Rinnai CHS199100H Demand Duo H-Series Hybrid Water Heating System

Commercial only. The Demand Duo H-Series CHS199100H is a commercial water heating system, pairing a 119 gallon tank with a 199,000 BTU tankless unit. For a multi-family common laundry, a restaurant, a gym, or a hotel it's the right class of equipment. For a single-family home it is oversized and outside its rated application.

First hour delivery is 317 gallons at a 100 degree F rise. That's the number to size against for a peak-load hour, showers in a hotel or a morning rush in a locker room. The tankless side fires at up to 199,000 BTU/h and modulates down to 15,000 BTU/h, so it keeps recovering through the peak instead of draining a tank and waiting.

Gas is 3/4 inch MNPT and the water connections are 1-1/2 inch MNPT. The gas side comes with a swivel flex line that rotates 360 degrees and gives a 36 inch, 180 degree radius to reach the supply, plus a factory installed dirt leg, so you have some latitude on where the gas stub lands.

Both. The gas type is a specify-at-order choice: CHS199100HiN is the natural gas build and CHS199100HiP is the propane build. They are separate factory configurations, so pick the one that matches the fuel at the site.

Polypropylene, PVC, or CPVC. Sizes are 2 inch, 3 inch, 2x4 inch and 3x5 inch (50 mm, 80 mm, 50x100 mm, 80x130 mm). It will run concentric, twin pipe, room air, or common vent, so a mechanical room with an existing common vent stack or a sidewall concentric termination are both on the table.

Recirculation is supported and no aquastat is required. The DuoSmart digital controller handles both temperature setpoint and recirculation control on board, and the pump is part of the system. That removes the aquastat-and-timer stack you'd wire up on a conventional tank with a return loop.

Standard setpoint range is 98F to 140F, and the unit's full DHW range runs 98F to 185F. Anything above the standard band is a high-temperature application (sanitizing dish machines, laundry) and needs the appropriate mixing and scald protection downstream for any fixture serving occupants.

120 volt AC, 60 Hz, drawing 5.5 amps maximum, so a standard 120V circuit handles it. Running consumption is 265W, standby drops to 44W, and freeze protection pulls 148W when it engages. Size the branch circuit for the 5.5A max, not the running watts.

AHRI listed, built to ANSI Z21.10.3 and CSA 4.3, and ENERGY STAR certified on the CU199i tankless unit. Thermal efficiency is 97 percent and the CU199 is Ultra Low NOx compliant. Those are the lines a facilities or government submittal usually wants, along with the note that a Prop 65 warning applies.

The difference is where the heat is made. In the Demand Duo, a 199,000 BTU tankless heats the water and a 119 gallon tank stores it, so the tank never takes burner thermal stress. Rinnai's case for it is longer tank life, less downtime and leak risk, and repairing a component instead of replacing a whole system. It's also as much as 37 percent lighter than a high-efficiency tank, which matters on an upper-floor mechanical room or a retrofit where rigging is the hard part. A straight high-efficiency tank is the simpler box; the hybrid is the one to look at when peak draw is heavy and service life drives the decision.

150 psi is the maximum working water pressure. On a municipal supply running above that, or where thermal expansion can spike a closed system, you need a pressure reducing valve and an expansion tank ahead of it. That's a common miss on commercial retrofits where the old atmospheric tank tolerated more abuse.

The gas dirt leg, electrical access, and the condensate drain come factory installed, and the pump and DuoSmart controller are part of the system, so no separate aquastat or recirc control package. Field work is the gas connection at 3/4 inch MNPT, water at 1-1/2 inch MNPT, a 120V circuit, venting in PVC, CPVC or polypropylene, and routing condensate to an approved drain with neutralization where the local code calls for it.

No pilot, it uses direct electronic ignition, so there's no standing pilot to relight and no pilot gas burning between draws. It's also WiFi capable, which is what a property manager or MRO team wants for setpoint changes and fault alerts across a portfolio without a truck roll.