Unitary Products Group 5
246681-YTG-B-0607
CROSS LEAKAGE IN UERV’S (PURGE SECTORS)
The issue of cross leakage in rotary wheel based UERV's
used in space conditioning applications is often misunder-
stood. As a result, many systems are installed with purge
sectors and the additional fan capacity required to allow
these sectors to function when in fact they are unnecessary.
A better understanding of the rational for the purge sector,
and its history, allows us to dispense with the purge sector, its
added first cost and continuing cost of operation.
A purge sector minimizes the carry over cross leakage from
the exhaust into the supply (outside air) air stream by shunt-
ing a portion of the supply air back into the exhaust air stream
across the seal separating the exhaust and supply. This is
required in industrial applications where the exhaust carries
contaminants. This typically results in air volume being 15%
to 20% higher to get the desired air intake, and the cost asso-
ciated with it.
In space conditioning applications, where the ventilation is
operating to maintain acceptable indoor air quality, there are
no contaminants in concentrations large enough to cause
concern. Cross leakage in the UERV system results in a
small amount of the exhaust air, typically less than 5% in bal-
anced airflow, returning to the space. This is not contami-
nated air, as some would suggest. It is however air that
effectively never left the space. The operation cost of moving
this air is far less than that required for a purge sector. Do not
use the York UERV's in applications that have concentrations
of contaminants.
OPTIONAL ACCESSORIES - FIELD
INSTALLED
UERV Equipment Support - 8 inch (203 mm) high base for
support of the exhaust and intake end of the UERV. Must be
ordered separately from the UERV.
Equipment Support
UERV
Part No.
VR006 1ES0401
VR/P011 1ES0402
VR/P020 1ES0402
VR/P028 1ES0402
Equipment Support
UERV
Part No.
VR036 1ES0403
VR046 1ES0403
VR062 1ES0404
VR074
VR122
Roof Curb - A 14 or 24 inch (355 or 610 mm) roof curb is
required to match supply and exhaust openings of the UERV
with the rooftop units. York provides a full line of roof curbs to
match the specified unit. See specification pages for required
curb. Must be ordered separately from UERV.
Stand Alone Balancing Damper - Balancing dampers are
used with VO and VS models when ERV is connected to the
rooftop unit, not to ductwork on the roof.
TABLE 1: UERV OUTSIDE AIR CFM SELECTION BY CFM
Unit-Tons 300-550 600-1000 1100-1700 1500-2800 2800-3600 3400-4600 4800-5600 5500-6200 6000-8000 8000-13000
Rooftop
1.5 - 6 1.5 - 6
Stand Alone type ERV’s are available for all tonnage sizes.
7.5 - 12.5 7.5 - 12.5 7.5 - 12.5
15 - 25 15 - 25 15 - 25 15 - 25 15 - 25
30 - 50 30 - 50
Upflow 1.5 - 5 1.5 - 5
Horizontal 1.5 - 5 1.5 - 5 Stand Alone ERV’s are available for equipment room applications.
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