CaptiveAire D76, Инструкция по установке, эксплуатации и обслуживанию

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Air Flow Switch
Figure 20 - Air Flow Switch
There are both high and low airflow switches contained within one housing
( Figure 20 ) measuring the pressure drop across the burner. This is to
ensure that there is proper airflow (.15 inches wc to .80 inches wc ) across
the burner and proper combustion at all times. Both switches are wired in
series and have single pole double throw (one common contact, one
normally open contact, and one normally closed contact) switches that are
‘switched’ by air pressure.
There are two airflow tubes in the heater, located near the burner and profile
plate assembly (profile plates surround the burner and control air into the
burner section). In the case of clogged filters, blocked intake, excessive duct
static pressure, or a broken belt, the correct burner differential pressure may
not be achieved, not allowing the low airflow switch to close. The high airflow
switch protects against profile plate failures that cause excessive airflow
through the burner. In the event that the pressure drop across the burner is
not in the range of the airflow switch, gas flow to the burner is stopped by the
Flame Safety Control.
The graph in
Figure 21 illustrates the approximate CFM going through the
unit vs. the differential pressure measured by the airflow switch. Simply
measure the differential profile pressure drop at the airflow tubes in the unit
and match that value up to the matching unit curve below. This will show the
CFMs traveling through the burner and will indicate proper airflow or airflow
problems (too much or not enough). If the pressure drop is outside of the
.15” to .80” range, the blower RPM should be adjusted to fix airflow .
Figure 21 - CFM Charts
76 Profile Chart
400
600
800
1000
1200
1400
1600
1800
0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8
Burner Differential Profile Pressure (in. w.c.)
CF
M