HYDRO-FURNACE

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/627,322 filed Jan. 31, 2024, the entire content of which is herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002](NOT APPLICABLE)

BACKGROUND

[0003]The invention relates to a heating system and, more particularly, relates to a heating system providing heated water and air and related methods for use in recreational vehicles (RVs) or utility vehicles and boats. Utility vehicles can include ambulances, fire trucks, and military vehicles where hot water and hot air are required for certain procedures.

[0004]Conventional water heaters and furnaces designed for residential homes or commercial buildings are typically separate components, which are bulky, heavy, and require special mounting fixtures and safety devices. These conventional water heaters and furnaces are not suitable for use in or on mobile vehicles, such as RVs and boats.

[0005]Because space and weight are at a premium in RVs and boats, hot water heaters utilizing large tanks and furnace systems are undesirable, but nonetheless are today universally used. A typical tank-based water heater unit includes a burner and a tank with capacity that provides 5 to 10 gallons of hot water with recovery times ranging from 30 to 60 minutes. A typical forced air furnace with a separate burner and blower assembly also adds additional weight and occupies additional space.

SUMMARY

[0006]A hydro-furnace combines a hot water heater and an air handler resulting in a compact and efficient system suitable for RVs, utility vehicles and boats. The system can be housed in a single combined housing or may utilize separate housings. A control circuit is programmed to detect a decrease in temperature of the water in the holding tank and then sends a signal to ignite the water heater. Otherwise, the pump and blower may run regardless of whether the water heater is ignited. The system may also integrate a room temperature sensor to be controlled with three separate sensors: an output temperature of the water heater, an output temperature of the water holding tank, and the ambient room temperature sensor.

[0007]There is a significant benefit to eliminating the need for two separate gas appliances in an RV or the like due to cost and liability issues. An instantaneous heat exchanger is typically used to heat the water in a tank. The heat exchanger of a tank water heater is typically designed for 10 KBtu power, while space heating requires at least the 40 KBtu rating of the instantaneous unit to continuously supply the hot air to the vehicle.

[0008]To effectively heat water to 150 degrees F. (65.56 degrees C.) in a tank, it is helpful to prevent mixing of the inlet hot water and the outlet “return” water. The holding tank in the described system includes a diffusion tube on the hot water inlet. The diffusion tube prevents this mixing to “stratify” the water in the tank and prevent the hot water from exiting first.

[0009]In an exemplary embodiment, a hydro-furnace includes a water heater and a furnace component with a holding tank, a holding tank temperature sensor, a heater core, a pump, and a blower. The blower drives air across the heater core in a heat exchange relationship, and the pump drives a fluid circuit between the water heater, the heater core, and the holding tank. A control circuit coupled with at least the holding tank temperature sensor, the pump, and the blower is configured to activate the pump and the water heater when a temperature in the holding tank drops below a predetermined threshold temperature.

[0010]The hydro-furnace may further include a room thermostat coupled with the control circuit that measures a room temperature and enables a user to set a desired room temperature. In this context, the control circuit may be configured to activate the pump and the blower when the room temperature drops below the desired room temperature regardless of an operating status of the water heater.

[0011]The fluid circuit may include an outlet pipe from the holding tank, in series with an inlet in the water heater, in series with an outlet in the water heater, in series with the heater core, and in series with an inlet pipe into the holding tank. The outlet pipe from the holding tank and the inlet pipe into the holding tank may be offset in the holding tank to prevent water input to the holding tank from mixing with the water being output from the holding tank.

[0012]The hydro-furnace may further include an outlet pipe in fluid communication with the holding tank that delivers water from the holding tank to the water heater, and an inlet pipe in fluid communication with the holding tank that delivers water from the heater core to the holding tank. In this context, the outlet pipe and the inlet pipe may be offset in the holding tank to prevent water input to the holding tank from the heater core from mixing with the water being output from the holding tank to the water heater.

