Frequently Asked Questions

TANKLESS WATER HEATERS

Why don’t I have hot water as soon as I turn on the tap?
Unless you have a Rinnai recirculation solution, tankless water heaters do not produce instant hot water, but a Rinnai Tankless Water Heater does produce an endless supply of hot water. Just like with a tank water heater, the wait time to get hot water is dependent on the distance between your Rinnai and the location of any hot water faucet. It is normal to have a 1-2 second slight temperature drop as the water clears the line.

Can I still get hot water if the power is out?
In the event of a power outage, the Rinnai Tankless Water Heater will not operate. However, it can operate with a battery backup system, which are available as third party accessories.

Does a tankless water heater work differently with low-flow faucets or showerheads?
Typically there is no effect on low-flow faucets or showerheads. If you find you are not getting the hot water you need, counterintuitively, lower the temperature setting on your tankless water heater. This affects the hot/cold mix ratio and will activate the tankless unit for lower flow fixtures.

Also remember many single handled faucets have limit stops that affect the hot/cold mix at that fixture and may need to be adjusted.

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.

Please contact an installer near you.

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.

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 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 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.

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 are designed to always provide maximum performance and operating efficiency using either a ¾” or ½” gas line, as long as sufficient gas flow is available.

Because an undersized gas line can stress a tankless system and potentially reduce its life span, Rinnai Tankless Water Heaters, unlike other tankless water heater, are equipped with innovative technology that safely ceases operation if it detects inadequate gas flow in order to avoid compromising performance and efficiency.

The table below lists the maximum length for both ½” and ¾” gas lines when paired with each of Rinnai’s Tankless Water Heaters.

Gas Line Sizing Chart

How To Properly Size Your Gas Line:

  • Determine what type of gas is being utilized
  • Determine the inlet pressure
  • Determine the allowed pressure drop
  • Determine what other types of gas appliances are sharing the gas line
  • Determine the maximum loads expected on the whole system as stated in the National Fuel Gas Code

For complete information on gas sizing for Rinnai Tankless Water Heaters, consult the Operation and Installation Manual.

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.

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.

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.

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:

  • Transformer E (UL 1411)
  • Relay (UL 41515)
  • Wire & Conduit (UL 1430)

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 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.

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 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.

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.

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.

Find a Rinnai Independent Dealer or Advanced Comfort Expert

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.

Does a Rinnai Tankless Water Heater have a standing pilot?
No. Rinnai Tankless Gas Water Heaters have a direct-spark electronic ignition.

Can I use a recirculation line with Rinnai Tankless Water Heaters?
When continuous, on-demand hot water is needed, our tankless units work very well with a recirculation pump. Plus, the modulating technology and minimum fire rating of the Rinnai Tankless Rack System enables it to maintain consistent temperature in a return line with limited waste, only using the energy necessary to keep the line heated when required.

Commercial Water Heating

What kind of applications are best suited for Rinnai Tankless Water Heating Commercial Solutions?
Rinnai Tankless Water Heaters are perfectly suited for virtually any commercial application. Customers of all sizes and configurations in multi-family, hospitality, healthcare, education, food service, retail and more trust Rinnai to deliver an endless, efficient supply of hot water.

What types of products can the Rinnai Tankless Rack System replace?
The flexibility and capability of the TRS allows it to replace just about any existing water heating product, from domestic boilers to traditional tank-style water heaters, so long as the necessary gas, venting and installation requirements are present. In fact, the modular design can handle up to 4.9M BTU. And even in cases where demands are smaller, Rinnai Tankless Water Heaters can provide significantly more energy efficiency and reliability than tank-style water heaters.

Can I use a storage tank with Rinnai Tankless Water Heating Commercial Solutions? Do I need one?
Rinnai Tankless Water Heaters are designed to achieve peak efficiency and performance without the use of a storage tank. Because they only operate on-demand, they use far less energy than tank-style water heaters. However, they can be used in conjunction with a storage tank to suit the needs of a specific application. Please consult with Rinnai’s Application Engineering group to determine the best solution for your project.

Can I use a recirculation line with Rinnai Tankless Water Heaters?
When continuous, on-demand hot water is needed, our tankless units work very well with a recirculation pump. Plus, the modulating technology and minimum fire rating of the Rinnai Tankless Rack System enables it to maintain consistent temperature in a return line with limited waste, only using the energy necessary to keep the line heated when required.

Are the new C199 models condensing or non-condensing?
The C199 models are dedicated commercial condensing models.

Are there differences between the C199 and other Rinnai condensing products?
Yes, the differences for the C199 include:

  • A Thermal Efficiency rating
  • Commercial Energy Star designation
  • New common venting configurations (room air and sidewall intake with vertical exhaust)
  • Temperature settings from 98°F to 185°F — out of the box

What is the efficiency of the C199?
96% thermal efficiency — it does not have an Energy Factor like the residential models.

