Transcript Introduction to Structural Drying The Changing “State” of Water • Water exists in three states of matter: – solid (ice) – liquid (water) – gas (steam/vapour). •

Introduction to
Structural Drying
The Changing “State” of Water
• Water exists in three states
of matter:
– solid (ice)
– liquid (water)
– gas (steam/vapour).
• The primary factor that will
ultimately determine what state water will take is the amount of
energy each molecule contains.
• The more energy each water molecule possesses the more rapidly
it can move.
• When molecules are moving quickly enough the chemical attraction
that they have to each other is no longer sufficient to hold them
together.
The Changing “State” of Water
• There are several phase changes that can occur depending upon
whether energy is being added or removed.
• Requires more energy during the phase changes to change water
from one state to another than is required for almost any other type
of molecule.
The Drying Pie
• Humidity, airflow and
temperature directly affect
the state in which water
exists and the rate in
whichthe change occurs.
• The process requires restorers to change liquid water
into vapour (evaporation).
– Water vapour must be removed from the building
– Dehumidification
• by changing the vapour to water by cooling it
– Air exchange
• venting the moisture laden air out of the building and bringing in
air from outside.
Air movement
• Facilitates evaporation by removing the
boundary layer of humid air from around the
wet surface.
• Lowering the vapour pressure at the surface
• The more moisture a material contains the faster
the water will evaporate.
• Greater evaporation rates require more airflow
to maintain the lower vapour pressure across
the surface.
• As materials dry less air flow is required. WHY?
Air movement
• Road block - Large amounts of air movement creates two
problems.
• Air movement creates thermal loss (cools down).
– Cooler air and cooler surface materials
– Less energy is transferred to the moisture molecules
– Not sufficient energy to make the phase change to escape the material.
• Large quantities of air movers create a lot of heat energy (BTUs).
– In theory the heat created by the air movers aids in the drying process
as the heat energy is transferred to the water molecules
– BTUs created by the air movers can generate temperatures above 32
degrees
• outside of the efficient operating ranges of refrigerant dehumidifiers.
Humidity
• Dehumidification is used to remove
moisture from the air lowering the vapour
pressure
• Equipment used to create air movement
can continue to facilitate moisture
evaporating from the wet structure or
contents.
Humidity
• Road block – Limiting the temperature to the limitations
of the dehumidifier hinders the evaporation rate.
• By raising the temperature, relative humidity is reduced,
increasing the ability of the air to hold more moisture.
(Increasing thirst).
• Above 32 degrees the dehumidifier does not have
enough capacity to reduce the temperature of the
incoming air to dew point.
– hence condensation on the dehumidifier coils.
• Large amounts of air movement equipment can create a
lot of heat.
Humidity
•
As the amount of water in the structure decreases and the vapour pressure
becomes lower the efficiency of the dehumidifier is also reduced.
•
Lowering the temperature of the incoming air closer to 20 degrees towards
the end of the job ensures the dehumidifier can achieve the required
temperature drop to achieve dew point.
•
But it is in this phase additional energy in the form of heat accelerates the
drying process.
•
Common ways to control temperatures:
– use the building air conditioning system
– install portable air conditioning systems
– reduce or increase the amount of air movers
– temporarily use cooler air from outside the structure (commonly called burping).
– use a controlled heating drying system to control heat and humidity …..
Drymatic.
•
lower temperature cause the water to freeze condenser coils, dehumidifier
goes into to defrost cycle.
Temperature (Heat)
• Two main conclusions that can be drawn from
research
– At the beginning of the drying process where there is
a lot of free water not bound in the materials, a 10°C
temperature increase causes a doubling of the
evaporative rate.
• Equivalent to doubling the amount of air movers.
– Following this towards the end of the process where
evaporation is decreased due to water being bound in
the materials the terminal drying rate increases
rapidly with increases in temperature.
• Heat gives the water the energy required to make the phase
change from water to vapour.
