Energy recovery ventilator maintenance – Bard QERV-A4B User Manual
Page 6
Manual 2100-310D
Page
4
NOTE: Sensible performance only is shown for
winter application.
LEGEND
WVL = Winter Ventilation Load
WH
= Winter Heat Recovery
TABLE 3
WINTER HEATING PERFORMANCE
(INDOOR DESIGN CONDITIONS 70° F DB)
t
n
e
i
b
m
A
.
D
.
O
E
T
A
R
N
O
I
T
A
L
I
T
N
E
V
B
D
F
s
e
e
r
g
e
D
.
f
f
E
%
0
8
M
F
C
0
5
4
.
f
f
E
%
1
8
M
F
C
5
7
3
.
f
f
E
2
0
8
M
F
C
0
0
3
L
V
W
R
H
W
L
V
W
R
H
W
L
V
W
R
H
W
5
6
0
3
4
2
4
4
9
1
5
2
0
2
0
4
6
1
0
2
6
1
8
2
3
1
0
6
0
6
8
4
8
8
8
3
0
5
0
4
0
8
2
3
0
4
2
3
6
5
6
2
5
5
0
9
2
7
2
3
8
5
5
7
0
6
0
2
9
4
0
6
8
4
5
8
9
3
0
5
0
2
7
9
6
7
7
7
0
0
1
8
1
6
5
6
0
8
4
6
3
1
3
5
5
4
0
5
1
2
1
0
2
7
9
5
2
1
0
1
1
0
2
8
0
0
1
8
2
4
6
6
0
4
0
8
5
4
1
4
6
6
1
1
0
5
1
2
1
1
4
8
9
0
2
7
9
0
7
9
7
5
3
0
1
0
7
1
8
0
6
3
1
5
7
1
4
1
1
8
4
1
1
0
4
3
1
1
8
9
2
9
0
3
0
4
4
9
1
2
5
5
5
1
0
0
2
6
1
2
2
1
3
1
0
6
9
2
1
7
2
6
0
1
5
2
0
7
8
1
2
6
9
4
7
1
5
2
2
8
1
2
6
7
4
1
0
8
5
4
1
5
5
9
1
1
0
2
0
0
3
4
2
0
4
4
9
1
0
5
2
0
2
2
0
4
6
1
0
0
2
6
1
4
8
2
3
1
5
1
0
3
7
6
2
4
8
3
1
2
5
7
2
2
2
2
4
0
8
1
0
2
8
7
1
2
1
6
4
1
ENERGY RECOVERY VENTILATOR
MAINTENANCE
GENERAL INFORMATION
The ability to clean exposed surfaces within air
moving systems is an important design consideration
for the maintenance of system performance and air
quality. The need for periodic cleaning will be a
function of operating schedule, climate, and
contaminants in the indoor air being exhausted and in
the outdoor air being supplied to the building. All
components exposed to the airstream, including energy
recovery wheels, may require cleaning in most
applications.
Rotary counterflow heat exchanges (heat wheels) with
laminar airflow are “self-cleaning” with respect to dry
particles. Smaller particles pass through; larger
particles land on the surface and are blow clear as the
flow direction is reversed. For this reason the primary
need for cleaning is to remove films of oil based
aerosols that have condensed on energy transfer
surfaces. Buildup of material over time may
eventually reduce airflow. Most importantly, in the
case of desiccant coated (enthalpy) wheels, such films
can close off micron sized pores at the surface of the
desiccant material, reducing the efficiency with which
the desiccant can adsorb and desorb moisture.
FREQUENCY
In a reasonably clean indoor environment such as a
school, office building, or home, experience shows that
reductions of airflow or loss of sensible (temperature)
effectiveness may not occur for ten or more years.
However, experience also shows that measurable
changes in latent energy (water vapor) transfer can
occur in shorter periods of time in commercial,
institutional and residential applications experiencing
moderate occupant smoking or with cooking facilities.
In applications experiencing unusually high levels of
occupant smoking, such as smoking lounges,
nightclubs, bars and restaurants, washing of energy
transfer surfaces, as frequently as every six months,
may be necessary to maintain latent transfer efficiency.
Similar washing cycles may also be appropriate for
industrial applications involving the ventilation of high
levels of smoke or oil based aerosols such as those
found in welding or machining operations, for
example. In these applications, latent efficiency losses
of as much as 40% or more may develop over a period
of one to three years.