Nick,

I did not state nor have I assumed that my house is an idealized, perfectly
closed system with no flows in or out. There are, however, no longer
economical ways to further reach a 60X improvement to go from my present
"airtight" house to the Canadian 1 cfm "ideal" you refer to.

My original reply talked directly to the question raised by this specific
thread, namely, whether the Honeywell Humidicalc algorithm is recommended
versus the use of an outdoor temperature sensor. Your series of attacks and
comments have not offered any insights or contributions whatsoever on this
thread's topic. Since you have chosen to hijack this thread on another topic
with remarks which are critical and disparaging to my original reply, I have
felt obliged to respond. I do so reluctantly since my basic opinion is that
this exchange does not serve the original poster in answering his question
in any way, but instead, leads off in the path of your digression.

My prior comments center on the premise that energy to evaporate moisture
into the home is expended regardless of whether the humidifier, the furnace,
the hot water tank, the clothes dryer, or other appliance provides it.

A house with a less than perfect seal does indeed require more energy to
heat and humidify, and neither of us needs to further elaborate on such an
obvious distinction.....no doubt homes built to the newer Canadian standards
will use less energy and require less humidification.

I have never disagreed with the physical fact that energy is required to
evaporate water. My only disagreement was, and is, your assertion that a
humidifier inherently demands more heating fuel, and my reasons for so
believing are as simple as the observation that moisture evaporated into the
air requires energy from someplace. A family of 4 (to use your example)
burns additional energy in the activities you cite (cooking, bathing,
washing and drying clothes, etc.) to evaporate equivalent humidity that a
humidifier would provide. And in a perfect world where true adiabatic homes
with no flows or losses exist, the need for either would be moot.

Perhaps in some home in the future where there is only 1 cfm of 'leak' it
will be, as you assert, possible to avoid a humidification method entirely,
but I, for one, will reserve judgment until much more is known about the
consequential issues of mold, oxygen deprivation, smells, radon effects, and
other poor air quality issues.

Since the original topic remains unanswered by opinions other than my own, I
welcome your thoughts from Villanova's Electrical and Computer Engineering
Department as to how a Honeywell humidistat using only a software algorithm
might, as the original poster asks, compare to the method used by several
other manufacturers who add an outdoor temperature sensor to allow their
algorithms to adjust to outside changes.


Smarty



wrote in message
...
Smarty wrote:

... It takes 1000 Btu to evaporate a pound of water.

I disagree.

It takes 1000 BTU of energy to evaporate a pound of water.

So now you disagree with yourself? :-)

The house is a closed system...

If that were true, you would need DEhumidification in wintertime.

I have 2 degrees in engineering...

So this should be a piece of cake:

How much energy do you need to keep your house RH 50% at 70 F with
an indoor humidity ratio wi = 0.00787 pounds of water per pound
of dry air when the outdoor humidity ratio wo = 0.0025, with 200 cfm
of natural air leakage?

Hint: 70 F air weighs about 0.075 lb/ft^3.

A typical US house leaks about 200 cfm. An "airtight" US house might
leak 60 cfm. A 2400 ft^2 house that meets the Canadian IDEAS standard
might leak 1 cfm...

Nick