A condensate drainage device for gaseous fuel fired condensation boilers

Abstract: A condensate drainage device employed as a safety device for preventing the discharge gases produced by combustion from flowing out through the condensate drainage conduit, in condensation boiler apparatuses.

Description: This invention relates to a condensate drainage device for gaseous fuel fired condensation boilers. More particularly, this invention relates to a condendensate drainage device which is employed as a safety device in order to prevent the discharge gases produced by combustion from going out through the condensate drainage conduit in condensation boiler devices. As is well known, condensation boilers are a particular kind of heat generators, which are designed for cooling the combustion products down to a temperature below the dew point of the burnt gas, so that the partial condensation of water formed in the combustion reaction is obtained, said water usually leaving the boiler itself in the form of overheated steam. According to the rules in force at present, gas-fired boilers whose power is lower than 30,000 kcal/hr can be installed also inside domestic buildings. In that case, the pipe for discharging smokes is connected to the flue and,as an alternative,to the outside with a short connecting pipe through an outer wall. The condensate is then expelled through the sewer system of the house itself. In order to avoid that the discharge gases have the possibility of going also out through the condensate drainage conduit, the expedient is traditionally adopted of shaping the conduit itself as a "drain-trap" so as to create, with the liquid that forms and accumulates within such trap, a hydraulic seal of the conduit that allows the condensate to be drained whereas prevents the toxic discharge gases from passing, so that they cannot flow into the various rooms through the sewer system. It has been observed that sometimes working conditions can occur in such systems, in which no condensate forms or in which the condensate, though formed at first during the starting step, can evaporate successively. Among such conditions one could mention for instance the case in which a condensation boiler is installed in a conventional heating plant designed for operating at a return temperature higher than the dew point temperature. Under such condition, an amount of water sufficient to fill the drain trap is unlikely to form so that water for hydraulically closing said condensate drain trap lacks. Such condition is a situation of possible danger owing to the fact that burnt gases are so conveyed as to leave partially the pressurized combustion chamber through the condensate drainage connecting pipe so that they flow into the inhabited rooms. Accordingly, it is evident that there is the need for a further safety device that operates as a burnt gas interceptor and that prevents the burnt gases from flowing into the inhabited rooms when the hydraulic drain-trap does not form. In order to meet such requirement, this invention suggests that the boiler should be endowed with a condensate drainage device connected to the condensate-connecting tank, said device being provided with a closing member that opens just when in contact with water, and the invention also suggests that the drainage pipe of such device through which pipe the condensate is drained should be connected with a drain-trap connecting pipe which is series-assembled with the drainage device in order to ensure further safety against the leak of gases. In US-A4.856.550 a condensate drainage device is described, said device comprising a outer body consisting of a cover portion and of a bottom portion, wherein said bottom portion has a second portion for connection with the condensate drainage conduit; and a float, said float being provided is its top portion with a projecting part that is intended for engagement with a corresponding cavity provided in the inner part of said cover portion of said outer body. Accordingly, it is a specific object of this invention a condensate drainage device for gaseous fuel fired condensation boilers comprising an outer body consisting of a cover portion and of a bottom portion, wherein said bottom portion has a member for connection with the condensate drainage conduit; a float provided in its top portion with a projecting part that is intended for engagement with a corresponding cavity provided in the inner part of said cover portion of said outer body, characterized in that said cover portion of the outer body has a first member for connection with the inlet conduit of the condensate and of the burnt gases, in that said float is provided in its bottom position with a housing for a tight seal gasket, in that a gap for the passage of the condensate is provided between said float and said outer body, and in that said gasket housed within said annular housing is intended for engagement with the mouth of said connection portion, so preventing the condensate and/or the gas from being drained. Finally, again according to this invention, said second connecting member is provided with a connection with a drain-trap shaped drainage pipe, said pipe forming a further safety member. This invention has been disclosed just for illustrative and not for limitative purposes with reference to the enclosed drawings wherein: Figure 1 is an ensemble schematic view of a gas fired condensation boiler; Figure 2 is a schematic view of a boiler installed in a domestic building; Figure 3 shows an ensemble view of a boiler endowed with a drain-trap condensate drainage device; Figure 4 shows an ensemble view of a boiler which is provided with a condensate drainage device and with a draintrap device which is assembled internally; Figure 5 shows a side view of the condensate drainage device according to this invention; and Figure 6 shows a vertical cross-sectional view of the condensate drainage device. As can be observed in Figure 1, a conduit for the drainage of the condensate is provided in the traditional gas-fired boilers 1, said conduit being arranged directly below the condensate collection tanks or being provided at the base of the exchanger which is generally connected to the various members of the sewer system of the domestic building wherein it is inserted through a drain-trap connection pipe 3. Such last-mentioned pipe is arranged in a position outside the boiler 1 in the arrangement shown in Figure 2, whereas said pipe is provided, in the configuration shown in Figure 3, at a point corresponding to the lower portion of the device, on the bottom of the condensate collection space which is placed at the end of the smoke discharge conduit 5. Figure 4 illustrates on the contrary in a schematic way the arrangement of the condensate drainage device 6 according to this invention, said device being provided at a point corresponding to the lower portion of the boiler 1, and being connected to the condensate collection tank 4 through a pipe 7. This last-mentioned pipe, according to a preferred embodiment of this invention, is a stainless steel pipe preferably of 14 mm diameter, which is connected directly with the bottom of the heat exchanger, where the condensate is collected. Water flowing out of the condensate drainage device 6 is removed through a pipe 8 which is preferably silicone-treated and in the shape of a drain trap as a second safety member which is series-connected with said condensate drainage device 6. Figure 5 illustrates a side view of the condensate drainage device 6 together with the hydraulic connections 7 and 8. The device 6 consists indeed of a plastic material body made up of an upper portion 9 comprising the portion for connection with the inlet pipe of the burnt gas-condensate mixture as well as of a lower portion 10 comprising the connection with the drain-trap shaped pipe 8. A cylindrical float 4 provided with a cover 12 is arranged inside the outer body of the device 6 (see Figure 6), said float being guided along its vertical stroke and being illustrated respectively in the open and closed positions in Figure 6. A housing 13 for a gasket 14 that closes the orifice in the lower portion of the body of the condensate drainage device is provided in the lower portion of the body 11 of the float itself. When the boiler 1 is started, there is no condensate so that the drain-trap pipe 8 which is series-connected to the condensate drainage device 6 is empty. Because of the pressure existing in the combustion chamber, gases might flow through the drain-trap itself till reaching the outside environment. This is prevented indeed from occurring as a result of the fact that the float mentioned above is in the closed position, its gasket 14 pressing the neck 15 of the connection portion with said pipe 8, so preventing the gaseous mixture from leaking. When the first amount of condensate arrives, the volume between the body 10 of the condensate drainage device 6 and the body 11 of the float that is thus pushed upwards increases so as to make it possible to remove the gaseous mixture through the discharge orefice. The condensate water will thus flow into the draintrap 8 and will fill the same so that said pipe 8 will be a further safety member against the dispersion of gases into the environment. It is to be observed that a seat is provided in the cover portion 9 of said condensate drainage device, said seat performing the function of guiding and of acting as an end of stroke for the float during its vertical stroke, as the projecting portion 16 of the cover portion 12 of the float itself goes into engagement with said seat. In an analogous way, for a correct alignment of the float during its stroke, some ribs 17 having the function of a radial guide are provided in the inside of said body 10. In the steady state operation, just condensate flows out of the condensate drainage device. If no condensate water is formed as a consequence of malfunctioning, the float goes back into the closure position an intercepts the conduit even if the drain-trap downstream of the same becomes empty by accident.

