HAMWORTHY HEATING LTD. PUREWELL PERMANENT IGNITION 500001090/B
3
British Standards
BS 7074:
Application, selection and installation of
expansion vessels and ancillary equipment for
sealed water systems.
Part 2:
Code of practice for
low and medium temperature hot water systems.
BS 6891:
Installation of low-pressure gas pipework
of up to 28mm in domestic premises. (For larger
installations see
IGE/UP/1,
IGE/UP/1A
and
IGE/UP/10
)
BS 6644:
Installation of Gas Fired Hot Water Boilers
- 60kW to 2MW.
BS 6700:
Design, installation, testing and
maintenance of services supplying water for
domestic use.
BS 6880: Part 1, 2 & 3:
Code of practice for low
temperature hot water heating systems of output
greater than 45kW.
BS EN 60335, Part 1
. Safety of Household & similar
electrical appliances.
BS 3456, Part 201:
Electrical
Standards.
CP 342:
Centralised hot water supply.
Part 2: Buildings other than individual dwellings.
I. Gas E. Publications
IGE/UP/1
Soundness testing and purging of
industrial and commercial gas installations.
IGE/UP/1A
Soundness testing and direct purging of
small low pressure industrial and commercial natural
gas installations.
IGE/UP/2
Gas installation pipework, boosters and
compressors in industrial and commercial premises.
IGE/UP/10
Installation of gas appliances in industrial
and commercial premises Pt.1 flued appliances.
Health and Safety Executive: -
Guidance note PM5
- Automatically controlled
steam and hot water boilers.
CIBSE Publications: -"CIBSE Guide"
It is
impractical in this document to specify all relevant
information, but the following extracts from the above
references are emphasized since failure to comply
with these requirements will almost certainly result in
an unsatisfactory installation.
3.2 Feed Water Quality
If the boiler feed water has a high degree of
hardness, it is recommended that the water be
treated to prevent precipitation of scale or sludge in
the boiler water passageways. Details of additives
can be obtained from any reliable manufacturer of
water treatment products or the local water authority.
It should be noted however, that even if the boiler
water is of average hardness, not requiring
treatment, subsequent draining of the system for
repair or constant make-up water due to an
undetected leak would cause additional deposits and
gradual build-up of scale. It is essential therefore,
that leaks are attended to promptly and draining is
kept to an absolute minimum.
It is recommended that the system be flushed out at
least twice with hot water before any water treatment
is added. If any doubt exists regarding the internal
cleanliness of an old system, consideration should
be given to the fitting of a coarse filter in the return
pipework to the boilers.
3.3 Adequate Water Flow
The Hamworthy Purewell boiler is designed as a
quick response, low water content unit, able to run
continuously with maximum reliability. Care should
be taken in the initial design and layout having due
regard for adequate water flow through the boilers
and the influence of the system controls.
NOTE!
The Standards Authority recommend a minimum
return temperature of 50°C in all heating systems
other than condensing boilers.
Figure No. 2 shows recommended and minimum
water flows required. The control system and
valves, where fitted, should be regulated to avoid
lower flows occurring.
The flow corresponding to 22°C temperature rise
across the boiler is the minimum recommended flow
at any time. For boiler pressure drop see Figure No.
2.
Figure No. 2 - Flow-rate Pressure Drop Table.
Model
40
50
60
70
80
95
100
105
120
Flow @ 11°C
'
T rise
litres/second
0.87
1.08
1.30
1.52
1.74
2.06
2.17
2.28
2.6
Resistance mbar
5.1
7.84
15.69
20.59
26.47
37.25
41.12
50
84.31
Flow @ 15°C
'
T rise
litres/second
0.64
0.80
0.95
1.12
1.27
1.51
1.59
1.67
1.91
Resistance mbar
2.75
4.31
8.63
11.57
14.9
22.55
25
27.45
47.06
Flow @ 22°C
'
T rise
litres/second
0.43
0.54
0.65
0.76
0.87
1.03
1.08
1.14
1.3
Resistance mbar
1.27
2.06
4.12
5.49
7.06
11.76
12.94
13.23
22.55
