Most Frequent Function Failures And Their Causes; Operation Of Thermostat - Dražice OKHE 80-SMART Operating And Installation Manual

2.8 MOST FREQUENT FUNCTION FAILURES AND THEIR CAUSES

The thermostat is equipped with auto-diagnostics that allows display of some failure modes.
If a failure occurs, the failure symbol shows on the display and the failure code can be looked up in the
menu (Table 4).
Failure code
Failure description no failure bottom sensor failure upper sensor failure both sensors failed
Table 4
If one of the temperature sensors fails (Err1 or Err2), the boiler runs in NORMAL mode only (allows
emergency run of the heater), if both sensors fail (Err3), the heating element does not heat.
Other potential failures – Table 5.
Failure symptom
Water is cold
Water is constantly
dripping off the safety
valve
Table 5
Do not try to repair the failure yourselves. Seek either expert or service help. It does not take
much for an expert to remove the defect. When making a repair appointment, report the
type and serial number you find on the performance plate of your water heater.

3. OPERATION OF THERMOSTAT

Electronic thermostat for controlling electrical water heaters of DZ Dražice allows multiple operating modes
along with providing comfort functions. The thermostat contains a display and a five-key keyboard that
allows setting of the heater.
Err_ Err1
Potential failure cause

Low temperature is set on the
thermostat (applies to modes
NORMAL, HDO, ECO).

Heating element failure

The thermal fuse is activated
(relevant symbol lights on the
display).
high input pressure


defective safety valve
Err2 Err3
Solution

Set higher temperature on
the thermostat.

Seek an authorised service
centre.

Seek an authorised service
centre.

Use pressure control valve

Replace the valve
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