Claims: A condensate drainage device (6) for gaseous fuel fired condensation boilers (1) comprising an outer body consisting of a cover portion (9) and of a bottom portion (10), wherein said bottom portion (10) has a member for connection with the condensate drainage conduit (8); a float (11) provided in its top portion with a projecting part (16) that is intended for engagement with a corresponding cavity provided in the inner part of said cover portion (9) of said outer body, characterized in that said cover portion (9) of the outer body has a first member for connection with the inlet conduit (7) of the condensate and of the burnt gases, in that said float (11) is provided in its bottom position (10) with a housing (13) for a tight seal gasket (14), in that a gap for the passage of the condensate is provided between said float (11) and said outer body, and in that said gasket (14) housed within said annular housing (13) is intended for engagement with the mouth (15) of said connection portion, so preventing the condensate and/or the gas from being drained. A condensate drainage device (6) for gaseous fuel fired condensation boilers (1) according to claim 1 characterized in that the inner part of the bottom portion (10) of said outer body is provided with guiding ribs (17) which are intended for engagement with said float (11). A condensate drainage device (6) for gaseous fuel fired condensation boilers (1) according to claim 1, characterized in that said member for connection with said condensate drainage conduit (8) has a projecting upper portion (15) that is intended for engagement with said annular gasket (14).

Inventors: VETRINI GIANNI, VETRINI, GIANNI
Applicants: AFA TEC SRL, AFA-TEC S.R.L.
Application year: 1991
Main classification: F24H8
IPC codes: F24H8, F16T1