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ecovent Heat Recovery Units
Standard Wiring
& Fan Installa on
Differen al pressure
25
calcula on Fig.
Differen al pressure
26
curve Fig.
16
5
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
k is the fan nozzle coefficient (See Below Graph)
Δ
Measured differen al pressure: 150 Pa
q
q
q
q
Example:
Measured differen al pressure: 150 Pa
Air Volume: 0.48 m
•
is the air volume in m³/s
V
p
is the measured differen al pressure in Pa
W
= (142 150) / 3600
V
= (142 x 12.247) / 3600
V
= 1739 / 3600
V
= air volume = 0.48 m³/s
V
3
/s
www.ves.co.uk
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