How is Thermal Efficiency calculated?
It is the amount of energy delivered as heated water compared to the energy consumption of the water heater.

How is Thermal Efficiency different from Energy Factor?
Energy Factor is calculating the amount of energy delivered as hot water compared to the energy consumption of a residential water heater over a 24-hour period.

Is the C199 Energy Star rated?
Yes, it is Commercial ENERGY STAR® certified.

Will the Tankless Rack System come standard with the C199?
Yes, the Tankless Rack System with C199 and will begin shipping in late July. Single units will begin shipping in August.

What is the warranty period for the C199?
The commercial warranty is 5 years on the heat exchanger, 5 year parts, and 1 year labor.

Can the C199 be used in commercial and residential applications?
No. The C199 models are for commercial use only.

What kind of temperature control comes with the C199?
C199 models come with an MC-91-2 temperature controller (integrated into indoor models; provided with outdoor models) with temperature ranges from 98°F to 185°F and does not require the MCC-91 temperature controller. The controller is 98°F to 140°F out of the box and requires dip switch changes for temperatures over 140°F.

Is the C199 approved for high altitude?
Yes. It is approved for elevations up to 10,200 feet.

Is the C199 mobile home certified?
No. It is for commercial use only and is not mobile home certified.

What are the venting options with the C199?
In addition to the standard concentric venting and two pipe PVC (3” or 4”) new common vent solutions are now available.

  • Room air common vent with vertical exhaust
  • Common venting with side wall intake with vertical exhaust
  • Common venting is now ULC S636 approved

Is the Demand Duo certified as a single appliance?
The Demand Duo is an assembly with multiple and separately certified components. The tank, C199, controller, and pump are standalone certified components.

Where is the Demand Duo assembled?
Rinnai’s facility in Peachtree City, Georgia.

Can I replace a single tank in a multi-tank installation even if it’s another brand?
Yes. The Rinnai Demand Duo is designed to work in a multi-unit tank system regardless of manufacturer.

What is the efficiency of the Demand Duo?
The Demand Duo includes the C199 that has a 96% Thermal Efficiency and is Commercial ENERGY STAR® certified.

Does the Rinnai tankless unit modulate when recharging the storage tank?
Yes, the C199 will modulate its input based on the Delta T (change in temperature).

Can multiple Demand Duo units be installed together or tied into a recirculation system?
Yes, specifications are included in the manual.

How many tankless water heaters does it take to replace one Demand Duo?
It varies based on the geographical location and application conditions, however, the the Demand Duo is equivalent to two or three tankless units. Consult with a Rinnai Applications Engineer for sizing.

How is the Demand Duo sized for a job? Is it different than sizing a tankless water heater?
Several considerations are made with sizing the system – gas supply, gallons per hour (GPH) demand, and thermal rise space requirements.Consult with a Rinnai Applications Engineer for sizing.

Can the Demand Duo be installed with a second storage tank?
Testing is still underway for this installation type.

Can the Demand Duo be installed with TRS?
Because every commercial job is different, please contact the Commercial
application department to discuss options.

Does the Demand Duo qualify for rebates?
The C199 should qualify for tankless rebates and must be verified locally.

Can the Demand Duo be installed in a residential application?
This product is designed for commercial applications and does not carry a
residential warranty. For more information on Rinnai’s complete line of
residential products, visit rinnai.us.

Condensing Boilers

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 or flexible liner is approved. Local codes will dictate the ability to use this type of system. Contact your Rinnai dealer for more details if needed.

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.

Are Rinnai Condensing Boilers approved for cascading in large commercial or residential applications?
Yes, for Q Series, 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 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 with expansion tanks are limited to 30 psi maximum PRV due to their internal expansion tank.

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

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

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.

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.

Is a low loss header required for every application?
No, but recommended for most applications with multi-zones. 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.

Do you recommend using an outdoor reset sensor with your boiler?
Yes, 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 stainless steel—selected for resistance to corrosion.

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

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.

Direct Vent Wall Furnaces

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 40-120 watts depending on model.

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 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.

Do you manufacture an electric furnace?
No. Rinnai Direct Vent Wall Furnaces are natural gas or propane furnaces that have an electronic ignition.

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.

What colors are Rinnai Direct Vent Wall Furnaces?
Rinnai Direct Vent Wall Furnaces are beige. However, model numbers EX38C and EX22C are also available in white.

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:

  • Transformer (UL QL66-532NA)
  • Limit Switches (E52529)
  • Wire & Conduit (UL 1430)