Rinnai tankless

[BradLandreth]

I’ve done a lot of searching and working on this heater but can’t figure this out. I’ve used some advice from others that have had the same problem but it hasn’t completely remedied the issue.

Rinnai r-94-ls

Hot for three minutes then cold. Turn it off and right back on and it starts up again for another three minutes. There were no error codes in the beginning.

Cleaned the fan and exhaust and all, descaled it. Started it back up and it would run for four minutes then give me error code 10. The fan would get faster and faster and then the unit would finally shut off.

I removed the small sheet metal plate at the top of the unit where the fan draws air from and it works fine.

This leads me to one if two thoughts....

1. It isn’t properly vented and isn’t getting the right amount of air or something along those lines or....

2. The unit is having to work harder than it should requiring more air than it is getting.

So my questions are....

1. My unit is under the house and we are safe from the bad gas that I believe is supposed to recirculate when the vent works properly. Is it otherwise safe to use the unit until we figure out the problem?

2. Any thoughts on if the system may be working harder causing the shutdown or if it isn’t properly vented?

Thanks in advance!!!

 

[FDNY/RETIRED]

I start off by saying I am not a plumber or a professional. I own a Navien unit has a home owner. Plus a Quietside before that. But it seems you know what your doing. So here are my questions.
1. I figure the unit has been installed for sometime, Not a new install?

2. You said you cleaned the fan and exhaust, and after that you started getting a error code 10? Which says A Rinnai fault code 10 is an indication of either an issue with the air intake or a blocked flue. Your first step should always be turning your system on and off to see if the Rinnai fault code 10 has disappeared. If it hasn't, check the vent system for blockages and other issues that could prevent airflow. Which I guess you know already

So if all of a sudden you just started getting this error code after cleaning the fan and exhaust. Are you sure something isn't misaligned? When you say you cleaned the the fan. Did you actually take the fan out of the unit. To see if there is anything on the inside of the cage. I know you said you (removed the small sheet metal plate at the top of the unit where the fan draws air from and it works fine.)

Have you go outside where the intake and exhaust are and put your hand over the intake, and see how much suction you have? Also on the exhaust and see how much air flow coming out there is? Maybe there is something in the duct work that you really can't see.

3. Last and just by chance when you were checking the unit did you maybe by accident hit a dipswitch? I saw something about making sure the Dipswitch are in the proper positions.

I figure it isn't a gas flow problem since I would think there is a code for that

 

[Sponsor]

 

[Bannerman]

I removed the small sheet metal plate at the top of the unit where the fan draws air from and it works fine.

If this is a solid plate that is blocking the air opening, unless there is an alternate opening for air to enter, then it sounds as though you found the cause of the problem.

 

[FDNY/RETIRED]

Your right I read the first post wrong. I thought you took an inspection plate off to check the blower. You were getting airflow and it was clean. Then you put it back together and that's when your code 10 started. So you and Bannerman are right that was your problem. Unless there is another opening. Again is this just a new unit that was installed, Or have you had it for sometime? Because for it to just start doing it after say a year, and not right away on installation. I wonder why that would happen, if that plate was always there. It is under your house but you have no duct work to the outside just a unit sitting in an open space under your house?

 

[Fitter30]

Snow block air intake or ice exhaust

 

[Paulypfunk]

...Or lint, or leaves, or an animal nest. It sounds like you have traced the problem to the air intake piping. Check the entire run, run a snake or a rag on a wire through the length. Vacuum the inside from the opposite direction of normal flow? Any sags in the piping that might collect water? That piping is limited in the what size it can be, how long the snorkel can be and how many turns are in the piping. All of these conditions create friction that impede air flow. If the intake piping is was installed wrong to begin with it could become an issue if your fan blower is getting old and can’t pull as strong as it used to. If you are handy with a clamp style multimeter you can check the amp draw on the fan motor to see if it’s lagging. A few ideas for ya...

 

[Bannerman]

Although he didn't say how long it has been in use, I assume it has been for some time otherwise I would not expect he would have proceeded to descale it.

All I can find is the installation manual for an Rinnai r-94-LSi. I don't know what the differences will be for the 'i' model.

The LSi appears to be only configured for concentric venting (exhaust pipe inside a larger diameter combustion air intake pipe). Perhaps the LS is convertible so the plate that was removed may allow the unit to be converted to non-concentric venting to use two separate pipes? Perhaps it was installed with only an exhaust vent and the air inlet opening was not opened to install the combustion air inlet collar and piping?

Although there should be interlock switches to prevent operation unless the front cover is fully in-place, perhaps the front cover was not fully seated and was allowing sufficient air to leak to allow the unit to run OK for some time.

Without a full description and photos, or being there to observe for ourselves, all we can do is speculate.