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WD52/0/1997
2.7.5
Air Elimination
In the initial charge of water to the boiler system and in all subsequent additions
of water to the system some air will be dissolved in the water. As the water is
heated the air is driven out of the solution and will collect in high spots in the
system. These air bubbles can interfere with pumping and heat transfer and
must be eliminated.
Installation of air bleed valves at the high spot(s) in the system will allow for air
elimination when filling the system and will allow re-venting in a day or so after all
air has been driven out of solution.
2.7.6
Strainers
Debris in the heating
system can cause noise if
it enters the heat
exchanger. Fitting of a
Y-strainer ahead of the
circulating pump will trap
any debris left in the
system and will protect
the pump from damage.
The boiler guarantee
does not cover heat
exchanger failure due to
debris abrasion within the
system.
2.7.7
Pump Selection
The Keston boilers have low
water content heat
exchangers with a high
resistance to flow, when
compared with cast iron heat
exchanger boilers. As a result
selection of the correct pump
is essential in order to avoid
localised boiling within the
heat exchanger. The selected
pump must be capable of
maintaining the required flow
rate for the boiler against the
pressure losses contributed
by the boiler.
The Keston 130
condensing boiler offers a
hydraulic resistance of
3.0m (9.8ft) water at the
required flow rate of 50 l/m
(11 gpm).
If a single pump is to be used
for the entire installation the
Installation & Servicing Instructions
Chapter 2 - Boiler Connections
Y-Strainer will
collect any loose
debris in the piping.
The Keston 130 Condensing Boiler
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
10
20
Water Flow - L/min
Figure 2.7.7 : Pressure Loss Graph
Figure 2.7.6 Strainers
30
40
50
60
Page : 10
70
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