Note: Descriptions are shown in the official language in which they were submitted.
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HUMIDIFICATION APPARATUS AND METHOD
Field of the Invention
This invention relates to the field of humidification apparatus and methods of
use thereof.
Background of the Invention
Furnace-mounted air humidifiers are sometimes provided with an electro-
mechanical
humidistat to provide an automatic on/off control connected to govern
operation of the
humidifier. If the indoor humidity falls below the humidistat set point, the
humidistat will
enable the humidifier to add humidity when able. By contrast, if the humidity
is at, or above the
humidistat set point, power to the humidifier is interrupted to prevent
further moisture from
being added to the air, and thereby to prevent over-humidification. If the
indoor humidity is too
low, or too high, it may lead to health-related issues for occupants. These
phenomena may
include simple dry skin discomfort, or it may be related to more serious
respiratory illnesses.
Very high or low indoor humidity can also lead to damage inside the home. For
example, the
prevention of mold is sometimes a significant concern, and may arise as a
negative outcome of
over-humidification. Mold requires water, which can condense out of the air if
the warm
humidified indoor air comes in contact with a cold surface, such as a window.
A window
surface may function as a cold plate condenser. It the temperature of that
surface is below the
dew point temperature of the internal air, condensate will form. To the extent
that a window
assembly is a form of thermal resistance, even if it is desired to maintain a
constant internal
ambient temperature, the surface temperature of the glazing may vary as a
function of external
temperature.
Summary of the Invention
In an aspect of the invention there is a method of controlling humidity within
a building.
The method includes monitoring temperature within the building; monitoring
humidity within
the building; obtaining weather forecast data; and forward-adjusting humidity
within the
building as a function of the weather forecast data.
In a feature of that aspect, the method includes storing thermal performance
data of the
building, and using the thermal performance data in the step of forward
adjusting the humidity.
In another feature, the method includes collecting thermal performance data
from the building
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over time, calculating thermal performance co-efficients of the building from
the thermal
performance data; and using the thermal performance co-efficients in the step
of forward-
adjusting humidity in the building. In another feature, the method includes
obtaining the weather
forecast data from a data source by at least one of (a) a radio signal; and
(b) a telephonic signal.
In still another feature, the method includes storing a set of data
establishing upper and lower
humidity limits, and maintaining humidity adjustments within the upper and
lower humidity
limits. In a further feature, the method includes establishing upper and lower
bands to the
humidity set point, and operating an On-Off humidification process between the
upper and lower
bands of the humidity set point. In still another feature, the method includes
monitoring outdoor
temperature, comparing outdoor temperature with previously forecast
temperature, and adjusting
humidification to account for a difference between forecast external ambient
temperature and
actual external ambient temperature. In still yet another feature, the method
includes obtaining
external source inputs for at least one of (a) external relative humidity; and
(b) precipitation; and
calculating alternate thermal properties of the building adjusted therefor,
and using the adjusted
thermal properties when calculating humidity adjustment.
In another aspect, there is an humidity control apparatus for a building. It
has at least a
first temperature sensor mounted to monitor temperature inside the building.
There is at least a
first humidistat at which to a set humidity value is input, and at least a
first humidity senor
mounted to monitor humidity inside the building. The apparatus has a source of
weather forecast
data input and a memory of thermal properties of the building. There is a
processor connected to
manage the inputs and outputs, and to calculate outputs and to monitor
operation of the system.
The processor is operable to receive input values from at least the first
temperature sensor; at
least the first humidistat; and the source of weather data. The processor is
operable to monitor
observed temperature and observed humidity at least at the first temperature
sensor and at least at
the first humidity sensor respectively. The processor is operable to make a
forward projection of
humidity level within the building as a function of the weather forecast data
input. The control
apparatus is operable to output control signals to adjust humidity within the
building toward the
forward projection of humidity level.
