Patent Application
20120125268
1. Field of the Invention
The present invention relates generally to a water heater, and more particularly to a direct vent or power vent water heater and a method of testing for safety thereof.
2. Description of the Related Art
A conventional water heater exhausting gas after burning by convection is very dangerous to be mounted indoors since carbon monoxide generated from the water heater is fatal when the gas is accumulated in the rooms. An improved water heater, direct vent or power vent water heater, was provided, in which a blower is provided to exhaust the gas after burning, including carbon monoxide, out of the rooms and to raise the burning efficiency as well. The blower may provide more gas for burning to generate more heat. Jam or aging of the blower causes a poor ventilation of air in the water heater that burning will generate more carbon monoxide. However, user may think he/she is safe with the direct vent water heater without being aware that it is still dangerous with the direct vent water heater having a jammed or aged blower.
The primary objective of the present invention is to provide a direct vent water heater and a method of testing for safety of the water heater by testing a speed of the motor of the blower.
According to the objective of the present invention, a water heater includes a combustor, a gas valve, a blower, a detector, and an operating device. The gas valve is provided on a gas pipe to control a gas supply to the combustor. The blower has a motor to provide air to the combustor. The detector senses the speed of the motor of the blower. The operating device has a calculating unit electrically connected to the detector. The operating device is stored with a reference speed range under various gas supplies to control the gas valve to cut off the gas supply when the detector senses the speed of the motor of the blower is beyond the reference speed range.
For a method of testing for safety of a water heater includes sensing the speed of a motor of a blower of the water heater and examining the sensed speed to cut off the gas supply when the sensed speed is beyond a theory speed. The theory speed is a desired speed of the motor, based on an optimal mixing ratio of gas and air under the present gas supply of the gas valve.
The water heater 1 of the preferred embodiment of the present invention includes a combustor 10, a gas valve 20, a blower 30, a detector 40, an operating device 50, and an alarm device 60.
The combustor 10 is under a water pipe 101 to heat up water in the water pipe 101, and after burning gas of the combustor 10 is exhausted through an exhausting pipe 102.
The gas valve 20 is connected to a gas pipe 103 to adjust the gas supply to the combustor 10. The gas valve 20 may be the gas flow rate control valve taught in U.S. patent application 20090206291A1 which the valve is controlled by a current. The gas supply is positively proportional to the current. Any type of valve, such as swivel valve, may be incorporated in the present invention to adjust the gas supply.
The blower 30 is under the combustor 10, in which a DC brushless motor 32 is provided. The blower 30 has an inlet 30a and an outlet 30b that the motor 32 inhales air via the inlet 30a and compresses the air and blows it out to the combustor 10 through the outlet 30b. It is easy to understand that the speed of the motor 32 is positively proportional to the air supply, that is, the higher the speed of the motor 32 is, the greater air supply the blower 30 gives. On the contrary, the lower the speed of the motor 32 is, the less air supply the blower 30 gives.
As shown in
The operating device 50 has a calculating unit 51 electrically connected to the detector 40. The calculating unit 51 is stored with theory speeds according to various gas supplies. The theory speeds are based on the following theory. As shown in
As shown in
On the contrary, the curve B shows relationship between the gas supply and the speed of an aged motor 32. The motor 32 cannot speed up because of power loss that the speed sensed by the detector 40 is lower than the low critical speed. It has poor ventilation in the water heater 1 and generates carbon monoxide because of incomplete burning, which causes fatal danger.
The curve C shows relationship between the gas supply and the speed of a jammed motor 32. The pressure in the blower 30 rises quickly after the blower 30 is started and the speed kept high. The exhausting pipe may be suddenly jammed when the water heater 10 is working. It still makes the pressure in the blower 30 quickly rising and the speed of the motor 32 sharply rising (line D). These two conditions make the speed sensed by the detector 40 higher than the high critical speed and causes incomplete burning to generate carbon monoxide.
The operating device 50 controls the gas valve 20 to cut off the gas supply when it detects that the speed of the motor 32 is beyond the reference speed range. At the same time, the alarm device 60 may give a signal about this situation, like “blower aging” or “jam”, to remind the user to repair or to clean the water heater 1.
The operating device 50 further has a delay controller 52 electrically connected to the blower 30 to maintain the motor 32 of the blower running for a predetermined time after the gas valve 20 cuts off the gas supply. It may exhaust residual carbon monoxide out of the water heater 1.
The description above is a few preferred embodiments of the present invention and the equivalence of the present invention is still in the scope of claim construction of the present invention.
