suds9140
New Member
I've had issues with two different Rinnai tankless water heaters leaking from the heat exchangers over the past several years. I'm now on my second Rinnai tankless water (an RL94i) within the period of only 9 years. The first unit, which was installed when the home was built, started leaking from the heat exchanger after about 6 years, and was ripped out and replaced (it was going to cost more to replace the heat exchanger than to do a full unit replacement).
Earlier this year, about three years after the first unit was replaced, my second unit (also an RL94i) also started leaking from the heat exchanger. This time around I worked with a plumber to secure a replacement heat exchanger from Rinnai (they wouldn't send it directly to me) and did the replacement myself. It was a long and tedious process, but saved a lot of money and learned a lot along the way. That was about four months ago, and the unit has worked fine since, but I'm concerned the new heat exchanger will eventually start leaking just like the others did, due to some underlying issue I'm not aware of.
When the first unit started leaking, the plumber said it was probably due to no condensate line being installed, so when the replacement unit was installed he added one. When the second unit started leaking, he attributed it to scale build up in the heat exchanger. I do have hard water in my area and no water treatment system (yet), but I had been flushing both units with vinegar according to Rinnai's flushing procedure about twice a year, so I'm skeptical it was due to build up in the heat exchanger from hard water.
After inspecting the old heat exchanger from the most recent replacement, it looks like the leak might have been caused by condensate or outside water (rain infiltration) coming into through the exhaust vent and dripping down from the top of the unit onto the heat exchanger.
I've included some pictures and was hoping to get some input from those with more experience. I'd really like to prevent this from happening again. In one of the pictures you'll see how the first condensate line was installed by the plumber using PVC pipe. I've since replaced that with a condensate loop using clear tubing. For venting on the unit, it is just a straight shot from that 90 degree elbow to the outside wall of the house, so not a long distance at all.
Pictures:
Earlier this year, about three years after the first unit was replaced, my second unit (also an RL94i) also started leaking from the heat exchanger. This time around I worked with a plumber to secure a replacement heat exchanger from Rinnai (they wouldn't send it directly to me) and did the replacement myself. It was a long and tedious process, but saved a lot of money and learned a lot along the way. That was about four months ago, and the unit has worked fine since, but I'm concerned the new heat exchanger will eventually start leaking just like the others did, due to some underlying issue I'm not aware of.
When the first unit started leaking, the plumber said it was probably due to no condensate line being installed, so when the replacement unit was installed he added one. When the second unit started leaking, he attributed it to scale build up in the heat exchanger. I do have hard water in my area and no water treatment system (yet), but I had been flushing both units with vinegar according to Rinnai's flushing procedure about twice a year, so I'm skeptical it was due to build up in the heat exchanger from hard water.
After inspecting the old heat exchanger from the most recent replacement, it looks like the leak might have been caused by condensate or outside water (rain infiltration) coming into through the exhaust vent and dripping down from the top of the unit onto the heat exchanger.
I've included some pictures and was hoping to get some input from those with more experience. I'd really like to prevent this from happening again. In one of the pictures you'll see how the first condensate line was installed by the plumber using PVC pipe. I've since replaced that with a condensate loop using clear tubing. For venting on the unit, it is just a straight shot from that 90 degree elbow to the outside wall of the house, so not a long distance at all.
Pictures:
