Frequently Asked Questions
Water Heaters
Heaters
Boilers
Does a Rinnai Tankless Water Heater have a standing pilot?
What are the power supply requirements for a Rinnai Tankless Water Heater?
Can I install a Rinnai Tankless Water Heater myself?
Can Rinnai Tankless Water Heaters be used on houseboats or RVs?
Can a Rinnai Tankless Water Heater be used to heat a pool or spa?
What is the life expectancy of a Rinnai Tankless Water Heater?
What is temperature rise?
What is the minimum water flow required to operate a Rinnai Tankless Water Heater?
Can an external Rinnai Tankless Water Heater be used in cold climates?
What types of fuel do Rinnai Tankless Water Heaters use?
Do Rinnai Tankless Water Heaters have a UL Rating?
Does Rinnai manufacture an electric tankless water heater?
Does Rinnai offer a battery backup system?
Can a Rinnai Tankless Water Heater be installed in a mobile home?
What size gas line does a Rinnai Tankless Water Heater require?
Can a Rinnai Tankless Water Heater be converted to a different gas type?
Why does the fan continue to run after I turn off the hot water tap?
Why is white smoke coming out of the exhaust?
Why don’t I have any hot water when I open the tap?
Why do I have to wait to get hot water after turning on the tap?
What type of regular maintenance does a Rinnai Tankless Water Heater require?
What is the "cold water sandwich" effect?
Do Rinnai Direct Vent Wall Furnaces have a UL rating?
What types of fuel do Rinnai Direct Vent Wall Furnaces use?
What colors are Rinnai Direct Vent Wall Furnaces?
Can Rinnai Direct Vent Wall Furnaces be used in a mobile home or RV?
Can I install a Rinnai Direct Vent Wall Furnace myself?
Do you manufacture an electric furnace?
What are the power supply requirements for Rinnai Direct Vent Wall Furnaces?
What size Rinnai Boiler do I need?
Is it a requirement to program your Rinnai Condensing Boiler for each application or does it automatically adjust to the installation heat load?
Do you recommend using an outdoor reset sensor with your boiler?
What material is a Rinnai Condensing Boiler heat exchanger made of?
Is a low loss header required for every application?
What are the power requirements for a Rinnai Condensing Boiler?
Can a Rinnai Condensing Boiler protect itself and the system from freezing?
Is there a minimum and maximum Delta T for Rinnai Condensing Boilers?
What size expansion tank is required with a Rinnai Condensing Boiler?
Can multiple Rinnai Condensing Boilers be common vented?
What is the pressure requirement for the pressure relief valve (PRV) on Rinnai Condensing Boilers?
Are Rinnai Condensing Boilers approved for cascading in large commercial or residential applications?
What is the minimum activation rate for domestic hot water on Rinnai Condensing Combi Boiler models?
Can I vent a Rinnai Condensing Boiler to an existing chimney or vent system?
Does a Rinnai Tankless Water Heater have a standing pilot?

No. Rinnai Tankless Gas Water Heaters have a direct-spark electronic ignition.

What are the power supply requirements for a Rinnai Tankless Water Heater?

Rinnai Tankless Water Heaters require 120 volts AC, 60 Hz and less than three amps.

Can I install a Rinnai Tankless Water Heater myself?

Rinnai recommends that tankless water heater installation should be performed by a licensed contractor who is trained to handle the plumbing, gas, electrical and venting aspects of a tankless water heater and is aware of all local and national codes. Having a non-licensed professional perform the installation can cause operational and performance issues.

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Can Rinnai Tankless Water Heaters be used on houseboats or RVs?

Unfortunately, our tankless water heaters cannot be used in houseboats or RVs. However, we have specific units available that are certified to be installed in Mobile and Modular Homes. These units include both our Luxury and Value Series units.

Can a Rinnai Tankless Water Heater be used to heat a pool or spa?

Rinnai Tankless Hot Water Heaters cannot be used for heating pools or spas. The chemicals used would damage the components of the water heater.

What is the life expectancy of a Rinnai Tankless Water Heater?

The life expectancy of a Rinnai Tankless Hot Water Heater is up to 20 years. Actual performance will vary depending on water quality, usage rates, environmental conditions, and regular maintenance.

What is temperature rise?

