JPH0121407B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a water tube type water heater used for hot water supply and hot water heating. and a fan for forcibly supplying combustion air to the main gas burner and forcibly exhausting combustion gas through the heat exchanger installation section, and controlling the temperature of hot water supplied from the heat exchanger during hot water supply operation. The present invention relates to a water tube type water heater provided with a combustion amount control means during hot water supply operation that automatically adjusts the combustion amount of the main gas burner according to the hot water supply load detected by the hot water supply load detection means so as to maintain the temperature at a set temperature.

[Conventional technology]

Conventionally, in water tube type water heaters such as those described above, the operating mode of the fan during hot water supply operation is the entire range of combustion amount adjustment of the main gas burner during hot water supply operation, regardless of the adjustment of the combustion amount of the main gas burner according to the hot water supply load. One type operates the fan continuously at a constant blowing capacity over the entire period, and the other type proportionally controls the fan air flow rate in accordance with the adjusted combustion amount of the main gas burner over the entire range of main gas burner combustion amount adjustment during hot water supply operation. Things were warm.

[Problem to be solved by the invention]

However, with a type that simply operates the fan continuously at a constant blowing capacity over the entire range of main gas burner combustion amount adjustment during hot water supply operation,
Main gas burner combustion amount (expressed as input I _p )
The excess air ratio mo and thermal efficiency η change with the adjustment of ), there was a problem in which the excess air ratio mo increased significantly, resulting in a significant decrease in the thermal efficiency η during low combustion.

On the other hand, in a type that proportionally controls the air flow rate of the fan in accordance with the adjusted combustion amount of the main gas burner over the entire range of adjustment of the combustion amount of the main gas burner during hot water supply operation, Although the excess air ratio is maintained appropriately and the thermal efficiency is maintained high, the range in which the air volume can be proportionally adjusted in a normal fan is not very large (usually 1/2 to 1/2 of the maximum air volume).
2/3 of the air flow rate is the lower limit of the proportional adjustment range), and because the range width is limited, the air flow rate of the fan must be adjusted to the main gas burner over the entire range of combustion amount adjustment of the main gas burner. When trying to perform proportional control according to the amount of combustion, it is necessary to limit the combustion amount adjustment range of the main gas burner to a small range commensurate with the proportional adjustment range of the airflow amount in the fan when actually operating the water heater, or, It is necessary to expand the range in which the air volume can be proportionally adjusted by adopting a special air volume adjustment configuration, such as adjusting the air volume by controlling the number of fan rotations and controlling the number of fans. In addition, when the combustion amount adjustment range of the main gas burner is limited to a small range, there is a problem that the hot water supply capacity adjustment range of the water heater becomes small, resulting in a water heater that is less responsive to hot water supply load fluctuations and is less convenient to use. However, when a special airflow rate adjustment configuration is adopted, the fan configuration and fan control configuration become complicated, resulting in an extremely high device cost.

In view of the above-mentioned circumstances, an object of the present invention is to rationalize the adjustment form of the fan air flow rate during hot water supply operation, thereby avoiding complication of the fan configuration and fan control configuration, and at the same time The object of the present invention is to maintain a high thermal efficiency over the entire range of the main gas burner combustion amount adjustment range while allowing a wide amount adjustment range.

[Means to solve the problem]

The characteristic configuration of the water tube type water heater according to the present invention is that a water tube type water heating heat exchanger is provided in the combustion gas path from the main gas burner, and combustion air is forcibly supplied to the main gas burner and the combustion gas is exchanged with the heat exchanger. A fan is provided for forced exhaust air through the arrangement part of the exchanger, and the main unit is operated according to the hot water supply load detected by the hot water supply load detection means so as to maintain the temperature of hot water supplied from the exchanger at the set temperature in the hot water supply operation state. In a water tube type water heater equipped with a combustion amount control means during hot water supply operation that automatically adjusts the combustion amount of the gas burner,
As the control of the fan in the hot water supply operation state,
When the combustion amount of the main gas burner adjusted by the combustion amount control means during the hot water supply operation is equal to or higher than the set value, the air flow rate of the fan is proportionally controlled according to the adjusted combustion amount of the main gas burner, and the hot water supply operation is started. When the combustion amount of the main gas burner adjusted by the combustion amount control means is less than the set value, the fan is turned on to continue the combustion operation of the main gas burner in the hot water supply operation state by natural supply and exhaust by the draft action of the combustion gas. The reason is that a fan control means is provided when the hot water supply operation is stopped.
Its actions and effects are as follows.

