US20140007821A1

US20140007821A1 - Electronically-Controlled Tankless Water Heater with Pilotless Ignition

Info

Publication number: US20140007821A1
Application number: US13/762,641
Authority: US
Inventors: Gilberto Sánchez Villalobos; Epigmenio Guzmán Cabrera; Flavio Saúl Gocobachi Chávez
Original assignee: Calentadores de America SA de CV
Current assignee: Calentadores de America SA de CV
Priority date: 2012-07-06
Filing date: 2013-02-08
Publication date: 2014-01-09
Also published as: CL2013000166A1; AR089204A1; MX2012007938A; BR102013000487A2; CO6950089A1

Abstract

A rapid recovery tankless water heater operates by means of an electronic controller or card that regulates the operation of each of the system components, thereby optimizing gas consumption and minimizing the emission of gas pollutants. A multi-burner only ignites when certain conditions or predefined requirements in the electronic controller logic are met. Other factors contributing to improved water heater efficiency are: a) the water tank design which at the bottom has a water chamber surrounding the combustion chamber, and b) the use of a finned heat exchanger, which together with a core, successfully utilizes most of the thermal energy contained in the combustion gases. An air deflector device stops the entry of air currents at the top of the heater, thus stopping potential flame reversing and even flame extinction in the multi-burner.

Description

FIELD OF INVENTION

This invention refers generally to water heating equipment that maximizes its efficiency while reducing heat loss through use of a finned tube-type heat exchanger and water chamber surrounding the combustion chamber. This water heater is able to provide a constant supply of hot water and is controlled electronically.

INVENTION BACKGROUND

Instant or rapid-recovery tankless water heaters are currently available to meet the constant demand for hot water with the greatest possible gas fuel savings. In the case of instant-type heaters, however, the problem is that they must perform at minimum hydraulic operating pressure. In addition, in regions with an ambient temperature that can fall below zero degrees Celsius, the water contained in the coil of these types of heaters can freeze, and, due to their respective volumetric expansion, can cause coil breakage and consequently ruin the equipment. The PCT WO120071057864 patent publication offers an alternative for solving the frozen water problem in this type of heater, although the problem of minimum hydraulic operating pressure still remains, whereby instant-type heaters continue to be inadequate for use in most existing hydraulic installations, causing in many instances the necessary modification or integration of other components in the system for proper operation and increasing equipment cost.
The creation of a water heater similar to the one described in the previous paragraph responds to the need for constant water pressure in hydraulic systems, gas savings, and adaptability to different types of hydraulic systems in order to meet a constant demand for hot water.
The rapid-recovery tankless equipment mentioned in U.S. Pat. Nos. 7,982,164 and 7,985,943 do not require a minimum operating hydraulic pressure for proper functioning, as they are not the instant type. Nevertheless, the heaters described in the aforementioned patents use an electromechanical flow detector to send the hot water demand signal to the electronic controller. This flow detector presents a point of convergence for scale build-up, and when used in regions where water from the hydraulic network contains high salt concentrations, flow detector operation can be affected, altering equipment operation.
Invention Summary This invention's water heater eliminates the need for an electromechanical flow detector since it uses a system with two temperature sensors, one at the cold water inlet and the other at the hot water outlet. Thus, we can deduce that when the unit registers a 4° C. difference between the two temperature sensors, water is admitted. This water heater uses an electronically-controlled, ionized ignition system which gives the command to ignite under the following conditions:
a) Whenever a flow signal and the temperature sensor located at the hot water outlet detect a temperature below the maximum shut-off temperature programmed in the electronic controller.
b) It likewise will ignite when the temperature detected by both sensors is less than a preset value in the electronic controller as the minimum ignition temperature.
In this way, the water heater will only ignite when hot water is needed according to the programming in the electronic controller.
Objects and advantages of the invention are set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
This invention's water heater has been designed to include the following: a corrosion-resistant water tank which is sufficiently elongated at the bottom to create a water chamber surrounding the combustion chamber located over a multi-burner so that heat loss to the exterior of this area is minimized. A fin-type heat exchanger at the top of the tank allows capture of most of the thermal energy contained in the combustion gases and transferring it to the water contained in the tank. A 8.7-13.0 kW burner is supplied by gas from an electrovalve system. A bimetallic temperature detector functions to avoid overheating the water inside the equipment. Two temperature sensors are located at the cold water inlet and the hot water outlet, respectively. A first electrode generates a spark for igniting the burner and a second electrode detects the change in current produced at the first electrode due to ionization following burner ignition. An electronic controller that, when the hot water demand conditions are met and/or the water temperature in the heater is less than the preset temperature, sends current to the first electrode so that it is able to generate the burner ignition spark. An electrovalve system allows gas to flow safely to the burner once the electronic controller has sent the current to generate the spark in the first electrode. A screen in direct communication with the electronic controller allows the user to observe the state of the water heater at any given time.
This invention's entire set of components allows the water heater to operate while ensuring the safety of the user and of the water heater itself and maximizing gas fuel economy, without a permanently lit pilot light.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an overall view of this invention's water heater.