In a feature of that aspect the apparatus includes an "On" ¨ "Off' operation
having an
hysteresis band. In another feature, the apparatus has a water source input
and a valve mounted
to control flow through the input, and the controller is operable to output
environmental control
signals to adjust water flow through the valve. In a further feature, the
apparatus is operable to
adjust humidity within the building toward the forward projection of humidity
level. In still
another feature, the apparatus includes at least one sensor mounted to monitor
at least one of (a)
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the amount of airflow (Q) created by the furnace; (b) the temperature of the
water supply (Tw)
(c) the temperature of the furnace air (Ta). In a further feature, the
apparatus includes input data
values for at least one of (a) building volume; and (b) building heat loss co-
efficients; (c)
building moisture loss co-efficients; and (d) building air exchange rate co-
efficients.
In a further aspect there is an humidity control apparatus for a building. it
has at least a
first temperature sensor mounted to monitor temperature inside the building.
There is at least a
first humidistat at which to a set humidity value is input, and at least a
first humidity senor
mounted to monitor humidity inside the building. There is a source of weather
forecast data
input. There is a water source input and a valve mounted to govern flow of
water therefrom.
The controller has a memory of thermal properties of the building; and a
processor. The
processor is operable to receive input values from at least the first
temperature sensor; at least the
first humidistat and the source of weather data. The processor is operable to
monitor observed
temperature and observed humidity at least at the first temperature sensor and
at least at the first
humidity sensor respectively. The processor is operable to make a forward
projection of
humidity level within the building as a function of the weather forecast data
input. The
controller is operable to output control signals to adjust water flow through
the valve.
In another feature, the apparatus is operable to adjust humidity within the
building
toward the forward projection of humidity level. In still another feature, the
apparatus includes
at least one sensor mounted to monitor at least one of (a) the amount of
airflow (Q) created by
the furnace; (b) the temperature of the water supply (Tw); and (c) the
temperature of the
furnace air (Ta). In another feature the apparatus includes input data values
for at least one of (a)
building volume; and (b) building heat loss co-efficients; (c) building
moisture loss co-efficients;
and (d) building air exchange rate co-efficients.
The features of the aspects of the invention may be mixed and matched as
appropriate
without need for multiplication and repetition of all possible permutations
and combinations.
Brief Description of the Drawing
These and other aspects and features of the invention may be more readily
understood
with the aid of the illustrative Figures below, showing an example, or
examples, embodying the
various aspects and features of the invention, provided by way of
illustration, and in which:
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Figure 1 shows a schematic representation of a building, such as a house, and
elements
of an environmental control apparatus according to this description;
Figure 2 is a table of Temperature v. Time, correlating the set internal
temperature of the
building to the external fluctuation of temperature over a 24 hour period; and
Figure 3 is a table of Humidity v. Time over the same 24 hour period as in
Figure 2.
Detailed Description
The description that follows, and the embodiments described therein, are
provided by
way of illustration of an example, or examples, of particular embodiments of
the principles of the
present invention. These examples are provided for the purposes of
explanation, and not of
limitation, of those principles and of the invention. In the description, like
parts are marked
throughout the specification and the drawings with the same respective
reference numerals. The
drawings are substantially to scale, except where noted otherwise, such as in
those instances in
which proportions may have been exaggerated in order more clearly to depict
certain features.
By way of general overview, given the fluctuations in outdoor external ambient
temperature noted above, one way to reduce the likelihood of internal
condensation on the
windows, or to reduce the amount of condensate, the indoor humidity level may
be adjusted
downward when the outside air becomes colder. Conversely, as the outdoor
temperature rises,
the home occupant can safely bring the humidity set point higher for increased
comfort without
fear of condensation.
In that context, Figures la ¨ lh, illustrate in a general, schematic manner
the context of
the apparatus. To that end, there is an enclosure structure generally
indicated as a house 20.
Although it is identified as "house 20" this is intended to be generic of
houses, apartment
buildings, schools, offices, factories, storage spaces, stores, and so on, and
could as easily be
identified as "building 20" or "warehouse 20".
House 20 has an environmental control apparatus 22 that may include an air
conditioner,
a furnace, a heating distribution system 24, and a control unit 40.
