Tankless Water Heaters
blog.mizukinana.jp: Rinnai RU199iN Condensing Tankless Hot Water Heater, 11 GPM, Natural Gas, Indoor Installation : Everything Else
RU Model Series
Rinnai Water Heater Troubleshooting & How to Guide
We then replaced the vent with a PVC pipe which fixed the issue.
The heaters are made from high quality materials that improve their performance and pretty much make them maintenance free.
Solution: Turn OFF water flow on the hot water tap.