Rinnai tankless water heater base flashing problems

Any of you fellas getting calls about “leaking roofs” only to go out, check up and then find that the Rinnai tankless water heater base flashings have failed?

I’ve had a few Rinnai issues in the past but last week we recevied four calls about “leaking roofs” (three ours and one not ours). In each case the Rinnai base flashing accessory piece had failed…completely disentegrated. The base flashing kit is made of some sort of mesh (not hard metal) and then has a coating applied to the mesh. It seems the coating is not UV resistant and pretty much falls apart.

I believe this is an issue with their older base flashing accessory pieces and the new models are good to go. Rinnai does have a warranty claim form for processing claims, so they know about their problem. Typically the plumbing contractor installs the Rinnai products and we, as the roofer, merely install the base flashing for the plumber as a courtesy. Of course, now years later, the plumber acts as if he has no clue to why there would be a problem that he / she should step in and help resolve.

Do you have a pic of one of these things?

Yes. I’ve replaced at least a dozen or more in the past 4yrs. The base wears the coating off and all that’s left is the wire mesh. I sent an email to rinnai and left one with my local plumbing supply, but never got a reply. I’m checking to see if I have a photo of the base.

This is what it looked like from inside the attic. From outside it looked normal. The replacement base doesn’t seem to have the mesh in it.



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Does it need to be flexible?

Why not just use a regular B vent type flashing?

Hard to explain but the base flashing is made to fit the storm collar. It sort of articulating. They make one that’s up to about 7/12. Then a steep one. It’s all made of a type of plastic. Some are a pain, because you have to go in the area where the PVC fits on the heater and disconnect it. Others, I’ve been able to remove the cap and take it apart. For some reasons, plumbers want to glue the cap on.

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Thanks for posting the pics, rooferama. That is exactly what the ones look like that we’ve encountered. Rinnai does have a warranty claim form circulating.

Rinnai Tech Assistance at 1-888-746-6247