Distribution system 24 may
have, or be, a system of radiators or ducting and an air mover such as a
forced-air blower.
Environmental control apparatus 22 may sometimes be an HVAC system. Similarly,
house 20
includes an humidification unit, i.e., an humidifier, 30. In some embodiments
humidifier 30 may
be separate from apparatus 22, in others it may be part of apparatus 22.
Humidifier 30 may be
located in the forced air distribution ducting downstream of the heating or
cooling elements of
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the HVAC system. Where humidifier 30 is a separate unit or module, it may be
controlled
separately from environmental control apparatus 22 generally. That is, it may
have a stand-alone
control unit 41, separate from the control unit 39 of the heating and cooling
systems. However,
where humidifier 30 is part of apparatus 22 generally, it may share the same
automated control
unit. For the purpose of this explanation, a single control unit 40 may
control both temperature
and humidification functions. Since this need not be so, control unit 40 is
shown with an
intermittent demarcation separating the temperature functions and hardware
(control unit 39)
from the humidification functions and hardware (control unit 41). Control
units 39 and 41 may
be housed together, or they may be separate independent units. However it may
be, each control
unit has, or is, a processor, i.e., a CPU, for carrying out the various
control functions. Control
unit 39 has at least a first thermostat 26 at which the user inputs the
desired internal temperature
of house 20, or portions thereof. House 20 also has at least one temperature
sensor 28 monitored
by thermostat 26. Control unit 41 of humidifier 30 includes a humidistat 32 at
which a relative
humidity level is input. There is at least a first humidity sensor 34. Control
unit 39 receives
input values, i.e., input settings, for temperature, and monitors temperature
sensor 28. Control
unit 41 receives input values, i.e., input settings, for relative humidity and
monitors humidity
sensor 34. Control unit 41 also monitors temperature, whether at sensor 28, or
at its own
independent temperature sensor, or sensors, 38, e.g., in embodiments in which
it is a separate
unit. Even where temperature and humidity are controlled in a single unit,
they may have
different temperature sensors 28 and 38. Additionally, control unit 41 has a
data download input
42, and a memory 44, which may be separate from any download input or memory
of controller
39, or may be shared therewith. Data download input 42 is connected to a
weather forecasting
data source 46. There may be an external ambient temperature sensor 48, and a
solar sensor 50.
In some instances there may be a wind-speed sensor 52. Control unit 41 also
includes a clock
54, which may be a shared clock with control unit 39. There may be a direct
measurement of
inside an outside glass surface temperature of one or more windows. The output
of controller 41
is directed to govern operation of humidifier 30, as by turning humidifier
motor 56 "On" or
"Off'. Apparatus 22 also include a water source 57 and a water control valve
58. House 20 has
windows and doors, generically represented by window 36.
Memory 44 may be used, and in one embodiment is used, to store data pertaining
to (a)
weather data and weather rate-of-change data pertaining to the current weather
forecast; (b)
historic data characteristic of the thermal performance of the structure being
heated, cooled, and
humidified, such that the structure can be modelled for its thermal mass, the
thermal resistance of
the structure, and its effective thermal time constants, and the rate at which
it loses humidity (in
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the Winter) or gains humidity (in the Summer), this last being a measure of
the tightness and air
exchange rate of the structure.
The data stored can be determined by recording the actual performance of the
structure
under known conditions in terms of the heat lost driving potential between the
inside ambient
temperature Tai and the outside ambient temperature Tao. By measuring the rate
of temperature
difference decay with the heating and cooling system off, estimated values can
be obtained or the
thermal resistance of the structure. From these values, an expected
temperature differential
across the glazing may be estimated based on historic data. The thermal loss
and humidity loss
of the structure may also be a function of windspeed, solar radiation,
external humidity, or
external precipitation, and hence the various co-efficients may be adjusted
according to variation
in those parameters correlated with data downloaded from weather forecasting
services or as
observed at sensors 48, 50 and 52, for example.
