Hamworthy Sherborne Series, Installation, Commissioning And Service Manual

Page: 12 / 48

HAMWORTHY HEATING LTD
SHERBORNE 500001103/E
3.4 Time Clock Control
In order to avoid local overheating and progressive
calcium deposition at zero flow conditions where
boilers are operated from time clocks, provision
should be made for a 5 minute circulating pump
over-run after the last boiler has ceased firing.
NOTE!
Time clocks should not interrupt live, neutral or
earth connections, see Section 9.0: ELECTRICAL
SUPPLY for details. See Figure 9.1 for wiring details.
3.5 Minimum System Water Pressure
To comply with guidance note
PM5 (Health and Safety
Executive) , the minimum pressure requirements at the
boiler are given below as examples:-
1) Single installed boiler running at 82°C flow
temperature. Minimum head required is not less than 2
metres or 0.2 bar.
2) Single installed boiler running at 95°C flow
temperature. Minimum head required = 5.1 metres or
0.5 bar.
See Section 8.10.1
3) Modular boiler installation running at 82°C flow
temperature and 11°C rise across system. Minimum
head required = 4.3 metres or 0.42 bar.
4) Modular boiler installation running at 82°C flow
temperature and 15°C rise across system. Minimum
head required = 9.4 metres or 0.92 bar. See
Section
8.11 for Pressurised Water Systems.
4.0 LOCATION
4.1
(See Figures 2.1. & 2.2. for dimensions /clearances
and weights.) The location chosen for the boiler MUST
permit the provision of a satisfactory flue system and an
adequate air supply. The location must also provide
adequate space for servicing and air circulation around
each unit. This includes any electrical trunking laid along
the floor and to the appliance.
The boiler can be mounted directly onto a wall or
supported off a floor via a frame (optional HHL supply).
In either case the mounting surface should be a non
combustible flat and level surface capable of supporting
the weight of the boiler when full of water and any
additional ancillary equipment.
It is recommended that the boiler is secured to the wall
using M10 Rawlbolts (non HHL supply).
Any combustible material adjacent to the boiler and
the flue system must be so placed or shielded to
ensure that its temperature does not exceed 65°C.
Further details regarding boiler location are given in
BS
6644. & BS 5440 part 2.
5.0 GAS SUPPLY
5.1 Service Pipes
The local gas region must be consulted at the
installation planning stage in order to establish the
availability of an adequate supply of gas. An existing
service pipe must not be used without prior consultation
with the local gas region.
5.2 Meters
A new gas meter will be connected to the service pipe
by the local gas region, or a local gas region contractor.
An existing meter should be checked, preferably by the
gas region, to ensure that it is adequate to deal with the
rate of gas supply required.
5.3 Gas Supply Pipes
Supply pipes must be fitted in accordance with
BS 6891
or IGE/UP/2 . Pipework from the meter to the boiler must
be of adequate size. Do not use pipes of a smaller size
than the boiler gas connection. The complete installation
must be purged and tested for soundness as described
in
BS 6891 or IGE/UP/1 & IGE/UP/1A as appropriate.
5.4 Boosted Supplies
Where it is necessary to employ a gas pressure
booster, the controls must include a low pressure cut-off
switch at the booster inlet. The local gas region must be
consulted before a gas pressure booster is fitted.
5.5 Boiler House Control Valve
A manual valve for boiler house isolation shall be fitted
in the gas supply line. It shall be clearly identified and
readily accessible for operation, preferably by an exit.
5.6 Boiler Gas System Leak Check
The incoming mains gas supply must be capable of
supplying gas to the boiler at the required pressure and
volume, under all firing conditions. An isolating valve
and union is supplied for each boiler and is
accessible at the bottom left hand side.
Although the boiler receives a gas leak check prior to
leaving the factory, transport and installation may cause
disturbance to unions, fittings and assemblies etc.
During commissioning, a further test for soundness
MUST be carried out on the boiler gas pipework and
components.
Note:- Main Gas Supply Pressure -
Nat Gas - 20mbar
Propane - 37mbar
6