Problem - Noise - Miscellaneous; Hot Water; Problem - Temperature And/Or Quantity - Danfoss DHP-H Installation And Service Instructions Manual

Problem – Noise – miscellaneous
Cause
1. Vibrating protective sleeves on the pres-
sure switches.
2. Vibration noise from the electrical instal-
lation.
3. The heat pump is not level.

HOT WATER

Problem – Temperature and/or quantity
Cause
1. Defective 3-way valve motor.
2. Jammed 3-way valve insert.
The valve is not secure and releases hot
water to the radiators during hot water
production.
3. Air in TWS coil or water outer jacket.
4. Start temperature set too high for hot
water production.
5. Sensor fault, hot water sensor.
Hot water production is started by the hot
water sensor.
6. Large drain flow (>12l/min).
7. Water heater too small in relation to
requirement.
8. The operating pressure switch opens too
soon (at too low a pressure).
Hot water production ends when the oper-
ating pressure switch opens.
74
Troubleshooting
Establish where the vibration noise is com-
ing from.
Check for electrical steps or similar devices
screwed to the heat pump and wall. These
can cause vibrations and noise.
Check that the heat pump is level by using
a spirit level.
Check that the heat pump is supported by
all four feet
Troubleshooting
Check the function of the 3-way valve, that
it runs between the end positions by run-
ning a manual test.
Detach the motor and test closing and
opening of the valve by pressing the con-
trol arm
During hot water production:
• Listen for air.
• Check the temperature difference
between supply and return line.
Check that the start temperature is correctly
set. Should not be set above the factory set
value.
Check what the hot water sensor (the start
sensor) shows, is it a plausible/actual value?
Measure the resistance of the sensor, check
against the ohm table in the Measurement
points section.
Check how many litres of hot water (approx.
40°C) per minute drains from the tap. Use a
clock and bucket to measure the drain flow.
How large is the requirement and what is
the capacity of the heater?
Check the break pressure using manometer
apparatus.
VMBMA602
Remedy
Prevent the protection sleeve vibrating by
using insulation tape for example.
Carry out according to the installation
instructions.
If the heat pump is not level, adjust using
the feet.
Remedy
If the motor is defective, replace it.
If the insert jams, remove and clean it, or
replace it.
Bleed the system.
A Large temperature difference can indicate
air in the system.
• If the start value is set too high, reduce it
to the factory set value.
• If the system has a high (>+8°C) brine tem-
perature, you may have to reduce the start
value further for a longer running time.
If the sensor is defective, replace it.
If the drain water flow is greater than 12l/
min, stratification in the water heater is
affected, which reduces the hot water
capacity.
Suggested corrective actions:
• Install a pressure reduction valve on the
incoming cold water pipe.
• Change to a mixer with lower flow.
• Adjust the drain flow on the existing mixer,
do not open the tap fully.
Replace with a larger heater or supplement
with an extra heater.
E.G. supplement with an MBH TWS or an
electric heater.
If the pressure switch opens at the incorrect
pressure, replace it.
The replacement pressure switch can be
installed on the service output (Schrader
valve)