FR2550317A1 - Condensation gas boiler connected to a controlled mechanical ventilation installation. - Google Patents

Abstract

The duct for exhausting the combustion gases 13 opens out into the duct 1 for controlled mechanical ventilation in a zone which is at an underpressure with respect to atmospheric pressure, but having an underpressure whose absolute value is less than that of the zone of the duct 1 for controlled mechanical ventilation, which zone is situated downstream of the extraction mouth 4. An underpressure-generating member 3 is arranged in the duct 1 for controlled mechanical ventilation upstream of the extraction mouth 4. The duct for exhausting combustion gases 13 opens out into the duct 1 for controlled mechanical ventilation in a zone whose pressure is close to the pressure of the zone in which the combustion air required by the boiler is extracted. A pressure switch 5 measures the difference in pressure between a point in the duct 1 situated level with or downstream of the underpressure-generating member 3, and a reference pressure, and means are provided for triggering the safety device of the boiler when the differential pressure measured by the pressure switch 5 becomes less than a predetermined minimum value.

Description

GAS BOILER WITH CONDENSATION CONNECTED TO A
CONTROLLED MECHANICAL VENTILATION SYSTEM.

 The present invention relates to a condensing gas boiler connected to a controlled mechanical ventilation installation, that is to say a condensing boiler in which the combustion products are discharged directly into a controlled mechanical ventilation pipe ensuring the renewal of the ventilation air of a room.

 It is naturally advantageous to be able to use a common duct for the circulation, on the one hand, of the ventilation air of a dwelling and, on the other hand, of the combustion products to be evacuated. Such a provision, however, poses a problem as regards personal safety. It is in fact advisable to permanently guarantee that all of the combustion gases are evacuated towards the extraction outlet of the pipe and do not discharge towards the air inlet which opens into the ventilated room. In the event of backflow initiation, the boiler should be able to be immediately put in the shutdown or safety state, i.e. shut down the burner.

 Traditional gas appliances are already known, that is to say not intended to operate in condensation-recovery of the latent heat contained in the products of combustion of the gas, which are connected to a controlled mechanical ventilation installation also ensuring the evacuation of combustion gases. In this case, security is ensured from a thermal contactor which interrupts the operation of the appliance in the event of the combustion products overflowing by the draft cut-off, this overflow can correspond to a shutdown of the ventilation installation or insufficient exhaust air flow. This system is made possible by the high thermal level of the combustion products which are at a temperature generally above 1000C and often of the order of 1400C.

 Such a safety device cannot be used directly with a condensing appliance. Indeed, condensing gas boilers are characterized by a temperature of the combustion products which is variable depending on the speed of the appliance and is in a range of values between approximately 300 and 1000C. The temperature difference between the ambient air and the products of combustion is then generally too small to allow a thermal contactor to always always detect a malfunction of the ventilation resulting in a backflow of the products of combustion in local.

 The object of the present invention is to remedy the aforementioned drawbacks and to allow the connection of a condensing gas boiler directly to a controlled mechanical ventilation installation, with modulated or fixed flow, with effective monitoring of the proper functioning of the evacuation. combustion products which guarantees automatic safety of the boiler in the event of a breakdown of the controlled mechanical ventilation, regardless of the temperature difference between the combustion products and the ambient atmosphere.

 These aims are achieved by means of a condensing boiler connected to a controlled mechanical ventilation pipe, for which, in accordance with the invention, the flue gas discharge pipe opens into the controlled mechanical ventilation pipe in a vacuum area. with respect to atmospheric pressure, but having a depression, the absolute value of which is lower than that of the zone of the controlled mechanical ventilation pipe situated downstream of the extraction mouth; a pressure-reducing member is arranged in the controlled mechanical ventilation pipe upstream of the extraction mouth; the combustion gas evacuation pipe opens into the controlled mechanical ventilation pipe in an area the pressure of which is close to the pressure of the area in which the combustion air required for the boiler is taken up; a pressure switch is used to measure the pressure difference between a point in the pipe located at or downstream of the pressure-reducing member, and a reference pressure, and means are provided to trigger the shutdown or safety of the boiler when the differential pressure measured by the pressure switch falls below a predetermined minimum value.

 Said predetermined minimum value corresponds to a vacuum in front of the extraction mouth of between approximately 20 and 120 Pa and preferably less than approximately 50 Pa.

