Heat pump boiler and control method for the same

Abstract

Disclosed are a heat pump boiler and a control method for the same. The heat pump boiler includes an outdoor unit having an outdoor-unit heat-exchanger, a water pipe including a water-feed pipe and a water-return pipe connected to the outdoor unit to feed water to the outdoor unit or to return low-temperature or medium-temperature water produced in the outdoor unit to an external location, heat exchangers connected to the water pipe to produce medium-temperature or high-temperature water, a variable-capacity compressor connected to the heat exchangers, a buffer tank connected to the water pipe, and an externally-wound heat exchanger to collect waste heat radiated from the compressor. A temperature of water stored in the buffer tank is raised using the collected waste heat, and, during a defrosting operation, the water stored in the buffer tank is fed to the outdoor-unit heat-exchanger to defrost an evaporator of the outdoor unit.

1 . A heat pump boiler comprising:
 an outdoor unit comprising an outdoor-unit heat-exchanger for heat exchange between refrigerant and water;   a water pipe comprising a water feed pipe and a water return pipe, wherein the wafer feed pipe is connected to the outdoor unit to feed water to the outdoor unit, and the water return pipe is connected to the outdoor unit to return low-temperature or medium-temperature water and cold water produced in the outdoor unit to an external location;   a plurality of heat exchangers connected to the water pipe, in which refrigerant and water undergo heat exchange to produce medium-temperature or high-temperature hot water;   a compressor connected to the plurality of heat exchangers, wherein a capacity of the compressor is variable based on a set temperature of hot water;   a buffer tank connected to the water pipe and configured to store water therein; and   an externally-wound heat exchanger installed to the exterior of the variable-capacity compressor and serving to collect waste heat radiated outward from the compressor,   wherein a temperature of water stored in the buffer tank is raised using waste heat collected by the externally-wound heat exchanger, and   wherein, during a defrosting operation, the water stored in the buffer tank is fed to the outdoor-unit heat-exchanger of the outdoor unit while maintaining the raised temperature, to defrost an evaporator within the outdoor unit.   
     
     
         2 . The heat pump boiler according to  claim 1 , wherein the outdoor-unit heat-exchanger installed to the outdoor unit includes a plate-shaped heat exchanger, and uses R410A as the refrigerant. 
     
     
         3 . The heat pump boiler according to  claim 2 , wherein the outdoor-unit heat-exchanger is installed to the outdoor unit such that the outdoor unit is directly connected to the water pipe, and low-temperature or medium-temperature water and cold water are directly produced via operation of the outdoor unit. 
     
     
         4 . The heat pump boiler according to  claim 1 , wherein the plurality of heat exchangers include plate-shaped heat exchangers, and uses R134a as the refrigerant. 
     
     
         5 . The heat pump boiler according to  claim 4 , wherein the plurality of heat exchangers include a first heat exchanger serving as an evaporator during a heating operation, and a second heat exchanger serving as a condenser. 
     
     
         6 . The heat pump boiler according to  claim 1 , wherein a plurality of 3-way valves are installed in the water pipe to selectively switch a circulating direction of water. 
     
     
         7 . The heat pump boiler according to  claim 6 , wherein the water feed pipe of the water pipe is provided with two 3-way valves, and the water return pipe of the water pipe is provided with three 3-way valves. 
     
     
         8 . The heat pump boiler according to  claim 7 , wherein the two 3-way valves installed to the water feed pipe include:
 a first 3-way valve located adjacent to the outdoor unit to allow water to be directly fed from the external location to the outdoor unit, or to allow water to be fed from the buffer tank to the outdoor unit; and   a second 3-way valve located at an opposite side of the first 3-way valve to allow water to be directly fed from the external location to the outdoor unit, or to allow water to be fed from the external location to the second heat exchanger.   
     