Temperature (Heat)
• Road block – Simply heating up the structure
with heaters ensures vastly faster evaporation
rates.
• Uncontrolled heat and fast evaporation can lead
to overdying, differential drying or drying too
fast.
• Knowledge and technology required to
understand how much heat and how to control it
is now available.
• Drymatic!
of Drying
Three3 Phases
Phases
of Drying
Q l/day
Phase 2
Phase 1
Phase 1 is a critical point – failure to
mitigate at this phase will increase
drying times at phase 3
The drying system at phase 2 may
not be correct for phase 3
Phase 3
Time
Removal of
liquid water
Surface drying
Drying of material
Three Phases of Drying
• Phase 1 - Removal of Liquid Water - Extraction
– significantly affect the amount of drying equipment
– the time required to return the building and contents to equilibrium
moisture content.
– Effective extraction will also ensure less destructive methods of
restoration are required.
• Phase 2 - Surface Drying
– Surface drying of carpet underlay and surface water from building
materials such as timber and concrete.
• Phase 3 – Drying of Structural Materials
– Drying of water bound in materials.
– Different methods, knowledge and tools are required to get the
energy required to the bound water to ensure phase change.
Determining Equipment
Requirements
• Extraction
• Air movement
• Dehumidification
• Heat Drying Equipment
• Air Filtration Devices
Extraction
• Effective removal of standing water will
significantly affect
– The amount of drying equipment and
– the time required to return the building and
contents to equilibrium moisture content.
• Effective extraction will also ensure less
destructive methods of restoration are
required.
Extraction
• The greater the air flow and vacuum pressure, the more effective that
equipment will be
– Truckmounted equipment has significantly higher
airflow and vacuum pressure is more effective in
removal of standing water.
– Specialised portable flood extraction equipment
that uses shorter hose lengths and larger diameter
hoses (2 inch) can be effective.
• Portable equipment exhaust air should be vented outside of the building.
– Small vacuums such as shop vacs or wet vacs and domestic vacuums do
not provide adequate power for effective extraction.
Extraction Tools
• A weighted compression can use heavy weights or as a
stand on machine and works on the principle of
extracting/pushing the water out of the underlay through
the carpet and into the extraction machine.
• A vacuum sealed (water claw or equivalent) can be used
with truckmount and portable extraction equipment.
– As the vacuum sealed tool
requires water to create the
vacuum seal
– Recommended to first extract
with the tool to remove as
much water as possible from
the underlay
– Completing extraction with a
conventional carpet cleaning
wand.
Extraction Tools
• A conventional carpet cleaning wand
is not efficient at removal of water
from carpet underlay.
– Where specialised extraction tools are not
utilised it is recommended the carpet underlay
is removed.
– A carpet cleaning wand is effective for
extraction direct stick carpets.
– Extraction test to gauge the effectiveness of
extraction on carpet
Extraction Tools
• To ensure adequate extraction from hardwood
flooring
– install wood floor panels and attach them to a truck
mount or portable flood extractor for up to a hour
• Prior to installation of
Injectidry, interair.
• This process ensures as
much of the standing water
from below and from
between the boards is
removed prior to beginning
the process of attempting
to remove the bound water.
Air movement
• Air movers are used to facilitate evaporation by removing
the boundary layer of humid air from around the wet
surface.
• Air movers rapidly supply dryer air directly to the wet
surface and thereby lowering the vapour pressure at the
surface which facilitates faster evaporation.
• Secondly air movers are used to manage air movement
around the structure.
– Air management eliminates the need to use equipment in all affected
areas.
– Used to manage air pressure, humidity, and temperature or air quality.
Different types of air movers
• Traditional carpet dryers
– commonly referred to as air movers or
blowers.
– 3/4 hp motor, more static pressure.
• Static pressure is used by air movers
to lift carpet,
• With accessories used to duct air into small spaces
such as wall cavities and under cabinets and under
hardwood flooring.
