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EDTYW122 © Danfoss 05/08
Data sheet RA 2000
Thermostatic Radiator Valves
Capacity:
Low Pressure
Steam Applications:
Step-by-step selection technique
1. Before selecting valves, consider P-deviation.
2. Check that system pressure is below 15psig.
3. Determine load requirements for each valve.
Example:
Design load: 28MBH
Pipe Size: 3/4”
P-deviation ≤ 4°F
Conversion Factors:
Sq. ft. EDR to Btu/hr = Sq. ft. EDR x 240 (steam)
Btu/hr to Sq. ft. EDR = Btu/hr 240
1 MBH = 1,000 Btu/hr
Rating Abbreviations:
MBH = Thousands of Btu/hr.
EDR = Equivalent Direct Radiation
Solution:
From the table below a 3/4” valve will provide
28MBH at a 4°F P-deviation at a pressure drop
of 3psi. If the system pressure is 3psi or greater a
3/4” valve can be used.
Important
P-deviation refers to the difference between
the thermostat setting and the actual space
temperature. For best comfort and long life,
valves should be selected which provide the
design heating load at approximately a 4°F
P-deviation.
Pressure Drop 1 psig 2 psig 3 psig 4 psig 5 psig
P-Deviation °F 4 Fully open 4 Fully open 4 Fully open 4 Fully open 4 Fully open
Valve Size Rating Code
1/2” MBH 10 16 14 22 16 28 20 32 35 62
3/4” MBH 15 30 20 40 28 50 32 58 60 108
1” & 1-1/4” MBH 18 40 25 52 30 60 36 72 66 140
Hydronic Hot Water
Applications
Example:
Flow Required:
0.65 US GPM
Pipe Size: 1⁄2”
Solution:
Draw a line from 0.65 USgpm
until it intersects with the
dashed line for the 1⁄2” valve.
Draw a vertical line down to
find the additional system
pressure drop due to the valve
will be 0.6 psi.
Note: For best control, select valve
based on 4°F P-deviation and
maximum
5 psi pressure drop.
P-deviation is the difference
between the thermostat setting and
the actual space temperature. For
best comfort control and long life,
valves should be selected to provide
design flow at a 4°F P-deviation.
The shaded area represents
differential pressure above those
recommended for quiet operation.
The maximum differential pressure
ratings indicate the maximum
pressure at which valves regulate
satisfactorily. In order to prevent
noise, pumps that provide only
the required pressure should be
recommended. Experience shows
that in most systems a differential
pressure of
0.5 - 2.5 psi across the valve is
sufficient to provide the required
flow.
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