Mark MEGAFLEX, Technical Manual

Page: 57 / 58

EN
57
9.1 Service-maintenance table
When commissioning the boiler, it is recommended to measure load, CO
2
or O
2
, CO, T flow, T return,
ΔP air pressure switch and Psyphon pressure switch and write the values down in the table below.
Measure these values when the boiler is in equilibrium at maximum load (also see chapter 5.5).
During annual maintenance we advise to measure and write down these values also and compare them
to the previous values and analyse any changes.
Date gasflow [m
3
/h]
or load [kW]
CO
2
[%] CO [ppm] T
flow
[ºC] T
return
[ºC] Δ
P air
pressure switch
[mbar]
Δ
P siphon
pressure
switch
[mbar]
At the factory the maximum load of the boiler was measured within 5% tolerance from the nominal
maximum load.
In the field the load can decrease due to increased resistance in the boiler, the air inlet or the exhaust
outlet or due to malfunctioning of the fan or other causes.
At maximum load the installation should be designed for nominal ΔT of 15 K to 20 K.
When the ΔT is higher than 25 K, the boiler cannot continue at maximum load anymore and will start to
modulate because water flow through the boiler is insufficient.
T flow and T return can be read in “info mode” on the display (see 5.4 diagnostics)
Valves, malfunctioning pumps, dirt, corrosion products from the installation, dirty filters etc. can have
negative impact on water flow through the boiler.
Before ignition the boiler control checks ΔP aps during prepurge. During burner operation this check
will be carried out. If the value decreases over successive years, this could indicate a problem, e.g.
malfunctioning of the fan, dirty air inlet, dirty burner, dirty heat exchanger or dirty exhaust system.
Syphon pressure (P sps) should be lower than the maximum allowable flue resistance. If P sps is too high
(> 15 mbar), the boiler will be stopped.
In this case the exhaust system may be blocked.