Different types of air movers
• Low amp air movers
– smaller than ¾ hp, lower air movement
and lower static pressure.
– The advantage of using low amp air
movers
• more air movers can be used on one circuit
whilst generating large volumes of CFM
• generating less heat than traditional carpet dryer air movers.
– Used in less destructive restoration processes
• where excess heat generation will affect the performance of
dehumidifiers
• Where power supplies are limited.
Different types of air movers
• Low pressure axial fans
– used to move large volumes of air with lower amp
draw.
– drying long surfaces and open areas and carpets.
– not useful for pushing air into cavities and through
duct work.
– The advantage of using low amp air movers
• more air movers can be used on one circuit whilst generating large volumes
of CFM
• generating less heat than traditional carpet dryer air movers.
– Used in less destructive restoration processes
• where excess heat generation will affect the performance of dehumidifiers
• Where power supplies are limited.
Different types of air movers
• High pressure ventilating fans
– used with ducting to move large
volumes of air.
– used to generate strong positive or
negative air pressures
– used to manage air pressure, humidity, temperature
or quality.
– Specialty air movement equipment air mover adaptors
used to inject air flow under cabinets, into wall and
ceiling cavities and under hardwood flooring.
Different types of air movers
• Low Volume High Pressure Air Movement systems
– Interair Drying System or Intectitdry
– used when more pressure is needed but air volume is less important.
•
They can be setup in either positive pressure or negative pressure
•
used to dry cavities such as under cabinets,
wall cavities and under hardwood flooring.
•
100 CFM and produce up to 60 inches of
static pressure
– standard air mover typically produces 2-3
inches of static pressure
– Since cavities have a small volume of air space
the low CFM of the unit is effective in drying.
– Pressure is the main focus of the system.
– A large amount of pressure is required to push
or pull air through lengths of tubing, through
walls or other cavities or pull air through floor
board cracks and crevices.
Different types of air movers.
• Direct air drying systems and heat boosters
– specialised Direct Air Drying wall and floor matt systems
– constant warm air stream can be directed at wet surfaces
– warm air
stream will
quickly
remove the
boundary
layer and
promote fast
and efficient
evaporation
To estimate the number of air
movers required
(conventional dehumidification)
•
Determine the square meters and class
•
Divide the square meters by the factors as follows
– Class 1:
• divided the square meters by 14, then divide square meters by 28
– Class 2 or Class 3:
• divide the square meters by 4.6, then divide square meters by 5.6
•
The resulting number is the minimum and maximum range or air
movers needed
•
Additional airflow may be required for offsets such as closets and bay
windows
•
Speciality air movers maybe required if sub surfaces require air flow
•
The number of air movers may need to be increased or decreased through
out the drying process based on changes in the psychometric readings and
moisture readings.
Guidelines for placement of air
movers using
(conventional dehumidification)
• In a class 2 or class 3 water loss
– every 3 – 4 meters along the wall
• Air mover are placed at a 15 to 45 degree
angle facing the wall
• Air mover snout 2 – 3 cm of the wall but not touching it
• All air movers in each area will face the same direction
– ensure that air movers are creating a cyclone effect and not
pushing against each other
• The positioning of air movers may need altered through
out the drying process based on changes in the
psychometric readings and moisture readings.
Guidelines for number and
placement of air movers
(heat drying systems)
• Minimal air movement is required
• just enough air movement to ensure warm
air is circulated evenly around the
structure
• high energy systems air movement must
be enough to adequately ventilate the wet
air from the building.
Dehumidification
• Dehumidification is used to remove moisture
from the air so that the equipment, used to
create air movement, can continue to facilitate
moisture evaporating from the wet structure or
contents.
• A balanced drying system is achieved when the
rate of dehumidification exceeds the rate of
evaporation.
