EN
L-L 321.00-BM
34 / 64
Honeywell VR 420 / VR 425 valve
• Calibrate the gas pressure switch (5) on the gas ramp by
adjusting it to 70% of supply pressure
• Adjust the gas ramp pressure regulator to the value shown on
Tab. I.
• Connect a gauge to the upstream pressure intake (1) and a
second gauge to the downstream pressure intake (2) of the
gas ramp;
• Start the heater and read the supply pressure on the 1st
gauge. If necessary, adjust the gas valve pressure regulator
until reaching the correct supply pressure shown on Tab. I;
Warning
The gas valve group is set for a maximum supply pressure
of:
• 200 mbar for Honeywell VR 420 valve / VR 425
If the supply pressure exceeds this value, the valve safety
membrane may break and permanently block the valve.
• Read the work pressure on the 2nd gauge. If necessary, use
a screwdriver to adjust the gas valve pressure regulator (3) to
restore the work pressure shown on Tab. I or to restore
correct combustion values (see paragraph 4.8);
• If necessary, you can change the valve opening speed for
heaters equipped with a Honeywell or SIT valve group by
turning the adjustment screw (6): turn counterclockwise to
increase opening speed, clockwise to decrease the speed.
• Apply the adhesive label with the words “SET UP FOR ……” on the
gas valve group to specify the type of fuel and the new category
chosen.
You can continue and start up the heater only after it has been
prepared it according to the instructions for the work category to be
used.
4.8. REGULATING COMBUSTION AND ANALYSING COMBUSTION
PRODUCTS
Warning
The first start-up should always be carried out by a
specialised technician checking the correctness of the
combustion parameters.
Warning
The burner settings are pre-set at the factory and may not
comply with those required, therefore, the settings need to
be checked and, where necessary, corrected.
The adjustment values (gas fuel pressure, burner gas pressure,
combustion head position, air adjustment) for each of the burners
approved for these units are indicated in the “TECHNICAL
SPECIFICATION TABLE”.
The probe used to periodically check combustion and flue smoke
temperatures is to be inserted as indicated:
Combustion is clean and stable when combustion values are as
follows:
NATURAL GAS
G20 - G25
LIQUID GAS
G30 - G31
Index Bacharach
-
0 (white)
CO
2
8.5 ÷ 9.5 %
11.5 ÷ 12.5 %
Oxygen (O
2
)
4.5 ÷ 6 %
4.5 ÷ 6 %
CO
ma
100 ppm
100 ppm
You may have to change the burner settings due to the fuel used
and/or installation conditions (high altitude, air suction pipe with or
without Snorkel, etc.) if combustion parameters are not correct.
When inspection tests are completed, the hole drilled for the probe
must be sealed with a material that is resistant to high temperatures
and that ensures the tube remains airtight.
5. OPERATING INSTRUCTIONS
5.1. START
To start the heater:
• Make sure the switch (a) is set to “0”;
• Supply electrical power to the space heater by pulling up the
disconnecting switch on the electric power panel: the green lamp
(b) will light up indicating that power is being supplied to the panel;
•Turn switch (a) to position H or H+V: the burner will begin the start-
up and pre-wash cycle, after which the flame will ignite; after the
combustion chamber has been heating for a few minutes, the main
fan will start up;
Warning
The fan runs continuously in H+V mode, even when the
desired room temperature has been reached, and the
burner turns off.
Warning
In H mode, the fan only runs when the combustion chamber
is sufficiently hot. Therefore, when the desired room
temperature has been reached, the burner turns off and the
fan keeps running only until the combustion chamber has
cooled completely.
• If the heater does not work during the start cycle or work cycle,
consult “TROUBLESHOOTING” to find the cause of the malfunction.
Warning
If the burner goes into safety stop (lamp c) push reset
button (g) for 3 seconds to restart the heater.
4
6
3
2
5
1
