HAMWORTHY HEATING LTD
WARMWELL
500001091/F
8.3
Open Vent and Cold Feed Pipe
(See
BS 6644
for further information.)
Every boiler or group of boilers should have an open
vent pipe and cold feed pipe installed between the
boiler and the first water isolating valve. The
minimum bore (mm) of these pipes per installation is
shown in Figure 8.3.
The vent pipe must rise continually, it must not be
valved except by a design which when closed for
maintenance ensures the boiler is open to
atmosphere. The pipe shall be protected against
freezing where this might occur.
8.4
Altitude Gauge (Water Pressure Gauge)
Every boiler or group of boilers should be provided
with a gauge complete with isolating cock. See
Figure 1.1 (p2) for typical position.
8.5
Thermometer
See Figure 1.1 (p2) for typical position. A
thermometer complete with pocket should be fitted
in the pipework to indicate water flow temperature.
8.6
Drain Valves
Each boiler should have a 15mm NB drain valve
(not H.H.L. supply) fitted to drain the boiler only.
The heating system in total should have drain valves
as recommended by
BS 6644
. See Figure 1.1 (p2)
for recommended positions.
8.7
Circulating Pump
One or more circulating pumps will be required to
circulate water around the boilers and heating
system. Figure 2.2 (p4) shows the hydraulic
resistance of the boiler. The pump should be sited to
facilitate servicing. It is important to note that when
Warmwell boilers are used to replace boilers on an
existing system, the pumps should be checked for
performance against the new boiler waterside
pressure drop to ensure that the minimum flow rate
can be obtained. It is also important that the existing
system be flushed through twice to remove any
loose matter, which may have accumulated. If in any
doubt regarding the cleanliness of the system, a
coarse filter should be fitted in the return pipework to
the boilers.
8.0
WATER CIRCULATION SYSTEM
8.1
General
The Warmwell Boiler has a low water content and
the requirements of minimum water flow are given in
Section
8.8:Minimum Water Flow Rates
(p12) and
Figure 2.2 (p4). Recommendations for the water
circulation system are given in
BS 6644
and
CP
342
. The following notes are of particular
importance: -
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 (3in) 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. 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 has one Rc2 BS21 flow and one Rc2
BS21 return tapping. Flow and return headers
should connect boilers but sufficient length of
connecting pipe should be allowed to clear the casing
before connecting into the headers. The 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. Figure 1.1 (p2) shows typical layout.
5)
Due to the higher pressure losses of the
Warmwell heat exchanger compared to the
Purewell, it may be necessary to install a shunt
pump or balancing valve to enable correct flow
through these combined boiler systems. See Figure
3.3 (p6).
8.2
Pressure Relief Valve (Safety Valve)
Each boiler, or in the case of a modular installations,
each bank of boilers, must be fitted with a pressure
relief valve to
BS 6759
Part 1 and sized as shown in
BS 6644
.
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.
Figure 8.3. Cold Feed and Vent Pipe Sizes
Boiler Output
Feed
Vent
< 60 kW
19
25
60 kW - 150 kW
25
32
150 kW - 300 kW
32
38
300 kW - 600 kW
38
50
11
Содержание Warmwell 120
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