Relay unit heat exchanger

1. A relay comprising:

a first relay unit comprising a first heat-medium heat exchanger that exchanges heat between refrigerant and heat medium provided between an outdoor unit and an indoor unit and a second relay unit comprising a second heat-medium heat exchanger that exchanges heat between the refrigerant and the heat medium provided between the outdoor unit and the indoor unit;

a refrigerant circuit connecting the first relay unit and the second relay unit to the outdoor unit and configured to circulate the refrigerant; and

a heat medium circuit connecting the first relay unit and the second relay unit to the indoor unit and configured to circulate the heat medium,

the second relay unit being installed above or on a top of the first relay unit, wherein

the first relay unit includes a first pump configured to circulate the heat medium between the indoor unit and the first relay unit,

the second relay unit includes a second pump configured to circulate the heat medium between the indoor unit and the second relay unit, and

each of the first pump and the second pump has different horsepower.

2. The relay of claim 1 , comprising a stand including four leg portions and supporting the second relay unit on a floor surface on which the first relay unit is installed, wherein

the four leg portions are positioned on an outside of an outer periphery of a housing of the first relay unit,

in a first direction parallel to the floor surface, a distance between two of the four leg portions, the two of the four leg portions being adjacent to each other along the outer periphery, is shorter than or equal to a maximum value of a length of the housing of the first relay unit, and

in a second direction parallel to the floor surface and perpendicular to the first direction, a distance between two of the four leg portions, the two of the four leg portions being adjacent to each other along the outer periphery, is shorter than or equal to a maximum value of a length of the housing of the first relay unit.

3. The relay of claim 2 , wherein

an opening port is provided in a bottom plate of the second relay unit, and

a top plate of the first relay unit is inclined to a plane parallel to the floor surface.

4. The relay of claim 1 , further comprising

a first face and a second face which is a face different from the first face, wherein

the first relay unit is provided with

a first refrigerant pipe connected to the outdoor unit and configured to circulate the refrigerant between the outdoor unit and the first relay unit, and

a first heat medium pipe connected to the indoor unit and configured to circulate the heat medium between the indoor unit and the first relay unit,

the second relay unit is provided with

a second refrigerant pipe connected to the outdoor unit and configured to circulate the refrigerant between the outdoor unit and the second relay unit, and

a second heat medium pipe connected to the indoor unit and configured to circulate the heat medium between the indoor unit and the second relay unit,

a first side face of a housing of the first relay unit on which the first heat medium pipe is connected to the first relay unit and a first side face of a housing of the second relay unit on which the second heat medium pipe is connected to the second relay unit are parallel to each other and are located on the first face, and

a second side face of the housing of the first relay unit on which the first refrigerant pipe is connected to the first relay unit and a second side face of the housing of the second relay unit on which the second refrigerant pipe is connected to the second relay unit are parallel to each other and are located on the second face.

5. The relay of claim 4 , wherein the first face and the second face are parallel to each other.

6. The relay of claim 4 , wherein

a first opening port is provided in a top plate of the first relay unit,

a second opening port is provided in a bottom plate of the second relay unit at a position where the second opening port faces the first opening port, and

the relay comprises a header extending through the first opening port and the second opening port to connect the first heat medium pipe and the second heat medium pipe.

7. The relay of claim 6 , wherein

the header is provided with an air vent valve, and

a first opening port is provided in a top plate of the second relay unit at a position where the first opening port faces the air vent valve.

8. The relay of claim 1 , wherein each of the first pump and the second pump has horsepower of 120 kW or less.

9. The relay of claim 1 , wherein the first pump has horsepower greater than does the second pump.

10. The relay of claim 9 , wherein

the relay comprises

a first temperature sensor configured to detect a temperature of the refrigerant flowing out of the first heat-medium heat exchanger,

a second temperature sensor configured to detect a temperature of the refrigerant flowing out of the second heat-medium heat exchanger, and

a controller configured to control a rotation frequency of the first pump, and

the controller is

configured to determine whether a temperature difference between a value detected by the first temperature sensor and a value detected by the second temperature sensor is larger than or equal to a temperature threshold determined, and

configured to decrease a rotation frequency of the first pump when the controller determines that the temperature difference is larger than or equal to the temperature threshold.

11. The relay of claim 9 , comprising:

a first flowmeter configured to detect a flow rate of the heat medium flowing through the first relay unit;

a second flowmeter configured to detect a flow rate of the heat medium flowing through the second relay unit; and

a controller configured to control a rotation frequency of the first pump, wherein

the controller is

configured to determine whether a flow-rate difference between a value detected by the first flowmeter and a value detected by the second flowmeter is larger than or equal to a flow-rate threshold determined, and

configured to decrease a rotation frequency of the first pump when the controller determines that the flow-rate difference is larger than or equal to the flow-rate threshold.