     
         9 . The heat pump boiler according to  claim 7 , wherein the three 3-way valves installed to the water return pipe include:
 a third 3-way valve located adjacent to the outdoor unit to allow water to be directly returned from the outdoor unit to the external location, or to allow water to be fed from the outdoor unit to the first heat exchanger;   a fourth 3-way valve located at an opposite side of the third 3-way valve to allow water to be directly returned from the outdoor unit to the external location, or to allow water to be returned from the second heat exchanger to the external location;   a fifth 3-way valve located at an opposite side of the third 3-way valve to allow water to be directly returned from the outdoor unit to the external location, or to allow water having passed through the second heat exchanger to be used for heating or water supply.   
     
     
         10 . The heat pump boiler according to  claim 1 , further comprising a low-temperature pump to circulate water such that water is fed from the external location to the outdoor unit, or is returned from the outdoor unit to the external location. 
     
     
         11 . The heat pump boiler according to  claim 10 , wherein the low-temperature pump circulates water such that the low-temperature or medium-temperature water produced in the outdoor unit is again circulated to the outdoor unit by way of the first heat exchanger and the buffer tank. 
     
     
         12 . The heat pump boiler according to  claim 5 , further comprising a high-temperature pump to circulate water such that water fed from the external location is returned to the external location by way of the second heat exchanger. 
     
     
         13 . The heat pump boiler according to  claim 1 , further comprising an expansion tank to prevent increase in interior pressure due to change in the temperature of water. 
     
     
         14 . The heat pump boiler according to  claim 1 , further comprising:
 a low-temperature flow switch to sense the flow of water when water fed to the outdoor unit is returned to the external location, and   wherein the operation of the compressor installed to the outdoor unit is stopped if the flow of water stops, so as to prevent freezing and bursting or overheating of the outdoor-unit heat-exchanger due to abnormal operation of the outdoor unit.   
     
     
         15 . The heat pump boiler according to  claim 12 , further comprising a high-temperature flow switch to sense the flow of water circulated by the high-temperature pump, and to stop the entire system if the flow of water stops. 
     
     
         16 . The heat pump boiler according to  claim 1 , further comprising a defrosting pump to circulate water between the externally-wound heat exchanger and the buffer tank. 
     
     
         17 . The heat pump boiler according to  claim 16 , further comprising a solenoid valve to selectively intercept water circulated by the defrosting pump. 
     
     
         18 . A control method for a heat pump boiler to acquire low-temperature or medium-temperature water, the method comprising:
 feeding water from an external location into the heat pump boiler through a water feed pipe via operation of a low-temperature pump;   switching a first 3-way valve and a second 3-way valve, installed to the water feed pipe, to an outdoor unit such that the water fed into the heat pump boiler is directly fed to the outdoor unit through the water feed pipe;   producing low-temperature or medium-temperature water via heat exchange between the water fed to the outdoor unit and refrigerant by an outdoor-unit heat-exchanger installed to the outdoor unit; and   switching a third 3-way valve, fourth 3-way valve and fifth 3-way valve, installed to a water return pipe, to the external location to allow the low-temperature or medium-temperature water produced in the outdoor unit to be directly returned to the external location by the low-temperature pump, so as to return the low-temperature or medium-temperature hot water to the external location through the water return pipe.   
     
     
         19 . The control method according to  claim 18 , wherein the low-temperature or medium-temperature water, returned from the outdoor unit to the external location through the water return pipe by the low-temperature pump, is used as hot water for heating or water supply according to switching of the fifth 3-way valve. 
     
     
         20 . The control method according to  claim 19 , wherein the flow of water is sensed when water fed to the outdoor unit is returned to the external location, and a low-temperature flow switch is operated to stop operation of a compressor installed to the outdoor unit if the flow of water stops, so as to prevent freezing and bursting or overheating of the outdoor-unit heat-exchanger due to abnormal operation of the outdoor unit. 
     