[0013]The hydro-furnace may further include a mixing valve in fluid communication with the holding tank that outputs water from the holding tank to a faucet. The hydro-furnace may still further include a cold water inlet in fluid communication with the mixing valve, where the mixing valve mixes cold water from the cold water inlet with water from the holding tank before outputting through the faucet.

[0014]In another exemplary embodiment, a hydro-furnace includes a water heater and a furnace component with a holding tank, a holding tank temperature sensor, a heater core, a pump, and a blower. The blower drives air across the heater core in a heat exchange relationship, and the pump drives a fluid circuit between the water heater, the heater core, and the holding tank. The fluid circuit includes an outlet pipe in fluid communication with the holding tank that delivers water from the holding tank to the water heater and an inlet pipe in fluid communication with the holding tank that delivers water from the heater core to the holding tank. The outlet pipe and the inlet pipe are offset in the holding tank to prevent water input to the holding tank from the heater core from mixing with the water being output from the holding tank to the water heater. A control circuit is coupled with at least the holding tank temperature sensor, the pump, and the blower.

[0015]In yet another exemplary embodiment, a method of operating the hydro-furnace of the described embodiments includes the steps of driving air with the blower across the heater core in a heat exchange relationship; driving with the pump a fluid circuit between the water heater, the heater core, and the holding tank; and activating with the control circuit the pump and the water heater when a temperature in the holding tank drops below a predetermined threshold temperature.

[0016]The hydro-furnace may include a room thermostat coupled with the control circuit that measures a room temperature and enables a user to set a desired room temperature, and the method may include activating with the control circuit the pump and the blower when the room temperature drops below the desired room temperature regardless of an operating status of the water heater.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]These and other aspects and advantages will be described in detail with reference to the accompanying drawings, in which:

[0018]FIG. 1 is a schematic illustration of the hydro-furnace;

[0019]FIG. 2 shows an exemplary control circuit for the hydro-furnace; and

[0020]FIG. 3 is a perspective view of an exemplary hydro-furnace.

DETAILED DESCRIPTION

[0021]FIG. 1 is a schematic illustration of the hydro-furnace 10 according to the described embodiments. The hydro-furnace includes a water heater 12, a furnace component 14, and a control circuit 16 (FIG. 2). The water heater 12 can be any suitable construction incorporating a cool/warm water inlet 18, a heat exchanger 20, and a hot water outlet 22. In the exemplary schematic shown in FIG. 1, the water heater 12 additionally includes typical water heater components such as a burner, exhaust, thermostat, etc.

[0022]The furnace component 14 includes a holding tank 24 for water storage, a holding tank temperature sensor 26, a heater core 28, a blower 30, and a circulating pump 32. In use, the blower 30 drives air across the heater core 28 in a heat exchange relationship. The pump 32 drives a fluid circuit between the water heater 12, the heater core 28 and the holding tank 24. The fluid circuit includes an outlet pipe 38 from the holding tank 24 in series with the cool/warm water inlet 18 into the heat exchanger 20, in series with the hot water outlet 22 from the heat exchanger 20, in series with the heater core 28, and in series with an inlet pipe 40 into the holding tank 24.

[0023]With reference to FIG. 2, the control circuit 16 includes a circuit board 34 such as a DSI board or the like and communicates with the holding tank temperature sensor 26, the pump 32, and the blower 30. The tank temperature sensor is optional as the operation can be regulated using the outlet limit and the inlet limit shown in FIG. 2. The relays, temperature switches, diodes, etc. can be housed in a small box with the circuit board 34. In use, when a temperature in the holding tank 24 drops below a predetermined threshold temperature, the control circuit 16 activates the pump 32 and the water heater 12. In some embodiments, the outlet limit opens at 75 degrees C. (closes at 65 degrees C.) and controls the main burner, and the inlet limit opens at 45 degrees C. (closes at 55 degrees C.) and controls the HI/LO valve solenoid.

