14
ORIGINAL INSTRUCTIONS
VES Andover Ltd Eagle Close Chandlers Ford Ind. Est Eastleigh Hampshire SO53 4NF
Tel: 08448 156060 Fax: 02380 261204 E-mail: vesltd@ves.co.uk Web: www.ves.co.uk
Installation, Operation and Maintenance Manual
®
EVC
Heat Recovery Unit
Continued
Unit sizes 2 to 5 in the Ecovent
® EVC
range feature tapped inlet rings it is possible to establish
the volume flow rate by measuring the static pressure rise into the fan.
The centrifugal fans have infinite speed adjustment, the benefits of real energy savings are
apparent when the fan speed is reduced; this is best demonstrated when used in conjunction
with additional sensors such as air quality or occupancy.
Using a micro manometer and adjusting the fan speed it is possible to commission each fan to
the required air volume. Each fan section has a differential pressure tapping connection point;
by connecting your micro manometer to the appropriate pitot a differential pressure reading can
be taken. This measurement can then be applied to the calculation as below or by using the
differential pressure curve. Simply read across from the pressure measurement to the fan curve
and down to calculate the resultant air volume. If the unit features a fitted control panel this
action can be undertaken within the programming available; see the accompanying controls
documentation for further operational details.
Example:
Measured differential pressure: 150 Pa
This measurement can then be expressed in the following calculation:
where
q
V
is the air volume in m³/s
k is the fan nozzle coefficient (See Below Graph)
p
W
is the measured differential pressure in Pa
Measured differential pressure: 150 Pa
q
V
= (142 150) / 3600
q
V
= (142 x 12.247) / 3600
q
V
= 1739 / 3600
q
V
= air volume = 0.48 m³/s
Standard Wiring
& Fan Installation
5
Differential pressure
curve Fig.
24
Example:
Measured differential pressure: 150 Pa
Air Volume: 0.48 m
3
/s
Differential pressure
calculation Fig.
23
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
R
esi
st
anc
e
-
P
a
0
50
100
AirVolume - m³/s
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
•
243-1 K=68
445-1 K=96
446-1 K=142
262-1 & 362-1 K=60
547-3 K=180
