Commissioning
2
38
Installation and maintenance instructions for Buderus 500 - 24/S • 08/2006
Buderus • http://www.buderus-domestic.co.uk
Subject to modifications resulting from technical improvements!
z
The optimum gas/air ratio is - 5 Pa (-0.05 mbar).
The pressure difference should be between -10 and 0 Pa
(see fig. 56).
If this is not the case then adjustment is needed:
z
Remove the safety screw with a flat head screwdriver
(fig. 57, item 1).
z
Adjust the adjustment screw of the burner pressure to the
correct gas/air ratio using a (4 mm) socket head wrench
and by referring to fig. 56.
z
Replace the safety screw (fig. 57, item 1).
z
Set mains power switch to "
0
" (see fig. 51, item 1).
z
Shut the gas shut off valve (see fig. 52, item 1).
z
Remove the tube from from the burner-pressure testing
nipple (see fig. 54, item 1).
z
Tighten the screw on the burner-pressure testing nipple.
z
Open the gas shut off valve (see fig. 52, item 2).
z
Turn the mains power switch to "
1
" (see fig. 51, item 1).
2.1.7
Gas rating test
z
Isolate all other appliances.
z
Press the service button "
A
" to set the boiler to full load.
z
Ensure that there is no modulating of the fan gas valve.
z
Carry out the Gas Rating procedure as described in
"Essential Gas Safety' 3rd edition on pages 169-176.
2.1.8
Checking for leaks while boiler is in operation
z
Use an approved leak detector to check all connections for
possible leaks. The product must be certified as a gasleak-
testing agent.
z
Do not allow the product to come into contact with the
electrical wiring.
fig. 56 Pressure difference of gas/air ratio at partial load
wrong
wrong
correct
left turn
right turn
-15
-10
-5
0
5 (Pa)
-0.15
-0.10
-0.05
0.00
0.05 (mbar)
fig. 57 Adjust gas/air ratio
CAUTION
Check the test nipples for gas tightness.
NOTE
Technically it is not necessary to use a
combustion analyzer for CO
2
measurements.
The CO
2
level is secured by the gas/air ratio as
described above.
A combustion analyzer, if available, can be
used to confirm CO
2
levels (see technical
specifications on page 7).
