Can anyone please tell me why the water temperature fluctuates wildly over a short period of time such as whilst taking a shower? I’m not sure of the age of this hot water system. Could it be on the way out or is it a part that requires changing?
Sounds to me like the first thing I would check is the setting in the machine that controls the low flame setting, second thing I would look at is the shower rose itself to make sure it is not blocked or restricted in any way which would also cause the heater to go hot and cold. Fluctuation in water temperatures from this machine is usually only small things those being a poor gas pressure and not set up correctly, a restriction in water flow at the outlet, a weak or stretched diaphram in the water valve, or simply the heat exchanger and water heater simply needs a clean and full service done by a Bosch serviceperson in your area.
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