The maximum flow rate that our tankless hot water heaters can produce depends on temperature rise — the difference between the set temperature of the unit and that of the incoming ground water. For instance, if you set the temperature of the unit to 120° F and the incoming groundwater temperature is 60° F, the temperature rise is 60°.

The lower the set temperature, and the higher the incoming groundwater temperature, the more hot water flow the unit can produce and vice versa. If sized correctly for your application, the unit(s) should not have a problem producing enough flow for your hot water needs.

What is the minimum water flow required to operate a Rinnai Tankless Water Heater?

Please keep in mind that Rinnai Tankless Gas Water Heaters need to see a demand of over 0.4 to 0.6 gallons per minute of water flow through the hot side in order to ignite and 0.26 gallons per minute to stay in operation. If the flow rate falls below this level, the unit will turn off because it senses that hot water is no longer needed.

There are several possible solutions to minimum flow rate issues: lowering the temperature on the unit to a more comfortable temperature to avoid cutting in too much cold water; cleaning the inlet water filter on the cold water inlet of the unit (sediment buildup in the filter can decrease flow into the unit); cleaning or removing the aerators from showerheads or fixtures; or replacing low-flow showerheads or fixtures.

If you believe that this is not the issue, contact your original installer or plumber to service the unit.

Can an external Rinnai Tankless Water Heater be used in cold climates?

Yes. Rinnai Tankless Water Heaters feature freeze protection for outside temperatures as cold as -22° F (-30° C) for indoor models or as cold as -4° F (-20° C) for outdoor models when protected from direct wind exposure, as long as there is both power and gas supply to the appliance. The pipes feeding the unit MUST be heat-traced and insulated to provide freeze protection.

Rinnai strongly recommends the installation of an optional drain-down system on units installed outside in cold climates. This system, if installed, will allow all water inside the unit to drain out if there’s a power and/or gas outage or a component failure in the product. See the owner’s manual for optional drain-down system piping.

What types of fuel do Rinnai Tankless Water Heaters use?

Rinnai Tankless Water Heaters operate using natural gas or propane and have an electronic ignition.

Do Rinnai Tankless Water Heaters have a UL Rating?

Rinnai Tankless Water Heaters are not UL certified, but are certified by CSA International to ANSI Z21.10.3 Standard Gas Water Heaters, Volume III, Storage Water Heaters with Input Ratings Above 75,000 Btu/h. However, the following internal electrical components are UL certified:

  • a. Transformer E (UL 1411)
  • b. Relay (UL 41515)
  • c. Wire & Conduit (UL 1430)
Does Rinnai manufacture an electric tankless water heater?

We do not make an electric model. There are several potential drawbacks to electric tankless water heater units: First, the power requirements of electric units large enough to provide hot water for a typical household can be prohibitive. For example, a unit that can provide three gallons per minute with an 80° F temperature rise would require about a 150 amp 230VAC circuit. This is about eight times the power required for a three-ton central air conditioning system.

Second, the relative operating cost of electric tankless water heaters is much higher than gas water heaters. Based on national averages, electricity costs almost twice as much per BTU as natural gas. Even with propane, gas tankless water heaters are considerably less expensive to operate than those that run on electricity.

Does Rinnai offer a battery backup system?

We do not offer a battery backup system—also known as an Uninterrupted Power Supply (UPS)—for our products. Please check with your local retail store for a UPS that may be suitable for your needs.

Can a Rinnai Tankless Water Heater be installed in a mobile home?

We have specific tankless water heaters available that are certified for installation in Mobile and Modular Homes. These units include both our Luxury and Value Series units.

What size gas line does a Rinnai Tankless Water Heater require?

Rinnai Tankless Water Heaters typically require a ¾" gas line to provide a sufficient gas supply to the unit’s burner. However, if there is sufficient pressure and the gas line is short enough, there are some cases where a ½" gas line can be used, which is the most common size used in the United States and Canada. This can make switching from a tank-style water heater to a tankless water heater faster, easier and less expensive.

As with all tankless water heater applications, installers should check and abide by local gas-pipe size and licensing rules and codes.

Can a Rinnai Tankless Water Heater be converted to a different gas type?

Rinnai offers a limited Field Conversion Program. Kits for converting gas tankless water heaters from natural gas to propane or vice versa are available for most models. Please have your installer/service provider call 1-800-621-9419 to find out if your model qualifies and to obtain a detailed step-by-step conversion instruction kit.

