Rinnai boilers, not Rinnai water heaters
Rinnai dates to 1920 in Japan, when Hidejiro Naito and Kanekichi Hayashi founded the company, and Rinnai America Corporation was set up in 1974. The American company is based in Peachtree City, Georgia. In North America the name mostly means tankless water heaters, which heat water and nothing else.
This page is about Rinnai's other product line: wall-hung condensing boilers that heat the house through baseboard, radiators or floor tubing. Rinnai makes them as heat-only boilers and as combi boilers that also make domestic hot water. Our boiler and radiant heat page covers the systems they run, from radiant slabs to fin-tube baseboard.
How do you read a Rinnai I-SERIES+ model number?
The current residential line is the I-SERIES+, rated 96% AFUE. Heat-only models end in S and run from the IP060S to the IP199S. Combis end in C and carry two numbers: the IP120199C is rated 120,000 BTU for heating and 199,000 BTU for hot water. That split is the point of a combi. Hot water takes a lot of burner for a few minutes, while heating the house takes much less for hours.
Rinnai lists four built-in zones and seven heating reset curves for the I-SERIES+, and every Rinnai boiler series runs on natural gas or propane. The combis heat the house and make hot water at the same time, and Smart-Circ recirculation is available on them. Rinnai's earlier boilers, the high-output I-Series and the compact M-Series, are still out there; an M090CN, for example, is an M-Series natural gas combi with 90,000 BTU of heating.
The I-SERIES+ door recall
Rinnai, with the Consumer Product Safety Commission, recalled wall-mounted I-SERIES+ boilers with model numbers IP175S, IP199S, IP175199C and IP199199C sold from September 2024 through February 2025. Incorrect screws can keep the boiler door from sealing, which can let carbon monoxide escape. If you own one of those four, look it up through Rinnai's recalls page and follow the remedy it gives. The smaller I-SERIES+ sizes aren't on the list.
Every home with a gas boiler needs working CO alarms, and Minnesota law requires one within 10 feet of every sleeping room. Our CO alarm placement guide shows where they go.
What goes wrong with Rinnai boilers in a Minnesota winter?
Condensate. A condensing boiler drains acidic water all winter. Rinnai sells a neutralizer kit that raises the pH before the water reaches the drain, and its media has to be replaced when it's spent. A condensate line that freezes on a sub-zero night backs up and shuts the boiler down, so we check the trap, the neutralizer and where the line runs.
Venting in snow. Rinnai boilers can vent through a concentric kit that needs one wall or roof opening, or with 2-inch PVC, CPVC or polypropylene pipe. Sidewall terminations near the ground frost over and get buried in drifts. Keep them clear after every big snow.
Gas supply. The largest combis fire at up to 199,000 BTU when someone runs hot water. A long or undersized gas line, or a propane regulator that can't keep up, shows up as ignition errors in the middle of a shower. We measure gas pressure at full fire before we replace any part.
Zones and air. Four zones on one small wall-hung boiler means a stuck zone valve or air in one loop shows up as one cold room. We check the pressure, bleed the loop and test the zone wiring, then read the code on the display against Rinnai's I-SERIES+ diagnostic-code guide. Where radiant floors share a boiler with baseboard, our radiant floor vs baseboard guide explains why the two need different water temperatures.
Booking Rinnai boiler service
Call 612-429-3465 from 7am to 9pm, seven days a week. No-heat calls get priority. A service call is a $79 trip charge, waived when you approve the repair, and you get a written, flat-rate price before we start. Completed repairs carry our 1-year parts-and-labor warranty.
Have the model number from the rating label ready. With Rinnai, the number alone tells us the series, the size and whether it's a combi. If a boiler is past saving, we quote a replacement that fits the house, and a boiler swap normally needs a mechanical permit. For another maker's wall-hung combi, see our Navien page.
Rinnai questions
Is my Rinnai boiler part of the recall?
Only if it's one of four I-SERIES+ models: IP175S, IP199S, IP175199C or IP199199C, sold from September 2024 through February 2025. Rinnai says incorrect screws can keep the boiler door from sealing, which can let carbon monoxide escape, and it runs the recall with the Consumer Product Safety Commission. The smaller I-SERIES+ sizes aren't on the list. Rinnai's recalls page links to the model lookup, and we can check the rating label for you on a visit.
My Rinnai makes hot water but doesn't heat the house. Is it a boiler?
Probably not. Rinnai's best-known products are tankless water heaters, which only make domestic hot water. A Rinnai boiler has heating supply and return pipes running out to baseboard, radiators or floor tubing, and current I-SERIES+ model numbers start with IP. If the unit only has gas, cold water and hot water connections, it's a water heater, which this page doesn't cover.
Can a Rinnai combi keep up with hot water in a Minnesota winter?
Usually, if it was sized for the house. Rinnai lists a maximum hot water flow of 9.8 gallons per minute on the IP120199C, but that's a ceiling. Real flow drops as the needed temperature rise grows, and Minnesota tap water is coldest in late winter. I-SERIES+ combis heat the house and make hot water at the same time, so a long shower doesn't leave the baseboard cold.
Do Rinnai boilers run on propane?
Yes. Rinnai says all of its boiler series support natural gas or propane, and it publishes a gas conversion manual for the I-SERIES+. A conversion needs the right parts and a combustion check with an analyzer afterward. That makes a compact wall-hung Rinnai workable in lake places and farmhouses outside the gas lines, as long as the propane line and regulator can feed its full input.
How do I keep my Rinnai boiler warranty?
Start with the installation and owner's manual, which is where Rinnai puts the boiler warranty terms for your model, and register the boiler with Rinnai. Rinnai's warranty page warns that units bought from unapproved online sellers, or with the factory serial number removed or altered, lose the warranty. We can pull the manual for your model number and go over the terms with you.
Sources
- Rinnai official site rinnai.us