FIG. 2 shows an exploded view of the main components: water tank, drain valve, outer body, electrovalve system, electronic controller and air dispersion device.

FIG. 3 is a cross-sectional view of the top of the heater.

FIG. 4 is a cross-sectional view of the bottom of the heater.

FIG. 5 is a view of the card or electronic controller.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to particular embodiments of the invention, one or more examples of which are illustrated in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated as described as part of one embodiment may be used with another embodiment to yield still a further embodiment. It is intended that the present invention include these and other modifications and variations.
This invention's water heater (1) shown in FIG. 1 is designed to withstand a pressure greater than 1.0 MPa. The steel water tank (2) is porcelainized on the areas in contact with water to prevent corrosion.
The cold water inlet (3) is located to the upper-right of the water tank (2), likewise, the hot water outlet (4) is located at the upper left of the tank (2). Additionally, on the lower part of the water tank (2), there is a coupling that connects the water tank (2) to the exterior, allowing draining and cleaning of the water tank (2) through a conveniently placed valve (6).
An electrovalve system (8) supplies gas to a multi-burner (7) providing the energy needed to heat the water. The capacity of the multi-burner (7) depends on the size of the equipment, which in turn will depend on user requirements.
The multi-burner (7) and an electrovalve system (8) regulate the safe flow of gas. This electrovalve system (8) is protected by a screen (9) from thermal radiation. The electrovalve system (8) is connected to the multi-burner (7) to enable the transfer of gas fuel between components. The electrovalve system normally is closed until the electronic controller (10) sends the signal to open once the following hot water demand and/or water temperature conditions have been met:

- a) Whenever a flow signal and temperature sensor located at the hot water outlet (12) detect a temperature less than the maximum preset shut-off temperature on the electronic controller (10); or
- b) Whenever the temperature detected by both temperature sensors (11 and 12) is less than the preset value on the electronic controller as the minimum ignition temperature.

The electronic controller (10) sends the signal to close off the electrovalve system (8), thus stopping the flow of gas fuel to the burner when both of the previously mentioned conditions have not been met.
The temperature sensors located at the cold water inlet (11) and the hot water outlet (12) are inserted in a connection made of brass, bronze or other corrosion resistant material and these, in turn, are joined to a water tank at the cold water inlet and hot water outlet, respectively.
The two cables for each of the temperature sensors (11 and 12) must be in contact in the end inside the water tank, with the opposite end connecting to the electronic controller (10), just as with the gas feed electrovalve system (8). There is a bimetallic safety device (13) on the side of the temperature sensor at the hot water outlet (12), that operates whenever the water tank (2) overheats, interrupting the flow of current to the electronic controller (10). This bimetallic safety device allows suspension of system operation in case the water temperature exceeds a preset value. Thanks to its configuration, the temperature sensors (11 and 12) allow the electronic controller (10) to identify the condition of the demand for water whenever there is 4° C. difference between both temperature sensors (11 and 12). Therefore, the water heater (1) only restarts operation when the temperature in the bimetallic safety device (13) is less, e.g., 4° C., than the specified safe temperature.
The electronic controller (10) regulates the operation of the different water heater components, and when it receives a temperature signal indicating a difference of more than 4° C., for example, between the temperature sensor at the hot water outlet (12) (T_s) and the temperature sensor at the cold water inlet (11) (T_e) (T_s−T_e>4° C.), it sends a direct current signal to the ignition electrode (14) shown in FIG. 4 in order to generate the electric spark for lighting the multi-burner (7).
The ignition electrode (14) is situated no more than 4 mm above one of the burners of the multi-burner (7). After 3 seconds and with the electric spark in operation, the electronic controller (10) sends a signal to the electrovalve system (8) for sequential opening of the electrovalves of this system (8) so that gas is able to flow to the multi-burner (7). Once the multi-burner (7) ignites, the ionizing electrode (15), (shown in FIG. 4) and situated no more than 4 mm above one of the burners in the multi-burner (7), detects the flame by means of an ionization process and sends the signal to the electronic controller (10).
If the flame signal is not received by the electronic controller (10) within 5 seconds, or if the signal is intermittent during the same period of time, or if the burner of the multi-burner (7) goes out at any time, the electronic controller (10) sends a signal to the electrovalve (8) feeding gas so that it will close immediately and block the water heater operation (1) for a period of 10-15 seconds to allow the dissipation of gas in the combustion chamber (16) and performance of an electronic check of the components connected to the electronic controller (10).
After the previously mentioned period of 10-15 seconds, a water heater (1) restart is performed until obtaining of a continuous signal of a flame in the multi-burner (7). Should this signal not be detected after a total of three attempts, the electronic controller (10) will send a signal for an error message to appear on the screen (17), indicating that as a safety measure the system has been temporarily blocked.
Once the electronic controller (10) detects the signal indicating that a flame exists, the water in the water tank (2) will heat up until the temperature sensors at the cold water inlet (11), T_e, and hot water outlet (12), T_s, send a signal to the electronic controller (10) indicating that the specified temperature has been reached. In turn, the electronic controller (10) sends a signal to close the gas-fed electrovalve system (8).
Although the ignition cycle reactivates, it shuts off when any of the previously mentioned conditions occur.
The electronic controller (10) is supplied electrically from a power source (18) using any combination of replaceable batteries, rechargeable batteries or direct connection to an electric grid, as shown in FIG. 2. In turn, the electronic controller (10) distributes the current supply to the various components to which it is connected.
The water chamber (19) shown in FIG. 4 surrounds the combustion chamber (16), minimizing heat loss toward the sides of the combustion chamber (19), and under it are the multi-burner (7) and its support (20). On the inside face of the water tank (2) is a heat exchanger (21), shown in FIG. 3, the front of which is made up of a set of fins, which capture most of the thermal energy in the combustion gases, although they give up this energy later to the water in the tank (2), that is, through the successful transfer of 80%-95% of the thermal energy in the combustion gases to the water in the tank.
In the center of the heat exchanger (21) is a core (22) in the shape of a cylindrical vessel (see FIG. 3), whose function is to retard and redirect the combustion gases in their outbound path, forcing them to pass through the heat exchanger fins (21).
As seen in FIG. 3, the exterior of the water tank (2) is thermally insulated through the application of an insulator (23) or low thermal conductivity material covering, such as polyurethane, mineral wool, ceramic fiber, fiberglass or any other known medium.
The water heater (1) has an exterior plate body (24) shown in FIG. 2, which is covered with a rust-resistant electrostatic paint to improve product aesthetics, and it ensures that the insulator (23) stays around the water tank (2), and protects both the insulator (23) and the water tank itself (2) from the environment.
The exterior plate body (24) shown in FIG. 2 has a housing for the electronic controller (10) and openings on the base in the area where the multi-burner is located (7) for the intake of air needed for combustion.
The electrovalve system (8), along with the power source (18), is located on the left side of the exterior plate body (24). Both the electrovalve system (8) and the power source 18) are protected from heat radiation from the multi-burner (7) by a pair of screens (9).
As can be seen in FIG. 5, the electronic controller (10) contains a series of buttons for the user to operate the heater.
The valve (6) located on the lower right side of the equipment allows drainage and cleaning of the water tank (2).
The air baffle (25) shown in FIG. 2 stops air currents from entering the top of the heater, potential flame reversing, and even flame extinction in the multi-burner.
Most of the time, the water heater (1) is not in operation, except when any of the previously mentioned ignition conditions occur. For this reason, it provides a reduction both in gas consumption and, as a consequence, in the emission of gas pollutants into the environment.
Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims.

