© Danfoss | 2022.11| 17
LGB53080
Termix VX-IV - 3 Series DS Fully insulated
Filling of the primary heating system
First fill
When carrying out the first fill, the heat exchanger must be slowly filled
with water until it reaches working pressure.
Pressure gauge
The HTG pressure gauge indicates the pressure of the HTG system. This
instruction must be followed strictly to avoid dangerous situations.
Supply hose
An isolation valve with plug is installed in the HTG return line. To fill the
system, the isolation valve must first be closed, the plug removed and a
supply hose connected. On re-opening the isolation valve, system fill can
commence.
Filling stop
When filling the system with water, the pressure gauge should be observed
closely. Filling must stop when the pressure gauge shows a pressure
approximately 1-2 bar higher than the pre-pressure setting. The isolation
valve is then closed, the hose removed and the plug replaced.
Pre-pressure
The expansion vessel is supplied prepressurised to 0.5 bar. The
pre-pressure required for the individual HIU will depend on system head
(the distance between the lowest and highest point in the system), for
example:
Height (m)
Presssure (bar)
0-5
0,5
5-10
1,0
10-15
1,5
15-20
2,0
Re-tighten connections
After water has been added to the system and the system has been
put into operation, re-tighten ALL connections.
26
see diagram
Filling of the secondary heating system
A flushing bypass or similar should be mounted.
Only introduce heating network water in the HIU once it has been flushed.
Commissioning
Before start-up check that:
• Pipes are connected in accordance with the symbols indicated on the
HIU.
• Then slowly open the isolation valve(s) so that the HIU fills with water.
• Ensure that all union fittings and swivel nuts have been re-tightened.
• The heating circuit must be vented before commissioning.
• Monitor the HIU’s operation in regard to temperature, pressure, thermal
expansion and leaks.
• Provided the HIU functions in accordance with the dimensioning
regulations, it can be put into use.