These kits are available directly from Rinnai, and will be shipped only after the installer/service provider has contacted Rinnai’s technical support services and consulted one of our technical specialists, to ensure the installer/service provider performing the conversion is qualified to do so. The Field Conversion Program is available for products which have been installed and where gas type availability has changed. It will not be approved for use in conversion of non-sold inventory or mobile homes.

Why does the fan continue to run after I turn off the hot water tap?

The fan is designed to continue running for a short time after the flow of water stops. This is to ensure constant water temperatures during rapid starting and stopping, as well as exhausting any residual gas flue products from the unit.

Why is white smoke coming out of the exhaust?

During cold weather, when the exhaust temperature is much hotter than the outside air, the exhaust fumes condense producing water vapor.

Why don’t I have any hot water when I open the tap?

Make sure the tankless water heater is connected to gas, water and electricity supplies, and that the power is turned on and the gas is turned on.

Why do I have to wait to get hot water after turning on the tap?

The wait time to get hot water is primarily determined by the distance between the water heater and the point of use. Rinnai Tankless Hot Water Heaters produce hot water within a few seconds of first water flow from a cold start. However, you must purge all the cold water out of the pipe between the hot water heater and your point of use. For example, if your kitchen sink is 50 feet from the hot water heater and the water flow rate is one gallon per minute, it should take approximately 90 seconds for hot water to reach your sink.

Because of their small size, you can place Rinnai Tankless Water Heaters in locations that you could never place a tank. If you can place your hot water heater close to your primary points of use—such as your kitchen or master bath—you drastically reduce the wait time.

What type of regular maintenance does a Rinnai Tankless Water Heater require?

There are two types of periodic maintenance that your service technician can perform to keep your Rinnai Tankless Water Heater running smoothly:

The in-line screen filter should be checked periodically for debris (time between filter checks will be dependent on water quality).

The unit should be flushed periodically (time between flushes will be dependent on water quality) to keep the unit free of scale and lime. This process should be completed by a professional installer. Please contact an installer near you.

What is the "cold water sandwich" effect?

The term "cold water sandwich" effect is used to describe the introduction of cold water into the hot water supply line during frequent on/off operation of an instantaneous hot water heater. When present, this effect appears as a momentary drop in hot water temperature as it is discharged from a hot water supply outlet (i.e., shower, tub, or faucet). It’s a phenomenon that is present in the operation of all instantaneous and on-demand tankless water heaters, but is minimized with the high-tech design of Rinnai Tankless Water Heaters.

Rinnai Tankless Water Heaters are microprocessor–controlled, and when water flow ceases, they remain in a "ready-to-fire state" for approximately one minute. If water flow begins within the first minute following water flow stoppage, the water heater will fire back up within one to two seconds. This minimizes the "cold water sandwich" effect that would otherwise be experienced with a less innovative tankless water heater.

Do Rinnai Direct Vent Wall Furnaces have a UL rating?

Rinnai Direct Vent Wall Furnaces are not UL certified, but are certified by CSA International to ANSI Z21.86 Standard Vented Gas-Fire Space Heating Appliances. However, the following internal electrical components are UL certified:

  • a. Transformer (UL QL66-532NA)
  • b. Limit Switches (E52529)
  • c. Wire & Conduit (UL 1430)
What types of fuel do Rinnai Direct Vent Wall Furnaces use?

Rinnai Direct Vent Wall Furnaces are natural gas or propane furnaces that have an electronic ignition.

What colors are Rinnai Direct Vent Wall Furnaces?

Rinnai Direct Vent Wall Furnaces are beige. However, model numbers ES38 and EX22C are also available in white.

Can Rinnai Direct Vent Wall Furnaces be used in a mobile home or RV?

Rinnai Direct Vent Wall Furnaces are approved for mobile homes and manufactured homes; however, they are not approved for RVs.

Can I install a Rinnai Direct Vent Wall Furnace myself?

Rinnai recommends that direct vent wall furnace installation should be performed by a licensed contractor who is trained to handle the plumbing, gas, electrical and venting aspects of a direct vent wall furnace and is aware of all local and national codes. Having a non-licensed professional perform the installation can cause operational and performance issues.

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Do you manufacture an electric furnace?

No. Rinnai Direct Vent Wall Furnaces are natural gas or propane furnaces that have an electronic ignition.

What are the power supply requirements for Rinnai Direct Vent Wall Furnaces?

