22
When measuring the expansion vessel bladder precharge pressure, using a tyre gauge, the
system must be cold (less than 25°C) and the system pressure must be relieved (by manually
operating the system pressure relief valve) in order to obtain an accurate reading.
3.2.2 System Filling
For the WS18 appliance a filling point complete with a filling loop is supplied fitted to the
expansion vessel. The filling loop
must
be disconnected from the mains supply after filling. A
system pressure when cold of 1 bar is recommended. After filling, vent all air from the system.
The plastic plugs of the auto air vent(s) factory fitted to the appliance must be loosened when
filling the system in order to bleed the air from the appliance.
3.2.3 System Pressure
Water loss from the system is indicated by a reduction in pressure on the pressure gauge. In
the first week of operation it is normal to see a drop in system pressure. After this time the
system pressure must be rechecked and the system refilled. Failure to do so may lead to
appliance faults.
The system pressure should be checked periodically by means of the pressure gauge at the
expansion vessel (see Figure 4). The WS18 appliance comes complete with an integrated
expansion vessel, pressure gauge and filling loop. The minimum pressure, as indicated by the
black needle, must not be less than 0.5 bar when the appliance is cold and typically around 2.5
bar when the appliance is at normal operating temperature. If the pressure is outside this range
contact Warmflow or your installer.
Special attention must be given to the concentration of corrosion inhibitors in the system water
where there is a need for topping up or refilling. Inhibitor concentrations must be restored to the
concentrations specified by the inhibitor manufacturer.
Frequent or routine refilling and topping up of the system should not be necessary on an
ongoing basis and may prove harmful to the appliance. Should topping up prove necessary on a
frequent or routine basis you must contact Warmflow or your installer.
3.2.4 Pressure Relief Valve
Any pressure relief valve fitted to the appliance or system must be able to discharge externally
to a drain where the discharge can be seen but cannot cause any injury or damage. No other
valves should be positioned between the relief valve and discharge termination.
3.2.5 Low Pressure Switch
Where there is a significant loss of water from the system the appliance thermostats may fail to
operate which would result in serious damage to the appliance. To prevent this, a low pressure
cut out switch set at 0.5 bar is fitted to the appliance. The switch will automatically reset when
the pressure is restored.
3.2.6 Condensate Trap
The Warmflow wood pellet boiler is a
noncondensing
appliance, however some condensate
may be generated at cold start up. For this reason a condensate trap is fitted to collect any
condensate which may form, see Figure 24 below. The condensate trap is fitted with a length of
flexible plastic drainage hose. The drainage hose should be connected to an internal soil stack
or waste pipe, an external gully hopper or soakaway. It is recommended that the drainage pipe
should have a minimum fall of 1:20.
