GROWING GOURMET - Anto2ni.it

changes per hour required during the primordia
formation period, full humidification within
the growing room is difficult if drawing in dry,
outside air. This problem is solved through the
conditioning of outside air in an intermediate
chamber called apreconditioning plenum. The
preconditioning plenum is usually located outside
of the growing room. Its purpose is to
elevate humidity and alter temperature to levels
adjustable by the in-room environmental systems.
One preconditioning plenum can supply
several growing rooms, if properly designed.
In cold climates or during the cold winter
months, the preconditioning plenum can be
largely humidified using steam. Steam provides
both moisture and heat. Thermostats
located in the preconditioning plenum and/or
growing room activate solenoid valves on live
steam lines coming from an on-duty boiler.
Steam is sent downstream to a square-shaped
grid of interconnected pipes. Holes have been
drilled to orient the flow of steam towards the
center. The main air system blower pushes the
steam from the preconditioning box into the
growing rooms. Each growing room has its
own high volume axial fan which inflates the
ducting and distributes the humidified, and
heated air. Since moisture will collect in the
polyethylene ducting, provisions must be made
for removing this condensate. The simplest solution
is to slant the duct at a slight angle. The
condensation can then drip directly into the
channel drain running lengthwise down the
center of the room. (See Figure 393.)
When temperature in the growing room exceeds
prescribed levels, the thermostat will
close the in-line solenoid valve. Humidity will
fall. A humidistat sensing the humidity in the
preconditioning plenum takes control, opening
a separate solenoid valve, sending cold water
down-line, activating the mist nozzles. The
THE GROWING ROOM 477
cold water lines should be positioned in a fashion
so that they are not damaged when the
steam lines are in operation. The goal here is to
elevate humidity to 75-80% rH. Independent
humidifiers or mist nozzles located high in the
growing rooms control the remaining 25% of
the humidity required for primordia formation.
Some companies offer systems which utilize
compressed air (100-400 psi) misting systems
that emanate a fog-like cloud of humidity. With
proper filtration and maintenance these systems
work equally as well although typically
are much more expensive to install.
Swamp coolers generate humidity and
lower temperature of the incoming air. They
work especially well when the outside air temperature
is high and the humidity is low. These
types of evaporative coolers can also be incorporated
into the design of a preconditioning
box. Heat exchangers must be carefully engineered
for maximum effect. The cultivator is
encouraged to consult a reputable HVAC
(Heating, Ventilation & Air Conditioning) specialist
before installation of any of the
above-mentioned systems. Often times, independent
systems with manual-control
over-rides perform better, in the long run, than
all-in-one packages. The cultivator must have
alternatives for humidity should equipment fail
for any reason. The value of one saved crop can
easily offset the expense of a simple back-up
system.
11) Insect control Flies are the bane of the
mushroom cultivator. Once introduced, a
single, pregnant fly can give rise to hundreds of
voracious offspring in a few weeks. (For a complete
description of the flies and their life
cycles, please consult The Mushroom Cultivator
(1983) by Stamets & Chilton.) Many
models of insect traps are available. "Bug
zappers" electrocute flies when they come in
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