Memory 44 also includes tabulated values of the ranges of acceptable internal
relative
humidity as a function of internal ambient temperature. Such as table may be
as follows:
TABLE 1
OUTDOOR TEMP
MAXIMUM INDOOR RELATIVE HUMIDITY @ 20
C
-30 C OR COLDER 15%
-30 C TO -24 C 20%
-24 C TO -18 C 25%
-18 C TO -12 C 35%
-12 C TO 0 C 40%
Data download input 42 is a data monitor at which control unit 40 receives
weather
forecast information. This information may be provided by a dedicated data-
link, such as a
phone line, or it may be provided through an internet connection.
Manually adjusting a humidistat according to changes in outdoor temperature
may not
generally be practical for widespread residential or commercial use. A self-
adjusting humidistat
using an outdoor temperature sensor is an improvement. However, installation
of a wired
outdoor sensor is a project that may not be readily undertaken by an average
home-owner, for
example. Wireless outdoor temperature sensors simplify the installation, but
all outdoor
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temperature sensors require careful placement in order to avoid false readings
from direct and/or
reflected sunlight as well as snow and ice accumulation.
In addition to practical challenges, a self-adjusting humidistat using an
outdoor
temperature sensor is subject to control lag. Changes in the state of indoor
humidity often fall
behind changes in outdoor conditions as the response time for the indoor
humidity to change is
usually much slower than a change in outdoor temperature. The delay can be as
long as several
hours to several days depending on several variables related to the home
structure and humidifier
performance.
In that light, rather than reacting to actual changes in outdoor temperature,
apparatus 22
provides an improved automatic self-adjusting humidistat. By downloading
weather forecast
data it anticipates future changes in outdoor temperature, and the timescale
over which such
changes may be expected to occur. Note that even a first derivate forward
approximation of
temperature or humidity relative to time may tend to provide a worthwhile
improvement. In that
context, apparatus 22 uses a self-tuning algorithm to self-correct, or self-
adjust, the timing of
changing the indoor humidity set point.
That is, to anticipate future changes in outdoor temperature, the automatic
self-adjusting
humidistat of apparatus 22 has a control algorithm that receives real-time
temperature and
humidity forecasting data for its geo-location. This information is stored in
memory 44 of
controller 40. It then compares the temperature and relative humidity of the
space to be
humidified with the expected conditions and the time lag to be expected in the
structure. For
example, if the initial manually elected relative humidity is higher than the
maximum value of
the range in Table 1, then controller 40 turns of the humidifier, i.e., turns
off the electrical power
to humidifier motor 56, until such time as the relative humidity at humidity
sensor 34 falls below
the bottom limit of the selected relative humidity range.
It may be noted that the humidity control of apparatus 20 is an On/Off
control, with an
upper limit, a lower limit, and a hysteresis band width between the upper and
lower limits. The
width of the hysteresis band is narrower than the width of the permissible
humidity range at any
given temperature in Table 1. Therefore, there may be an initial manual input
selection of
humidity that is in the middle of the range, or more moist than the middle, or
less moist than the
middle. Once the controller has established operation in a band in the middle
of the selected
range, it is able to stay between the upper and lower limits of the On/Off
range.
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It may be that the received temperature forecast data indicates that
temperature is going
to fall a certain amount over a given time period, e.g., as day turns to
night. From the historical
data, controller 40 has the parameters required to extrapolate forward
humidity over time, e.g., as
the inside surfaces of the glazing cool. It may then reduce the flow of
humidification water to
shift the humidity band to a lower level as the outside temperature cools.
Since this process
typically occurs over a number of hours, and since the predictive software has
data to determine
both the reduction in humidity level required and the time available, it can
calculate the
appropriate slope of the time rate of change of humidity, and adjust the
center point of the
On/Off hysteresis range accordingly, so that the humidity slowly steps down in
increments over
time.
This may perhaps be understood with the aid of Figures 2 and 3. For the
purpose of this
discussion, it is assumed that the building is house 20, and that the
inhabitant sets both the
desired internal temperature and the desired internal relative humidity at 10
a.m. Clearly this
time is arbitrary, and is chosen for the convenience of explanation.