     
         21 . A control method for a heat pump boiler to acquire medium-temperature or high-temperature water, the method comprising:
 discharging low-temperature or medium-temperature hot water, which is produced as water is fed to an outdoor unit via operation of a low-temperature pump, from the outdoor unit by the low-temperature pump;   switching a third 3-way valve, installed to a water return pipe, to a first heat exchanger to allow the low-temperature or medium-temperature hot water discharged from the outdoor unit to be moved to the first heat exchanger through the water return pipe, and performing heat exchange between the low-temperature or medium-temperature hot water moved to the first heat exchanger and refrigerant in the first heat exchanger;   changing the refrigerant, which absorbs thermal energy from the low-temperature or medium-temperature water via heat exchange in the first heat exchanger, into high-temperature refrigerant via a compressor, and transmitting the high-temperature refrigerant to a second heat exchanger;   switching a second 3-way valve installed to a water feed pipe to feed water from an external location to the second heat exchanger, so as to enable heat exchange between the refrigerant transmitted to the second heat exchanger and the water in the second heat exchanger; and   producing medium-temperature or high-temperature water as the water fed to the second heat exchanger is raised in temperature via heat exchange with the refrigerant in the second heat exchanger, and returning the medium-temperature or high-temperature hot water to the external location.   
     
     
         22 . The control method according to  claim 21 , wherein a first 3-way valve installed to the water feed pipe is switched to the outdoor unit such that the low-temperature or medium-temperature hot water having passed through the first heat exchanger is returned to the outdoor unit by way of a buffer tank. 
     
     
         23 . The control method according to  claim 22 , wherein a capacity of the compressor installed between the first heat exchanger and the second heat exchanger is variable based on a set temperature of hot water, to improve heating efficiency. 
     
     
         24 . The control method according to  claim 23 , wherein waste heat radiated from the compressor is collected by an externally-wound heat exchanger installed to the exterior of the compressor, and a temperature of water stored in the buffer tank is raised using the waste heat collected by the externally-wound heat exchanger. 
     
     
         25 . The control method according to  claim 24 , wherein a defrosting pump is operated to circulate the water, the temperature of which has been raised using the waste heat collected by the externally-wound heat exchanger, through the buffer tank, and a solenoid valve is provided to selectively intercept the water circulated by the defrosting pump. 
     
     
         26 . The control method according to  claim 21 , wherein a high-temperature pump is operated to feed water to the second heat exchanger, or to return water having passed through the second heat exchanger to the external location. 
     
     
         27 . The control method according to  claim 26 , wherein a fifth 3-way valve, installed to the water return pipe, is switched such that the medium-temperature or high-temperature hot water, which is returned from the second heat exchanger to the external location through the water return pipe by the high-temperature pump, is used as hot water for heating or water supply. 
     
     
         28 . The control method according to  claim 27 , wherein the flow of water circulated by the high-temperature pump is sensed, and a high-temperature flow switch is operated to stop the entire system if the flow of water stops. 
     
     
         29 . A control method for a heat pump boiler to feed high-temperature water to an outdoor-unit heat-exchanger installed to an outdoor unit and defrost an evaporator installed to the outdoor unit, the method comprising:
 controlling a plurality of 3-way valves installed to a water feed pipe and a water return pipe and a high-temperature pump, to prevent circulation of water to an external location;   stopping operation of a defrosting pump and closing a solenoid valve, to prevent high-temperature hot water stored in a buffer tank from being discharged from the buffer tank; and   operating a low-temperature pump and controlling a first 3-way valve installed to the water feed pipe, to allow the high-temperature hot water stored in the buffer tank to be moved to the outdoor-unit heat-exchanger and used to defrost the evaporator installed to the outdoor unit.   
     
     
         30 . The control method according to  claim 29 , wherein a temperature of the hot water stored in the buffer tank is sensed using a temperature sensor installed to the outdoor unit, and if the temperature of the hot water stored in the buffer tank is excessively lowered, the water having the lowered temperature is discharged from the buffer tank.