The Rinnai tankless water heater provides a continuous supply of hot water at a preset temperature. Once electricity, water, and gas supplies are connected, the Rinnai water heater produces hot water whenever a hot water tap is open.
Ignition is electronic. There is no pilot light consuming gas while the water heater is not being used. The gas burner lights automatically when the hot water tap is opened and goes out when the tap is closed.
The temperature can be precisely set from 98-140 degrees F, and the outgoing hot water is constantly monitored by an electronic controller.
This lightweight (46 lbs) gas appliance uses a direct vent configuration where air is brought in from the outside and combustion gases are exhausted to the outside. Wall-mounted installation and a small footprint (10"D x 14"W x 26" H) save space.
Evaluation
The unit performed flawlessly in our tests, and produced hot water on demand as promised.
Flow was diminished when two people were running separate high-flow baths or showers at the same time, so it's best to run only one tub or shower at a time. This is because the unit adjusts the water flow to maintain the temperature setting. Flow may also vary from summer to winter due to the difference in ground water temperature. The R94LSi can provide 3.7 GPM (gallons per minute) at an 85 degree temperature rise (assuming 35 degree groundwater raised to 120 degree output).
The Rinnai tankless water heater saves energy on hot water, but the savings may be hard to quantify since having 'unlimited' hot water means owners may often use more water via long showers, Jacuzzi-type spas, etc. Comparing apples-to-apples in hot water use, however, the tankless unit can save up to 30% over a tank water heater. Timing the length of hot showers before and after installing the unit may enable a more accurate comparison of usage versus energy costs.
If you are physically close to the water heater, you may hear the regular cycling of its internal fan, but this was judged not to be an issue in most homes, especially when the unit is installed in a garage or utility area outside the main living space.
Rinnai recommends the unit be installed by a state qualified or licensed contractor trained by Rinnai, and based on stories we've heard about possible impacts of installation errors, this is sound advice.
Issues and Troubleshooting
The Rinnai water heater has the ability to check its own operation continuously. If a fault occurs, an error code will flash on the display of the control panel. This assists with diagnosing the fault, and may enable you to correct a problem without a service call; but also makes it easier to identify the problem when inquiring about service.
We also found these troubleshooting tips from the Rinnai owner's manual helpful:
Problem: I don't have any hot water when I open the tap.
Answer: Make sure there is gas, water, and electricity to the Rinnai water heater (power is turned on and the gas is turned on).
Problem: When I was using the hot water, the water got cold.
Answer: If you adjusted the flow from the tap to lessen it, you may have gone below the minimum flow required. The Rinnai Water Heater Requires a minimum flow rate to operate. Decrease the temperature setting at the remote controller or increase the water flow.
Problem: When I open a hot tap, I do not immediately get hot water.
Answer: Hot water must travel through your plumbing from the water heater to the faucet. The time period for hot water to reach your fixture is determined by the amount of water in the plumbing system between the water heater and the fixture, water pressure, and the flow rate of the fixture.
Problem: After I turn off the hot water tap, the fan on the Rinnai water heater continues to run.
Answer: 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.
Power Outage
Since the ignition is electronic and AC-powered, what happens when the neighborhood power goes out? Rinnai says you can use a battery power backup like you use for your computer, so power outages do not necessarily mean you'll run out of hot water.
Conclusion
This Rinnai tankless water heater will provide hot water as needed at lower overall cost. Installed and operated according to the manufacturer's directions, it will produce virtually all the hot water you need, and with its unobtrusive and reliable operation, you will likely forget you're using a tankless model.
