Never Run Out of Hot Water: Rinnai Demand Duo H-Series CHS398100HCXViN Commercial Hybrid Water System

The Rinnai Rinnai CHS HCX Series (CHS398100HCXVIN) is a commercial hybrid water heating system that pairs a 119-gallon storage tank with two 199,000 BTU tankless engines, delivering 398,000 BTU combined and a First-Hour Delivery of up to 551 gallons at a 100°F rise. Because the tankless engines do the actual heating rather than a burner inside the tank, there's no thermal stress wearing down the tank over time, which means a longer service life than a standard high-efficiency commercial tank. The two tankless units also provide built-in redundancy, so a service issue with one engine doesn't mean a "no hot water" event for the whole building. It's built for restaurants, hotels, office buildings, spas, and healthcare facilities that can't afford to run out of hot water during peak demand.

Key Features

Hybrid Redundancy That Prevents Downtime

With two independent 199,000 BTU tankless engines feeding the 119-gallon tank, this hybrid water system keeps producing hot water even if one engine needs service, which is exactly the kind of downtime that costs a hotel or restaurant real money. The 551-gallon First-Hour Delivery gives it the buffer to absorb sudden demand spikes without a lag in recovery.

High Efficiency Without the Trade-Offs

A 0.98 Uniform Energy Factor and 97% thermal efficient CX199 tankless engines put this system well ahead of a conventional commercial tank on operating cost. It's also Ultra Low NOx compliant and ENERGY STAR certified, which can help facilities meet stricter regional emissions requirements.

Smart Control, No Aquastat Needed

The DuoSmart Digital Controller manages temperature precision and recirculation electronically, eliminating the aquastat that traditional tanks rely on and giving facility managers tighter control over performance. Wi-Fi capability adds remote monitoring, so problems can be caught before they turn into a service call.

Designed for Faster, Easier Installation

The Gas Swivel Flex Line rotates a full 360 degrees with a 36-inch, 180-degree radius, which makes lining up the gas connection far less of a headache during install. A factory-installed gas dirt leg, ready electrical access, and preassembled condensate drain cut down on the fieldwork needed, and at roughly 37% lighter than a comparable high-efficiency tank, it's easier to maneuver into mechanical rooms.

Product Details

• 119-gallon tank with two 199,000 BTU tankless engines (398,000 BTU combined)
• First-Hour Delivery up to 551 gallons at a 100°F rise
• 0.98 Uniform Energy Factor
• 97% thermal efficient CX199 tankless engines
• ENERGY STAR certified
• Ultra Low NOx, SCAQMD compliant
• DuoSmart Digital Controller, no aquastat required
• Recirculation capable
• Wi-Fi capable for remote monitoring
• Gas Swivel Flex Line for flexible gas hookup
• As much as 37% lighter than a comparable high-efficiency tank
• Redundant tankless engines reduce risk of "no hot water" downtime
• 6-year tank warranty, 8-year heat exchanger warranty, 5-year parts warranty

Rinnai has been innovating home and water heating since 1920, offering high-efficiency tankless water heaters, boilers, and HVAC systems.

Additional Information

• Brand: Rinnai
• MPN: CHS398100HCXViN
• Series: Demand Duo H-Series (CHS-HCX2)
• Product Type: Commercial hybrid tank-tankless water heating system, vertical configuration
• Tank Capacity: 119 gallons
• Max Input: 398,000 BTU (two 199,000 BTU tankless engines), 15,000 BTU minimum
• Fuel Type: Natural gas
• Dimensions: 33" W x 79" H x 40" D
• Weight: 530 lb
• Connections: 1-1/2" MNPT gas, 1-1/2" MNPT hot and cold water
• Electrical: 120V, 60Hz

Rinnai CHS398100HCXViN FAQ

What size commercial application is the CHS398100HCXViN designed for?

With a 551-gallon First-Hour Delivery and 398,000 BTU combined output, this system is built for mid-to-large commercial applications like restaurants, hotels, office buildings, spas, and healthcare facilities where hot water demand spikes unpredictably throughout the day. If your building's peak demand is lower, Rinnai's smaller Demand Duo configurations or a single Sensei CX tankless unit may be a better fit and a lower upfront cost.

How does the hybrid tank-tankless design prevent "no hot water" events?

Instead of one burner heating the tank directly, the CHS398100HCXViN uses two independent 199,000 BTU tankless engines to heat the water before it reaches the 119-gallon tank. If one tankless engine needs service, the other keeps producing hot water, so a single component issue doesn't take the whole system offline the way it would with a traditional single-burner tank.

What's the difference between this vertical model and the horizontal or ASME versions in the H-Series lineup?

The CHS398100HCXViN is the vertical, standard-tank configuration, which has a smaller footprint but a taller overall height at 79 inches. Rinnai also offers horizontal configurations for lower-clearance mechanical rooms and ASME-certified tank versions for facilities like hospitals that require ASME-rated pressure vessels, so the right variant depends on your ceiling height and any code requirements for your building type.

What are the gas and water connection requirements for installation?

The system connects via 1-1/2" MNPT for both the gas supply and the hot and cold water lines. The Gas Swivel Flex Line rotates a full 360 degrees with a 36-inch, 180-degree radius, which gives installers real flexibility in lining up the gas connection without having to reroute existing piping.

What's covered under the Demand Duo H-Series warranty?

The CHS398100HCXViN carries a 6-year warranty on the tank, an 8-year warranty on the heat exchanger, and a 5-year warranty on parts and components, which is roughly double the warranty length of most standard commercial tanks. If you have questions or need assistance sizing your pump, then the Plumbing Deals team can help! Use the live chat feature, email at contact@plumbingdeals.com, or give us a call at 888-682-5956!

Weight	890.0 lb
Collection	CHS HCX Series
Height	81.10 in.
Horse Power	1/3
Length	36.00 in.
Room	Utility
Width	28.30 in.
Inventory Number	RINCHS398100HCXVIN
MPN	CHS398100HCXVIN

• Spec Sheet
• Installation Guide
• Owner's Manual
• Warranty
• Rebate Flyer