Rinnai Direct Vent Gas Wall Furnaces require 120 volts AC, 60 Hz and 121 watts.

What size Rinnai Boiler do I need?

Your Rinnai dealer can help you evaluate what size Rinnai Home Heating and Water Heating Boiler is right for your space by conducting an industry-standard heat loss calculation. Boiler selection will also be dependent on overall system design, type of heat delivery, etc.

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Is it a requirement to program your Rinnai Condensing Boiler for each application or does it automatically adjust to the installation heat load?

Programming is not required at commissioning. However, fine-tuning of the system will allow maximum performance and efficiency. Your Rinnai dealer can help. To find a Rinnai dealer near you, click here.

Do you recommend using an outdoor reset sensor with your boiler?

In most cases, an outdoor reset sensor is recommended for and is included with all Rinnai Condensing Boilers.

What material is a Rinnai Condensing Boiler heat exchanger made of?

Rinnai Condensing Boiler heat exchanger tubing is made of 316 stainless steel—selected for resistance to corrosion.

Is a low loss header required for every application?

Yes. A low loss header—also referred to as a hydraulic separator —is included with every Rinnai Boiler. The low loss header isolates the boiler from the rest of the system to protect the components within the boiler (heat exchanger, pump, etc.) and to optimize overall performance, efficiency and longevity for the Rinnai Boiler.

What are the power requirements for a Rinnai Condensing Boiler?

Rinnai Boiler Heating Systems require 120 volts/5 amps of power. Contact your Rinnai dealer with questions regarding your power supply. To find a dealer near you, click here.

Can a Rinnai Condensing Boiler protect itself and the system from freezing?

Rinnai Condensing high-efficiency Gas Boilers are designed to fire and circulate the pump as needed to help prevent freezing. This does not, however, guarantee the entire heating system is protected, and can depend on the overall system design in your application.

Is there a minimum and maximum Delta T for Rinnai Condensing Boilers?

Delta T is defined as the difference between incoming groundwater and a water heater's (in this case, a boiler's) set temperature. Delta T helps determine the flow range of a boiler.

A Rinnai Condensing Boiler will always try (through the pump or the BTU output) to maintain its default and most efficient temperature, which is 36° F. If its Delta T does not stay between 18° F and 45° F, burner operation will temporarily cease and a warning (or error) code will be displayed. Please understand this is only on the boiler side of the operation. The system or secondary loop will likely have a different Delta T based on system design. With a low loss header, the Delta T of the boiler and secondary loop do not have to match.

What size expansion tank is required with a Rinnai Condensing Boiler?

The size of the expansion tank depends on the size of the overall system. Rinnai E Series Boilers come equipped with an integrated expansion tank in anticipation of smaller overall systems, while Rinnai Q Series Boilers come with a slightly larger expansion tank.

Your Rinnai dealer can help ensure you have the right expansion tank for your system.

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Can multiple Rinnai Condensing Boilers be common vented?

At this time, it is not recommended to common vent multiple Rinnai Condensing Boilers.

What is the pressure requirement for the pressure relief valve (PRV) on Rinnai Condensing Boilers?

In closed-loop (not domestic hot water) applications, an ASME approved 30-psi pressure relief valve is included with every Rinnai Condensing Boiler. However, since the maximum allowable working pressure of the boiler's heat exchanger is rated by ASME up to 45 psi, the installer can replace the 30-psi PRV to suit the needs of the application.

Rinnai E Series Boilers are limited to 30 psi maximum PRV due to their internal expansion tank.

Are Rinnai Condensing Boilers approved for cascading in large commercial or residential applications?

Yes, but common venting is not yet approved and a custom-sized low loss header may be required for cascading units.

Rinnai's cascade controller can address up to eight Rinnai Heating Boilers. Five controllers will also cascade together for a total of 40 units.

What is the minimum activation rate for domestic hot water on Rinnai Condensing Combi Boiler models?

For the Rinnai Q175 Combi Boiler, there is no minimum domestic hot water activation rate, since the domestic hot water is coming from a storage tank.

For Rinnai E Series models, a flow sensor activates domestic hot water at 0.4 gallons per minute or more.

Can I vent a Rinnai Condensing Boiler to an existing chimney or vent system?

Yes. Venting of Rinnai Condensing Boilers through a stainless steel chimney liner is approved. Local codes will dictate the ability to use this type of system. Contact your Rinnai dealer for more details if needed.

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