THERE ARE CERTAIN CONDITIONS in parts of Australia which render these on-demand systems (those with no permanent pilot flame) inoperative, two of which are described below, and their solutions.

1) INSECT (MOSTLY NATIVE BEE) INGRESS. This damage becomes immediately noticeable as a drop in water temperature, partially-lit burners, and black smoke-deposits from un-burned gas.

THE CAUSE:  Small bees find their way to the air-gas intake ports and lay their eggs etc. in the tubing, blocking the gas. This causes a yellow, smokey flame, or none at all, from the gas jets affected, and black carbon deposits from the chimney.

THE SOLUTION: Remedially, to dismantle and clean the gas-mix tubes affected: a job taking one hour. Permanent, to screen all air ingress and egress with flame-proof wire- mesh suitable to exclude the insects concerned, mostly small bees, though there may be other insects involved. The manufacturer may be concerned that this action may affect air-flow, particularly if any screening becomes blocked over time, so regular cleaning may be necessary.

2)  INTERNAL CONDENSATION.  There are certain weather conditions, particularly in elevated areas, which result in a TEMPERATURE-INVERSION, usually at night. During these situations, which may be quite common, the internal cold metal parts of the BOSCH HYDROPOWER attract copious condensation as warmer, saturated air surrounds the system. This renders the piezo  spark inoperative, soaked as it is during these periods. This effect takes place entirely WITHIN the casing of the BOSCH HYDROPOWER.

THERE IS NO SUITABLE SOLUTION to this problem, unless a position sheltered from the effect of the TEMPERATURE-INVERSION  can be found for the heater. A desperate measure is to light the pilot manually whilst the piezo is operating; quite safe, but requiring some considerable manipulation not within the capability of the home-owner. An easier solution is to give the piezo and pilot a quick spray with de-watering fluid prior to turning on the hot water: still a painful exercise, as the cover must be removed.

All complaints to the local Australian distributors of these hot-water systems are brushed aside as being without foundation, and it is possible that considerable money is wasted by home-owners, ignorant of the true cause of the problems,  in fruitless repairs. The frustration of cold water from the hot tap is unfortunately at the worst times of day; late night and early morning.