For a true 100-gallon gas water heater, compare the Rheem G100-400A and Rheem G100-270: both are gas tank models, while the 400A has the higher listed burner input. The MIZUDO and Ranein are gas tankless alternatives, not 100-gallon tanks. The listed Rheem 50-gallon model is electric, so it does not meet the gas or capacity requirement.
| Product | Type | Best For |
|---|---|---|
| Rheem G100-400A | 100-gallon natural gas tank | High-demand commercial applications |
| Rheem G100-270 | 100-gallon gas tank | Buyers seeking a 100-gallon gas model |
| MIZUDO Tankless | Natural gas tankless | Homes considering a space-saving alternative |
| Ranein Tankless | Natural gas tankless | Higher stated flow-rate needs |
| Rheem PROE50 M2 | 50-gallon electric tank | Electric replacement shoppers only |
Rheem G100-400A 100-Gallon Natural Gas Heater
Best for: Commercial or other high-demand applications that need a large storage tank and substantial burner input. The listed 399,000 BTU rating is the highest specified among the tank models in this selection.
The product features a universal tank design and a universal space-saver design. Those features may be relevant when evaluating a replacement or planning equipment placement, but confirm the unit’s dimensions and installation requirements before purchase.
Why it was selected: It directly matches the 100-gallon gas search and provides a clearly stated capacity and BTU rating. Limitation: This is a large-input commercial model; verify that the building’s gas supply, venting, and installation site are suitable with a qualified professional.
Rheem G100-270 100-Gallon Gas Water Heater
Best for: Buyers who specifically want a 100-gallon gas tank and are comparing a second Rheem option. Its product listing identifies it as a 100-gallon, 270,000-BTU gas tank water heater.
Why it was selected: It is one of the few supplied products that matches both the requested fuel type and tank capacity. Compared with the G100-400A, its listed BTU input is lower, a distinction buyers can use when discussing recovery needs and gas capacity with an installer.
Limitation: The supplied features do not provide further details about venting, dimensions, efficiency, or recovery rate. Confirm the full manufacturer specifications and local installation requirements before choosing it.
MIZUDO 120,000-BTU Natural Gas Tankless Heater
Best for: Buyers open to a tankless alternative who want app controls and flexible installation options. This natural gas model lists a maximum flow of 5.1 GPM and is described for two to four outlet points.
Its features include Wi-Fi and app control for temperature settings, energy-use monitoring, and maintenance notifications. The listing also describes indoor or outdoor conversion with accessory kits and temperature stability within 1°F through flow monitoring and gas modulation.
Why it was selected: It offers a different way to address hot-water demand without a 100-gallon storage tank. Limitation: It is not a 100-gallon heater, and outdoor conversion kits are purchased separately. Check the listed flow capacity against simultaneous household use.
Ranein 8.5-GPM Natural Gas Tankless Heater
Best for: Buyers comparing tankless units with a higher stated flow rate. The listing specifies 8.5 GPM, 190,000 BTU, indoor installation, and use for four to six water points.
The described features include on-demand hot water, a wall-mounted compact body, anti-freeze protection, and a blower that adjusts its speed in response to external wind pressure and water temperature. The unit uses standard 3/4-inch NPT water inlet fittings, according to the listing.
Why it was selected: It is a natural gas option for shoppers who may prefer a tankless format over a large storage tank. Limitation: It is not a 100-gallon tank. Confirm venting, gas supply, and site requirements before installation.
Rheem PROE50 M2 50-Gallon Electric Heater
Best for: Buyers who are actually shopping for a 50-gallon electric replacement, not a 100-gallon gas heater. The listing describes it as suitable for households with three to five people or homes with three or more bathrooms.
Features include an enhanced-flow brass drain valve, automatic thermostat, anode rod, and a space-saving design for replacement situations. It is listed at 18.75 amps.
Why it was selected: It helps distinguish a nearby search result from the requested product category. Limitation: It is electric and half the requested tank capacity, so it is not a direct substitute for a 100-gallon gas model.
Buying Guide: How To Choose A 100-Gallon Gas Water Heater
Do you need a tank or a tankless unit?
A 100-gallon tank stores hot water for later use. A tankless heater warms water on demand and is specified by flow rate rather than storage capacity. Compare the product type as well as the fuel: the MIZUDO and Ranein are gas tankless models, not 100-gallon tanks.
How should you compare BTU input?
BTU input indicates the burner’s rated heat input, but it does not by itself establish recovery performance or suitability. The listed Rheem tank models are rated at 399,000 BTU and 270,000 BTU. Ask an installer to assess hot-water demand, gas supply, and the manufacturer’s full specifications.
What installation details matter?
Before ordering, confirm available space, access for moving the heater, venting configuration, gas-line capacity, and applicable local codes. Large gas equipment should be assessed and installed by a qualified professional. For tankless models, also compare flow rate with the number of fixtures likely to operate at once.
Is a 100-gallon tank right for your building?
Choose capacity based on peak demand and recovery needs, not household size alone. A large storage tank may suit some high-demand uses, while a tankless system may fit buyers prioritizing a compact format. Compare the complete specifications and have a professional size the system for the property.
Frequently Asked Questions
Which listed product is a 100-gallon gas water heater?
The Rheem G100-400A and Rheem G100-270 are the listed 100-gallon gas tank options.
What is the difference between the two Rheem 100-gallon models?
The supplied product information lists 399,000 BTU for the G100-400A and 270,000 BTU for the G100-270. Compare their complete specifications and installation requirements before deciding.
Are the MIZUDO and Ranein 100-gallon heaters?
No. They are natural gas tankless water heaters. Their listings specify flow rates, not 100-gallon storage capacity.
Is the Rheem PROE50 M2 a gas model?
No. It is a 50-gallon electric water heater, so it does not match a 100-gallon gas requirement.
Should I install a large gas water heater myself?
Have a qualified professional verify gas supply, venting, placement, and local code requirements. The correct installation depends on the specific unit and building.