9
Viceroy GTS -
Installation & Servicing
GENERAL
5 FILLING THE SYSTEM
Filling shall be performed with a low flow rate from a low point in
the boiler room in order to ensure that all the air in the boiler is
bled from the high point of the system.
Always stop the pump before filling.
IMPORTANT.
Instructions for starting up the boiler for the first
time after the system is fully or partly drained:
If all the air is not bled naturally to an expansion tank which is
open vented, the system must include manual bleed valves, in
addition to automatic air vents which bleed the system when it is
operating. The manual bleed valves are used to bleed all the high
points of the system and to make sure that the filled system is free
of air before the burner is turned on.
General
Recommendations relating to the water system are contained in
BS. 6880.
7 SEALED (PRESSURISED) SYSTEMS
6 OPEN VENTED SYSTEM REQUIREMENTS - minimum static head requirements
The Viceroy GTS boiler has a minimum static head
requirement of 2.5 metres (8 feet approx.) depending on
the particular characteristics of the system design (see
diagram). The information provided is based on the
following assumptions.
1.
An open vent/safety pipe connection is made
immediately after the flow connection.
2.
A cold feed/expansion pipe connection is made to the
system return pipe within 0.75m of the boiler return
connection.
3.
The maximum flow rate through the boiler is based on
a temperature difference of 11ºC (20ºF) at full boiler
output with the circulating pump positioned in the flow of
the system.
4.
The boiler is at the highest point of the system.
Systems designed to rise above the flow connections
will, of course, automatically require a minimum static
head higher than shown.
5.
The position of the open vent/safety pipe above the
expansion cistern water level is given as a guide
only. The final position will depend upon particular
characteristics of the system. Pumping over of water
into the expansion cistern should be avoided.
6.
Both open vent/safety pipe and cold feed/expansion
pipes must be of adequate diameter to suit the output of
the boiler (see table below).
Working pressure 6 bar maximum.
Particular reference should be made to BS. 6644: Section
2; Subsection 11 and Guidance note PM5 "Automatically
controlled steam and hot water boilers" published by the Health
and Safety Executive.
The information and guidance given below is not intended to
override any requirements of either of the above publications
or the requirements of the local authority, gas or water
undertakings.
In general commercial closed pressurised systems are provided
with either manual or automatic water make up.
In both instances it will be necessary to fit automatic controls
intended to protect the boiler, circulating system and ancillary
equipment by shutting down the boiler plant if a potentially
hazardous situation should arise.
Examples of such situations are low water level and operating
pressure or excessive pressure within the system. Depending
on circumstances, controls will need to be either manual or
automatic reset. In the event of a shutdown both visual and
audible alarms may be necessary.
Open vent
safety pipe
750mm
Cold feed/
expansion pipe
H = 2.5m
To
pump
Pressure
relief
valve
FLOW
RETURN
Shunt pump
(if required)
Note: Height, H, MUST be
increased if necessary to
comply with the min.
head required by the
pump manufacturer
BOILER
This diagram does not show safety valves & water
flow switches etc necessary for safe operation
Expansion
cistern
har5966
Expansion vessels used must comply with BS. 4814 and must be
sized on the basis of the total system volume and initial charge
pressure.
Initial minimum charge pressure should not be less than 0.5
bar (7.2psi) and must take account of the static head and
specification of the pressurising equipment. The maximum water
temperatures permissible at the point of minimum pressure in the
system are specified in Guidance Note PM5.
When make up water is not provided automatically it will be
necessary to fit controls which shut down the plant in the event
of the maximum system pressure approaching to within 0.35bar
(5psi) of the safety valve setting.
Other British Standards applicable to commercial sealed systems
are:
BS. 6880: Part 2
BS. 1212
BS. 6281: Part 1
BS. 6282: Part 1
BS. 6283: Part 4
Boiler Output kW
Open Vent (mm)
Cold Feed (mm)
301 to 600
50
38
600 and above
50
50