[Effect]

In other words, in the above configuration, if the setting value is determined so that the combustion amount adjustment range of the part above the set value out of the total combustion amount adjustment range of the main gas burner corresponds to the proportional adjustable range of the air blowing amount in the fan,
In the main gas burner combustion amount adjustment range that exceeds the set value, the air excess ratio can be maintained appropriately and thermal efficiency can be maintained at a high level by proportional control of the fan air flow according to the adjusted combustion amount of the main gas burner. .

On the other hand, when the set value is set in this way, the fan is stopped in the main gas burner combustion amount adjustment range where it is less than the set value (i.e., the range in which proportional adjustment of the air flow rate in the fan is impossible), and the fan is stopped and the combustion gas is drafted. By continuing the combustion operation of the main gas burner during hot water supply operation with natural supply and exhaust due to the action, the fan, which is no longer able to proportionally adjust the air flow according to the adjusted combustion amount of the main gas burner, continues to operate pointlessly. Therefore, it is possible to avoid the situation where the excess air ratio increases significantly due to a further decrease in the combustion amount of the main gas burner, which would result in a drastic decrease in thermal efficiency. In the air supply and exhaust, there is a self-adjusting change in air supply and exhaust depending on the combustion amount of the main gas burner to some extent, so by adopting a special air flow adjustment configuration, proportional control of the fan air flow can be used to control the main air flow for the portion below the set value. A slight decrease in thermal efficiency is unavoidable compared to one that continues up to the gas burner combustion amount adjustment range, but it is possible to maintain thermal efficiency on average over the entire main gas burner combustion amount adjustment range where it is less than the set value without significantly decreasing the thermal efficiency. Can be maintained high.

〔Effect of the invention〕

As a result, we have simplified the fan configuration and fan control configuration without adopting a special airflow adjustment configuration to expand the range in which the fan airflow can be proportionally adjusted. The combustion of the main gas burner has been adopted to ensure a wide range of thermal efficiency without being restricted to a small value according to the proportional adjustable range of the airflow amount in the fan, and to maintain a wide range of thermal efficiency, although there is a slight decrease in the low combustion range below the set value. The amount can be maintained at a high level over the entire range, the fan configuration and fan control configuration are simple, so the equipment cost is low, and the combustion rate of the main gas burner can be adjusted over a wide range, so the hot water supply capacity can be adjusted over a wide range. Therefore, we have been able to provide a water tube type water heater that is excellent in its ability to respond to hot water supply load fluctuations, is easy to use, and is also extremely superior overall as it maintains high thermal efficiency and has low running costs for hot water supply operation.

〔Example〕

Next, embodiments will be described based on the drawings.

FIG. 1 shows a water tube type water heater for hot water supply and hot water heating, and a water tube type first heat exchanger 3A for hot water supply is connected to the combustion gas path from the first main gas burner 2A.
In addition, a second water tube-type hot water heating heater is also installed in the combustion gas path from the second main gas burner 2B.
A heat exchanger 3B is provided.

A first electromagnetic valve SV ₁ , a governor G ₁ , and a proportional valve PCV are interposed in the fuel gas supply path 5A for the first main gas burner 2A, and a second A solenoid valve SV ₂ , a governor G ₂ , and a control valve CV are interposed.

The control valve CV is provided with a bypass passage with an orifice 0 that allows a set minimum amount of fuel gas to pass even when the control valve CV is closed.