 Advantageously, the upstream part of the controlled ventilation pipe which comprises the pressure-reducing member and into which the combustion air intake and the combustion gas discharge pipe open, as well as the pressure-reducing member, are associated with the boiler. proper in an integrated package. The boiler is then equipped with its own security system with respect to controlled mechanical ventilation.

 According to a first embodiment, for which the boiler is of the type with a sealed combustion circuit, the combustion air intake and the combustion gas evacuation duct open into the controlled mechanical ventilation pipe, downstream of the depression-causing organ, in an equilibrium zone.

 In this case, the pressure-reducing member may be constituted by a simple diaphragm or by a calibrated movable flap located in the vicinity of the entrance to the controlled mechanical ventilation pipe. The use of a calibrated movable flap ensures modulation of the ventilation flow.

 According to this first embodiment, the reference pressure is constituted by the ambient atmospheric pressure.

 According to another possible embodiment, the combustion air intake is carried out at ambient atmospheric pressure outside the controlled mechanical ventilation pipe and the combustion gas evacuation pipe opens into the upstream controlled mechanical ventilation pipe. of the primary organ, in an area where the pressure is barely below ambient atmospheric pressure.

 In this case, the pressure-reducing element can be constituted by a venturi and the pressure switch measures the pressure difference between the neck of the venturi and the reference pressure.

 According to a variant, the depriogenic organ can be constituted by a diaphragm and the pressure switch measures the pressure difference between a point located downstream of the diaphragm in the controlled ventilation pipe and the pressure preferably.

 According to this second embodiment, the reference pressure can be constituted by the ambient atmospheric pressure or by the discharge pressure of the burner fan.

 The inlet portion of the controlled mechanical ventilation pipe located upstream of the deprinous organ: ogen collects, coaxially or not, the combustion gases from the combustion gas evacuation conduit, and it even opens into 'ambient atmosphere.

 An auxiliary air inlet, for example provided with a calibrated movable flap, may be provided in the controlled mechanical ventilation pipe downstream of the deprinc6eue member so as to allow the modulation of ventilation rates.

 According to another particular characteristic, the means provided for triggering the securing of the boiler comprise a contactor controlling the burner of the boiler and mounted so that the burner is stopped in the open position of the contactor.

Other characteristics and advantages emerge from the description which follows, of particular embodiments of the invention, with reference to the accompanying drawing, in which
FIG. 1 is a schematic view showing a condensing boiler with a sealed combustion circuit connected according to the invention to a controlled mechanical ventilation installation, and
FIGS. 2 and 3 schematically show two alternative embodiments of the invention in which a condensing boiler with an air intake external to the controlled mechanical ventilation pipe has an evacuation of the combustion products in said pipe,
If we refer to Figure 1 we see a sealed combustion heat generator 2 associated with conduits 1, 14 of a controlled mechanical ventilation installation (hereinafter abbreviated by the initials VMC).

 The extraction mouth 4 located at the junction of the portions 14, 15 of controlled mechanical ventilation pipes makes it possible to modulate, in a conventional manner, the ventilation rate of the room in which the boiler 2 is placed between a minimum flow rate and a maximum flow rate . The minimum flow rate must naturally be compatible with proper operation of the boiler 2 which is connected to line 1, 14 of VMC.

 The upstream part 1 of the VMC pipe has an end opening 10 leading to the atmosphere in the room where the boiler is located 2. A pressure-reducing member 3 such as a diaphragm or, as shown in FIG. 1, a tared movable flap, is mounted following the opening 10 of the upstream part 1 of the VMC pipe to put the pipe 1, 14 in depression with respect to the atmosphere, at an intermediate pressure between that which prevails behind the extraction outlet X and the ambient pressure of the room where the boiler is installed 2.

The use of a tared movable flap 3 makes it possible to regulate this depression during the modulation of the ventilation flows. A preferential air passage orifice 8 can then allow an air passage corresponding to the minimum flow when the shutter 3 is in the closed position.

The heat generator 2 with a sealed combustion circuit draws the fresh air necessary for the combustion of the gas through a pipe 11 originating in the upstream part 1 of the pipe
CMV, downstream of the depressive organ. The combustion products of the heat generator 2 are themselves discharged into line 1, 14 of VMC through a line 13 which opens downstream of the line 11, but in an area where the vacuum remains at a value close to that prevailing at the place where the conduit is born 11.

