How DrySooner Automation Works
Every 6 minutes the system reads each sensor, evaluates safety safeguards and control rules in strict priority order, and automatically turns drying machines on or off. This page explains the science behind each decision and the material limits that drive it.
Automation Safeguards and Rules
Safety checks run before normal RH cycling every cron cycle. The first rule that fires wins — lower-priority rules are not evaluated for that cycle.
Any fresh interior sensor on the job reports RH below the job's emergency threshold (default 30 %)
ALL active drying machines on the job turn OFF, physical shutoff is confirmed by re-reading each plug, an operations alert is sent, and the shutoff latches until a technician manually resets the job
This is a job-wide safety net, not part of the per-room control loop below — it runs for every running job regardless of whether unattended automation is armed or paused, so a technician relying on manual switches still gets the same emergency floor protection.
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Evaluated first, before and independently of the material-based control loop (rules 1–6): the cron checks every active job's interior sensors each cycle and, the moment any fresh reading falls below the configured threshold, commands every active drying-machine plug OFF, re-reads each plug to confirm the relay physically opened, and stamps the job so it will not re-fire. Because it does not depend on automationEnabled, it also protects jobs being run manually via the dashboard's power toggle.
- Strategic cascaded drying system (internal reference)— Sections 6 and 7.1
Specifies a job-level emergency RH floor as a last-resort safety net, independent of the per-room control policy, so an over-dry excursion cannot continue even if per-material automation is off or misconfigured.
Paired sensor has no reading, or the latest reading is older than the configured offline threshold (default 130 minutes, tuned to the battery sensors' ~2h reporting cadence)
Paired drying machine turns OFF and an operations alert is sent
Remote automation is only safe when the controller has fresh temperature and RH data. If a sensor battery dies, the hub drops offline, or the property network stalls, the machine must not keep running on old conditions.
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The strategic remote-drying document calls out data dropout as a material-damage risk: uncontrolled heat or over-drying can continue after telemetry stops. The fail-safe choice is to remove drying energy, alert a technician, and require fresh telemetry before automated control resumes.
- Strategic cascaded drying system (internal reference)— Sections 6 and 7.1
Lists sensor failure / data dropout as a risk and specifies stale-data auto-shutoff once the last reading exceeds the configured offline threshold.
Sensor RH drops to or below the material minimum (e.g. 35 % for hardwood)
Drying machine turns OFF immediately — overrides normal RH cycling
Hygroscopic materials exchange moisture with the air. An excessively dry room can cause shrinkage, cracking, gapping or delamination, but the safe envelope depends on the material, construction, finish and product instructions. This controller floor is a provisional operating safeguard, not a universal damage threshold.
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Every hygroscopic material has an Equilibrium Moisture Content (EMC), which depends on temperature, RH, material history and construction. The app stops at the selected provisional floor and requires a comparative material reading; it does not infer a universal EMC or damage threshold from room RH alone.
- IICRC S500— Section 10 — Structural Restoration, Drying Goals
Explicitly states that drying ceases when materials return to their pre-loss Equilibrium Moisture Content (EMC) — not maximum possible dryness. Over-drying is recognised as a cause of secondary damage.
⚠ Section numbering may vary between 4th (2015) and 5th (2021) editions — verify against your copy.
- IICRC S500— Section 3 — Psychrometry and the Science of Drying
Explains the relationship between RH and EMC. Lowering ambient RH creates vapour pressure differential that draws moisture from materials — but going too low causes over-drying.
⚠ Verify section against your copy.
- NWFA — Water Damage Repair Guide— p. 12 (2019 Edition)
"Do not allow RH to fall below 30 % for prolonged periods." EMC target 6–9 % for wood flooring.
Sensor temperature reaches the material buffer, the 35 °C desiccant soft limit, or the 38 °C cascade hard limit
The affected drying machine turns OFF — desiccants stop before LGRs when heat is the only issue
High temperature can accelerate surface drying, change material equilibrium moisture content and reduce equipment efficiency. Product-specific temperature limits, direct surface observations and the selected provisional profile govern. The 1.5 °C buffer gives the controller a reaction window before its policy ceiling is reached.
