Operational Problems - Danfoss DHP-A Service Instructions Manual

Service instructions
Refrigerant
R407C
2.4

Operational problems

The tables in the following section apply to all types of heat pump and collector solutions.
The tables list the most probable and common causes of the problem first. When troubleshooting 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.
2.4.1 Alarm
Problem – Alarm LP (low pressure switch)
Cause
1. Blocked strainer on the brine cir-
cuit.
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 jam-
med.
5. Cable break or loose cable to low
pressure switch.
6. The low pressure switch opens
too soon.
7. Incorrect type of anti-freeze, must
be in accordance with instructions.
Danfoss Heating Solutions
Domestic heat pumps
Pressure switch
Low pressure switch
Operating pressure switch
High pressure switch
Troubleshooting
Check that the strainer is not blocked.
Listen for air in the heat pump and brine circuit.
Check that the stopcock or 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 there is no air in the heating system.
▪ Check that both cables are connected to the
pressure switch.
▪ Using the buzzer, check that there are no ca-
ble breaks. In order to do this, disconnect 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 pres-
sure than indicated (mark pressure). Check us-
ing the manometer apparatus.
▪ Defective pressure switch, always open.
Check that the correct type of anti-freeze is used.
Remedy
Clean the strainer if necessary.
Bleed the brine circuit according to the in-
stallation 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 screwdriver for
example.
Open closed valves or taps.
Check, and, if necessary, clean the strainer.
If necessary, bleed the heating system ac-
cording to the installation instructions
If a cable has come loose, reconnect it.
If there is a cable break, replace the cable.
If the low 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 refil-
led with a new mixture.
VIGFI102
Break pressure
0.08 MPa
2.85 MPa
3,10 MPa
9