– Conventional Refrigerant
– Low Grain Refrigerant
– Desiccant
Conventional refrigerant
dehumidifiers
• Air temperatures between
18 and 32 degrees
• Minimum specific humidity of
65 grains per pound.
• Used for class 1 water loss situations such as
drying wet carpet and underlay.
• Conventional dehumidifiers perform very well for
class 1 water loss situations
– not suitable for drying structural building materials.
Low Grain Refrigerant
Dehumidifiers (LGR)
• Low grain refrigerant dehumidifiers (LGR) achieve
higher efficiency by incorporating a pre cooling
stage which provides the dehumidifier with
precooled air to process.
• work most efficiently with air temperatures
between 18 and 32 degrees
• minimum specific humidity of
35 grains per pound.
• LGRs are recommend for most water loss
situations including drying of some more porous
structural components.
• all brands all makes and models
performance can be improved by managing air temperatures.
– Higher temperature with a maximum temperature of 30 degrees is
optimal at the beginning of the job where high humidity exists
– gradually lowering temperatures to a minimum of 20 degrees is optimal
towards the end of the job where lower humidity exists.
Low Grain Refrigerant
Dehumidifiers (LGR)
• Common ways to control temperatures
– use the building air conditioning system
– install portable air conditioning systems
– temporarily use cooler air from outside the structure (commonly
called burping)
– Where additional heat is required to increase temperature
thermostat controlled convection heat dry systems such as
Drymatic can be used.
• When comparing dehumidifier capacity and performance
look at the AHAM rating not the total daily capacity
• plus look at the performance of the dehumidifier in LGR
conditions of specific humidity of 35 – 65 gpp)
Dri-Eaz LGR 7000
• Easily outperformed it’s closest
competitor and AHAM
• Under LGR conditions outperformed
the competition by as much as 40%.
• Advanced Crossflow Technology to
maximize energy utilization
• Plus - Built-in sensors constantly monitor
real time performance data to automatically
calculate ideal operating parameters – such as
fan speed and cycle duration.
Desiccant Dehumidifiers
•
As usually only 75% of the process air is returned to the structure negative
air pressure is usually created in the structure.
– Care to ensure the quality of the makeup air entering the structure.
•
achieve a very low specific humidity of 10 grains per pound
•
efficient at drying structural components such as hard wood floors and wall
cavities.
•
Capacity of desiccant
dehumidifiers is
expressed in the
volume of air that can
be processed per hour
either CFM or CMH of
the process air exiting
the dehumidifier.
•
High volume desiccant
dehumidifiers are very
good at structural drying
as they produce large
volumes of warm dry air.
To estimate the number of
dehumidifiers required to start the job
• Determine volume of air (L x W x H)
• Note the capacity of the dehumidifiers
– AHAM litres per day rating of the refrigerant/LGR
– Process air out cubic meters per hour (CMH) of the
desiccant.
• Determine the classification of water loss
– Class 1, Class 2, Class 3 or Class 4
Dehumidification Factor Table
Class 1 Class 2 Class 3 Class 4 Units
Conventional
Refrigerant
6
2.4
1.8
N/A
Cubic meters per litre
LGR
6
3
2.8
3
Cubic meters per litre
Desiccant
1
2
3
2
Air exchanges per hour
Refrigerant/LGR
• Cubic meters ÷ Dehumidification factor =
AHAM Litres required
• Divide the AHAM litres required by the
AHAM litres of the units to be installed to
get the minimum number of units required
to start the job
– round up
Desiccant
• Cubic meters x Dehumidification factor =
CMH required to start the job
• Divide the CMH required by the CMH of
the process out air of the units
• round up
Dehumidification Factors
• A guide for the minimum dehumidification equipment required to
ensure a dehumidification exceeds evaporation.
– i.e. a balanced drying system
• After initial setup dehumidification may need to be increased or
decreased based on changes in the psychometric readings and
moisture readings.
• Relative humidly should not linger above 60% for any length of
time.