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The controller uses the lower of the material policy buffer, desiccant soft limit and cascade hard limit. These are DrySooner operational safeguards. The source review did not establish a universal temperature at which every plasterboard, wood, carpet or adhesive system is damaged; manufacturer and specialist limits override the app.
- IICRC S500— Section 12 — Equipment, Instruments, and Tools
Notes that LGR dehumidifiers lose performance significantly above 32–38 °C and may activate high-pressure bypass, rendering them ineffective while continuing to add heat.
⚠ Verify section against your copy.
- DrySooner source review — gypsum temperature policy— Provisional controller rule
The former 52 °C ambient calcination claim was not verified and is not used as a material threshold. The controller uses the lower versioned board-profile temperature limit and requires manufacturer or specialist confirmation.
- NWFA — Moisture, Hydration & Wood Floors— Temperature Sensitivity
Lignin (wood's natural binder) undergoes plastic deformation above ~35 °C, making cupping and warping permanent rather than recoverable.
At least five valid readings span 30 minutes and the rolling hourly or 24-hour RH-drop budget approaches the slowest selected material's current staged limit
Warn at 75 %, turn drying equipment OFF at 90 %, and hold it off until utilisation falls below 60 %
The controller can keep drying aggressively while it has rate budget, then stop before the provisional staged material rate is exceeded. Assessment, stabilisation and equalisation use half the base cap; verified bulk drying can use the full base cap. The slowest selected material always governs.
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The controller compares smoothed ambient-RH readings at the beginning and end of each rolling window. A 0.5 percentage-point allowance reduces false trips from sensor noise. The hourly allowance is prorated to the available window; the 24-hour budget is also checked whenever enough history exists. No reviewed source publishes these percentage-point rates as universal material damage limits.
- DrySooner provisional humidity-tolerance policy— Version 2026-07-22
Defines the provisional material-specific hourly and 24-hour RH-drop budgets and the controller's 75/90/60 percent warning, stop and restart utilisation thresholds.
Sensor RH exceeds the selected policy restart point, enough valid history exists, and rolling rate budget is available
Drying machine turns ON
This is the core drying duty. When the air carries more moisture than the target ceiling, the vapour pressure difference between the wet structural materials and the air is too small to drive meaningful drying. The dehumidifier removes moisture from the air, lowering its vapour pressure and re-establishing the differential that pulls moisture out of the structure.
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Drying occurs because of vapour pressure differential — moisture moves from areas of higher vapour pressure (wet materials) to lower (dry air). A dehumidifier lowers the air's absolute moisture content (gr/lb). This app records room-air GPP and its trend; it cannot calculate equipment grain depression without separate inlet and outlet measurements, so GPP is diagnostic rather than a standalone shutoff rule.
- IICRC S500— Section 12.5 — Applying Psychrometrics to Water Damage Restoration
Drying occurs when the vapour pressure of the wet material is higher than the vapour pressure of the surrounding air. Lowering the air's gr/lb creates the differential needed to pull moisture out of materials.
⚠ Verify section against your copy.
- IICRC S500— Chapter 10 — Psychrometrics
Grain depression (gr/lb in minus gr/lb out of the dehumidifier) is the standard measure of equipment effectiveness. A positive depression confirms active water removal.
⚠ Verify section against your copy.
Sensor RH reaches the selected material policy's control target and the paired machine is on
Drying machine turns OFF and stays off until RH rises above the policy restart point again
A separate stop target and restart point prevent short-cycling while keeping the emergency RH floor reserved for safety. Reaching the air-control target does not mean the material or job is dry.
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Hysteresis is a standard engineering control technique. The selected policy stores a distinct equipment OFF target and ON restart point, while rolling hourly and 24-hour budgets can stop equipment earlier if RH is falling too quickly.
- IICRC S500— Annex A — Psychrometric Modelling and Control
Supports use of deadbands/hysteresis in equipment control to prevent short-cycling and maintain stable drying conditions.
⚠ Verify section against your copy.
- DrySooner drying controller policy— Equipment cycling hysteresis
The stop/restart gap is an engineering control policy used to prevent rapid relay cycling. It is not attributed to ASHRAE 90.1 and is not a material damage threshold.
How Governing Limits Work
When a job has multiple materials, the system applies the most conservative limits across all of them — this is called the governing limit.
