Page 11
4.3 Fault Location Table
Before attempting to locate faults on the Herz HIU please ensure the following:
The primary flow temperature is correct
The primary flow rate is correct
There is sufficient primary pump pressure to allow circulation through the Heat Exchangers
5.0 Technical data
The HIU is designed for maximum PN10 primary side working pressure
Maximum district heating flow temperature is 90°C
Minimum differential pressure between primary flow and return is 30kPa
Minimum cold water pressure to the HIU is 2.5 bar
5.1 Appendices
Operating data
Function schematic
Spare parts list
Water quality parameter table
Dimensional drawings
Problems with
hot water
Long wait for hot
water at the tap
Check the bypass circuit
Check the primary heating circuit
Pressure temperature
controller is leaking
Replace the Pressure temperature controller
Pressure temperature
controller sticks
Replace the Pressure temperature controller
Temperature of the
hot water is too low
Increase the flow temperature on the heat source
Check the valves settings on the unit
Check/Clean the primary flow strainer
Check the settings on the primary heat pump
Check the heat exchanger and, if necessary, replace
Check the Pressure temperature controller and, if necessary
replace
