The cost to install a Rinnai tankless water heater has no Rinnai-specific published total, so the closest sourced figure is the general gas tankless installed range of $3,293 to $3,859, per Homewyse, dated May 2026. The Rinnai unit itself is $900 to $1,995 (Fixr, January 31, 2025); venting and gas line work make up the rest.
Hot Water Brief is an independent cost-research site. We are not a contractor and do not perform the work ourselves.
That gap is the story of a tankless install: venting, gas supply work and labor, not the nameplate on the unit. Homewyse's estimate is built on an 8.5 gpm unit at a 35 degree F rise. Rinnai's own RU199iN is rated up to 199,000 BTU/H input with a 3/4 inch MNPT gas connection, per Rinnai, so a full-size Rinnai install can run past the general stand-in once venting and gas line work are priced in.
| Cost line | Range | Source, dated |
|---|---|---|
| Rinnai tankless gas unit, equipment only | $900 to $1,995 | Fixr, January 31, 2025 |
| General gas tankless installed total, not Rinnai-specific | $3,293 to $3,859 | Homewyse, May 2026 |
| National average, all tankless fuels, installed | $2,500 to $4,500, average $2,811 | Fixr, January 31, 2025 |
For the full line-item breakdown of that range, see the complete cost guide.
For the unit price by brand, see how much a Rinnai tankless water heater costs.
No dated source from a manufacturer, cost calculator or standards body publishes an installed total specific to Rinnai equipment. What is published is a unit price by brand and a general installed range by fuel type. Treat any 'Rinnai installed for $X' figure that carries no source and no date as unverified.
That is not an oversight. Cost calculators like Homewyse price a job by fuel type, flow rate and temperature rise, since those drive labor hours, not the brand on the case. A gas tankless install needs the same vent path, gas supply check and permit whether the unit is a Rinnai RU199iN or a competitor's model with a similar flow rating.
If a company quotes an installed price for a specific Rinnai model, ask for the line items separately: equipment, labor, venting and any gas line work. That breakdown is checkable against the published ranges above. A single bundled number with no breakdown is not.
Rinnai's condensing models, like the RU199iN, vent through 2 inch PVC, CPVC or polypropylene pipe up to 65 feet, or 2 by 4 inch concentric pipe, per Rinnai. Non-condensing models, like the RE199iN, need metal venting sized 3 by 5 inch concentric, with runs up to 150 feet. That material difference changes labor cost on install day.
The reason comes down to the heat exchanger. A condensing unit pulls extra heat from the exhaust before it leaves the building, which cools that exhaust enough to run through plastic pipe rather than metal. The RU199iN reaches a 0.95 UEF this way, per Rinnai's product page, while the non-condensing RE199iN, without that second heat exchanger, rates 0.82 UEF, also per Rinnai.
Both sit above the federal floor of 0.80 to 0.81 UEF for gas fired instantaneous water heaters made before May 6, 2029, per 10 CFR 430.32(d). A non-condensing Rinnai unit clears that floor without the plastic venting or the higher efficiency number.
| Model | Condensing | UEF | Venting | Max run |
|---|---|---|---|---|
| RU199iN | Yes | 0.95 | 2 inch PVC, CPVC, PP, or 2 by 4 inch concentric | 65 feet |
| RE199iN | No | 0.82 | 3 by 5 inch concentric, metal | 150 feet |
That venting swap changes material cost too, and a condensing install adds its own extra step, covered below.
Rinnai tankless water heaters run on either a 1/2 inch or 3/4 inch gas line, as long as the line delivers enough gas flow, per Rinnai. For a 199,000 BTU/H model such as the RU199i or RE199i, Rinnai's own sizing table allows up to 50 feet on 1/2 inch pipe or 175 feet on 3/4 inch pipe, natural gas.
That is shorter than it sounds: a meter-to-heater run through a basement and up an exterior wall can eat 50 feet fast, especially in a retrofit. Rinnai publishes separate length tables by model and by gas type, since propane and natural gas behave differently under pressure.
The 2012 National Fuel Gas Code update made 1/2 inch piping a workable option for many Rinnai installs where a 3/4 inch upgrade was previously common, per Rinnai's June 14, 2012 announcement. That mattered most for emergency replacements, where a full gas line upgrade would have added time and cost right after a tank failure. The RU199iN's own gas port is a 3/4 inch MNPT fitting regardless of upstream pipe size, so a 1/2 inch supply line still connects through a reducer, it just caps how far that line can run before a licensed installer needs to size up.
| Rinnai gas line max length | 1/2 inch pipe | 3/4 inch pipe | Fuel |
|---|---|---|---|
| RU199i, RU199e, RUR199i, RUR199e, 199,000 BTU/H | 50 feet | 175 feet | Natural gas |
Confirm the actual meter-to-heater distance against Rinnai's table before assuming an existing line works as is.
A bundled Rinnai installation quote typically covers the unit, a vent kit sized to the model, gas connection work, mounting and labor, priced as one number without a Rinnai-specific published total. Ask for those items broken out separately and check the equipment line against Fixr's $900 to $1,995 unit range so the labor and materials portion is clear.
For a condensing model, that bundle often adds a condensate line and, in some jurisdictions, a neutralizer. Rinnai's own product listing for its condensate neutralizer states that condensate from gas combustion carries a very low pH that can harm septic and sewage systems, which is why the company recommends a neutralizer on all condensing gas appliances. That accessory and its labor sit outside the general installed range above, the same as for any condensing tankless unit regardless of brand.
For a non-condensing model, skip the condensate line but expect a metal vent run instead of PVC, which typically costs more per foot in material. A permit fee also applies in most jurisdictions for a gas appliance swap, as a line item separate from both equipment and labor.
None of these line items change because the nameplate says Rinnai. They change because of venting distance, gas line length and whether the model condenses, the same three drivers behind every tankless install regardless of brand.
Every figure on this page is listed here with its publisher and, where the publisher states one, its date. If a number is not traceable to this list, it should not be treated as sourced.
Prices and specifications change. Check these dates against today before treating a figure as current.
No dated source publishes one. The closest sourced stand-in is the general gas tankless installed range of $3,293 to $3,859, per Homewyse, dated May 2026, which prices an 8.5 gpm unit and is not specific to Rinnai equipment or its higher-flow models like the RU199iN.
A 1/2 inch or 3/4 inch line, depending on distance from the meter and the gas flow available, per Rinnai. For a 199,000 BTU/H model such as the RU199i or RE199i, Rinnai's table allows up to 50 feet on 1/2 inch pipe or 175 feet on 3/4 inch pipe, natural gas.
Yes. Condensing models like the RU199iN vent through 2 inch PVC, CPVC or polypropylene pipe up to 65 feet, or 2 by 4 inch concentric pipe. Non-condensing models like the RE199iN need metal venting sized 3 by 5 inch concentric, with runs up to 150 feet, per Rinnai.
Rinnai's condensing RU199iN rates 0.95 UEF and its non-condensing RE199iN rates 0.82 UEF, per Rinnai's product pages. Both exceed the federal minimum of 0.80 to 0.81 UEF for gas-fired instantaneous water heaters made before May 6, 2029, per 10 CFR 430.32(d).
Often yes. Rinnai recommends a condensate neutralizer on all its condensing gas appliances, since combustion condensate carries a very low pH that can harm septic and sewage systems, per Rinnai's neutralizer product page. That accessory and its installation sit outside the general installed range and outside the unit price alone.
Independent Research
Published ranges for tank and tankless replacement, the failures that justify a repair, and the ones that do not. Sourced, dated, and free to read.