 In Figure 1, there is shown an upstream part 1 of horizontal pipe bent upwards at its end to connect to the pipe part 18 which includes the extraction mouth 4. The vertical pipe 13 for discharging the burnt gases of the boiler 2 partially penetrates and opens into the angled part of connection between the horizontal pipe part 1 and the pipe 14.

 The arrangement described above with a location of the upstream VMC pipe part 1 in the immediate vicinity of the boiler 2 lends itself to making the whole of the boiler 2 and the pipe part 1 in integrated form within 'A unit 20 which presents with respect to the outside a simple air intake 10 and a connection to the main line 14 of VMC containing the extraction mouth 4. This allows increased ease of installation.

 The arrangement of the duct 11 for extracting air and of the duct 13 for discharging the burnt gases makes it possible to avoid sweeping of the heating body by suction due to controlled mechanical ventilation, when the boiler is stopped, because there is no no vacuum in the boiler 2. The circulation of the combustion products in the boiler takes place via the fan (not shown) of the condensing boiler which can be located either downstream or upstream of the burner at forced air.

 A shutter system can also be added to the sealed combustion circuit of the boiler so as to prevent any sweeping of the heating body by thermal draft when the burner stops. Furthermore, a diaphragm 6 is preferably disposed in the conduit 13 for discharging the burnt gases, so as to adjust the excess air or the power of the burner.

 An essential aspect of the present invention, which contributes to guaranteeing the safety of the persons present in the room where the VMC pipe 1, 14 which also receives the combustion gases from the boiler, opens out, resides in the presence of a pressure-reducing device ( pressure switch) 5 which controls the differential pressure prevailing between on the one hand the zone of duct 1, 14 of VMC to which the duct 11 of air intake for the boiler 2 and the duct 13 of evacuation of the burnt gases of the boiler 2, and, on the other hand, the ambient atmosphere of the ventilated room where the boiler is located. We thus see in FIG. 1 a pressure switch 5 measuring the differential pressure between a point 12 located in the section 1 of pipe VMC between ducts 11 and 13 and a point 16 located outside the boiler 2.

 When the differential pressure measured by the pressure switch 5 becomes lower than a threshold value for which there is not yet an overflow of the combustion products in the room, a control member associated with the pressure switch 5 makes it possible to stop the supply of the burner to gas, which causes the boiler to shut down or go into safety.

The control member can be constituted by a contactor which is preferably wired in a positive way, that is to say which is normally closed and triggers the trip when it is open.

 The set threshold value, which depends on the type of boiler 2, and on the configuration of all the parts 1,3,8,10,11,12,13,14, is generally between approximately 20 and 120 pascals and is preferably less than about 50 Pa.

 The water vapor which continues to condense in the pipe 1, 14 returns to the boiler through the interior of the pipes 11, 13 and is then removed with the water vapor condensed inside the boiler.

 Figures 2 and 3 show variants of a second embodiment of the invention for which a condensing boiler 102 with non-sealed combustion circuit is connected to a line 112, 114 of VMC. In this case, the air supply to the boiler 102 is carried out from the ambient atmosphere of the room where the boiler 102 is located independently of the VMC line 112, 114.

 In FIG. 2, we see the duct 113 for evacuating the combustion gases from the boiler 102 which engages in the lower part 111 of the duct 112, 114 of VMC, open to the atmosphere with biante, at its mouth 110. A deprimogenic member constituted by a venturi 108 is located above the pipe part 111 into which the pipe 113 for evacuating combustion gases penetrates. Above the venturi 108, that is to say downstream of the latter, an auxiliary air inlet constituted for example by a calibrated movable flap 103 can make it possible to modify the ventilation rate of the VMC duct 112, 114. The extraction loop 104 located at the junction of the V pipes: ZC 514 and 115 (the pipe 115 being located downstream of the pipe 114) is itself identical to the extraction mouth 4 of FIG. 1 and can modulate the ventilation rates of the room between a minimum permanent flow compatible with proper operation of the boiler and a maximum flow corresponding to intensive ventilation. The distribution of the pressure drops between on the one hand the auxiliary air inlet 103 and on the other hand the venturi 108 is such that the flow rate passing through the latter is substantially constant.

