Hot Flushing; Checking The Gas Pressure - Keston 50 - GC Installation And Servicing Instructions

WD50/0/1996
4.6

HOT FLUSHING

a.
b.
c.
4.7

CHECKING THE GAS PRESSURE

With the boiler running measure the burner pressure at the burner pressure test nipple.
The gas setting is factory adjusted to within the required range and should not normally
need re-adjustment unless the unit has also been converted to LPG as part of the
installation. If the reading is incorrect then check such factors as soundness of the air and
flue pipe joints and the gas inlet pressure (20 mbar required). If all joints are sound and
the gas inlet pressure is satisfactory remove the brass dust cap covering the burner
pressure adjustment screw on the gas valve (See fig. 4.7). Set the gas pressure to the
required value as stated in table 1.4 by turning the exposed burner pressure adjustment
screw (clockwise will increase burner pressure, anti-clockwise will decrease burner
pressure). Replace the brass dust cap to cover the burner pressure adjustment screw.
4.8 TIMING THE GAS METER - NATURAL GAS
Model
Keston 50
Keston 60
Keston 80
After the boiler has been started, and with no other appliances using gas, time the gas
meter to be certain that the unit is running at the proper gas input. Determine the cubic
feet of gas passing through the meter and determine the input in Btu per hour. Input must
be within plus or minus 5% of the rated input.
Time, in seconds, the time taken to pass 2 cubic feet of gas through the meter (ie one
revolution of a 2 cu ft dial) or 0.1 cubic metres if the meter is of the new metric digital type.
Refer to table 4.8 to determine the input to the boiler and the time required for 2 ft
Installation & Servicing Instructions
Chapter 4 : Commissioning
Allow the system to heat up,
checking for water soundness.
Follow instructions provided with
the cleaning agent, ie Fernox
Supafloc. Turn off the boiler and
flush the water system while still
hot. Thoroughly flush the system
with clear water.
Refill the system using a quality water treatment such as Fernox MB1 or Fernox
Super Concentrate. If aluminium radiators are used then Fernox Copal should be
used. For sealed systems, fill to the required Initial Design Pressure.
Btu/h Input Required
54,400
63,018
84,300
NB: 1011 btu/h per ft
Table 4.8 Meter Timings
Page : 25
The Keston 50, 60 & 80 Condensing Boilers
Fig 4.7
GAS VALVE
Burner pressure
Adjustment
Burner pressure
test nipple.
Seconds For 2 ft
Of Natural Gas
133.8
115.5
86.3
3
3
Seconds For 0.1 m
Of Natural Gas
236.2
203.9
152.36
3
(or
3