Rinnai Tankless Headache

bobmaier

My propane Rinnai was installed 6 years ago, it's been cleaned regularly, and worked without issue until last fall. Then it failed to light several times (code 14), always fixing itself after 12 - 24 hours. Finally, it wouldn't light off at all. My plumber, troubleshooting on the phone with Rinnai, determined the problem to be a thermal fuze failure. Rinnai sent a replacement, it was installed, and the unit was back on line. One month later, code 14 again. Same discussions with Rinnai, they suggested a heat exchanger replacement, and a new part was sent. While waiting for the part, after being off-line for 3-4 days, it fixed itself again - and lasted 3 more weeks until another code 14 failure. The new heat exchanger was installed. It worked for 4 months, then failed for two days, but again fixed itself for a week. Now I'm waiting for the plumber once again. Vents, gas pressures, water flow - all have been checked many times. The plumber and I are at wits end. It's basically a new unit except for the motherboard, and I've spent $900 so far. I'm ready for a plain electric tank. Any thoughts?

4Johnpipe

Which model Rinnai?

bobmaier

R85-1 REU2534FFU. I'm currently talking with Rinnai. They are thinking a vent issue, but it's been checked many times (and worked for 6 years). The plumber refuses to come now, and BTW, it's working again! But I know a failure is coming any time now.

4Johnpipe

How long of a run is the venting? Is it positively pitched to the exterior? I have seen the metal inner pipe deteriorate by collecting flue gas condensate on a horizontal run. The unit begins to intake unused gas and codes out. I am not positive without looking up the code 14 for that older unit.

bobmaier

The vent has the correct slope, has only two elbows, and is only 5 feet long. There is no evidence of any condensate anywhere in the system. The only potential issue is that the vent exits at ground level into a well 3 feet in diameter and 1.5 feet deep - plenty of circulation and airflow. Still working after two days. I lowered the temp to 110 to see if that will keep it going.

4Johnpipe

U B Link makes a snorkel termination product that is telescopic and will bring the termination well above ground. Rinnai is correct it is a venting issue. you are getting an inconsistent mixture of unused gas in the exhaust being pulled back for combustion. This is the same condition as I described above.

RobG

I agree with 4johnpipe, until you get the venting corrected you cannot proceed with troubleshooting. Mixing intake and exhaust into a window well is not conducive to a finely tuned appliance.

Mad Dog

Can u put up a picture? If that is vented in to a window well??? It's amazing it worked that long!. PLEASE post a pic of outside termination. Mad Dog

bobmaier

You folks may be helping me get to the bottom of this, and it sounds like my installer did a number on me. The ruler in the pic is 18" long, and the well is 15" deep. And although I've never found evidence of condensation in the unit, I cut a hole in the drywall to get a good view of the horizontal vent run to the outside wall - I put a level on it an there's no slope. There is a condensate unit on the second section of vent above the unit before it turns horizontal, but no drain line attached to it - it's capped off. I tried to disassemble the vertical vent to shorten it to try to put a slope in the horizontal run, but was not successful. (Is that a common problem? I got it off the tank, but couldn't separate the shorter pipes.) I found the Rinnai/Ubbink snorkel online, and I have a call in to another Rinnai certified gasman, hoping he'll return it and be able to attach the snorkel to existing venting without tearing up the wall or inner drywall. I just don't understand why it worked so long.....

4Johnpipe

Thanks for the picture...sorry you are dealing with this. If you notice the discoloration in the inner pipe that is a sign of condensate corrosion. That pipe should be a matte finish silver inside. I would recommend after seeing the picture to replace the short pieces of piping. The line should have pitch. The installer may be able to pitch outside. If pitched back the condensate collector drain should be piped away properly. When the new installer comes by notice the inner pipe when he takes apart the existing pipe. If its crusty and flaking replace the pipe.

RobG

4Johnpipe said:

Thanks for the picture...sorry you are dealing with this. If you notice the discoloration in the inner pipe that is a sign of condensate corrosion. That pipe should be a matte finish silver inside. I would recommend after seeing the picture to replace the short pieces of piping. The line should have pitch. The installer may be able to pitch outside. If pitched back the condensate collector drain should be piped away properly. When the new installer comes by notice the inner pipe when he takes apart the existing pipe. If its crusty and flaking replace the pipe.

