2.7.2
Sealed Systems
Sealed systems must be designed in accordance with BS 5449 and BS 7074 Pt1.
A typical sealed system is shown in Figure 2.7.2. It must include :
(i)
A safety valve fitted on the flow, adjacent to the boiler. It must be non
adjustable and preset to 3 bar. A drain pipe must be attached, at least as
big as the valve connection, and routed to drain in any area not
hazardous nor where it may be subject to freezing.
(ii)
An expansion vessel complying with BS 4814 and sized in accordance
with the requirements of BS 5449 and BS 7074 Pt 1. The vessel must be
positioned on the inlet to the pump.
(iii)
A filling point, in accordance with local water authority requirements.
(iv)
A method of system make-up (automatic or manual), in accordance with
local water authority requirements.
(v)
There must be no permanent connection of mains water to the boiler
system.
(vi)
The installation must be designed to work with flow temperatures of up to
110
o
C.
WD51/2/1997 Chapter 2 - Boiler Connections The Keston 170 Condensing Boiler
Installation & Servicing Instructions
Page : 8
Boiler
Rad. 2
Rad. 1
Pump
Minimum
9ft Height
Cylinder
Figure2.7.1 : Open Vented System Diagram
Keston
Valve
Valve
Expansion
Pipe
Expansion
Tank
28mm
Minimum
By-pass
Bal.
Valve
L/S
Valve
Strainer