– If it does… inadequate extraction or not a closed drying chamber
• With adequate extraction relative humidity of 40% or below should
be achieved within the first 24 hours
– If it does… inadequate extraction, not close drying chamber, or
recalculate dehumidification required
Understanding Thirst
• Practical exercise
Understanding Thirst
Understanding Thirst
Understanding Thirst
Start of the job
100% - 60% =
40% Thirst
End of the job
100% - 40% =
60% Thirst
Understanding Thirst
100% - 33% =
67% Thirst
100% - 20% =
80% Thirst
Understanding Thirst
• Adding 10 degrees at the beginning
– 40% x 167.5%
= 67% thirst
100% - 33% =
– increases the thirst of the air by 167.5%
67% Thirst
• Adding 20 degrees at the beginning
100% - 20% =
– 40% x
80% Thirst
200% = 80% thirst
– increases the thirst of the air by 200%
Understanding Thirst
100% - 7% =
93% Thirst
100% - 14% =
86% Thirst
100% - 24% =
76% Thirst
Understanding Thirst
• Adding 10 degrees at the end
– 60% x
100% - 7% =
126.7%
= 76%
93% Thirst
thirst
– increases the thirst of the air by 126.7%
•
100% - 14% =
Adding
degrees
86%20
Thirst
at the end
– 60% x 143.3% = 86% thirst
100% - 24% =
76%
Thirst
– increases
the thirst of the air by 143.3%
• Adding 30 degrees at the end
– 60% x 155% = 93% thirst
– increases the thirst of the air by 155%
Why can’t I raise the temp of the job when
using a dehumidifier?
• Temperature drop required
by the dehumidifier to reach
dew point (condensation on
the coils)
Dew Point
– 20 deg – 6.5deg = 13.5 deg
• Adding 10 degrees it still
below 30 deg so the
dehumidifier should still work
right?
– 30 deg – 6.5deg = 23.5 deg
– The dehumidifier does not
have enough capacity to
achieve the temperature
drop required to reach dew
point
–
About 18 degrees does not mater which make
model or brand
Why does the dehumidifier not work
efficiently below 18 degrees?
Water freezes at
zero degrees
• Temperature drop
across the coils of 18
degrees
• 18 degrees in the room
minus 18 degrees
across the coils = zero
• Water freezes at zero
• Dehumidifiers goes into
defrost cycle, starts up
again, minimal time
goes into back into
defrost cycle again…
and so on
Heat Drying Equipment
• two main conclusions that can be drawn from research
– at the beginning of the drying process where there is a lot of
free water not bound in the materials, a 10°C temperature
increase causes a doubling of the evaporative rate.
– towards the end of the process where evaporation is decreased
due to water being bound in the materials the terminal drying
rate increases rapidly with increases in temperature. [1]
•
[1] C. Hall, W. D. Hoff M. R. Nixon, Water Movement in Porous Building
Materials VI. Evaporation and Drying in Brick and Block Materials; Building
and Environment, Vol. 19, No. 1, pp. 13 20, 1984
Heat Drying Equipment
• The installation of air moving and dehumidification
equipment in phase 3 of the drying regime will continue
to assist in the evaporation of the surface and
subsurface moisture,
– the use of air movers and dehumidifiers alone have limited
ability to decrease the drying times of structural building
materials where water is bound in difficult to dry wet hardwood,
concrete, tile and brickwork.
• Introducing heat energy and better interaction of the
equipment and using target drying attachments
increases the efficiency of standard drying equipment.
Hence, drying times can be significantly reduced.
High Energy Systems
• Use an external source of energy which
operates by heating outside air over ceramic
plates or in ovens
– heated by using propane/butane.
• Hot air is driven into the building by fans which
is used to create a very hot environment as the
lower vapour pressure within this hot air stream
generates faster evaporation within the higher
vapour pressured materials
• Moist warm air is continually flushed from the
building.
