[0001] The present invention generally relates to gas-fired heating apparatus and, more
particularly, an improvement to the water circuit of a wall-mounted gas-fired boiler
for combined room heating and domestic hot water service.
[0002] As known, the water circuit of wall-mounted gas-fired boilers for combined service
generally comprises a primary circuit connected to the room heating units in which
hot water for room heating is circulated and a secondary circuit for the production
of hot water for domestic use.
[0003] The secondary circuit is usually connected to a water supply pipe which is branched
off from the water mains.
[0004] Before putting the boiler into operation, the water circuit and the room heating
units connected thereto through pipes must be filled with water in order to test the
boiler and to permit it to be operated.
[0005] For this purpose, the water circuit is generally provided with water filling means.
[0006] In a conventional boiler, the water filling means is generally formed of a pipe branched
off from the secondary circuit and connected to the primary circuit of the boiler.
A manually operated ON-OFF valve is provided in this pipe which when in open position
permits the primary circuit to be filled with water and when in closed position disconnects
the primary circuit from the secondary circuit.
[0007] The provision of this pipe with ON-OFF valve makes the water circuit rather complex
also for the difficult accessibility of the ON-OFF valve.
[0008] Therefore, the present invention is aimed at providing a wall-mounted gas-fired boiler
for combined service in which the water circuit comprises water filling means capable
of offering better accessibility and less maintenance with lower costs than those
of conventional water filling means which are known in the art.
[0009] More in particular, the water circuit of the wall-mounted gas-fired boiler for combined
service includes a primary circuit in which the hot water for room heating is circulated
and a secondary circuit in which hot water for domestic use is circulated and is characterized
in that it comprises a three-way valve arranged so as to connect the primary circuit
or the secondary circuit to the water mains or to disconnect both therefrom.
[0010] According to a feature of the present invention, the three-way valve in its first
position disconnects the primary circuit and the secondary circuit from the water
mains, in its second position connects the room heating primary circuit to the water
mains in order to permit it to be filled with water and in its third position connects
the secondary circuit to the water mains.
[0011] Of course, during boiler operation, the three-way valve is set in its third position,
i.e. with the secondary circuit connected to the water mains.
[0012] The features and advantages of the present invention will be clearly understood from
the following detailed description together with the accompanying drawings, wherein:
Fig. 1 diagrammatically shows a conventional water circuit of a wall-mounted gas-fired
boiler for combined service,
Fig. 2 diagrammatically shows the wall-mounted gas-fired boiler for combined service
according to the present invention,
Fig. 3 is a front elevation view of the fittings assembly of the boiler illustrated
in Figure 2, and
Fig. 4 is a perspective view of the three-way valve used in the water circuit of the
wall-mounted gas-fired boiler for combined service illustrated in Figure 2.
[0013] For the sake of semplicity, in the following description all the parts corresponding
in form and/or function are designated by the same reference numerals.
[0014] In Figure 1 there is generally indicated by 10 the water circuit of a combined service
wall-mounted gas-fired boiler according to a well-known configuration.
[0015] The water circuit of the boiler comprises a primary circuit 11 in which hot water
for room heating is circulated and a secondary circuit 12 in which hot water for domestic
use is circulated.
[0016] The primary circuit 11 comprises a primary heat exchanger 13, a differential pressure
operated three-way change-over valve 14, a pressure-surge reducing valve 15, a by-pass
pipe 16 with its relevant by-pass valve 17, a circulation pump 18 provided with an
air separator, a spring-loaded safety valve 19 which is set at the maximum overpressure
of the primary circuit, an expansion tank 20, a water supply pipe M and a water return
pipe R for the room heating units, for example radiators.
[0017] Located under the primary heat exchanger 13 are a gas burner 21 connected to a gas
supply pipe 20 through an ON-OFF valve 22 and a modulating valve 23.
[0018] The secondary circuit 12 comprises a secondary heat exchanger 24, a domestic water
flow limiter 26, a domestic water inlet pipe E and outlet pipe U. The domestic water
inlet pipe E is connected to the water mains D through an ON-OFF valve 27.
