1307SDH_RDH--EN,page 21/32
TWO STAGE BURNERS SETTING & ADJUSTMENT
The SDH/RDH air heaters can be optionally equipped
with two stage burners. The type of gas control fitted is
the "Honeywell" VR 4601P/B or VR 4601A/B either are
fitted with a two-stage pressure governor model
V4336A. Regulation is possible for the pressure range
1,5 - 20 mbar for natural gas and 4 -37 mbar for propane
gas. The appliances are fitted with a relay to ensure that
during burner start-up the initial firing rate is 100% to
ensure good burner cross lighting.
Adjusting the burner pressure may only be carried out
by suitably qualified persons.
Setting (refer to figure 14) :
Allow time for pressure to stabilise before and during
making adjustments.
a. Lever off the plastic cover cap
b. Maximum high rate setting must
be adjusted
first after which the minimum low rate setting can be
adjusted. Any adjustment of the maximum setting
influences the minimum setting.
c. Do not adjust maximum or minimum settings above
or below the pressures stated on the air heater data
plate.
Adjusting maximum pressure setting :
a. Energise high/low regulator, set gas control in
operation and wait until an outlet pressure is
recorded on pressure gauge.
b. Use a 10 mm screwdriver to turn adjustment screw
for maximum pressure setting clockwise to increase
and counter-clockwise to decrease pressure until
desired maximum pressure is obtained.
c. Check maximum pressure setting several times.
Adjusting minimum pressure setting :
a. Disconnect electrical connection of high/low
regulator.
b. Set gas control in operation and wait until an
outlet pressure is recorded on pressure gauge.
c. If minimum pressure setting needs adjustment
then use a 3.5 mm screwdriver to turn adjustment
screw for minimum pressure setting, clockwise to
increase or counter-clockwise to decrease
pressure, until desired minimum pressure setting
is obtained.
d. Wire high/low regulator in circuit.
e. Check maximum pressure setting, re-adjust if
necessary and check minimum pressure again.
Figure 14 :
Table 6 : High/low burner gas pressures and low rate consumption values
025 030 035 043 055 073 100
nat. G20 mbar 7,50 7,70 7,40 7,10 8,30 7,10 6,10
prop. G31 mbar 14,00 12,70 16,30 15,90 16,60 13,90 14,80
nat. G20 mbar 1,90 1,90 1,90 1,80 2,10 1,80 1,50
prop. G31 mbar 3,50 3,20 4,10 4,00 4,20 3,50 3,70
nat. G20 m³/h 1,39 1,68 2,01 2,42 3,15 4,20 5,59
prop. G31 kg/h 1,02 1,24 1,48 1,79 2,32 3,09 4,12
(1) -
-
Low fire rate must not be reduced below the values stated above for 50 % RATING
Gas consumption @ 50%
Ref. 15°C, 1013mbar (1)
Note : burner pressures for propane gasses are approx. Based on regulated supply pressure
nat gas G20 net calorific value 34,02 MJ/m³ @ 15°C & 1013 mbar
prop gas G31 net calorific value 88,00 MJ/m³ @ 15°C & 1013 mbar
Model
Pressure @
100%
Pressure @
50%
Burner
pressure
10
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