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Customer Review

29 of 34 people found the following review helpful
2.0 out of 5 stars Rinnai RL94iN Natural gas tankless water heater, April 7, 2012
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This review is from: Rinnai RL94iN Natural Gas Tankless Water Heater, 9.4 Gallons Per Minute (Tools & Home Improvement)
Rinnai RL94iN Natural Gas Tankless Water Heater, 9.4 Gallons Per Minute

Occasionally it works correctly. However, frequently when attempting to take a bath with nothing else running, it runs hot for less than a minute and then turns cold (continuous hot turned on). We got the RL94iN since this was the top of the line for residential use. If you leave it on, it cycles and you get another burst of hot followed by cold again --unacceptable.

We called Rinnai and they say that we must be attempting to draw too much hot water. We tried decreasing the flow with the same results.

Frustrated John Mitchell email:
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Showing 1-10 of 10 posts in this discussion
Initial post: Nov 24, 2012 5:24:19 AM PST
Leon says:
You may have a "scald proof" shower control. The are factory set to 120 degrees. Of a couple hundred installs I had 2 clients with the complaint of hot-cold. I told them to set the Rinnai to 115 degrees and no problem. Also you may have a shower head that has some build up in teh fine holes which could cause this. Clean the holes thoroughly or replace the head (they are cheap). you may also want to set the Rinnai at 115 degrees to see if this solves the problem.

In reply to an earlier post on Mar 21, 2013 7:44:49 AM PDT
margaret says:
I have the same problem. The heater worked just fine for about a year. Now I have to baby it to get it to heat at all and I have had the problem of it just quitting mid shower, too. I will lower the temperature to 115º but I really want it hotter than that for dish washing.

In reply to an earlier post on Mar 21, 2013 2:36:54 PM PDT
I hd another plumber check it out and he said that I needed a a larger gas pressure and I had it put in and everything is great.
I also found that the tankless water heatersare even more sensitive to deposit buildups. Net is that it also needs to be flushed once a year. Rinnia people sent me a reminder to do that and the reinstallation with more gas capability was recommended.
Thanks for your comments.

Posted on Apr 20, 2013 12:18:18 PM PDT
Big Bird says:
I have installed many of these units- I have never heard anything but praise, and never a service call. On other units turning up the temperature too high will shut them off, and "waffling" of hot/cold occurs because of a less sensitive flow control sensor. I haven't that problem with Rinnai

In reply to an earlier post on Apr 20, 2013 12:57:06 PM PDT
margaret says:
I will check with a plumber to see if I have this problem. Thank you.

In reply to an earlier post on Apr 20, 2013 12:59:55 PM PDT
margaret says:
Mr. Reese,
I have had nothing but problems. I have the unit flushed every year - no help. I have turned the thermostat down to 115º and I still have problems. The plumbers with whom I have spoken have said what you said. I will look into the gas pressure issue.

In reply to an earlier post on Aug 2, 2013 11:39:07 AM PDT
trbizwiz says:
Two things on pressure. If it is more than 60 feet form the valve it may require a 1.25 inch gas line, and if it is more that 25 feet it will require a 1 inch gas line. Also the gas regulator on your Natural gas inlet may not have enough flow. Anyone considering buying one of these should gall their gas company prior and make sure how much their meter can flow.

In reply to an earlier post on Aug 22, 2013 2:12:15 PM PDT
Since it is a issue with the installer not providing a large enough gas line to the unit(by the way, did you have an authorized installer do the work?) How about revising your crappy 2 star review to reflect that the unit itself is good, your installer=not so good. It bugs me when people on Amazon(or any other site) give bad reviews to a product, when it is in fact the installers fault! Just a suggestion.

P.S.-The install & operation manual online clearly describes sensitivity to water quality & the required maintenance for this unit if you had cared to read it before you bought. You can hardly blame Rannai for this(and other branded units also require flushing.) If you had cared to check any of this out before you bought or talked about maintenance issues with a Authorized installer/dealer, you would know. Just my opinion.

Posted on Aug 22, 2013 3:26:01 PM PDT
Rinnai Guy says:
He did not say causing a hot water leak. He said varying temperature (warm to hot). There are some shower valves that are designed to be "scald proof" with an upper limit usually 120 degrees. When the incoming hot water temperature is more than 120 degrees (using 120 degrees as the baseline), it automatically will divert water from the cold side to mix with the hot water to limit the temperature to 120 degrees. This is especially obvious with a tankless water heater when the water heater temperature is set at 120 degrees or higher. To overcome this, set the water heater at 115 degrees and it usually will solve the problem. Please do not give tankless water heaters a bum rap. I have installed a couple hundred of them and had only 2 occasions of the shower temperature fluctuation. Set at 115 degrees and problem solved. With a tankless water heater you can set the exact water temperature and turn the shower to full hot and you will get consistent water temperature plus or minus 1 degree. If you do not want to go down and up the basement steps to change temperature, most tankless water heaters have additional thermostats for purchase to change temperature at location. Possible solution is to replace the shower valve with a new "scald proof" valve or one without the "scald proof" feature.
"Shower valve...causing" - There can be some plumbing nightmares by having incorrect plumbing that may cause water to be diverted to where it should not go. Or there may be some kitchen sink faucets that have a "scald proof" feature causing the problem. In my years of plumbing I have never seen one but nowadays any thing like this is possible. You may need a plumber to check the piping or mixer valve to determine the problem and correct it.
Some tankless water heater installers do not allow for adequate BTUs of gas to run the unit. The gas line is not large enough to give consistent volume of gas. It is volume not pressure as indicated in another response. Propane ½ lb (12 inches water column) pressure, natural gas 1/4 lb (6 inches water column) pressure. If the pipe size (or stainless gas tubing) is not large enough for the distance, yes, then you will have a pressure drop at the unit. Consulting a gas pipe sizing chart will give an easy answer for pipe size. Too many who are not acquainted with gas needs will not install the right size pipe. The outcome is that the unit will fire and in a short time the flame will go low or out until the gas can build up enough again so that the unit will full fire. This causes warm and hot water fluctuations.
If you have "hard water" get a water softener or go to and purchase the Whitlam Flow-Aide Kit (white vinegar DOES NOT work). Flush twice per year. Maintenance like changing oil in your car.
Proper installation, great success.
Wish I could be there to help you but I am at the other end of the U.S. Wishing you good success.

In reply to an earlier post on Oct 13, 2013 5:34:38 PM PDT
If you are on a well system, check your pressure tank and your well pressure switch. If the pressure tank is not working properly (they wear out in as little as 5 years), the problems you are describing could be caused by easily fixed well pressure issues.
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