103
GB
VAV: installation of the air control line pL and the control line of the combustion chamber pF
Screw connections for plastic flexible hoses are available (Ø internal 3.9).
ATTENTION! Do not disassemble and replace.
Lay the air control line pL and the combustion chamber line pF on the measuring points of the air pres-
sure and combustion chamber.
If pF is not connected, close the fitting aperture.
ATTENTION! Lay the control lines in a way that the condensate does not penetrate the pressure sta-
biliser.
Proposal for installation:
Use a metal pipe with internal diameter of 6 mm for connection to the combustion chamber.
Centre the fitting for the air control line and mount it in straight piping with a length of at least 10 x DN.
Arcs, bottlenecking, discharges or air regulation elements must be at least 5 x DN from the fitting.
VAV
Regulation of the minimum flow rateWith burner minimum flow rate, it is possible to modify the gas/air
ratio by intervening on the regulation screw “N”.
Factory setting
Transmission ratio of the gas with the air: V = 1:1, zero point N = 0.
Attention! pL – pF ≥ 0.4 mbar
Regulation time for the reference valve (butterfly valve for air):
min. to max. > 5 s
min. to max. > 5 s
Pre-regulation:
- Regulate the black point N and the transmission ratio V at the scale according to the indications of the
burner manufacturer.
- Measure the pressure of the gas pG.
- Start the burner at minimum flow rate. If the burner does not start, turn N slightly in dir and
repeat start-up.
- Progressively take the burner to the maximum flow rate and, if necessary, adapt the pressure of the
gas on V.
- Regulate the minimum and maximum power on the air regulation element according to the burner
manufacturer’s indications.
Final regulation:
- Take the burner to minimum flow rate.
- Analyse the discharge gas and regulate the gas pressure on N on the basis of the value desired of
the analysis.
- Take the burner to maximum flow rate and regulate the gas pressure on V on the basis of the value
desired of the analysis.
- Repeat the analysis at maximum and minimum flow rate, if necessary correct N and V.
Regulate the pressure switch (see below).
- Close all of the measuring points
– do not close the pF fitting eventually not used.
- It is recommended to start the burner with a power exceeding that of the minimum flow rate (start-up
flow rate) in a way to obtain a constant flame.