A first thermistor _T1 for detecting the hot water temperature from the first heat exchanger 3A is attached to the hot water outlet path 6A from the first heat exchanger 3A as a hot water supply load detection means. A second thermistor _T2 is attached to the hot water supply path 6B extending to the heating radiator 7 to detect the temperature of hot water supplied from the second heat exchanger 3B as a heating hot water supply load detection means.

In the hot water supply operation state, the proportional valve PCV is activated based on the hot water temperature detected by the first thermistor _T1 .
The automatic operation automatically adjusts the combustion amount of the first main gas burner 2A according to the hot water supply load so as to maintain the hot water temperature detected by the first thermistor _T1 at the temperature set for hot water supply. In the operating state, the control valve CV is based on the hot water temperature detection by the second thermistor _T2 , and
By automatic operation of the second solenoid valve SV ₂ , the combustion amount of the second main gas burner 2B is adjusted according to the hot water supply load for heating so that the hot water supply temperature detected by the second thermistor T ₂ is maintained at the temperature set for hot water heating. Equipped with a combustion amount control means during hot water supply operation that automatically adjusts the
The hot water supply at the set temperature is stably performed and continued.

In addition, in hot water heating, only the temperature of the return hot water from the radiator 7 is raised, but in hot water supply, it is necessary to raise the temperature of general city water to the hot water supply temperature, so the first main gas burner for hot water supply is used. The burner 2A has a considerably larger capacity than the second main gas burner 2B for hot water heating.

Furthermore, regarding the combustion amount adjustment of the first main gas burner 2A for hot water supply, the combustion amount is adjusted by throttling the supplied fuel gas amount using a proportional valve PCV over the entire adjustment range. In hot water heating, it is necessary to have a capacity adjustment range as wide as possible to provide comfortable heating, so when adjusting the combustion amount of the second main gas burner 2B for hot water heating, the part of the adjustment range that exceeds the set value is In the adjustment range, the combustion amount is adjusted by throttling the amount of supplied fuel gas using the control valve CV, and in the adjustment range below the set value, the amount of supplied fuel gas is adjusted to the set minimum amount limited by orifice 0. Intermittent fuel gas supply is performed by opening/closing control of the second solenoid valve SV ₂ while the fuel gas is fixed, and the combustion amount is adjusted by adjusting the supply time (so-called duty control) in the intermittent fuel gas supply.

The supply/exhaust structure 4 for intake of combustion air and discharge of combustion gas includes both heat exchangers 3A,
A forced exhaust passage 4A communicating with the installation part of the second heat exchanger 3B is provided, and a natural exhaust passage 4B is separately provided which mainly communicates with the installation part of the second heat exchanger 3B. An air supply path 4C is provided.

The forced exhaust passage 4A takes in combustion air from the air supply passage 4C, forcibly supplies the combustion air to both the main gas burners 2A and 2B, and exchanges heat with the combustion gas from the main gas burners 2A and 2B. Forced exhaust passage 4
A fan 1 is provided for forcibly collecting and discharging the gas from A. On the other hand, when the fan 1 is stopped, the combustion gas mainly passes through the installation part of the second heat exchanger 3B due to the draft effect of the combustion gas. The combustion gas is naturally exhausted from the natural exhaust passage 4B, and along with this, combustion air is taken in from the air supply passage 4C.

In adjusting the combustion amount of each main gas burner 2A, 2B according to the hot water supply load and heating hot water supply load by the aforementioned combustion amount control means during hot water supply operation,
When the sum of the adjusted combustion amounts of the first main gas burner 2A and the second main gas burner 2B is equal to or greater than the set value in the combustion amount adjustment of the second main gas burner 2B described above (i.e., the sum of the adjusted combustion amounts of the first main gas burner 2A and the second main gas burner 2B When both are operated for combustion at the same time, when the first main gas burner 2A having a larger capacity than the second main gas burner 2B is operated for combustion alone, and when the second main gas burner 2B is operated with a combustion amount exceeding the set value. (equivalent to the case where combustion is operated independently), the fan 1 is operated and the air flow rate of the fan 1 is proportionally controlled according to the sum of the adjusted combustion amounts of both main gas burners 2A and 2B by controlling the rotation speed of the fan 1. , and when the sum of the adjusted combustion amounts of both main gas burners 2A and 2B is less than the above-mentioned set value (that is, when the second main gas burner 2B is operated independently with a combustion amount less than the above-mentioned set value by duty control) (equivalent to) includes a fan control means during hot water supply operation that stops the fan 1 so as to continue the combustion operation of the second main gas burner 2B by natural supply and exhaust by the draft action of combustion gas using the natural exhaust passage 4B. It's equipped.

