Figure E1 Water Data - Hamworthy Purewell VariHeat 65he Installation, Comissioning And Servicing Instructions

APPENDIX E - WATER DATA
Model
Water Connections (Flow & Return)
Maximum Water Pressure
Water Content (not including headers)
System Design Flow Rate @ 11°C ΔT Rise
Minimum Flow Rate @ 15°C ΔT Rise
Waterside Pressure Loss @ 11°C ΔT Rise
Waterside Pressure Loss @ 15°C ΔT Rise
Figure E1 - Water Data
E1.1 Water Circulation System
The Purewell VariHeat 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.
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 R2" male flow (indicated with a red spot) and return (indicated with a blue
spot) connections. Boilers should be connected by flow and return headers. Headers should be
connected to the system in a 'reverse / return' arrangement (the water flow in each header is in the
same direction) to ensure equal flow in each module, or with a 'single pipe header system'. Figure
E1.2 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 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 2.0 metres or 0.2 bar.
2) Single installed boiler running at 90°C flow temperature. Minimum head required = 3.0 metres or 0.30 bar.
3) Modular boiler installation running at 82°C flow temperature and 11°C rise across system. Minimum head required =
4.4 metres or 0.43 bar.
4) Modular boiler installation running at 82°C flow temperature and 15°C rise across system. Minimum head required =
6.5 metres or 0.64 bar.
E1.3 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 a
capped R¾" stub pipe for the fitting of a safety valve (not supplied). 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.
Boiler Output
60 - 150kW
150 - 300 kW
300 - 600 kW
HAMWORTHY HEATING LTD
WATER DATA
Feed mm Vent mm
25
32
38
PUREWELL VariHeat he
65he
- bar g
6
- litres
1.4
- litre/s
1.0
- litre/s
- mbar 50
28
- mbar
32
38
Figure E1.1 Cold Feed and Vent Pipe Sizes
50
53
85he 105he 125he
R2" male
7
6 9
1.9 2.3
1.4 1.7
80 192
47 98
9
2.7
2.0
270
149
500001170/K