Here is what the L5 has in terms of sensors. This is based on actually inspecting the unit, rather than relying on the documentation
or just speculating.
flow sensor. It is connected to a microswitch and prevents the unit from firing unless there is sufficient water
flow. If the unit is running and the flow drops, it will shut down.
2. Water overtemp sensor. Located on the hot water pipe near the outlet, it will shut down the unit if the outgoing water temp is too high. The water must get pretty hot for it to kick in, but it does work. I know this from actual experience.
3. Flame sensor. A thermocouple located in the flame. This allows the unit to detect ignition and to shut down if the flame goes out.
4. Heat sensor. A thermocouple located high in the heat exchanger
. It detects if the unit is actually heating
up. It is unclear exactly how this is used but it is another sensor that can help detect improper operation. It is also unclear if this is used for overtemp detection.
also implements a 20 minute timer, which shuts down the L5 if it has been running for 20 minutes. This is a safety
feature in case someone leaves the unit on and just walks away.
It would be nice if Eccotemp documented the units behavior more precisely, but for a $120 consumer product, it is not likely. Still, given the price
, the set of sensors and the control system is pretty good. It is better than the $1000 Bosch unit I replaced.
Hope this clears up any misunderstandings of what is actually in the L5. And no, I have no connection to the company.