In other words, as a control of the fan 1 in the hot water supply operation state or the heating hot water supply operation state (see Fig. 2),
A main gas burner combustion amount adjustment range where the sum of the adjusted combustion amounts of both main gas burners 2A and 2B (represented by input I _p ) is greater than or equal to the above-mentioned set value In this case, both main gas burners 2A and 2B are controlled proportionally to the amount of air blown by the fan according to the sum of the adjusted combustion amounts (input I _p ) of both main gas burners 2A and 2B.
Excess air ratio for the entire combustion configuration including A and 2B
Thermal efficiency η by maintaining mo appropriately (see graph)
(see graph '), and on the other hand, the sum I _p of the adjusted combustion amount of both main gas burners 2A and 2B becomes less than the above-mentioned set value In the main gas burner combustion amount adjustment range where it is impossible to adjust the combustion amount, by stopping the operation of fan 1 and continuing the combustion operation with natural supply and exhaust due to the draft effect of the combustion gas, proportional control of the air flow amount is no longer possible. In order to avoid the situation where the excessive air ratio greatly increases due to the pointless continuous operation of fan 1 in which the main gas burner combustion amount further decreases, and the thermal efficiency decreases considerably, rate mo
is maintained as appropriately as possible (see graph), thereby making it possible to maintain thermal efficiency η high on average (see graph '), albeit with some decrease.

In FIG. 1, 9 is an expansion tank and 10 is a pump.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a water heater showing an embodiment of the present invention, and FIG. 2 is a graph showing the correlation between the combustion amount (input) of the main gas burner, excess air ratio, and thermal efficiency. 1...Fan, 2A, 2B...Main gas burner, 3A, 3B...Heat exchanger, _T1 , _T2 ...Hot water supply load detection means.

Claims (1)

[Claims] 1. Water tube type water heating heat exchangers 3A, 3B are provided in the combustion gas path from the main gas burners 2A, 2B, and combustion air is forcibly supplied to the main gas burners 2A, 2B, and the combustion gas is A fan 1 is provided for forcibly exhausting water through the heat exchangers 3A and 3B through the installation portion of the heat exchangers 3A and 3B, and the hot water supply system is configured to maintain the temperature of the hot water supplied from the heat exchangers 3A and 3B at a set temperature in the hot water supply operation state. The main gas burner 2A, according to the hot water supply load detected by the load detection means T1 _{, T2} .
The water tube type water heater is provided with a combustion amount control means during hot water supply operation that automatically adjusts the combustion amount of the water heater 2B, and the fan 1 is controlled by the combustion amount control means during hot water supply operation in the hot water supply operation state. When the combustion amount of the main gas burners 2A, 2B is equal to or higher than the set value, the amount of air blown by the fan 1 is proportionally controlled according to the adjusted combustion amount of the main gas burners 2A, 2B, and the combustion amount control means during hot water supply operation The adjusted main gas burners 2A, 2B
hot water supply operation fan control means for stopping the fan 1 in order to continue the combustion operation of the main gas burners 2A, 2B in the hot water supply operation state by natural supply and exhaust by the draft action of the combustion gas when the combustion amount of the combustion gas is less than the set value; Water tube type water heater. 2. The combustion amount control means during hot water supply operation adjusts the combustion amount above the set value by throttling the supplied fuel gas amount, and adjusts the combustion amount below the set value by setting the minimum fuel gas amount. The water tube type water heater according to claim 1, which is executed by adjusting the supply time in intermittent supply.