Matal discharge pipe
from tundish, with
continous fall.
Min. 300 mm
Tundish
Safety device
(e.g. temperature
relief valve)
Metal discharge pipe
from temperature relief
valve to tundish
Possible
wall
Discharge
below fixed
grating
Fixed
grating
Trapped
gulley
Max 600 mm
Resistance created by
each elbow or bend
Maximum resistance
allowed, expressed as
a lenght of straight pipe
(i.e. no elbows or
bends)
Minimum size of dis-
charge pipe from tun-
dish
Minimum size of dis-
charge pipe
Valve outlet size
0.8 mmup to 9 m22 mm15 mmG1/2
1.0 mmup to 18 m28 mm15 mmG1/2
1.4 mmup to 27 m35 mm15 mmG1/2
1.0 mmup to 9 m28 mm22 mm<G3>/4
1.4 mmup to 18 m35 mm22 mm<G3>/4
1.7 mmup to 27 m42 mm22 mm<G3>/4
1.4 mmup to 9 m35 mm28 mmG1
1.7 mmup to 18 m42 mm28 mmG1
2.3 mmup to 27 m54 mm28 mmG1
HARD WATER AREAS
Usually, there should not be a problem in installing
VVM 320 in areas of hard water as the operating tem-
perature is 50–60 °C.
CLEANING THE CLIMATE SYSTEM
When the water heater and the climate system have
been filled with water, VVM 320 must operate at max-
imum normal temperature for at least one hour. There-
after the system must be drained of water and refilled.
Before installing the heat pump in an existing system,
it is important that the system is properly flushed
through.
Even if the heat pump is to be installed in a new system,
the heat pump and system should be flushed.
NOTE
Ensure that cleaning agent has been removed
from the entire system before adding inhibitor.
After flushing an inhibitor should be used for long-term
anti-corrosion protection.
NIBE Energy Systems Limited recommends water
treatments (supplied by e.g. Fernox and Sentinel) spe-
cifically designed for heat pumps.
BOILER AND RADIATOR VOLUMES
VVM 320 is equipped with a
pressure expansion vessel of
10 litres.
The pre-pressure of the pres-
sure expansion vessel must be
dimensioned according to the
maximum height (H) between
the vessel and the highest posi-
tioned radiator, see figure. A
pre-pressure of 0.5 bar (5 mvp)
means a maximum permitted
height difference of 5 m.
The maximum system volume
excluding the boiler is 220 litres at the above pre-pres-
sure.
15Chapter 4 | Pipe connectionsNIBE VVM 320
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