[0019] The domestic water is prepared in the secondary heat exchanger 24. When the user
demands domestic hot water, the hot water which has been heated in the primary heat
exchanger 13 is diverted by the three-way change-over valve 14 into a pipe 28 connected
to the secondary heat exchanger 24 so as to flow therethrough and heat the domestic
water. Then the hot water returns to the primary circuit 11 on the suction side of
the circulation pump 18 and upstream the expansion tank 20. A check valve 29 is suitably
provided in the pipe 28.
[0020] In Fig. 1 there is also shown the water filling means for filling the primary circuit
11 and the room heating units connected thereto through the pipes M,R. The water filling
means comprises a pipe 30 which is branched off from the secondary circuit 12 and
is connected to the primary circuit 11. A check valve 25 and a manually operable ON-OFF
valve 31 are provided in the pipe 30. The ON-OFF valve 31 in open position permits
the primary circuit 11 to be filled with water and in closed position disconnects
the primary circuit 11 from the secondary circuit 12.
[0021] Referring now to Fig. 2, there is shown the water circuit of the combined service
wall-mounted gas-fired boiler according to the present invention. As can be seen,
the water circuit is different from that shown in Figure 1 in that the water filling
means of the primary circuit 11 comprises only a three-way valve 32. The three-way
valve 32 is connected to the water mains D, to the domestic water inlet pipe E and
to the water return pipe R from the room heating units. The check valve 25 is located
between the three-way valve 32 and the return pipe R. The valve member of the three-way
valve 32 can take three operative positions, namely: a first position in which it
disconnects both the primary circuit 11 and the secondary circuit 12 from the water
mains D, a second position in which it connects the primary circuit 11 only to the
water mains D and a third position in which it connects the secondary circuit 12 only
to the water mains D.
[0022] As can be seen in Fig. 3 of the drawings, the three-way valve 32 is arranged on a
connection plate P of the boiler support frame T. The connection plate P usually serves
as a lower transverse member of the boiler support frame T of the kind described herein
and it embodies the various fittings of the water circuit.
[0023] Apart from the three-way valve 32, the supply and return pipe fittings 33, 34 for
circulating the room heating water, the domestic water outlet fitting 35 and the gas
inlet fitting 36 are mounted onto the connection plate P.
[0024] The three-way valve 32 is connected to the heating water return fitting by means
of a connection pipe 37.
[0025] Fig. 4 is a perspective view of the three-way valve 32. There can be seen the attachments
32D,32E,32R for connection to the water mains D, to the domestic water inlet pipe
E and to the water return pipe R from the room heating units, respectively. A valve
control lever L is provided for operating the three-way valve 32.
[0026] The advantage of using a three-way valve 32 as a water filling means for filling
the boiler water circuit instead of the well-known water filling means can be clearly
understood by comparing the water circuits shown in Figures 1 and 2. As a matter of
fact, it can be noted that the water circuit of the invention has a smaller number
of components since the three-way valve 32 undertakes the functions of the ON-OFF
valves 27,31 and the pipe 30 that connects the primary circuit 11 to the secondary
circuit 12 of the boiler so that these components become unnecessary. Therefore, the
water circuit of the boiler according to the present invention has a more rational
configuration and is less expensive to manufacture. Further, also filling operations
of the water circuit are more simple to perform because the operator has to maneuver
one valve only.
1. A water circuit (10) for a wall-mounted gas-fired boiler for combined service including
a primary circuit (11) in which the hot water for room heating is circulated and a
secondary circuit (12) in which hot water for domestic use is circulated, characterized
in that it comprises a three-way valve (32) arranged so as to connect the primary
circuit (11) or the secondary circuit (12) to the water mains (D) or to disconnect
both therefrom.
2. Water circuit according to claim 1, characterized in that the three-way valve (32)
in its first operative position disconnects both the primary circuit (11) and the
secondary circuit (12) from the water mains (D), in its second operative position
connects the primary circuit (11) only to the water mains (D) and in its third operative
position connects the secondary circuit (12) only to the water mains (D) for the purpose
of preparing the domestic hot water when requested by the user.
3. Water circuit according to claim 2, characterized in that during boiler operation
the three-way valve (32) is set in its third operative position, i.e. with the secondary
circuit (12) connected to the water mains (D).