ZIC · Edition 09.22
EN-7
➔ δ
M
:
Gas density reflected in the flow rate curve
in kg/m
3
(lb/ft
3
)
➔ δ
B
:
Gas density in operating state in kg/m
3
(lb/ft
3
)
➔
p
M
:
Gas pressure reflected in the flow rate curve
➔
p
B
:
Gas pressure in operating state
1
Read the gas pressure p
gas
and air pressure p
air
from the enclosed flow rate curve for cold air on
the basis of the calculated flow rates Q.
[mbar (inch WC)]
[m
3
/h (ft
3
/h)]
p
gas
p
air
p
air
p
gas
Q
air
Q
gas
➔
Note possible capacity changes due to positive
or negative pressures in the furnace/combustion
chamber. Add positive pressures or subtract neg-
ative pressures.
➔
As not all the effects caused by the equipment are
known, setting the burner using the pressure values
is only approximate. It is possible to set the burner
precisely by measuring the flow rates or flue gas.
5.4 Restrictors
➔
The air volume required for the low-fire rate at a
given air pressure is determined by the ignition
position of a butterfly valve, a bypass hole in the air
valve or an external bypass with restrictor.
5.5 Hot air compensation
➔
The combustion air pressure
p
air
must be increased
in hot air operating mode (lambda = constant).
0
50 100 150 200 250 300 350 400 450 500 550 600
100
150
200
300
250
Air temperature [°C]
Air pr
essur
e p
air
[%]
➔
The gas pressure is increased by 5–10 mbar.
➔
The total burner capacity
P
gas
rises as the air tem-
perature increases.
0
50 100 150 200 250 300 350 400 450 500 550 600
100
110
120
Air temerature [°C]
Total capacity P
tot
[%]
5.6 Burners with electrodes with air connection
➔
Burner head marking (..D) or (..E)
purge air tube
purge air nozzle
d=4.5mm
Rp 1/4
10
20
30
40
1
2
3
p [mbar]
0
10
20
30
40
0
1
2
3
Pressures for purges electrodes
Q purging air [m
3
/h]
➔
A purge air volume of approx. 1.5 to 2 m³/h per
electrode is recommended.
➔
The purge air may not be switched off until the
furnace is cold and formation of condensation is
no longer possible.
5.7 setting the air pressure for low fire and
high fire
1
Shut off the gas and air supply.
➔
Air measuring nipple
L
, outside dia. = 9 mm (0.35").
2
L
➔
Loosen the screw 2 turns.
3
4
Fully open the air supply.
5
p
atm.
p
air
0
➔
p
atm.
= atmospheric pressure.
Low-fire rate
➔
The burner must only be ignited at low-fire rate
(between 10 and 40% of the rated capacity Q
max
–
