Honeywell A4021 Series Product Handbook page 6

manual reset
error + lock--out
12
13
14
15
Fig. 5. General flow chart valve proving (given timings
for A4021A1002/1010
STANDBY
start
0
no
self test
1
15 = OK ?
yes
open valve 2
2
(5 sec.)
stabilization
3
time (3 sec.)
no
pressure
10
= low ?
yes
wait
4
(22 sec.)
no
pressure
= low ?
11
yes
open valve 1
5
(5 sec.)
stabilization
6
time (3 sec.)
no
pressure
= high ?
yes
wait
7
(22 sec.)
no
pressure
= high ?
yes
enable
ignition 8
controller
no pin 12
connected
?
yes
enable
ignition
controller
no
self test
= OK ?
yes
each 4 hours
Table 2. Sequence timings for normal operation
State
0 STANBY
1 self--test + memory test
2 V2 powered
3 waiting for pressure to get low
4 wait
5 valve 1 powered
6 waiting for pressure to get high
7 wait
8 waiting for ignition controller to start
9 RUN period, every 4 hours self--test
10 alarm, "error during test valve 1"
11 alarm, "valve 1 failing/leaking"
12 alarm, "error during test valve 2"
test valve 1
13 alarm, "valve 2 failing/leaking"
14 alarm, "error heat demand"
15 alarm, "self--test error"
1)
Timings depending on O.S. numbers, shown
A4021A1002/1010
2)
STANDBY can be infinite time period
3)
Depending on pre--purge and start--up time of the used
ignition controller
4)
When during the test sequence a fault is discovered by the
A4021, the system will go into a non--volatile lock--out and
generate an alarm "self test error" (see also
Troubleshooting section).The "self test error" also occurs
when the anti--recycle--counter reaches the value 10, see
also page 10 of the Product handbook.
Leakage ≥ 0.1 % of maximum flow rate.
5)
WARNING
test valve 2
No standard valve proving after lock--out of the
ignition controller.
Valve proving after lockout maybe required, this can
be achieved by special wiring diagrams. E.g. when a
DTSP switch is used to reset the ignition controller
and interrupting the heat--demand for the A4021A.
RUN
9
5
Description
5)
5)
4)
EN2R--9023 9705R0--NE
1)
Time (s)
2)
infinite
< 2
5
3
22
5
3
22
3)
indefinite
indefinite
indefinite
indefinite
indefinite
indefinite
indefinite