Tankless water heater: problems with maintaining temperature

by TomJ
(Wakefield, MA)

I have a Bosch outdoor propane fired hot water heater. I recently had it serviced and the service technician found one of the 3 sensors was unattached. The O&M; manual does not show where it was attached, so we left it unattached. Also, when taking showers, the water starts out hot, then gets cold without any apparent reduction in flow, then gets hot again. Is this due to the sensor not being attached, or perhaps that the water filter needs to be cleaned?