HIUs
Module 7 – Error Codes
The objective for training in Part 7 is an overview over error codes and how to resolve them
Very high primary / district return temperature.
E2 Error warning – both Heating and DHW not available.
In installations where Radiators are
at very high temperatures, then this is a
warning that the return temperature is higher
than the maximum allowed in parameter 20,
as measured at the primary return
temperature sensor.
As this is a safety function, the PICV
closes until the sensor on the primary
return sees a temperature drop of 10C
below the parameter 20 set point for
maximum.
Check parameter 20 is set correctly, if
too low, reset this at 5C higher than secondary
heating flow set temperature.
Check the temperature probe is positioned
correctly.
Reset (turn power on and off) to recalibrate the
PICV actuator.
Reduced hot water production (possible blockage)
E3 Error warning – both heating and DHW still available.
The controller is recognising that the HIU performance is not as the algorithm predicts. The energy transfer is poor.
Heat transfer is inefficient, hot water production reduced and temperature control unstable.
If signs of blockage it could be the strainer is blocked or the PHE is partially blocked with lime scale.
Check PICV fully open – check flow on the heat meter, low flow now would prove a blockage of
some sort is the issue.
No control for hot water (DHW) supply temperature.
E4 Error warning – Heating is still available, DHW is not.
No hot water.
The controller has detected that the
hot water temperature control behaviour is
consistent with the sensor being in the
wrong position, and shut down hot water
production as a safety precaution.
The HIU will automatically rest after 10
minutes, but repeat the shutdown again if
the issue is not resolved.
Check DHW temperature sensor
position is correct. Reposition.
Then system reset, turn off the power at the
supply, and then turn on again to allow the PICV
actuator to re-calibrate its position.
Reduced heating performance.
E5 Error warning – No heating No DHW.
Heating is not reaching the set point so is performing poorly or not at all.
Heating stops after 20 minutes and shows the E5 code.
Resets after 30 seconds
Or Error LEDs on the pump?
Check the following:
Power ON and OFF at the mains switch, this allows the PICV to recalibrate, and in doing this will allow a small flow into the PHE, which then proves the PICV and Diverter not at fault
No heating or hot water. Intermittent E6 error code
E6 Error warning – No heating No DHW.
No heating or hot water. Intermittent E6 error code
Temperature information from the heating temperature sensors is wrong or unusual.
Return temperature to high with no control.
This error code is showing that either:
High heating secondary return temperature warning. mode operation is inefficient. Over-shoot of temperature on the heating return.
E7 Warning – both Heating and DHW are still available.
The return temperature is too high and
the HIU is warning the operator that heating
High heating secondary return temperature warning. mode operation is inefficient.
This warning bringing attention to
the operator that heating is not operating at
it’s design temperatures. Various causes
may be considered, example all TRVs may
be closed with only 1 x small radiator open,
but the room thermostat is still calling for
heat. The return temperature is much too
high, so the HIU ceases heating for 10
minutes.
The E7 will automatically reset itself
after 10 minutes. Attention should be paid to the
set up of the heating radiators and controls.