If the inside ambient temperature Li of house 20 is constant, and the external
ambient
temperature L. is constant, then the set point humidity would be represented
by straight
horizontal line 60. If that were so, then the controller would regulate
humidity between the
upper limit band shown by dashed line 62, and the lower limit band shown by
dashed line 64. If
that were the case, and assuming an On/Off control with a decaying exponential
arc on both the
humidifying (i.e., "On") and de-humidifying (i.e., "Off') portions of the
cycle, the system would
want to operate on a periodic sharktooth performance output between the upper
and lower bands.
However, Figure 3 has been drawn to show that at night the upper band 62 would
tend to
intersect, and cross, the maximum permitted relative humidity line, 66, which
conforms to Table
1 for outside temperature curve 70 and inside set point temperature 72 of
Figure 2. Conversely,
in the warmest part of the day during the afternoon, the nominal set point
curve 60 and the lower
limit band 64 would intersect and cross under the minimum permitted relative
humidity line 68.
In those respective situations, whatever value might have been set manually,
the
controller over-rides the manually set value to make sure that the observed
result does not fall
outside the range established by Table 1. Therefor, at roughly 1 p.m., the
system would set a
higher internal value to follow curve 68 to prevent the air in the building
from becoming too dry.
This condition would prevail until about 5:00 p.m. or 5:30 p.m. Later on, in
the evening and
night, near 2:00 a.m. the level of humidity might be too moist, and
undesirable condensation
might occur on the "On" leg of the saw tooth or shark tooth. Accordingly, when
the upper limit
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is reached, the humidifier is shut off, and does not come back on until the
lower band is
intersected, and so on.
However, using the method and apparatus described herein, when the temperature
and
relative humidity set points are established by the inhabitant at 10:00 a.m.,
the first thing the
controller does is to determine whether the set point input at humidistat 32
(in effect, the target
value for humidity) is above or below the actual observed values. The
controller establishes the
difference between the actual value and the set point value. It then sends
signals to the furnace,
the air conditioner and the humidifier, as appropriate, to cause the system to
work toward the
input set point. Where only humidification is being controlled, the controller
need not send
signals to the air conditioner, or furnace, and need not be connected to
either of them. Assuming
that the system has reached a point within the range permitted under Table 1.
Looking only at humidity, in Figure 3, if the controller concludes that the
humidity needs
to rise, then it looks for the value at the shut-off condition, i.e., the
instantaneous value of the
upper band. Based on the historic data for the structure, and based on the
weather forecast data it
has received, the controller can make an estimate of the time to run the
humidifier, and the value
of relative humidity it needs to establish to intersect the upper limit band
of the curve. In this
case, however, the controller will be following curve 80 which has been
adjusted to account for
the variation of the outside air temperature according to the weather forecast
data stored in
memory. Curve 80 has upper and lower "On-Off" bands shown as dashed lines 82
and 84
respectively. So, accordingly, the controller will be looking for an observed
humidity value
corresponding to the value of upper band 82, as at point 90 as indicated. Once
this point has
been reached the humidifier is shut off, and the humidity in the structure
decays according to the
loss and air interchange properties of the structure. These properties have
also been stored in
memory, and from these values controller 40 can estimate the intersection time
and humidity at
the next point 92, at which the humidifier it to be turned "On".
Alternatively, values for some or
all of these properties may have been entered into memory, such as values for
(a) building
volume; and (b) building heat loss co-efficients; (c) building moisture loss
co-efficients; and (d)
building air exchange rate co-efficients. Over time, controller 40 may record
data to verify the
accuracy of pre-programmed or manually input building structure properties,
and may adjust the
stored property values according to actual performance. Whether or not
estimated, on both the
"up" leg to point 90 and the "down" leg to point 92, the controller is
constantly sampling at the
humidity and temperature sensors to determine whether the humidity has fallen
below the lower
band intersection point for the outside temperature from the weather forecast
for that time of day,
as adjusted according to the properties of the structure. It also calculates
whether the lower limit
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according to Table 1 has been crossed. To the extent that the time of
intersection does not meet
the predicted time, the controller can re-calculate the decay parameters for
the structure. On a
windy day, the decay may be faster than on a calm day, and the time to
humidify the structure
may be longer, for example.
