Classic
Slimline FF
-
Installation & Servicing
9
5
SEALED SYSTEM REQUIREMENTS
1. General
a.
The installation must comply with the requirements of BS 6798
and BS 5449.
b.
The installation should be designed to work with flow
temperatures of up to 82°C.
c.
All components of the system, including the heat exchanger of
the indirect cylinder, must be suitable for a working pressure of 3
bar (45lb/in
2
) and temperature of 110°C. Care should be taken in
making all connections so that the risk of leakage is minimised.
2. Cylinder
The cylinder must be either of the indirect coil type or a direct
cylinder fitted with an immersion calorifier which is suitable for
operating on a gauge pressure of 0.35 bar (5 Ib/in
2
) in excess of the
safety valve setting. Single feed indirect cylinders are not suitable for
sealed systems.
3. Make-up Water
Provision must be made for replacing water loss from the system,
either:
a.
From a manually fitted make-up vessel with a readily visible water
level. The vessel should be mounted at least 150 mm (6") above
the highest point of the system and be connected through a non-
return valve to the system, fitted at least 300 mm (12") below the
make-up vessel on the return side of the domestic hot water
cylinder or radiators.
b.
Where access to a make-up vessel would be difficult, by pre-
pressurisation of the system. Refer to 'Filling'.
4. Mains Connection
There must be no direct connection to the mains water supply or to
the water storage tank supplying domestic water, even through a
non-return valve, without the approval of the local water authority.
5. Filling
The system may be filled by one of the following methods:
a.
Through a cistern, used for no other purposes, via a ball valve
permanently connected directly to a service pipe and/or a cold
water distributing pipe. The static head available from the cistern
should be adequate to provide the desired initial system design
pressure. The cold feed pipe from the cistern should include a
non-return valve and a stop valve with an automatic air vent
connected between them, the stop valve being located between the
system and the automatic air vent. The stop valve may remain
open during normal operation of the system if automatic water
make-up is required.
b.
Through a self-contained unit comprising a cistern, pressure booster
pump (if required) and, if necessary, an automatic pressure reducing
valve and flow restrictor. The cistern should be supplied through a
temporary connection from a service pipe or cold water distributing
pipe.
This unit may remain permanently connected to the heating system
to provide limited automatic water make-up. Where the temporary
connection is supplied from a service pipe or distributing pipe which
also supplies other draw-off points at a lower level, then a double-
check valve shall be installed upstream of the draw-off point.
c.
Through a temporary hose connection from a draw-off tap supplied
from a service pipe under mains pressure. Where the mains
pressure is excessive, a pressure reducing valve shall be used to
facilitate filling.
The following fittings shall form a permanent part of the
system and shall be fitted in the order stated.
A stop valve complying with the requirements of BS 1010, Part 2
(the hose from the draw-off tap shall be connected to this fitting).
A test cock.
A double-check valve of an approved type.
• Thoroughly flush out the whole of the system with cold water,
without the pump in position.
• With the pump fitted, fill and vent both system and pump until the
pressure gauge registers 1.5 bar (21.5lb/in
2
). Examine for leaks.
• Check the operation of the safety valve by manually raising the
water pressure until the valve lifts. This should occur within ± 0.3
bar (± 4.3lb/in
2.
) of the pre-set lift pressure.
• Release water from the system until the initial system design
pressure is reached.
• Light the boiler and heat the system to the maximum working
temperature. Examine for leaks.
• Turn off the boiler and drain the system while still hot.
• Refill and vent both system and pump.
• Adjust the initial pressure to the required value.
Note.
The method of filling, refilling, topping up or
flushing sealed primary hot water circuits from
the mains via a temporary hose connection is
only allowed if acceptable to the local water
authority.
GENERAL
