Bosch 715 ES... Flow rate requirements? Fixable?

[TheZster]

I've got a Bosch gwh 715 ES... 8 years old - in a property I'm renovating. According to specs.... she should fire up when flow rate hits >.5gpm. Not happening!! I open up a fixture with a flow rate of 1gpm (confirmed)... nothing.... I open up an additional fixture of "probably about the same" - and I've got hot water all day long as long as two fixtures are creating a demand..... (want a hot shower - turn on the hot water in the bathroom sink also)….

I've cleaned the filter - lowered the temp, raised the temp, etc.... and it still does the same thing.....

Is this thing repairable? I'll admit - I'm not a plumber - I can plumb a whole house by code - easily enough - but dealing with this has me flummoxed.... I'd hate to call out a plumber who would have to "go through the installation manual" to figure out what I've already figured out. I understand Bosch quit selling tankless in the US a number of years ago (2004?)…. so "experts" might be a bit difficult to find.

Any suggestions would be greatly appreciated.... before I go out and spend another $1000+ on a new Rheems….

Thanks,

Z

 

[Dana]

Since it's flow related, the flow sensor could be failing. If you can find one on the cheap (or at all) it may be worth risking the cost of the sensor itself as a diagnostic/repair measure, but it's not worth investing a lot in an unsupported 8 year old tankless. It might still be under warranty (many tankless units have 10 year warranties), what do the Bosch tech support people say?

Bosch is still selling tankless water heaters in the US, but not the GWH 715 ES. If it's less than a decade old they should still be offering tech support on the thing.