When point 92 is reached, the humidifier is turned on, and the controller
calculates the
time and humidity at which it expects to intersect the upper band at point 94.
It them monitors
time, temperature, and humidity for convergence on the upper band limit. This
process repeats
over and over, throughout the day. So, it may be observed that the target for
the 'On" or "Off'
condition is not the nominal set point value but rather (a) the nominal set
point value adjusted for
(b) the external temperature curve; and (c) the half width (i.e., up or down)
of the hysteresis loop
between the "On" and "Off' bands to either side of the mean curve.
As may be noted, at some times of day the On portion of the cycle is longer or
shorter,
and the corresponding "Off' portion of the cycle depending on whether the
external ambient
temperature is rising or falling. Thus the time ratio or the "On" and "Off'
portions of the curve
will vary over time during the day.
In summary, in self-adjusting mode, the humidity set point will change, or be
modified
by the controller, in accordance with established industry guidelines relating
outdoor temperature
to an acceptable indoor relative humidity level such as may tend to prevent or
to reduce
condensation on windows 36. The value of the set point adjustment is obtained
by comparing
the user entered set point to maximum target set point values for indoor
humidity at 20C are as
shown in Table 1.
In one embodiment, outdoor temperature is used to adjust the RH set point
value to be
the predicted lowest outdoor temperature value in the next 24 hours as
downloaded from the
external data source using values nearest to the system's geo-location. If the
humidistat set-point
is lower than the maximum indoor RH at the predicted outdoor temperature as
per Table 1, no
action is taken. If the user entered set-point is higher than the maximum
indoor RH at the
predicted outdoor temperature as per Table 1, the humidity set point will
adjust to the maximum
indoor RH value as per Table 1. To determine the optimum time to initiate an
adjustment action,
the system accumulates indoor temperature and relative humidity data to
establish rates of
change in humidity in its installed environment, from which the physical heat
transfer constants
of the structure can be determined. That is, the average rate of humidity loss
is established using
data recorded when the humidifier is not in operation. This rate is used to
determine the time to
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stop humidification in order to reach a lower maximum set point. The average
rate of humidity
gain is established using data when the humidifier is in operation. This rate
is used to determine
a start time for recovery towards the user entered set point when safe to do
so.
The foregoing apparatus and operation of that apparatus provide an auto-
adjusting
relative humidity set point based on forward looking data and calculation of
rate of change
(up/down) based on logic to determine optimum time for OFF and ON. The system
also works
to control input water flow, e.g., by controlling valve 58 to reduce wasted
water. That is, based
on the same approach to ramping supply to match the forward predicted set
point by taking the
difference between the current humidity and the predicted forward humidity in
the next
increment of time, and dividing that difference by the time available gives a
calculated time rate
of change. From the calculated physical properties of the structure based on
past performance,
the controller can determine the mean rate of operation required to reach the
target set point at
the future time. Where the outside temperature is rising, the level of
humidification required,
and consequently the mean flow of water to humidifier 30, will tend to be
larger than when the
outside temperature is falling and the system is letting the net flow of
humidity out of the
structure fall. In that context, the rate of inflow at valve 58 can be
adjusted to correspond to the
expected required flow over the approaching time period. This can also be
achieved by sampling
relative humidity at first and second points in time for a fixed water flow
rate to humidifier 30.
Where that flow rate does not keep the change in relative humidity within the
On/Off hysteresis
band to either side of the adjusted set point curve, then valve 58 is adjusted
incrementally either
to close or to open, as the case may be. At the next time interval, the
calculation is made again,
and valve 58 is adjusted up or down once more as appropriate to cause
convergence of the
sensed humidity level with the expected calculated adjusted curve. This occurs
repeatedly. In
this example, controller 41 may have sensors that monitor actual water flow
rate, but it need not
measure the absolute flow rate where controller 41 is operating on knowing
whether "more" or
"less" humidity is required, and adjusts valve incrementally over several time
periods.
