HAMWORTHY HEATING LTD
64
MILBORNE
500001130/J
APPENDIX E - WATER DATA
WATER DATA
Model
381
382
501
502
Water Connections (Flow & Return)
G 1” male
Maximum Water Pressure
-
bar g
6
Minimum Water Pressure
-
bar g
0.5
Water Content (not including headers)
-
litres
3.5
4.9
7.0
9.8
Design Flow Rate @ 20°C
∆
T Rise
-
litre/s
0.42
0.55
0.84
1.1
Waterside Pressure Loss @ 20°C
∆
T Rise
-
mbar
300
700
E1.1 Water Circulation System
The Milborne boiler has a low water content and the requirements of minimum water flow are given in the above
table. Recommendations for the water circulation system are given in BS 6644 and CP 342.
The following details are of particular importance for the correct installation of the water circulation system:
1) In a combined central heating and hot water system the hot water storage vessel must be of the
indirect cylinder or calorifier type. The hot water storage vessel should be insulated, preferably with
not less than 75mm (3”) thick mineral fibre, or its thermal equivalent.
2) Circulating pipework not forming part of the useful heating surface should be insulated to help prevent
heat loss and possible freezing, particularly where pipes are run through roof spaces and ventilated
cavities. Cisterns situated in areas which may be exposed to freezing conditions should also be
insulated. Furthermore, insulation exposed to the weather should be rendered waterproof.
3) Drain valves must be located in accessible positions which permit the draining of the whole system,
including the boiler and hot water storage vessel.
4) Each boiler module has G1” male flow and return connections. Boilers should be connected by flow
and return headers. Hamworthy strongly recommend that boilers are connected in a primary circuit
configuration utilising a low loss header arrangement to enable secondary circuits to be connected to
the header. Figure E1.1.1 on the following page show typical layouts.
5) Ideally, individual valves should be fitted to each module to enable isolation from the system,
however, the arrangement must comply with the requirements of BS 6644.
E1.2 Pressure Relief Valve (Safety Valve)
The most important single safety device fitted to a boiler is its safety valve. Each boiler module is provided with an
integral safety valve terminating in a 22mm stub pipe on the base of the boiler. BS 6644 provides comprehensive
information for the selection and location of safety valves and attention is drawn to the higher capacity
requirements of safety valves for pressurised hot water systems.
E1.3 Altitude Gauge (Water Pressure Gauge)
Every boiler or group of boilers should be provided with an altitude gauge complete with isolating valve. See
Figure E1.1.1 for typical position.
E1.4 Thermometer
A thermometer complete with pocket should be fitted in the pipework to indicate water flow temperature. See
Figure E1.1.1 for typical position.
E1.5 Drain Valves
Each boiler should have a 15mm NB drain valve (not Hamworthy Heating Ltd supply) fitted in the boiler return to
drain the boiler only. The heating system in total should have drain valves as recommended by BS 6644. See
Figure E1.1.1 for typical position.
E1.6 Circulating Pump
It is recommended by Hamworthy Heating, that the
primary pump MUST be controlled from the Master boiler
to
ensure synchronised operation - refer to fig. 4.6.
