Patent Publication Number: US-2011058796-A1

Title: Water heater arrangement

Description:
This invention is relating to a water heater arrangement for serving utility hot water outlets, which includes a gas-operated water heater or a combined circulation heater and water heater means that has a cold water inlet and a warm water outlet pipeline. 
     At homes and in places of small hot water demand, gas water heaters are generally used. Among them we can find circulator types that are operated by water flow evoked by opening of a hot water tap at a water-taking spot. Heating of water included in the pipe section between the water heater and the spot of water taking, as well as slow start of heat transfer for heating at the beginning of the flow causes that even for a relatively long time, only cold or not sufficiently heated water reaches the spot of water taking. This disadvantage is annoying especially in case of intention to take a small amount of hot water, when in time and in water there is a large wasted and practically not utilised amount. Devices generally at the start of water flow begin to work with maximum gas burner power, which however may lead to overheating after the mentioned initial period, and this can also be annoying, e.g. at, the next opening that is repeated within a short time, where the user does not anticipate overheated water. 
     Moreover, gas-operated storage heater boilers—that include a built-in buffer container—are also used. Hot water is transferred to the place of water taking from this buffer container. The container is heated in a controlled way, what results in a more smooth gas burner power consumption characteristic. If the size of the buffer container is small then this does not significantly increase the dimensions of the device, but hot water will run out quickly. If the buffer container is large then run-out will occur later, but gas energy used for heating may appear as superfluous if no hot water is taken for a long time. This disadvantage can be reduced by increasing the heat insulation, which may lead to increase of cost. 
     It is also possible to use a buffer container placed out of the device, by which the dimensions of the device will not increase, but to reach the controlled temperature a separate circulation pump must be used, which is also costly. 
     These solutions have a common disadvantage that in case of absence of gas supply they do not provide any hot water, or only with a large buffer container are suitable for a more significant temporary hot water supply. 
     Another frequent category of water heaters uses electric heating, and in the heat insulated device container it stores stand by hot water of controlled temperature. Its advantage is the possibility of simply and cheap accomplishment of temperature regulation. Its disadvantage is, however, that generally they require more space than circulation gas devices and consume significant electric power. A further disadvantage is that in case of longer power cuts there is not hot water supply. 
     The object of this invention to find a solution that even in case of taking frequently or only small amounts of hot water eliminates the delay effect, and at the same time it is of favourable energy consumption, requires little initial investment and is operable even in the absence of considerable energy supply. 
     The invention is based on the recognition that it can be combined the advantages of gas-operated water heaters with the advantages of electric water heaters of small-size container, and with this arrangement it can be achieved optimal operation and practically unchanged overall device size. 
     A further advantage of this arrangement is elimination of the effect occurring while taking very small amount of hot water, when due to the small amount the gas water heater does not start automatically, and even into the storage heater container only cold water flows in, which after many small takings stores only cold water. In the solution applied by us, however, the electric storage heater boiler constantly heats the water until reaching the preset temperature, that is during the pauses between the short intervals. Thereby it provides both the heat balance and minimization of the size of the container. 
     The object of the invention is achieved by a water heater according to the introductory paragraph, in which a storage type electric water heater is inserted serially into the hot water outlet pipeline, which electric water heater is equipped with a thermostat. 
    
    
     
       Further we present the invention by drawings, where 
         FIG. 1  is a gas-operated water heater device with electric water heater according to the invention, connected from outside, 
         FIG. 2  is a gas-operated water heater device with electric water heater according to the invention, connected in built-in way. 
     
    
    
     In  FIG. 1  an optional gas-operated circulation water heater device  1  is shown. The gas-operated water heater device  1  has a cold water inlet pipeline  2  and a hot water outlet pipeline  3 . Into the latter, in serial arrangement, an electric water heater  4  according to the invention—outside connected to the previous part—is inserted. The electric water heater  4  has an electric connector  8  connected to a heating wire as well as a thermostat  5  that detects the temperature of the stored puffer water and controls the heating wire accordingly. According to  FIG. 1  the electric water heater  4  is inserted into the hot water outlet pipeline  3  outside of the gas-operated circulation water heater device  1  but in its close vicinity. This arrangement can be advantageous from the point of view of effective utilization of space. In such a case, it can be expedient to cover the container of the electric water heater  4  by heat insulating material, because due to its external placement it is not contacted with significant amount of available extra heat. The electric water heater  4  can be placed even further from the gas-operated circulation water heater device  1  in the hot water pipeline towards the water taking spot. 
     In case of another embodiment, which is shown in  FIG. 2 , the electric water heater is built-in into the gas-operated circulation water heater device  1 . Its advantage is that it is not necessary to lead or disassemble the hot water pipeline. Its another advantage can be that in case of proper design and placement the buffer storage container of the electric water heater  4  can utilize the waste heat otherwise non-usable that evolves in the gas-operated circulation water heater device. For this purpose we can use a heat transfer element that penetrates into the combustion space  7  of the gas-operated circulation water heater device  1 , and by heat transfer it preheats the water amount included in the electric water heater  4 , thereby reducing the amount of electric energy necessary for heating to a preset minimum temperature. This heating is performed in a controlled way, i.e. the thermostat  5  keeps the water included in the electric water heater  4 , that is in the buffer container. 
     It is enough to choose a low storage capacity for the electric water heater  4  that works as a buffer container, because it serves basically for compensation of temperature delay and overshoot of the gas-operated single water heater or combined circulation water heater device  1 . For this generally it is enough to apply a buffer container smaller than 20 litres, e.g. 5-15 litres. Yet with such buffer volumes we get at the spot of water taking a completely steady temperature that is adjustable by the thermostat  5  of the electric water heater  4 . The electric water heater  4  heats the system also in the period beyond taking water, therefore a small-size container is sufficient. We can choose this temperature also for relatively low, this will not prevent that possibly much hotter water supplied by the gas-operated water heater device  1  with some time delay, will also reach the water taking spot. When the tap at the water taking spot is closed, the water remaining in the container of the electric water heater  4  will be of higher temperature than it is preset by the thermostat  5 . Then, until cooling back the water included in the buffer container the operation of electric heating is not required. By this we can achieve favourable energy consumption, environment-friendly operation. 
     By the arrangement according to the invention it can be provided that in case of absence of gas or heavy electric current there is a possibility for taking of utility hot water. At the same time, disadvantageous delay of gas-operated water heating with more favourable economy is also eliminated, because water included in the buffer container of electric heating balances slow reaction in temperature or overheating either in case of single water heater or combined circulation water heater devices. Buffer container of electric heating with a relatively small size will increase dimensions to a little extent only and consumes little electric energy. In case of integration with the gas-operated device the buffer container does not require significant heat insulation. 
     LIST OF REFERENCES 
       1  gas-operated water heater device 
       2  cold water inlet pipeline 
       3  hot water outlet pipeline 
       4  electric water heater 
       5  thermostat 
       6  heat transfer element 
       7  combustion space 
       8  electric connector