[0024]With continued reference to FIG. 2, the hydro-furnace may also include a room thermostat 36 coupled with the control circuit 16 that measures a room temperature and enables a user to set a desired room temperature. In use, the control circuit 16 is configured to activate the pump 32 and the blower 30 when the room temperature drops below the desired room temperature, regardless of an operating status of the water heater 12. That is, the pump 32 may circulate water through the water heater 12 to the heater core 28 without activating/igniting the water heater 12, depending on the temperature of the water in the holding tank 24.

[0025]In some embodiments, the outlet pipe 38 from the holding tank 24 and the inlet pipe 40 into the holding tank 24 are offset in the holding tank 24 to prevent water input to the holding tank 24 from mixing with the water being output from the holding tank 24. That is, the arrangement serves to “stratify” the water in the holding tank 24 and prevent the hot water from exiting first. A diffusion tube or “dip tube” may serve to prevent hot and cold water from mixing. Alternatively, a manifold 42 may facilitate stratifying the water in the holding tank 24. The exemplary manifold shown in FIG. 1 uses a tank with a single port, and the hot water extends through the input fitting and is carried to the top of the tank, away from the outlet that collects the water at the bottom of the tank. The same purpose can be achieved with a tank that uses two ports. In this configuration, the input port is channeled to the top of the tank to favor stratification of water temperature and prevent repeated ignitions reducing possible noise.

[0026]With continued reference to FIG. 1, the furnace component may further include a mixing valve 44 in fluid communication with the holding tank 24. The mixing valve 44 outputs water from the holding tank 24 to a faucet. In some embodiments, the system may additionally include a cold water inlet 46 in fluid communication with the mixing valve 44. The mixing valve 44 mixes the cold water from the cold water inlet 46 with the hot water from the holding tank 24 before outputting through the faucet. The water stored in the holding tank 24 is maintained at a higher temperature than desirable for faucet use, and mixing the water from the holding tank 24 with the water input via the cold water inlet 46 lowers the temperature of the water output from the faucet. The cold water inlet 46 can also replenish water to the holding tank 24.

[0027]When the unit is first turned on, the pump 32 is activated, and water is circulated from the holding tank 24 to the water heater 12 until the water reaches the desired operating temperature in the holding tank 24. The desired operating range for space heating is between 55-75 degrees C. For water heating, the temperature in the tank can vary within the same range since the outlet temperature can be set by the mixing valve, which can be set by the user between 35-50 degrees C.

[0028]When the room thermostat 36 turns on, the pump 32 circulates the water from the holding tank 24 to the water heater 12, and the blower 30 is activated. The hot water passes through the heater core 28 and returns to the holding tank 24. If the water temperature is within the operating range, the water heater 12 is not ignited even though water is flowing via the fluid circuit.

[0029]When the blower 30 forces air from the environment to flow through the heater core 28, the air is heated and is sent to a chamber space (plenum) or the like. A positive pressure in the plenum distributes the air through ducts to the vehicle. This process removes heat from the water, and the temperature of the water in the holding tank 24 decreases until the control circuit 16 detects the lower temperature limit of the operating range for the water in the holding tank 24. The control circuit 16 in that event is programmed to trigger a new ignition of the water heater 12 to replace the heat removed from the holding tank 24 by the blower 30.

[0030]In use, a constant power burn of proper intensity, e.g., 3-4 kW in combination with a maximum temperature limit (60 degrees C.) is suitable for the hydro-furnace of the described embodiments. The proper ignition temperature and the power burn values can be established by testing the hardware adopted in the final configuration.

[0031]FIG. 3 shows an exemplary configuration of the hydro-furnace 10 with the water heater 12 in a separated housing. The water heater 12 and furnace component 14 could also work together within a single housing.

[0032]As noted, there is a significant benefit to eliminating the need for two separate gas appliances in RVs, utility vehicles or boats due to cost and liability issues. The hydro-furnace of the described embodiments combines the use and functionality of the hot water heater with a furnace to provide hot water and warm air to the RV users using the same hot water in a holding tank. The fluid circuit is also configured to “stratify” the water in the tank and prevent hot water from exiting first.

[0033]While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.