Controller 41 does "know" the absolute position of valve 58, based on the
recorded observations
of its own historic operation and collection of data, and if, in future, it
calculates that a given
flow condition is required to reach the set point target over a given time
interval, it can, based on
that recorded historic data move valve 58 to the same condition as previously
used to achieve the
same time rate of change in building 20 more generally. So, it calculates the
difference in future
humidity from present humidity as delta(y), and the time available to make
that change as
delta(x). From this rate, the starting point value, and the time interval
until the next data point,
it calculates the expected end point at the end of the next time interval. It
verifies that the
calculated future end point humidity is within the permitted range of Table 1,
and adjusts it
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accordingly if necessary. V. e., if it isn't, then the slope dy/dx must be
adjusted either up or down
to follow a curve that will lie within the range of values of Table 1. This
will give the nominal
curve. The system then predicts the shape of the predicted saw-tooth On-Off
curve and
superposes that sawtooth on the base nominal curve to predict the next On/Off
point. At any
period in time, controller 41 senses the humidity at senor 32, and can
evaluate whether the
humidity in building 20 is following the expected course. If it is not
following the expected
course of the saw tooth at any given point in time, then humidifier motor 56
is be turned "On" or
"Off' as appropriate to converge with the expected saw-tooth curve value at
the given point in
time, and, to the extent that humidifier 30 may then tend to use more or less
water than predicted
in that time interval, the water supply flow may be adjusted up or down at
valve 58 to correspond
to the change in needed supply.
Accordingly, by this calculated forward time-rate-of-change approximation, or
forward estimate, then results in controller 41 adjusting the effective
humidity range sought by
humidifier 30, and adjusting the water supply rate yield a method by which
automatically to
adjust water flow supplied to humidifier 30 to tend to improve, or husband,
water utilization by
providing increased (or decreased) humidity with reduced water loss. This
water loss based on
external temperature variation (for a fixed internal set temperature) or based
on both internal and
external temperature variation may occur with or without a humidity sensor,
such as sensor 32.
US 6,354,572 describes a method for metering water flow to humidifier to
reduce wasted water.
In that system of metering, the apparatus uses pre-set ON and OFF times for
water supply and is
not sensitive to external factors that influence humidifier performance such
as (a) the amount of
airflow (Q) created by the furnace; (b) the temperature of the water supply
(Tw); (c) the
temperature of the furnace air (Ta); and (d) the volume of the House being
humidified.
In the system described herein, the apparatus of system 22 may include sensors
operable
to monitor any combination of those parameters, or to store volumetric data in
memory.
By sensing and monitoring any combination of one or more of these factors, the
self-
tuning, or self-adjusting, control adjusts the water supply ON (valve 58 open)
pad quenching
time and OFF time (valve 58 closed) pad drying time in order to increase or
decrease the amount
of water flowing to humidifier 30, and to reduce the water flowing to drain.
This is
accomplished by collecting, storing and comparing the rate of change in
humidity during a
humidification cycle, using that data to adjust water valve 58 OPEN/CLOSED
times. A sensor
may, or may not be located downstream of humidifier 30 to verify water flow to
drain.
Date Recue/Date Received 2022-05-06
- 13 -
The features of the various embodiments may be mixed and matched as may be
appropriate without the need for further description of all possible
variations, combinations, and
permutations of those features.
The principles of the present invention are not limited to these specific
examples which
are given by way of illustration. It is possible to make other embodiments
that employ the
principles of the invention and that fall within its spirit and scope of the
invention. Since
changes in and or additions to the above-described embodiments may be made
without departing
from the nature, spirit or scope of the invention, the invention is not to be
limited to those details,
but only by the appended claims.
Date Recue/Date Received 2022-05-06