And make sure that the burners and heat exchanger are cleaned in the process.

Bob Bona

That term is so wrong, you've got blowback and cross contamination going on. What about snow? Yikes. Once thats corrected the burner and internals must be inspected for decay.

bobmaier

After taking a good look at the unit and venting, finding it all spotless and running perfectly (one of the very best he's seen), and a new and knowledgeable tech performing checks with Rinnai on the phone, I'm back to waiting for the next failure so they can try to determine what's actually cutting the power while the unit is failed. Everyone is frustrated. BTW, haven't had snow near the vent in years.

4Johnpipe

Thumb through this service manual while you wait for the next failure. I am surprised that the vent termination did not seem to be an issue with the new service tech...

bobmaier

Thanks for the manual. I also have a copy of the Troubleshooting Manual, which states that if all else fails, the last step for a code 14 failure is replace the pc board. Both techs asked Rinnai about this, but Rinnai says that in 15 years they've never had a board cause a code 14. They've sprung for thermal fuzes and a heat exchanger - maybe they just don't want to give me a board! The bi-metal fuze is under suspicion as of this writing. And while we understand the potential of a vent problem, there's lots of clean airflow around the exit, and my question still remains - why would it suddenly work fine after being inop for several days? Anyway, still working like a champ after one week.

bobmaier

Status update. The unit failed again after working for a week or so. This time, with the unit failed and totally cooled down, we jumped the bi-metal fuze and it fired right up. We could duplicate the failure easily. We replaced the fuze and all's well. (After removal and at room temperature, the old fuze read open on an ohm meter. Just for the heck of it, I put it in my freezer, then took a reading . . . it had closed.) Fingers are now crossed. The bi-metal fuze had not been replaced during any of the previous maintenance actions.

Jack

Bob, regardless of what the tech saw, the unit working perfectly, the unit is not vented correctly. I would put a picture of your vent in my "hall of shame" for contractor install trainings. It needs to be changed. Look at the area surrounding the water htr. You could use the snorkel (I tried to replace the "S" with a dollar sign, but autocorrect can be such a pitn). You can also look at what is above the water heater. I run vents up behind kitchen cabinets, in the corners of lazy Susan ( little people required), in the base of exterior wall closets, etc.
I have to say that I am amazed that the unit has functioned this long and this well with that vent. Your service tech found it operating properly, but that is a "point in time". Gusting winds, changes in wind directions, putting a garbage can or lawnmower next to that well can totally change the situation.
Good find and well done on that sensor.

SWEI

4Johnpipe said:

U B Link makes a snorkel termination product that is telescopic

Sounded like an interesting solution, but it took a bit of searching to find the company http://www.ubbink.com/

Would you mind sharing which product?

thanks~

Mad Dog

I've seen otherwise good and legit licensed outfits "solve?" The venting issue like the picture here: "...you're NUTS...you don't need no stinkin snorkel kit ( to bring vent terminal above highest snow load)..we just dig down in front of it!" I've seen jobs like this that inspectors passed....but at least they were initially 6" or so above grade....that's in a window well!..........astonishing! Mad Dog

Jack

Try this link http://www.rinnai.us/documentation/downloads/72410.pdf
It is the Uubink installation manual from Rinnai.

4Johnpipe

Its on page 12 actually looks like a Rinnai part now. Available in non condensing also...
http://www.rinnai.us/documentation/downloads/R-CNWH-E-23_r4.pdf

SWEI

Jack said:

http://www.rinnai.us/documentation/downloads/72410.pdf
It is the Ubbink installation manual from Rinnai.

Thanks, Jack. Still doesn't permit a below grade transition through the building wall from what I can see.

4Johnpipe

Rinnai does not want to subject the gaskets between sections to standing water. They actually have an adhesive tape called watertite or watersafe. I still wouldn't do it.

Jack

SWEI said:

Jack said:

http://www.rinnai.us/documentation/downloads/72410.pdf
It is the Ubbink installation manual from Rinnai.

Thanks, Jack. Still doesn't permit a below grade transition through the building wall from what I can see.

Correct. It is a gasket end joint, not a glued joint. If we said it was ok, folks would bury it. You know, out of sight, out of mind?