Claims

1-5. (canceled)

6. A rapid-recovery tankless water heater, comprising:

a multi-burner disposed below a combustion chamber;

a corrosion resistant water tank having a water chamber surrounding the combustion chamber;

a finned heat exchanger configured around a center core in an upper part of the combustion chamber, the core serving to redirect combustion gases through the heat exchanger;

and electrovalve configured with the multi-burner to control gas flow to the multi-burner;

an electronic controller, the electrovalve in communication with the electronic controller;

a bimetallic safety device disposed to detect water temperature within the water tank, the bimetallic safety device in communication with the electronic controller to cease operation of the water heater upon detected water temperature exceeding a preset value;

an ignition electrode in communication with the electronic controller to ignite the multi-burner;

an ionized electrode in communication with the electronic controller to detect ignition of the multi-burner;

a first temperature sensor at a cold water inlet to the water tank, and a second temperature sensor at a hot water outlet from the water tank, the first and second temperature sensors in communication with the electronic controller to generate a hot water demand flow signal upon a present temperature differential between the first and second temperature sensors; and

an air baffle configured atop the water tank to minimize air currents from entering the combustion chamber.

7. The water heater as in claim 6, wherein the electronic controller is configured to send an ignition spark signal to the ignition electrode under the following conditions:

(a) when there is a hot water demand flow signal and temperature sensed by the second temperature sensor at the hot water outlet is less than a preset cutoff temperature; or

(b) temperature detected by both of the first and second temperature sensors is less than a preset minimum ignition temperature value.

8. The water heater as in claim 7, wherein the electronic controller is configured to send a signal to the electrovalve to stop gas flow to the multi-burner when both of the ignition signal conditions are not met.

9. The water heater as in claim 6, wherein the electronic controller is configured to send a signal to the electrovalve to open and let gas flow to the multi-burner after a preset time delay from generating an ignition spark signal to the first electrode,

10. The water heater as in claim 9, wherein the electronic controller is configured to send a single to the electrovalve to stop gas flow to the multi-burner under any of the following conditions: (a) an ignition signal is not received from the second electrode after a preset time from generation of the ignition spark signal to the first electrode; (b) an ignition signal received from the second electrode is intermittent during a preset time from generation of the ignition spark signal to the first electrode; or (c) the multi-burner goes out at any time.