Tifford wants to select a corn stove that
(a) has a set point control
(b) has turndown ratio for night and day
(c) makes flyash rather than a solid ash cake
ALL ARE BIG MISTAKES!
The advantages of a corn stove include
(a) Affordably eliminates temperature and RH swings which are inherent of conventional HVAC with set point controls
(b) Provides affordable steady heat and RH at all times without excessive waste of energy to run non-functional or partially functional humidifiers and dehumidifiers
(c) Eliminates flyash, smoke, dust, germs, excess moisture, skin problems from RH or vapor pressure swings.
Low cost corn stove heat can be most easily by addressed by discussing the terms associated with HVAC heating and cooling. Temperature, humidity, and R value may sound like common terms. How about web bulb temperature (wbt), dry bulb temperature (dbt), relative humidity (RH), dew point temperature(dpt), Wall Insulation "R" value as a function of RH?
1. Humidity is the measure of the amount of water vapor in air or
2. Total Air Pressure - The total pressure, ambient pressure,
baromtetric pressure or atmospheric pressure of air or a specified
gas is the sum total of each of the partial pressures of all the
gasses in the mixture added together. To calculate barometric
pressure (total ambient air pressure = 14.696 psia) Add the partial
pressure of 12% oxygen plus the partial pressure of 78% nitrogen
plus the partial pressure of the water vapor due to relative
humidity plus the partial pressure due to trace gasses in air. The
barometric pressure decreases with altitude to zero as there are no
gasses present in the vacuum of outer space.
3. Partial Pressure of water vapor (Pw) is the pressure exerted by
water vapor in the air(gas). The portion of the total air (or gas)
pressure exerted by any one gas is called the partial pressure of
the subject gas. The water vapor component in air (a gas) is the
partial pressure of water. Partial pressure is expressed in units of
pressure such as mbar, Pascal, mmHg, in.Hg (Dalton's Law of Partial
4. Saturation Vapor Pressure (Pws) is the maximum pressure of water
vapor that can exist at a given temperature as expressed in units of
pressure. Saturation vapor pressure occurs at 100% RH. Add more
water vapor and it rains or condenses. Drop the temperature and
likewise it rains or water condenses as on a window pane that is
colder than the dew point.
5. Relative Humidity (RH) is the ratio of the actual partial
pressure of water vapor to the saturation vapor pressure at the gas
temperature, expressed as a percentage (%). RH can not exceed 100%
because the water vapor condenses to liquid water or rain.
6. Dewpoint (Td) is the temperature at which condensation (dew)
begins to form as the air (a gas) is cooled. Td is the temperature
(C or F) at which the gas is saturated Pw=Pws, The dry bulb
temperature and wet bulb temperature are equal at 100% RH.
7. Mixing Ratio or Humidity Ratio (x) is the ratio of the water
vapor mass per unit mass of dry air. Although dimensionless humidity
ratio is often expressed as grams per kilogram (g/kg) or grains per
8. Enthalpy (h) is the measure of the total energy in a humid gas.
The total energy is the sum of the sensible and latent heat or the
sum total heat energy of the dry oxygen & nitrogen(gas) plus water
vapor plus other impurities. Enthalpy is energy per unit by weight,
kilojoules per kilogram (kj/kg), British Thermal Units per pound
(BTU/lb). Wet air hold more energy than dry air. Humid air cost
more to heat that dry air. Leakage of heated wet air of high RH to
the outside is more costly than leakage of dry air to the outside
because the wet air holds more energy than dry air. It cost less to
heat dry air to a higher more comfortable temperature than to boil
or evaporate hot water to make one feel warmer at a lower
9. Wetbulb Temperature (Tw) is the temperature indicated by a sling
psychrometer as sheathed in wet wicking. Wet bulb temperature is
compared to dry bulb temperature as measured by a conventional dry
or fixed mercury wall thermometer with no breeze or air velocity
influence. Wet bulb temperature measurement is influenced by the
rate of evaporation of moisture from the wet bulb wicking of the
thermometer. Air RH (Relative Humidity) determines the fixed
relationship between wet bulb temperature and dry bulb temperature.
It takes the same amount of heat but is more healthy and sensibly
more comfortable to heat a room to 76 deg F and 50% RH than to drop
the room temperature to 65 deg F at 70% RH. Conventional HVAC
heaters with temp control point set at 65F may swing down to 60F
automatically driving RH to 70% which is an uncomfortable
temperature to the sensible human. Some molds, germs and viruses
thrive and readily multiply at 70% RH. A stable corn stove heater
cost the same amount of heat to raise the same dry air to 76 deg F
which will automatically drop the RH to 50% which is well within the
sensible safe and healthy comfort zone.
10. Sensible Temperature is the sensible reaction of the human body
to detect a level of comfort or discomfort as related to room
temperature and relative humidity. The sensible comfort zone is
defined to be between 30% RH and 60% RH at temperatures between 68
deg F and 76 deg F. Human body discomfort increases as temperature
and relative humidity progress beyond the defined comfort zones. In
general, the healthy atmosphere likewise is considered to be inside
the comfort zone. High RH or low RH, for example, provide ideal
breeding conditions for bacteria, molds, germs, viruses and
increased agitation for sensitivity to human allergies.
11. Corn Stoves - RH of 50% is healthy at the temperature of
comfort. The extreme high temperature of the corn stove improves the
possibility of neutering or killing most germs in the air prior to
heat distribution into the room. The damp coils of the conventional
HVAC swinging the temp and RH through the dew point provide ideal
damp breeding conditions. The HVAC blower actuates and distributes
the germs & molds throughout the house through the air registers.
The stable temperature of the corn stove allows one to control the
room temperature and room relative humidity well within the safe and
healthy comfort zone.
12. Room Temperature - Increased RH increases the sensible
temperature of the human body and makes the body feel warmer at a
given dry bulb temperature primarily because water vapor (high room
RH) conducts energy better than dry air (low RH). It should be
noted that it cost less to heat dry air than wet air. With the corn
stove it cost less to raise the dry bulb room temperature of the
room than the cost of heat to boil water to make one feel warmer
than they really are (low dry bulb temp).
13. HVAC Set Point - Conventional HVAC systems have a temperature
control set point about which the room temperature swings. As shown
above, the relative humidity technically can not be prevented from
swinging as the room temperature swings about the control set point.
Humidifiers and dehumidifiers are technically incapable of adding
and subtracting enough moisture to maintain fixed RH as the room
temperature swings about the control set point. The corn stove
allows one to control both the relative humidity and the room
temperature because both RH and room temperature are fixed and