The lowest max-temp of all selected materials. For example, a timber limit can govern even when another structural material tolerates a higher room temperature.
The highest RH minimum. If one material must not go below 35 % and another 40 %, the floor is 40 %.
The lowest RH maximum. If materials allow 55 % and 50 % respectively, the ceiling is 50 %.
This protects every material present — the most sensitive item governs. The material whose temperature limit is lowest is named in the dashboard header so technicians know which item is driving the constraint. Pack-out and specialist-only profiles do not blend into the envelope: they block unattended automation until resolved.
Rate-Limited Control Cycling
Each selected policy has a control target and restart point. The rolling hourly and 24-hour rate guard can turn equipment off earlier when RH is falling too quickly.
The controller keeps a deadband between the ON and OFF points so machines do not hunt around one setpoint. It warns at 75 % of either rate budget, stops at 90 %, and only restarts below 60 %. The absolute RH floor and temperature ceiling remain higher-priority shutdowns.
Time alone never advances a material to bulk drying. Any recorded cracking, warping, delamination or other distress blocks unattended drying. In a mixed room, every material is evaluated independently and the lowest current hourly and 24-hour caps govern the equipment.
Material Risk Reference
These cards provide material-risk background and source-review context. The job material selector is the source of the live, versioned DrySooner operating policy, including subtype-specific hourly and 24-hour rates. Manufacturer, project or approved specialist limits override those defaults.
Grains per Pound & Dew Point
The dashboard shows grains/lb and dew point alongside RH. Here is why they matter.
Grains per pound is absolute humidity — the actual weight of water vapour in one pound of dry air (7,000 grains = 1 lb). Unlike RH, it does not change when temperature changes. A falling gr/lb line means moisture is physically leaving the structure. IICRC S500 uses grain depression (gr/lb entering the dehumidifier minus gr/lb leaving) to prove the equipment is actively removing water.
Dew point is a temperature — the point at which the air would become saturated if cooled. It measures the same thing as gr/lb but is more useful for damage prevention: if any surface in the room (e.g. a cold wall or window) drops below the dew point, condensation forms and re-wets materials. Dew point prevents rewetting, but neither dew point nor ambient RH proves material completion. Completion requires comparative moisture-content, substrate, or specialist evidence.
Standards Framework
These sources inform the provisional policy, but most do not publish universal ambient RH-drop rates. Versioned DrySooner defaults remain provisional until manufacturer, project, or approved specialist limits are verified.
- IICRC S500Standard and Reference Guide for Professional Water Damage Restoration (4th/5th Edition). The primary international standard for structural drying. Governs psychrometric targets, material drying goals, and equipment operation.
- NWFANational Wood Flooring Association — Water Damage Repair Guide (2019). Governs solid and engineered hardwood drying limits.
- ATFA Technical Bulletin 2018-02Australian Timber Flooring Association — moisture and hardwood floors. Provides Australian species–specific thresholds.
- AS 1684Australian Residential Timber-Framed Construction. Defines structural timber moisture content requirements for structural integrity.
- AS/NZS 1080.1Timber — Methods of Test — Moisture Content. Used to verify timber drying goals.
- AS 1884 / ASTM F2170Concrete subfloor testing methods. The applicable covering manufacturer or project specification supplies the acceptance criterion.
- AS/NZS 2455.1Textile floor coverings installation — defines subfloor condition requirements.
- Gypsum Association GA-216 / GA-231Gypsum board installation and water-damage assessment guidance. These documents do not establish a universal ambient RH-drop rate.
- Gypsum manufacturer bulletinsProduct-specific guidance overrides the app's provisional board-subtype policy when verified.
- CRI — Carpet and Rug InstituteCarpet maintenance and care standards. Latex binder humidity requirements.
- ACI 302.1RConcrete floor and slab construction — slab curling and differential drying.
- AICCMAustralian Institute for Conservation of Cultural Material — document and artwork environmental standards.
- DrySooner controller policyThe equipment stop/restart gap and rate-control buffer prevent cycling and overshoot; they are engineering settings, not material-science claims.
IICRC S500 is a proprietary standard available from iicrc.org. Section references in this guide are based on industry research and the 4th (2015) and 5th (2021) editions. Verify all section numbers against your official copy before use in formal documentation or client reports.