We have a problem where our Rinnai natural gas tankless water heater randomly goes cold and stays cold unless you turn off the water for a few seconds and let it reset. Looked around at a lot of confusing stuff online and eventually found the only thing that works is to have another hot water source running at the same time. Thinking this was a low flow issue i tried things like turning the thermostat down as low as tolerable and trying to remove flow limiters in our 2.5 gpm shower heads (the most annoying time for this to happen.) The attempts do not reliably stop it from happening. Does anyone else have this issue and have a hopefully simple solution? We have dealt with it just fine but are getting ready for a major remodel so if there is a solution now is the time. We have asked plumbers and they don't really have an idea.