High Energy Systems
High Energy Systems
• Requires more consistent monitoring to
stop excessive drying taking place
• There can be thermal stress on the
surface of delicate materials due to the
low specific humidity of the air passing
over the surface creating fast surface
drying without transfer of energy to the
moisture within the material.
High Energy Systems
• Particularly good for drying subfloors.
• Air movement out of the sub floor area must exceed the air
movement into the sub floor area to ensure negative air pressure in
the space.
• Ensure no cross contamination of the rest of the building from air
borne particulate or contaminants from within the sub floor area.
• To heat the inside the building
the air movement used to
“flush” the structure should
be enough to create neutral or
slightly positive air pressure.
• Thermostat controls to turn air
movers on and off work well in
this application.
Convection Systems
• Convection Systems heat air by electrical element or by
heat exchange systems which usually use a heated
glycol solution.
• Gradually increase the temperature of the room
increasing the ability of the air to hold more moisture
allowing faster evaporation.
• Gradually heat the surfaces and materials that are wet,
which in turn increases the rate of evaporation.
• Heating elements fuelled by electricity and are less
expensive to run than the high energy or heat exchange
systems.
Convection Systems
• Heating up the air within the room increase the ability of
that air to allow more evaporated moisture into it by
reducing its relative humidity
• Warm air rising and cool air falling in the room creates
gentle air movement across the wet surfaces
• Wet air has to be removed and be replaced with drier air
• Systems use an air exchanging method, where the warm
wet air in the room is periodically flushed to the outside
and pre heated fresh air from outside or preconditioned
drier air from unaffected areas is pumped in to replace
it.
Drying Intelligence - Drymatic
•
The Drymatic’s unique operation is based upon it’s evaluation of the
humidity and temperature of the room to be dried and then operating in the
mode that provides maximum drying effect.
•
in ‘re-circulation’ mode tales air from within the room being dried and
continually re-heating it until pre-set temperature and humidity levels have
been reached.
– These settings can either
be determined by the
technician or the default
settings of the machine.
•
It then switches automatically
to ‘exhaust mode’ warm wet
air is extracted from the from
the room and replaced with an
equal amount of fresh
pre-heated air from
an unaffected area
Drymatic Operating Modes
• Re-circulation Mode
• Exhaust Mode
Drying Intelligence - Drymatic
• Adding controlled heat to the environment speeds up the drying
process by promoting evaporation of moisture from the wet
structure and contents.
• Increasing the ambient temperature allows the air to take on a
higher water vapour content, which is then removed out of the
property.
• Within limits defined by the
user, the Drymatic will
monitor and adjust the
room’s environment,
constantly optimising and
exchanging the moist air
with warm, dry air in a controlled
manner to remove odours and
ensure a faster, fresher and
more efficient drying environment.
Drying Intelligence - Drymatic
• Sensors can be used to specify a drying goal based on a known ‘dry’
material ensuring that the property is not over-dried or under-dried.
• The infra-Red sensors communicate with the machine and enable
the user to track the progress of specific walls/floors/ceilings within
a room.
• Optional On-Board SMS Text Messaging Facility can communicate
with a drying technician to notify them of any important events
during the job.
Drymatic Boost Box
•
2 kilowatt heating system gradually
reaches its set temperature over a set
period of time depending on which setting
it is on
•
designed to use in line with existing air
moving equipment and dehumidifiers,
as a standalone heating system, as an
external boost for the Drymatic or to heat
up the air entering a Drymatic Floor & Wall System
– operating dial is set with these settings:
• DADs System - maximum 30 degrees, (works at this temperature setting in
conjunction with dehumidifiers at the beginning of the drying process)
• Boost for Drymatic - maximum 40 degrees,
• Auxiliary Heater - maximum 50 degrees.
•
Also the 10 amp system allows the use of an airmover on standard
domestic electrical circuits without causing any problems.
