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www.ves.co.uk
ecovent
Heat Recovery Units
Con nued
Ecovent Counterflow Units (EVC 2 to 5 and EVCB 2 to 4) feature tapped inlet rings. It is possible
to establish the volume flow rate by measuring the sta c 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 conjunc on
with addi onal sensors such as air quality or occupancy.
Using a micro manometer and adjus ng the fan speed it is possible to commission each fan to
the required air volume. Each fan sec on has a differen al pressure tapping connec on point;
by connec ng your micro manometer to the appropriate pitot a differen al pressure reading can
be taken. This measurement can then be applied to the calcula on as below or by using the
differen al 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 fi ed control panel this
ac on can be undertaken within the programming available; see the accompanying controls
documenta on for further opera onal details.
Example:
Measured differen al pressure: 150 Pa
This measurement can then be expressed in the following calcula on:
where
q
V
is the air volume in m³/s
k is the fan nozzle coefficient (See Below Graph)
p
W
is the measured differen al pressure in Pa
Measured differen al 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
Differen al pressure
curve Fig.
26
Example:
Measured differen al pressure: 150 Pa
Air Volume: 0.48 m
3
/s
Δ
Differen al pressure
calcula on Fig.
25
•
243-1
K=68
445-1
K=96
446-1
K=142
262-1
&
362-1
K=60
547-3
K=180
EVCB385-1
&
485-1
K=120
Standard Wiring
& Fan Installa on
5
