TES & S500
What Do the Standards say about Heat Drying and TES?
Pages 7 – 88 of the S500 is the “Standard” section. This summarizes what is the “standard of care” in the water damage restoration industry. The standard not only recognizes every one of the principles of drying used by TES, it recognizes the science behind TES, but in many situations, heat based drying systems (also called thermal drying systems in the S500) using negative pressure along with dehumidification by exchange of indoor air with outdoor air is the RECOMMENDED method. When the standard uses the term “recommended” this is the advised or suggested method to meet the standard of care.
The standard section is followed on pages 89-317 by an expanded reference guide. The standard is taken from this reference guide.
Let’s look at several of the many examples that prove conclusively that S500 supports direct application of heat and TES. Numbering refers first to the page, then to the section and subsection where this information can be found.
P. 184.2.4.4 Temperature control is important to control evaporation rate. Temperature application, modification and control are important basic principles for safe, effective drying
6.1.3 (page 20) Restorers should manage both air & surface temperature in order to enhance drying and avoid potential related damage…
P. 20 6.1.1 “Restorers should manage airflow to exchange humid air from a space with more favorable air...”This is exactly how TES removes warm, moist air.
P. 39 9.10.8.4.4 When drying wood flooring attempt to reach target humidity of 45% or less. Ambient temperature may be increased to expedite both evaporation and dehumidification.This is precisely what TES does; increase the temperature to expedite evaporation.
P. 49 12.1.11 Ventilating the structure may be an effective way to reduce the build up of excess humidity. Of course, TES set-up normally uses ventilation to reduce humidity.
P.51 12.1.20 Controlling airflow increases evaporation. Note the third bullet point – Means to increase the rate of evaporation include increasing air or surface temperature.
P. 52 12.1.22 “Controlling Temperature to Accelerate Evaporation - ...the temperature of the wet materials themselves impacts the rate of evaporation significantly. Water in its vapor phase (gas) has much higher energy than water in its liquid phase. Therefore significant energy is required for evaporation. ...”
P. 52 12.1.23 “Applying Heat Directly to Materials - ... thermal energy transfer and other systems employing direct heat application can be used to increase the temperature of wet materials.... Additional direct heat can accelerate drying of wet materials, especially, dense, less-permeable materials.”
P. 55 12.3.1.1 “Techniques for Drying Carpet & Cushion ...Partial Floating: Carpet is disengaged at one corner and heated air is injected under the carpet but on top of the cushion. The carpet acts as an insulator to maintain heat in close proximity to wet surfaces.”
P.58 12.3.2.10.1 Encourages use of vac panels on wood flooring
P.58 12.3.2.10.4 “Heat on materials – Drying walls, solid wood flooring or the underside of subfloors, such as plywood, can be accelerated using heat.”
This section also recommends the use of heat along with negative pressure (vac panels) for drying wood floors.
P.60 12.3.8“After removing excess moisture, concrete should be dried using a combination of controlled dry air movements...or direct heat application.”
P.6112.4.1.1 For drying wood framing the Standard states “Low vapor pressure, often combined with hot dry air movement across material surfaces, may be required to ensure sufficient drying.”
P. 64 12.4.4.1“With stone or tile flooring installed over wood subflooring materials, restorers should introduce hot, low humidity air below the subfloor”
P. 6412.4.4.5On the subject of drying water trapped between layers of flooring (or walls) the standard says “Restorers should accelerate drying using rapid movement of dry (often hot) air across the top or bottom surfaces of the assembly as well.”
Even with the drying of contents, the standard recommends the use of directed air flow and controlled heat. (P.7614.4.4)
TES uses the general principles set forth in the S500 standards, thorough extraction, air flow and control of temperature.
The science behind TES – vapor pressure and increasing differential in vapor pressure is the key to evaporation according to the S500.
The use of a partial or soft float of the carpet is approved by the standard. Direct application of heat for drying carpet, sub floors, walls, wood floors, stone or tile flooring and wood framing are all recommended practices. They also need heat for layered materials. Any restorer who can not follow these recommendations is not meeting the standards.
TES can even be used for contents in some situations.
The Reference Guide section reinforces these points. In several places, the reference guide even uses the same illustration that has been used to promote TES. For example Chapter 4 (beginning on the bottom of page 105) discusses vapor pressure differential with the illustration of an inflated balloon.
Chapter 5 states that “Air movement has the capacity to increase the rate of evaporation by adding additional energy to the surface of the wet materials by supplying warm air to cooler, wet surfaces.”
In fact Chapter 5 on Psychrometery, the science of drying, sums up the principle of TES in one paragraph, ““Knowing the direct relationship of SH to vapor pressure and dew point allows restorers to determine the direction of moisture movement. High SH moves to lower SH. Lower SH increases the potential for evaporation from wet materials. This is important because evaporation occurs if the vapor pressure of the air is lower than the surface vapor pressure of the wet material.”
SH means “specific humidity.”
Just a few pages later in that same chapter we get another confirmation that the science of TES works just as we have been explaining it. “Temperature plays an important role on the vapor pressure in the material. As heat is applied to a material, energy is added to the moisture present in the material. Evaporation can be increased by raising the temperature of a material and consequently the internal vapor pressure.”
Chapter 6 continues to examine the science of drying. What can the restorer do to get a structure to dry? This is how chapter 6 answers, ““the restorer’s ability to influence drying can be stated as follows: ‘Initially, with surface and free water, faster rates of evaporation are achieved when air is warmer, drier and moved faster closer to a wet surface and materials are either made warmer and/or more permeable. As materials become drier, application of air with lower humidity at the surface of a material, and increasing internal material temperatures will most effectively promote drying.’ ”
Chapter 6 continues by saying “...vapor pressure plays a significant role in moving moisture out of the material.” “When heat is applied to material with bound moisture, the bond between absorbed moisture and wood is more readily broken, thereby releasing vapor. This released vapor increases the vapor pressure within the building material, which seek lower vapor pressure (air).” – Page 131
There is even a whole section of the reference guide on heat drying systems. For those who are worried that their traditional methods of measuring relative and specific humidity and grain depression don’t seem to apply when a directed heat drying system is in use, the Reference Guide explains, “Heat drying systems require different calculation of results than traditional systems. Often SH increases while RH decreases. This is a result of large volumes of moisture released from materials. This is a desired result. Air with high SH is then exhausted from the building.”
We could go on with a dozen more quotations showing the current S500 standard recognizes, approves and even recommends heat based drying systems. But the above should be enough to make the point that the science behind TES, the application of directed heat drying and the proven results are in harmony with S500 standards and that any restorer who can not make use of directed heat drying is “sub-standard!” If you would like some more information you can reach me at 727-657-1563.
Respectfully,
TES Drying System