Potterton Promax 15 HE Installation And Servicing Instructions page 11

Pressure
Safety
Gauge
Valve
Expansion
Vessel
Boiler
System Drains
at Low Point
Fig. 11
Method of determining minimum
value of expansion vessel volume for
sealed systems using Baxi Boilers
Vessel Charge
Pressure (Bar)
0.5
1.0
1.5
Example :- System Volume = 75 litres
Vessel Charge Pressure = 1.0 bar
Initial System Pressure = 1.5 bar
Then :- 75 x 0.152 = 11.4 litres
Expansion Vessel Volume
Table. 1
Where a vessel of the calculated size is not obtainable
then the next available larger size should be used.
Supplied By www.heating spares.co Tel. 0161 620 6677
3 Litre
Top Up Bottle
Air
(if required)
Vent
Filling
Point
Pump
Max Boiler Flow
Temp = 82° C
Multiply Total
Initial System
Water Content Of
Pressure (Bar)
System By (Litres)
0.5 0.067
1.0 0.112
1.5 0.207
2.0 0.441
1.0 0.087
1.5 0.152
2.0 0.330
1.5 0.125
2.0 0.265
NOTE
6.0 System Details
6.7
1. SAFETY VALVE - A safety valve complying
with the requirements of BS 6750 Part 1 must be
fitted close to the boiler on the flow pipe by
means of a horizontal or vertically upward
connection with no intervening valve or
restrictions and should be positioned to facilitate
testing. The valve should be pre-set and non-
adjustable to operate at a pressure of 3 bar (45
Ibf/in 2 ). It must be arranged to discharge any
water or steam through a pipe to a safe outlet
position.
Radiator
2. PRESSURE GAUGE - A pressure gauge of
Circuit
minimum range 0-4 bar (0-60 Ibf/in
pressure indicator must be fitted to the system,
preferably at the same point as the expansion
vessel in an easily visible position.
3. EXPANSION VESSEL - An expansion vessel
complying with the requirements of BS 4814 must
be fitted to the system by means of a connection
close to the inlet side of the circulating pump in
accordance with the manufacturers instructions,
the connecting pipe being unrestricted and not
less than 15mm (
of the vessel should be suitable for the system
water content and the nitrogen or air charge
pressure should not be less than the system
static head (See Table. 1).
Further details of sealed system design can be
obtained from BS 5449 and the British Gas
publication entitled 'Specifications for Domestic
Wet Central Heating Systems'.
4. FILLING POINT - A filling point and an
approved stop valve to BS 1010 must be fitted at
low level and the method used for filling the
system should be approved by the local water
undertaking. For further details see BS 6798.
5. MAKE UP SYSTEM - A method of replacing
water lost from the system should be provided
either by means of a make up vessel of not more
than 3 litres (5 pints) capacity, mounted above
the highest point of the system, or by
re-pressurisation of the system.
6. VENTING - A method of venting the system
during filling and commissioning must be
provided by fitting automatic air vents or by
venting manually.
7. HOT WATER STORAGE - The hot water
storage vessel must be of the indirect coil type.
All components used in the system must be
suitable for operation at 110°C (230°F) and at the
pressure allowed by the safety valve.
Sealed Systems
(Fig. 11)
2 ) with a fill
1 / in) nominal size. The volume
2
11