Data Sheet
Radiator thermostats for one-pipe and two-pipe systems
6
VD.51.Q1.
12 © Danfoss 10/2003
DKCD
The P-band value depends on the chosen valve i.e.
RA-FN 15 will work with a P-band of 2K.
RA-FN 20 will work with a P-band of about 1.4K.
The Kv-value can also be calculated on the basis of
the formula
Kv
=
Q
Q(m
3
/h),
∆
p (bar)
√ ∆
p
0.044
=
0.044 x 3600 = 0.158 m
3
/h
1000
Kv
=
0.158
= 0.71
√
0.05
Note: 1m
3
/h = 0.278 l/s
Capacities
Use the following sizing charts
to select the correct valve for
the radiator in question.
Heat requirement:
2.05 kW
Temperature drop:
11°C
Differential pressure
across the radiator:
0.05 bar (5 kPa)
Solution:
Water flow through the radiator per hour:
Q =
2.05
= 0.044l/s
4.2 x11
Capacity with P-band between 0.5K and 2K with RA 2000 sensor
Note:
As with any device which
imposes a pressure drop
system, noise may occur under
certain flow/pressure conditions.
To ensure quiet operation,
maximum pressure drop should
not exceed 40 to 45kPa.
Example
RA-FN
for two-pipe systems
RA-G
for one-pipe systems
