20
10.3 - Pump pressure/flow rate curves
Single pump
Legend
1
30RY 017-033
2
30RY 040-070
3
30RY 080
Pressure supplied, kPa
Water flow rate, l/s
50
75
100
125
150
175
200
225
250
275
300
0
1
2
3
4
5
6
7
8
1
2
3
50
75
100
125
150
175
200
225
250
0
1
2
3
4
5
6
7
8
1
Dual pump
Pressure supplied, kPa
Water flow rate, l/s
Legend
1
30RY 040-080
When the circuit is cleaned, read the pressures at the
pressure gauge (entering water pressure - leaving water
pressure), expressed in bar and convert this value to kPa
(multiply by 100) to find out the plate heat exchanger
pressure drop.
Compare the value obtained with the theoretical selection value.
If the pressure drop measured is higher than the value specified
this means that the flow rate in the plate heat exchanger (and
thus in the system) is too high. The pump supplies an excessive
flow rate based on the global pressure drop of the application.
In this case close the control valve one turn and read the new
pressure difference.
Proceed by successively closing the control valve until you
obtain the specific pressure drop that corresponds to the nominal
flow rate at the required unit operating point.
-
If the system has an excessive pressure drop in relation to
the available static pressure provided by the pump, the
resulting water flow rate will de reduced and the
difference between entering and leaving water
temperature of the hydronic module will be increased.
To reduce the pressure drops of the hydronic system, it is
necessary:
-
to reduce the individual pressure drops as much as
possible (bends, level changes, accessories, etc.)
-
to use a correctly sized piping diameter.
-
to avoid hydronic system extensions, wherever possible.
10.2 - Pump curve and water flow control as a
function of the system pressure drops
Example: 30RY 080 at Eurovent conditions of 3.8 l/s
Water flow rate, l/s
Legend
1
Pump curve, 30RY 080
2
Plate heat exchanger pressure drop (to be measured with the pressure gauge
installed at the water inlet and outlet)
3
Installation pressure drop with control valve wide open
4
Installation pressure drop after valve control to obtain nominal flow rate
Pressure drop, kPa
0
20
40
60
80
100
120
140
160
180
200
2
4
6
8
7
3
5
2
1
4
3
