Systems and methods for whole-house dehumidification based on dew point measurements

• US 20060086112A1
• Filed: 10/27/2004
• Published: 04/27/2006
• Est. Priority Date: 10/27/2004
• Status: Active Grant

• Current Assignee: Research Products Corporation
• Original Assignee: Research Products Corporation
• Inventors: Bloemer, John M., Higgins, Timothy E.
• Granted Patent: US 7,574,871 B2
• Time in Patent Office: Days
• US Class Current: 62/176.600
• CPC Class Codes: F24F 11/0008 for air-humidification F24F11/30 takes precedence
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: F24F 3/153 with subsequent heating, i.e. with the air, given the required humidity in the central station, passing a heating element to achieve the required temperature
• CPC Class Codes: G05D 22/02 characterised by the use of electric means

Abstract

A dehumidifier system is connected to an interior space of a building through supply and return ducts, either directly and/or through an HVAC system. Controllable dampers can be used to select how the dehumidifier system is connected to the interior space and the HVAC system. The dehumidifier determines the dew point of the ambient air from temperature and relative humidity measurements taken at location(s) of relative humidity and temperature sensors. Based on the determined dew point, the dehumidifier system determines whether to operate. The temperature and relative humidity sensors can be located in the interior space or within the dehumidifier, where they project into the air stream flowing through the dehumidifier. The dehumidifier system operates in response in part to blower calls to the HVAC system and controls the HVAC system and a ventilation system to distribute the dehumidified air and outside air throughout the building.

Claims

32. A method for dehumidifying at least one interior space of a structure, the structure having an HVAC system that includes an HVAC return duct, an HVAC supply duct, an HVAC blower and at least one HVAC control device that outputs blower call signals, the HVAC blower turned on by the HVAC system in response to the blower call signals, using a dehumidifier connected to the at least one interior space by at least the HVAC system, the dehumidifier comprising a housing and a compressor, a blower, a temperature sensor and a relative humidity sensor located within the housing, the method comprising:

determining if a measurement event has occurred; and

if a measurement event has occurred;

turning on the blower of the dehumidifier;

optionally turning on the HVAC blower;

waiting for a first predefined period;

measuring a temperature of an ambient atmosphere within the housing using the temperature sensor after the first predefined period has elapsed;

measuring a relative humidity of an ambient atmosphere within the housing using the relative humidity sensor after the first predefined period has elapsed;

determining a dew point temperature for the interior space based on the measured temperature and relative humidity;

determining if the determined dew point temperature is above a predetermined dew point temperature; and

if the determined dew point temperature is above the predetermined dew point temperature

turning on the compressor of the dehumidifier,

drawing air to be dehumidified from at least the HVAC return duct through at least at least one dehumidifier return duct;

dehumidifying the drawn air; and

returning the dehumidified air to at least the HVAC supply duct through at least at least one dehumidifier supply duct.

33. The method of claim 32, wherein waiting for the first predefined period comprises waiting for two minutes.

34. The method of claim 32, wherein:

determining if a measurement event has occurred comprises determining if a blower call signal has been output.

35. The method of claim 34, wherein:

the dehumidifier has a current air cycle interval; and

determining if a blower call signal has been output comprises determining if the output blower call signal is a first blower call signal of the current air cycle interval.

36. The method of claim 35, wherein determining if a measurement event has occurred further comprises determining that a measurement event has occurred only if the output blower call signal is the first blower call signal of the current air cycle interval.

40. A dehumidifier system usable to dehumidify an interior space of a structure, the dehumidifier system comprising:

a compressor;

a set of coils;

a blower;

a housing, the compressor, the set of coils and the blower contained within the housing;

a control system;

at least one dehumidifier return duct; and

at least one dehumidifier supply duct, wherein;

the housing is at least indirectly connected to the at least one interior space by the at least one dehumidifier return duct and the at least one dehumidifier supply duct,

the control system determines whether a measurement event has occurred; and

the control system, in response to an occurrence of a measurement event, determines whether to dehumidify air drawn from at least the interior space.

41. The dehumidifier system of claim 40, further comprising:

a temperature sensor that outputs a temperature measurement of air to be dehumidified; and

a humidity sensor that outputs a humidity measurement of air to be dehumidified;

wherein, in response to the occurrence of a measurement event, the control system inputs the temperature and humidity measurements, and determines, based on the temperature and humidity measurements, whether to operate at least the compressor to dehumidify air that is at least indirectly supplied to the housing from the interior space and to supply dehumidified air at least indirectly to the interior space from the housing.

42. The dehumidifier system of claim 41, wherein:

the at least dehumidifier return duct supplies a stream of air to be dehumidified to the housing that is at least indirectly drawn from the interior space;

at least one of the temperature and humidity sensors are located within the housing such that the at least one of the temperature and humidity sensors is upstream of the at least one coil and the at least one of the temperature and humidity sensors senses the at least respective one of the temperature and humidity of the air supplied to the housing to be dehumidified.