 It will be noted that the lower part 111 of the line V2oC channels the combustion products coming from the gas appliance 102 as well as part of the room ventilation air. There is thus an araulic disconnection between the boiler 102 and the VMC network. The depression in the driving part 111 is only a few pascals.

 In the case of the variant of FIG. 2 which incorporates a pressure-reducing member constituted by a venturi 108, or a similar vacuum-boosting member, the latter increases the vacuum prevailing in the pipe portion 112 as a function of the fluid flow rate. This increased depression is of the order of 2 to 3 times the depression prevailing in the duct 112 in the absence of a depressive body and, as in the case of FIG. 1, can be between approximately 20 and 120 pascals, and is chosen with a preference of less than about 50 Pa.

 A pressure switch 105 which plays a role similar to the pressure switch 5 in FIG. 1 compares the vacuum measured at the neck of the venturi 108 at atmospheric pressure. When the differential pressure measured by the pressure switch 1G5 becomes lower than a threshold value for which the air entrainment flow rate in the line 111, 112 is no longer sufficient to guarantee non-delivery of the combustion products to the opening 110, the pressure switch 105 controls, by means of a contactor, the stop of the burner operation.

 The fan 107 and the diaphragm 106 shown in the conduit 113 for evacuating the combustion gases have the schematic configuration of the elements usually present in a condensing boiler.

 The variant of Figure 3 is similar to that of Figure 2, and the identical elements have the same references.

However, in FIG. 3 we see a pressure-reducing organ constituted by a diaphragm 109, or another similar device which does not cause amplification of the depression as a function of the flow through. In this case, the control pressure tap in the pipe 112 carried out at the neck of the venturi 108 in the embodiment of FIG. 2, is carried out downstream of the diaphragm 1C9 and this control pressure is applied to the pressure switch 105 which compares it to atmospheric pressure. In the event of insufficient vacuum downstream of the diaphragm 109, the pressure switch 105 then controls the safety of the boiler.

 In the case of Figure 3, as in the case of the embodiments of Figures 1 and 2, the vacuum provided for proper operation, and therefore the threshold value below which the safety of the boiler occurs corresponds to a vacuum in the VMC lines 14 and 114 which may be low or moderate, for example of the order of 20 to 50 pascals for the threshold value.

 In the embodiments of FIGS. 2 and 3, the vertical lower parts 111, 112 of the VC pipe can be associated with the boiler 102, and with the pressure gauge member 105, during manufacture, within an assembly integrated unit 120, a single connection to the external part of the VMC 114 pipe being then necessary during the installation in situ. In the same way, in the mcde of réallsâtZcn of 1 = FIG. 1, the pressure switch 5 is advantageously integrated during manufacture into the unitary assembly 20. In the three cases of FIGS. 1, 2 and 3 the boiler is then equipped with its own VMC security system.

 A device not shown in Figures 2 and 3 must be put in place so as to recover and channel the water which continues to condense in parts 111, 118 of the CMV and to evacuate it with the condensed water vapor inside the boiler 102.

 Furthermore, as in the case of FIG. 1, a shutter system can, for the variants of FIGS. 2 and 3, be added to the combustion products evacuation pipe 113 so as to prevent any sweeping of the heating body by thermal draft or suction of the VMC when the burner stops.

 It will be noted that, in the case of the embodiment of FIGS.

2 and 3, according to an alternative embodiment, the measured control pressure can be compared by the pressure switch not to atmospheric pressure, but to a reference pressure constituted by the discharge pressure of the burner fan.

 In the various embodiments described above, it is possible to pass either all or only part of the ventilation flow rate through the boiler while being able to provide the possibility of modulating the ventilation flow rate. If the entire ventilation flow passes through the boiler, the pressure-reducing member must necessarily consist of a movable flap 3 in the case of the embodiment of FIG. 1, and a movable flap 103 should also be used in the case of embodiments of FIGS. 2 and 3, this in order to allow modulation of the ventilation rate to be ensured.

 In the case where only a fixed part of the ventilation flow rate passes through the boiler, the pressure-reducing member 3 can then be constituted by a diaphragm and in the case of the embodiment of FIGS. 2 and 3, the shutter 1C3 can be omitted. In the case where only a minimum ventilation flow passes through the pipe 14, 114, an independent variable-flow outlet provided with a movable flap may be disposed in the vicinity of the pipes 14, 114 to allow modulation of the overall ventilation flow.

