Rinnai Water Heaters - Recent Questions, Troubleshooting & Support

One thing they don't tell you about tankless heaters is that when they turn on, they may cause the lights in the house to flicker. Make sure that you have a good breaker panel (one that is relatively new with plenty of capacity) and run a circuit specifically for the tankless heater.

Rinnai Water... | Answered on Apr 27, 2020

Push breaker(s) fully off and then back on.
... then open the tankless and carefully test across the terminals where wires connect to heater...
Tape tester leads to wood sticks to keep hands away from power
Following link has wiring for tankless electric

Rinnai Water... | Answered on Oct 28, 2019

I wonder if you have this problem below caused by a drop in water pressure from someone flushing a toilet or a washing machine. I would call the company to remedy this issue.

17. What is a cold water sandwich effect? The term “cold water sandwich effect” is a term that is used to describe the introduction of cold water into the hot water supply line during frequent on/off operation of an instantaneous water heater. The cold water sandwich effect, when present, 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). This phenomenon is present in the operation of all instantaneous, tankless style, water heaters, but is minimized with the high tech design of Rinnai water heaters.
The technology built into the Rinnai water heaters is designed to minimize the cold water sandwich effect. Rinnai water heaters are microprocessor controlled and when water flow through them ceases, they remain in a “ready to fire state” for approximately 1 minute. If water flow through a Rinnai water heater begins within the first minute following water flow stoppage, the water heater will fire back up within 1 to 2 seconds. This minimizes the cold water sandwich effect that would otherwise be experienced with a low tech tankless water heater. It should be noted that the cold water sandwich effect cannot be removed completely from tankless style water heaters. The safety standards developed to insure the safe operation of water heaters require a delay in the ignition sequence of all gas water heaters.
While the cold water sandwich effect cannot be completely eliminated from standard plumbing systems, it can be eliminated from plumbing systems that have a supply and return hot water circulating system. Rinnai has developed 2 methods to eliminate the cold water sandwich effect in residential hot water circulating systems.
The first (and preferred) method to remove the cold water sandwich from circulating systems utilizes a small electric tank water heater (powered up) that is used with a dual purpose. The small water heater acts as a mixing tank to eliminate the cold water sandwich effect from the Rinnai water heater and it uses its electric heating element to offset the heat losses from the hot water circulating system.
The second method to remove the cold water sandwich from circulating systems utilizes a small 2 to 6 gallon storage tank installed on the hot water outlet of the Rinnai water heater. This tank acts as a mixing tank to blend the cold water sandwich with hot water and eliminating its effect at fixtures.

Rinnai Water... | Answered on Jul 12, 2019

Unplug it and plug it back in it should work

Rinnai Water... | Answered on Apr 04, 2019

Code 12 is a flame failure.
First step in diagnosing the root of the issue is to check for any separation, obstruction, or failure in the vent system.
Second step is to use the isolator kit under the heater to flush the heat exchanger with vinegar or rectorseal calci-free.
These two things are a great starting point to working on any tankless water heater. Flame failure can be as simple as the heat exchanger being clogged not allowing the sensors to work properly or the exhaust being mixed with the air intake. If the problem persists I would suggest having a Rinnai Certified Tech look at the heater.

Rinnai Water... | Answered on Mar 02, 2019

Do not spend 500 on plumber to determine that condensate drain was not installed properly on vent line, and that acidic water from combustion by-product has been dripping down into tankless and burning hole through the special-alloy heat exchanger instead of going down into floor drain and corroding your plumbing pipes.
Do not spend hours fulfilling the required monthly and yearly maintenance, or spend money on service call each year to get the burner cleaned and gas pressure checked on your tankless computer that heats water...
Instead, fix any tankless problem, any brand tankless, same day do-it-yourself for $385, by replacing 1 part: the whole thing:http://waterheatertimer.org/How-to-install-gas-water-heater.html
Do not install tankless.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Rinnai Water... | Answered on Dec 01, 2018

Flame failure is code 12 Check flame sensor is clean

Rinnai Water... | Answered on Aug 05, 2018

if the tank is stainless steel it should last 30 years or more however most are not and if they last 10 years it still is not cost effective since they cost so much more than conventional

Rinnai RV53i... | Answered on May 31, 2018

inconsistent water pressure adjust pressure switch

Rinnai Water... | Answered on Mar 27, 2018

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