Operational Problems - Danfoss DHP-AX Installation And Service Instructions Manual

Break pressure pressure switches
Refrigerant
R407C
15.4

Operational problems

BB E B
T he tables in the following section apply to all types of heat pump and collector solutions. This means that cer-
tain information does not apply to DHP-AX.
The tables have the most probable and most common causes of the problem listed first. When troubleshoot-
ing the cause of a problem start with the first cause and go down the list. There may be more than one way of
troubleshooting a cause where the most probable is given first.
15.4.1 Alarm
Problem – Alarm LP (low pressure pressure switch)
Cause
1. Blocked strainer on the brine
circuit.
2. Air in the brine circuit.
3. Closed taps, main tap or filler
cock on the brine circuit.
4. The circulation pump for the
brine circuit is defective or has
jammed.
5. Cable break or loose cable to
low pressure pressure switch.
6. Low pressure pressure switch
opens too soon.
7. Incorrect type of anti-freeze,
must be in accordance with
instructions.
46 – Service
Pressostat
Low pressure pressostat
Operating pressure switch A
Operating pressure switch B
High pressure pressostat
Troubleshooting
Check that the strainer is not blocked.
Listen for air in the heat pump and brine
circuit.
Check that the shut-off cock/any other
taps are open.
Check:
• That the circulation pump spins.
• That the shut-off valves are open.
• That the strainer is not blocked.
• That no air is in the heating system.
• Check that both cables are connected
on the pressure switch.
• Using the buzzer, check that there are
no cable breaks. In order to do this, dis-
connect the cables from the pressure
switch and circuit board.
• Incorrect pressure switch installed.
Higher break pressure than intended. See
marking.
• Pressure switch fault, opens at a higher
pressure than indicated (mark pressure).
Check using the manometer apparatus.
• Defective pressure switch, always open.
Check that the correct type of anti-freeze
is used.
Break pressure
0.08 MPa
2.65 MPa
2.85 MPa
3.10 MPa
Remedy
Clean the strainer if necessary.
Bleed the brine circuit according to the
installation instructions.
Open closed taps.
The circulation pump may have jammed,
if so, open the bleed screw and try to
release the paddle wheel using a screw-
driver for example.
Open closed valves or taps.
Check, and, if necessary, clean the strai-
ner.
If necessary, bleed the heating system
according to the installation instructions
If a cable has come loose, connect it.
If there is a cable break, replace the cable.
If the low pressure pressure switch opens
too soon or is always open, replace it.
If the incorrect type of anti-freeze is used,
the entire system must be drained and
refilled with a new mixture.
VMBMH302