43. The dehumidifier system of claim 42, wherein the at least one of the temperature and humidity sensors that is located within the housing projects into the stream of air supplied from the at least one dehumidifier return duct.

44. The dehumidifier system of claim 43, wherein the at least one of the temperature and humidity sensors that is located within the housing projects into a central portion of the stream of air supplied from the at least one dehumidifier return duct.

45. The dehumidifier system of claim 42, wherein, in response to the occurrence of a measurement event, the control system operates the blower and inputs the at least one of the temperature and humidity measurements from the at least one of the temperature and humidity sensors that is located within the housing.

46. The dehumidifier system of claim 45, wherein, in response to the occurrence of a measurement event, the control system operates the blower of the dehumidifier for at least a first time period before inputting the at least one of the temperature and humidity measurements from the at least one of the temperature and humidity sensors that is located within the housing.

47. The dehumidifier system of claim 41, wherein the control system determines a measured dew point temperature based on the input humidity and temperature measurements and determines, based on the measured dew point temperature and a set dew point temperature, whether to operate the compressor to dehumidify air at least indirectly supplied to the housing from the interior space and to supply dehumidified air at least indirectly to the interior space from the housing.

48. The dehumidifier system of claim 47, further comprising a dew point setting device connected to the control system, the dew point setting device inputting the set dew point temperature to the control system.

49. The dehumidifier system of claim 48, wherein, when the dew point setting device is operated to change the set dew point temperature by a least a first amount, the control system determines that a measurement event has occurred.

50. The dehumidifier system claim 41, wherein the temperature and relative humidity sensors are located outside of the at least one interior space

51. The dehumidifier system of claim 40, wherein the control system determines if the HVAC is currently responding to a cooling call or has finished responding to a cooling call within a first time period of receiving the measurement event, and, if the HVAC is currently responding to a cooling call or has finished responding to a cooling call within a first time period of receiving the measurement event, the control system waits until the first time period has elapsed since the HVAC system has finished responding to the cooling call before proceeding to respond to the measurement event.

52. The dehumidifier system of claim 40, wherein:

the structure has an HVAC system that includes an HVAC return duct, an HVAC supply duct, an HVAC blower, an HVAC equipment control device that controllably operates at least the HVAC blower in response to blower call signals and at least one HVAC system control device that outputs blower call signals;

the control system receives blower call signals output by at least one of the at least one HVAC system control device; and

the control system determines that a measurement event has occurred when the control system receives a first blower call signal within an air cycle interval.

53. The dehumidifier system of claim 52, further comprising an air cycle interval setting device connected to the control system, the air cycle interval setting device inputting the air cycle interval to the control system.

54. The dehumidifier system of claim 40, wherein:

the structure has an HVAC system that includes an HVAC return duct, an HVAC supply duct, an HVAC blower, an HVAC equipment control device that controllably operates at least the HVAC blower in response to blower call signals and at least one HVAC system control device that outputs blower call signals;

the control system receives blower call signals output by at least one of the at least one HVAC system control device; and

the control system determines that a measurement event has occurred when the control system has not received a first blower call signal before an occurrence of a first point in time before an end of an air cycle interval.

55. The dehumidifier system of claim 54, further comprising an air cycle interval setting device connected to the control system, the air cycle interval setting device inputting the air cycle interval to the control system.

56. The dehumidifier system of claim 40, wherein:

the structure has an HVAC system that includes an HVAC return duct, an HVAC supply duct, an HVAC blower, an HVAC equipment control device that controllably operates at least the HVAC blower in response to blower call signals and at least one HVAC system control device that outputs blower call signals;

the control system receives blower call signals output by at least one of the at least one HVAC system control device and outputs blower call signals to the HVAC equipment control device; and

in response to the occurrence of a measurement event, the control system determines if the HVAC system is in a blower mode, and, if the HVAC system is in a blower mode, outputs a pseudo blower call to the HVAC equipment control device.

57. The dehumidifier system of claim 40, wherein:

the structure has an HVAC system that includes an HVAC return duct, an HVAC supply duct, an HVAC blower, an HVAC equipment control device that controllably operates at least the HVAC blower in response to blower call signals and at least one HVAC system control device that outputs blower call signals;

at least one of the at least one dehumidifier supply duct is connected to the HVAC supply duct and includes a controllable damper connected to the control system;

at least one of the at least one dehumidifier supply duct is connected to the interior space and includes a controllable damper connected to the control system;

the control system, in response to the occurrence of a measurement event, determines if the HVAC blower is on; and

the control system, if the HVAC blower is on, operates the dampers in the at least one dehumidifier supply ducts to open the at least one dehumidifier supply duct that is connected to the HVAC supply duct and to close the at least one dehumidifier supply duct that is connected to the interior space.

58. The dehumidifier system of claim 57, wherein the control system, if the HVAC blower is not on, operates the dampers in the at least one dehumidifier supply ducts to close the at least one dehumidifier supply duct that is connected to the HVAC supply duct and to open the at least one dehumidifier supply duct that is connected to the interior space.