Claims (14)

 1. Condensing gas boiler into which the combustion products are discharged directly into a controlled mechanical ventilation pipe ensuring the renewal of the ventilation air in a room, (1; 111). characterized in that the combustion gas evacuation pipe (13; 113) opens into the mechanical ventilation pipe (1J111) controlled in an area in depression relative to atmospheric pressure, but having a depression whose absolute value is lower than that of the zone of the pipe (1; 111) of controlled mechanical ventilation located downstream of the extraction mouth (4; iOIt), in that a pressure-reducing member (3; 108; 109) is arranged in the mechanical ventilation pipe (1; 112) controlled upstream of the extraction mouth (4; 104); in that the combustion gas discharge pipe (13; 113) opens into the pipe (1; 111) of controlled mechanical ventilation in an area whose pressure is close to the pressure of the area in which the combustion air required for the boiler, in that a pressure switch (5; 105) is used to measure the pressure difference between a point in the pipe (1; 112) located at or downstream of the pressure-reducing element (3 ; 108; 109), and a reference pressure, and in that means are provided to trigger the shutdown or safety of the boiler when the differential pressure measured by the pressure switch (5; 105) becomes less than a value predetermined minimum.  2. Gas boiler according to claim 1, characterized in that said predetermined minimum value corresponds to a vacuum in front of the extraction mouth of between approximately 20 and 120 Pa and preferably less than approximately 50 Pa.  3. Gas boiler according to claim 1 or claim 2, characterized in that it is of the sealed combustion circuit type and in that the combustion air intake (11) and the gas evacuation duct of combustion (13) open into the line (1) of controlled mechanical ventilation, downstream of the pressure-reducing member (3), in an equi-pressure zone.  4. Gas boiler according to claim 3, characterized in that the pressure-reducing member (3) consists of a diaphragm located in the vicinity of inlet of the pipe (1) of controlled mechanical ventilation.  5. Gas boiler according to claim 3, characterized in that the pressure reducing member (3) consists of a calibrated movable flap located near the inlet of the pipe (1) of controlled mechanical ventilation.  6. Gas boiler according to claim 1 or claim 2, characterized in that the combustion air intake is carried out at atmospheric-ambient pressure outside the pipe (112) of controlled mechanical ventilation and in that the pipe ( 113) for evacuating the combustion gases opens into the controlled mechanical ventilation pipe (112) upstream of the pressure-reducing member (108; 109), in a zone (111) where the pressure is barely lower than atmospheric pressure ambient.  7. Gas boiler according to claim 6, characterized in that the pressure-reducing member (108) consists of a venturi and in that the pressure switch (105) measures the pressure difference between the neck of the venturi (108) and the reference pressure.  8. Gas boiler according to claim 6, characterized in that the pressure-reducing member (109) consists of a diaphragm and in that the pressure switch (105) measures the pressure difference between a point located downstream of the diaphragm (109 ) in the controlled mechanical ventilation line and the reference pressure.  9. Gas boiler according to any one of claims 6 to 8, characterized in that the inlet portion (111) of the controlled mechanical ventilation pipe (112) located upstream of the pressure-reducing member (108; 109 ) collects the combustion gases from the conduit (113) for evacuating the combustion gases, and opens itself into the ambient atmosphere thereby achieving a disconnection between the circuit of the combustion products of the boiler and the VMC.  10. Gas boiler according to claim 9, characterized in that a auxiliary auxiliary air inlet (103) is provided in the duct (112) of controlled mechanical ventilation downstream of the pressure reducing member (108; 109) so to allow modulation of the ventilation flow.  11.Gas boiler according to any one of claims 1 to 10, characterized in that said reference pressure is constituted by ambient atmospheric pressure.  12. Gas boiler according to any one of claims 6 to 10, characterized in that said reference pressure is constituted by the discharge pressure of the burner fan.  13. Gas boiler according to any one of claims 1 to 12, characterized in that the upstream part of the pipe (1) of controlled mechanical ventilation which comprises a pressure-reducing member (3) and into which open the combustion air intake. (11) and the combustion gas discharge pipe (13), as well as the pressure-reducing member (5), are associated with the boiler proper (2) in an integrated assembly (2C).  14. Gas boiler according to any one of claims 1 to 13, characterized in that the means provided for triggering the securing of the boiler comprise a contactor controlling the burner of the boiler and mounted so that the burner is stopped in the contactor open position.