply.

Smaller households can use these heaters for specific needs like kitchen sinks, laundry, and single bathrooms. For comprehensive home heating, consider tankless or larger tank-based systems that efficiently manage overall hot water demand.

How much space do I need for a 20-gallon water heater?

A standard 20-gallon water heater requires about 18 inches of floor space and 30 inches of wall clearance for proper ventilation. Allow 36 inches of space above the unit for maintenance access and ensure nearby surfaces can handle the weight (80-120 lbs fully loaded).

Consider installing the unit in a utility closet, laundry room, or designated HVAC space where temperature ranges stay between 40-90°F. Avoid direct sunlight and unheated garage locations to prevent tank freeze damage.

What maintenance is needed for a 20-gallon water heater?

Check the pressure relief valve and temperature/pressure relief valve annually to ensure they’re functional. Drain 1/4 to 1/2 gallon of water from the tank monthly to remove sediment and prevent mineral buildup that can affect heating efficiency.

Inspect the heating elements or burners every six months for proper function, and clean the heating elements or burners as needed to remove scale or debris. Replace the anode rod every 3-5 years or when less than 1 inch of aluminum remains to prevent tank corrosion.

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