•
The airmover plugs into the boost box, so that the intelligent drying system
can switch the airmover on and off as required.
Drymatic Boost Box
• 10 amp system allows the use of an
airmover on standard domestic electrical
circuits without causing any problems.
• the airmover plugs into the boost box, so
that the intelligent drying system can
switch the airmover on and off as required.
• 4 RH% sensors can be used.
• One of the sensor sockets is for a
control measurement (dry standard)
• the other 3 are for sensors to be
placed in the wet areas.
• Air mover and boost automatically
turns of when dry standard is reached
and maintained
The Drymatic Floor & Wall System
• Allows hot air to be
directed onto the
surface of a wet material
and this air turbulence
prevents the build up of
a static boundary layer
and therefore increases
the evaporation rate of
the material.
– inflated by standard
air-movers and using
the hot air generated
by the Drymatic into
the intake of the air-mover
– or by the “Boost box” in-line with a standard air mover.
• The versatility of the Drymatic Floor & Wall System allows for target
drying to surfaces with the addition of thermal energy (heat) being
directed onto those wet areas, thus increasing evaporation.
To estimate the number of
Drymatics required to start the job
• As a general rule of thumb
– depending on the amount of moisture present in the structure, and the
potential for thermal loss.
• Large windows, lots of wet contents
• Determine the number of large LGR dehumidifiers required to start
the job from the above table and divide by three.
• The calculation gives you the number of dramatic systems required
– add boost boxes and drying mats to compensate for wetter materials
and thermal loss or to target dry wetter areas.
• Install minimal air movers to ensure adequate circulation of warm
air through the structure.
• The circulation of air coming in and out of the drymatic is typically
enough for most rooms.
Combination Drying Systems
• Can be used to enhance performance of heat drying
systems.
– dehumidification can be used to precondition air from an
unaffected area prior to heating
– dehumidifiers can be used in effected areas in initial stages of
drying provided the temperature of the air within the structure is
controlled and does not exceed the effective operating range of
the dehumidifier (maximum 32 degrees).
Combination Drying Systems
• Advanced heat drying systems monitor
temperature and humidity.
• Systems that do not have pre-set temperature or
humidity controls are required to be set up with
air movement to continually flush hot wet air
from the building
– or air movers that are thermostatically controlled to
flush warm wet air from the building.
Combination Drying Systems
• Less air movement is required when using
heat drying systems.
• Evaporation created by larger amounts of
air movement directed across a wet surface
causes thermal loss.
• Typically air movement used in heat drying
is used to gently circulate warm air around
the structure and heat wet surfaces.
• Low amp air movers set on low speed are
best suited for this purpose
Direct Fired Heating Systems
• Direct fired heating systems, such as direct fired LPG burners are
not recommended.
• Heat exchanger
systems ensure
combustion
by-products
and moisture
created by
burning fuels
are separated
from the
heated air
used to dry
the structure.
Thermal Loss
• Setting up heat drying systems can at times be bit more complex
than traditional drying using dehumidifiers and air movers.
• Many water loss situations require thought about how the system
should be set up to ensure maximum efficiency.
– Target heating a smaller area is much more efficient than attempting to
heat up the whole structure.
– The use of tenting or containment to contain the heat to only areas that
are wet will greatly improve the efficiency of the heat drying system.
• Particular care must be taken to evaluate where heat can be lost
from the drying envelope.
– Large amount of wet contents
– Cold surfaces such as large uninsulated
glass doors and windows.
– Tiled bathrooms that are not wet should
be isolated.
Air Filtration Devices
•
•
•
Commonly referred to as air scrubbers, negative air
machines or HEPA filters.
Air movement used to create evaporation create high
levels of air borne particulates and possible contaminants
reducing air quality
Occupants and contractors are at risk of significant discomfort from the
reduced air quality.
– very young, elderly, occumpanyts have respiratory illnesses such as asthma, or
are immune compromised.