59. The dehumidifier system of claim 57, wherein:

at least one of the at least one dehumidifier return duct is connected to the HVAC return duct and includes a controllable damper connected to the control system;

at least one of the at least one dehumidifier return duct is connected to the interior space and includes a controllable damper connected to the control system; and

the control system, if the HVAC blower is on, operates the dampers in the at least one dehumidifier return ducts to open the at least one dehumidifier return duct that is connected to the HVAC return duct and to close the at least one dehumidifier return duct that is connected to the interior space.

60. The dehumidifier system of claim 59, wherein the control system, if the HVAC blower is not on, operates the dampers in the at least one dehumidifier return ducts to close the at least one dehumidifier return duct that is connected to the HVAC return duct and to open the at least one dehumidifier supply duct that is connected to the interior space.

61. The dehumidifier system of claim 57, wherein:

at least one of the at least one dehumidifier return duct is connected to the HVAC return duct and includes a controllable damper connected to the control system;

at least one of the at least one dehumidifier return duct is connected to the interior space; and

the control system, if the HVAC blower is on, operates the damper in the at least one dehumidifier return duct to open the at least one dehumidifier return duct that is connected to the HVAC return duct.

62. The dehumidifier system of claim 61, wherein the control system, if the HVAC blower is not on, operates the damper in the at least one dehumidifier return duct to close the at least one dehumidifier return duct that is connected to the HVAC return duct.

63. The dehumidifier system of claim 57, wherein:

at least one of the at least one dehumidifier return duct is connected to the HVAC return duct;

at least one of the at least one dehumidifier return duct is connected to the interior space and includes a controllable damper connected to the control system; and

the control system, if the HVAC blower is on, operates the damper in the at least one dehumidifier return duct to close the at least one dehumidifier return duct that is connected to the interior space.

64. The dehumidifier system of claim 63, wherein the control system, if the HVAC blower is not on, operates the damper in the at least one dehumidifier return ducts to open the at least one dehumidifier supply duct that is connected to the interior space.

65. The dehumidifier system of claim 40, wherein:

in response to the occurrence of a measurement event, the control system determines if a measured dew point temperature of the air to be dehumidified is above a set dew point temperature, and, if the dew point temperature of the air to be dehumidified is above the set dew point temperature, the control system turns on at least the compressor to dehumidify the air to be dehumidified.

66. The dehumidifier system of claim 65, wherein the control system operates the compressor for at least a first time period.

67. The dehumidifier system of claim 66, further comprising a frost sensor associated with the set of coils, the frost sensor outputting a measured frost temperature to the control system, wherein:

after the control system operates the compressor for at least the first time period, the control system determines if the measured frost temperature is less than a first temperature, and

if the measured frost temperature is less than a first temperature, the control system determines an amount of time that the measured frost temperature has been less than a first temperature.

70. The dehumidifier system of claim 67, wherein, if the measured amount of time is not greater than the first amount of time, the control system again determines the measured dew point temperature of the air to be dehumidified and, if the measured dew point temperature is above the set dew point temperature, the control system again operates the compressor for at least the first time period.

71. The dehumidifier system of claim 67, wherein, if the measured amount of time is not greater than the first amount of time, the control system determines the measured dew point temperature of the air to be dehumidified, and, if the measured dew point temperature is not above the set dew point temperature, the control system turns off the dehumidifier compressor and blower.

72. The dehumidifier system of claim 67, wherein, if the measured frost temperature is not less than the first temperature, the control system again determines the measured dew point temperature of the air to be dehumidified, and, if the measured dew point temperature is above the set dew point temperature, the control system again operates the compressor for at least the first time period.

73. The dehumidifier system of claim 67, wherein, if the measured frost temperature is not less than the first temperature, the control system again determines the measured dew point temperature of the air to be dehumidified, and, if the measured dew point temperature is not above the set dew point temperature, the control system turns off the dehumidifier compressor and blower.

74. The dehumidifier system of claim 65, wherein, if the dew point temperature of the air to be dehumidified is not above the set dew point temperature, the control system turns off the dehumidifier blower if it is running and the HVAC blower if it is running.

75. The dehumidifier system of claim 40, wherein:

the structure has an HVAC system that includes an HVAC return duct, an HVAC supply duct, an HVAC blower, an HVAC equipment control device that controllably operates at least the HVAC blower in response to blower call signals, at least one HVAC system control device that outputs blower call signals and at least one ventilation duct connected to the HVAC return duct and that includes a controllable damper connected to the control system;

the control system, in response to the occurrence of a measurement event, determines if the HVAC blower is on; and

the control system, if the HVAC blower is on, operates the damper in the at least one ventilation duct to open the at least one ventilation duct to supply outside air to the HVAC system.

68-1. The dehumidifier system of claim 68, wherein the control system continues to input the measured frost temperature and determine if the measured frost temperature is at least equal to the second temperature until the measured frost temperature is at least equal to the second temperature.