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 affectthe state in which waterexists 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!

Three Phases of Drying

Phase 1 Phas

e 2

Phase 3

Time

Q l/day

Removal of liquid water

Surface drying Drying of material

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

3 Phases of Drying

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 inremoval of standing water.

– Specialised portable flood extraction equipment that uses shorter hose lengths and larger diameterhoses (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 thevacuum seal

– Recommended to first extractwith the tool to remove asmuch water as possible fromthe underlay

– Completing extraction with aconventional carpet cleaningwand.

Extraction Tools

• A conventional carpet cleaning wandis not efficient at removal of waterfrom 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 ofInjectidry, interair.

• This process ensures asmuch of the standing waterfrom below and frombetween the boards isremoved prior to beginningthe process of attemptingto 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 movementand lower static pressure.

– The advantage of using low amp airmovers

• more air movers can be used on one circuitwhilst 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 ofdehumidifiers

• 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 throughduct 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 largevolumes of air.

– used to generate strong positive ornegative 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 ofstatic pressure – standard air mover typically produces 2-3

inches of static pressure

– Since cavities have a small volume of air spacethe 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 pushor pull air through lengths of tubing, throughwalls or other cavities or pull air through floorboard 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 airstream willquicklyremove theboundarylayer andpromote fastand efficientevaporation

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 degreeangle 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 between18 and 32 degrees

• Minimum specific humidity of65 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 coolingstage which provides the dehumidifier withprecooled air to process.

• work most efficiently with air temperaturesbetween 18 and 32 degrees

• minimum specific humidity of35 grains per pound.

• LGRs are recommend for most water losssituations including drying of some more porousstructural components.

• all brands all makes and modelsperformance 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 closestcompetitor and AHAM

• Under LGR conditions outperformedthe competition by as much as 40%.

• Advanced Crossflow Technology tomaximize energy utilization

• Plus - Built-in sensors constantly monitorreal 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 desiccantdehumidifiers isexpressed in thevolume of air that canbe processed per houreither CFM or CMH ofthe process air exitingthe dehumidifier.

• High volume desiccantdehumidifiers are verygood at structural dryingas they produce largevolumes 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

End of the job100% - 40% =

60% Thirst

Start of the job100% - 60% =

40% Thirst

Understanding Thirst

100% - 33% = 67% Thirst

100% - 20% = 80% Thirst

Understanding Thirst

100% - 33% = 67% Thirst

100% - 20% = 80% Thirst

• Adding 10 degrees at the beginning– 40% x 167.5% = 67% thirst

– increases the thirst of the air by 167.5%

• Adding 20 degrees at the beginning– 40% x 200% = 80% thirst

– increases the thirst of the air by 200%

Understanding Thirst

100% - 14% = 86% Thirst

100% - 24% = 76% Thirst

100% - 7% = 93% Thirst

Understanding Thirst

100% - 14% = 86% Thirst

100% - 24% = 76% Thirst

100% - 7% = 93% Thirst

• Adding 10 degrees at the end– 60% x 126.7% = 76% thirst

– increases the thirst of the air by 126.7%

• Adding 20 degrees at the end– 60% x 143.3% = 86% 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)– 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

Dew Point

Why does the dehumidifier not work efficiently below 18 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

Water freezes at zero degrees

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 buildingthe air movement used to“flush” the structure shouldbe enough to create neutral orslightly positive air pressure.

• Thermostat controls to turn airmovers on and off work well inthis 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 thetechnician or the defaultsettings of the machine.

• It then switches automaticallyto ‘exhaust mode’ warm wetair is extracted from the fromthe room and replaced with anequal amount of fresh pre-heated air froman 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 theuser, the Drymatic willmonitor and adjust theroom’s environment,constantly optimising andexchanging the moist airwith warm, dry air in a controlledmanner to remove odours andensure a faster, fresher andmore 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 setperiod of time depending on which settingit is on

• designed to use in line with existing air moving equipment and dehumidifiers,as a standalone heating system, as anexternal boost for the Drymatic or to heatup 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 bedirected onto thesurface of a wet materialand this air turbulenceprevents the build up ofa static boundary layerand therefore increasesthe evaporation rate ofthe material.– inflated by standard

air-movers and usingthe hot air generatedby the Drymatic intothe 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 exchangersystems ensurecombustionby-productsand moisturecreated byburning fuelsare separatedfrom theheated airused to drythe 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 uninsulatedglass doors and windows.

– Tiled bathrooms that are not wet shouldbe 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 contaminantsreducing 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 moverswith specialized attachmentare used to push air underhardwood flooring

• Used in combinationwith heat dryingsystems this equipmentis 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

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