– In these cases AFDs are required.
•
•
Carbon or odour adsorbing material filters can be used to reduce odours
and VOCs (volatile organic compounds) or MVOCs (microbial volatile organic
compounds) often found in water loss situations.
AFDs can be used to manage air pressure on water loss situations where
there is potential to spread possible contaminants such as mould and
bacteria.
– Isolating areas and creating negative air pressure in areas that are potentially
contaminated is required.
•
CADR (clean air delivery rate) is expressed in CFM or CMH and is the
amount of actual clean air delivered by the unit after filtration.
Guidelines for the quality of AFDs
required to be installed:
• Determine volume (L x W x H)
• Determine the number or air exchanges
per hour (AEH) required
– 4 to 10 air changes per hour depending on
the level of contamination
• Cubic Meters x AEH = CMH/CADR
– round up
AFDs and Heat Drying Equipment
• An additional benefit to using heat
drying equipment
• Exchange moisture laden air with
fresh air from outside the structure
or preconditioned air from an
unaffected area.
• The process of air exchanges greatly
increases the quality of air within the
structure
Target Drying
• Tenting - dry and or hot air,
delivered under a polythene
envelope to create a
microclimate on the surface
of the damp material
Target Drying
• Matts use a process of impingement drying
– Air directed on to the surface is more effective than air blown
across the surface.
– The main reason for the improved effectiveness is that the
turbulence prevents the build up of a static boundary layer that
can insulate the surface from the drying medium.
Target Drying
• Side by Side - using wall drying matt, a constant hot air stream
can be directed at a wet wall to which the impingement method of
the air stream will quickly remove the boundary layer and promote
fast and efficient evaporation
• Water bound in materials above and around the mat will be draw
to the warm dry areas. Wet goes to dry
Target Drying
•
Injectidry or Interair delivers air
through small holes into building
voids to release trapped moisture
•
Either force air into or suck the
moisture laden air out of the
voids.
•
Useful for drying behind gyprock.
•
When sucking from wall cavities
HEPA filtration attachments on the
exhaust of the equipment is
required
Drying Timber Floors
• Injectidry or Interair air used in suction mode on timber
floors to create very low vapour pressure at the surface
of the floors boards.
• High pressure air movers
with specialized attachment
are used to push air under
hardwood flooring
• Used in combination
with heat drying
systems this equipment
is very effective
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Drying Timber Floors
Problems with differential drying
•
Problems can arise where wood is dried
from one side only, as this can
sometimes cause distortion to occur.
•
An example is when a wooden floor or
wood panelling is dried from the
surface only. At first the surface
becomes dry and the underside
remains damp.
•
The surface shrinks and the underside
remains swollen, causing the boards to
dip or “cup” in the centre.
•
Often this will flatten when the whole
board dries, but sometimes this
distortion will be permanent, ruining
the item and requiring replacement.
•
This problem can be avoided by
introducing dry air to both sides of the
material to even up the process.
Moisture meters
• Moisture sensors
• Non-Penetrating moisture meter
• Penetrating moisture meter
• Thermo-hygrometers
• Combination Meters
• Data Collection
• Thermal Imaging
Measuring Moisture in Building
Materials
• Quantitative Readings
• Qualitative Readings
• Dry Standard
• Equilibrium Moisture Content (EMC)
• Equilibrium Relative Humidity (ERH)
The Drymatic System
Installation Procedure
1. Air from outside
•
or preconditioned
air from an
unaffected area
2. Air to Outside
3. Heater Outlet
Optional
System Set-Up
• Step One – Connect Power
• Step Two – Insert Data Card (skip if not using)
• Step Three – Switch On
• Step Four – Error Code 0000
• Step Five – Reset Data Card (skip if not using)
• Step Six – Unlock and set dials
• Step Seven – Starting up
Practical
• Setting up Drymatic
• Setting up Injectidry