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10.1.6 Frost Protection
Where there is a risk to the boiler or installation from frost then a suitable frost thermostat
should be fitted. Alternatively the system could be dosed with an antifreeze agent. Combination
Boiler models are fitted with frost protection as standard to protect the fabric of the boiler only.
For all other External models covered by this manual, a Frost Thermostat Kit (Code FSK2) is
available as an optional extra. This also protects the fabric of the boiler only. Details of frost
protection for the fabric of the building can be found in section 6.4 of this manual.
10.1.7 Pipework
We strongly advise that all installation pipework is run in copper. However, if plastic pipe or
plastic coated pipe is used, it must be recommended by the pipe manufacturer for use with oil
fired appliances and, in any case, the last 1000mm of pipework connected directly to the
appliance must be of copper. All connections to the appliance must be made with compression
fittings.
10.2 Sealed Systems
10.2.1 Expansion Vessel
Refer to Section 4.2 of this manual for standards referencing details of expansion vessel sizing.
The values given in the table below are for total system volumes which include the water
content of the boiler details of which can be found in the Technical Data Section 5.4 of this
manual. System models up to 33kW are supplied with a 12 litre expansion vessel charged to
1.0 bar. Combination Boiler models are supplied with a 24 litre expansion vessel charged to 1.0
bar. This can accommodate a maximum combined boiler and system volume of 220 litres.
Expansion vessel pre-charge pressures should be evaluated and adjusted periodically, normally
as part of servicing.
When measuring the expansion vessel bladder pre-charge pressure, using a tyre gauge, the
system should be cold and the system pressure should be relieved (by manually operating the
system pressure relief valve) in order to obtain an accurate reading.
If the maximum total system volumes stated above are to be exceeded, additional expansion
capacity will be required.
INITIAL
CHARGE
VESSEL VOLUMES
1.0
2.7 5.4 8.2 10.9 13.6 16.3 19.1 21.8 24.5 27.2 30.0 32.7
SYSTEM
VOLUME
25 50 75 100 125 150 175 200 225 250 275 300
Do not allow the flexible hoses connected to the expansion vessel to become twisted, kinked or
flattened. This may cause collapse of hose bore compromising the function of the expansion
vessel.
10.2.2 System Boiler Filling
For all System and Combination Boilers 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 boiler must be loosened
when filling the system in order to bleed the air from the boiler, then re-tightened when filling is
complete.
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