CRYONIL
Patent pending
Energy-recovery ventilation · cold-climate frost control
Cryonil predicts where an energy-recovery core will frost and steers recovered exhaust heat to that spot — holding it above freezing while the rest of the core keeps recovering. No whole-core defrost. No added heat.
Push the outdoor temperature down and watch frost take the cold corner.
The problem
Frost starts in one geometry-determined corner of the core face — where the coldest incoming supply air opposes the most-cooled exhaust — and spreads from there. Existing controllers sense a single threshold and respond by treating the entire core, wasting energy and interrupting recovery across all the passages that aren't frosting.
The approach
Each is simple on its own. The combination — applied to a passive recovery core with no refrigerant circuit — is what makes the difference. Order matters: localize before you actuate, and actuate with recovered heat before adding any.
Spatially-resolved sensing across the core face — a temperature array, per-region differential pressure, a distributed fiber sensor, or a thermal model driven by inlet conditions — pinpoints the region approaching the freeze-and-dew-point threshold before frost accumulates.
Modulators — vanes, a segmented exhaust manifold, or variable inlet guide vanes — redirect a portion of the warm exhaust stream toward that region, lifting its surface above the threshold using heat the air is already carrying. No added energy source.
Acting before frost forms — with the minimum bias needed to hold the region above the criterion — keeps the corner safe while the rest of the core recovers normally, both air streams keep flowing, and ventilation is never interrupted.
Sensing & actuation
The core insight is that a passive counterflow or crossflow ERV has a deterministic cold corner — geometry and inlet conditions tell you where frost will nucleate. Cryonil puts eyes there and the means to warm it without interrupting the rest.
Because a counterflow or crossflow ERV has a geometry-determined cold corner, sensing only needs to cover that region and its advance. The modulator deflects a calibrated share of the warm exhaust stream into exactly that zone — nothing more.
How it works
Cryonil runs as background control while the ventilator operates normally. The order of operations is fixed: the energy-light move is always tried first, supplemental heat is the last resort, and the whole core is never the target.
Spatially-resolved temperature and pressure across the core, plus inlet temperature and humidity at both supply and exhaust inlets.
Estimate — by measurement, model, or both — the region approaching the freeze-and-dew-point threshold. Track how a frost front would advance.
Redirect warm exhaust toward that region — the minimum needed to hold its surface above the criterion using heat the exhaust already carries.
Watch the region recover its thermal margin above the criterion. Ease the bias back as conditions allow; apply hysteresis to prevent chatter.
If frost indication persists despite biasing, engage a localized heater or zoned bypass — for that corner alone, never the whole core.
Core types
Cryonil's frost-front localization and warm-exhaust-flow biasing apply across the three principal passive core types. The sensing array and modulator configuration adapt to each geometry; the control logic is the same.
The most common ERV type. Supply and exhaust flow in opposing directions through alternating channels separated by flat heat-exchange plates. The cold corner is geometrically fixed at the supply-in / exhaust-out edge.
Primary applicationA semi-permeable membrane transfers both heat and moisture, improving winter humidification. Frost management must account for the additional latent-heat flux at the frost-prone zone — Cryonil's biasing addresses both sensible and latent conditions at the cold corner.
ERV-specificA slowly rotating desiccant or sensible wheel alternates between the supply and exhaust streams. The frost-prone zone is an angular sector rather than a fixed corner. Cryonil's framework targets that sector, biasing exhaust dwell in the frost-prone arc.
Sector-zoned controlHow it compares
The contrast with whole-core defrost is not just about efficiency — it's structural. Once you localize the frost zone and use recovered heat to hold it, the entire response architecture changes.
| Attribute | No defrost | Whole-core defrost | Cryonil |
|---|---|---|---|
| Frost prevention | ✗ None — frost accumulates until blockage | ~ Reactive after accumulation | ✓ Predictive — acts before frost forms |
| Recovery during frost event | ✗ Degraded as frost blocks passages | ✗ Stopped across whole core during cycle | ✓ Maintained across remainder of core |
| Ventilation continuity | ✗ Reduced by blockage | ✗ Interrupted each defrost cycle | ✓ Both streams flow continuously |
| Energy for frost control | — Zero spent; damage accumulates | ✗ External heat or recirculation energy | ✓ Primarily recovered exhaust heat |
| Spatial sensing | ✗ None | ✗ Single threshold sensor | ✓ Zone-resolved across core face |
| Targeted actuation | ✗ None | ✗ Whole core | ✓ Frost-prone region only |
| Core type compatibility | All (passively) | All | ✓ Fixed-plate, membrane, rotary |
Why it holds up
The distinctions below are not marketing language — they are the specific technical deltas that differentiate Cryonil from adjacent frost-control art in the heat-pump and refrigeration fields, where defrost is better developed but operates on fundamentally different hardware.
Designed for plate, membrane, and rotary recovery cores with no refrigerant circuit — a structurally different world from heat-pump and refrigeration frost control, where the defrost mechanism is tied to the vapor-compression cycle.
The primary intervention reuses heat the exhaust stream already carries, rather than adding a heater as the primary actuator. The localized resistive heater is an explicitly sequenced fallback, not the lead mechanism.
Recovery is preserved across the remainder of the face. The whole core is never bypassed or stopped. This is the outcome that no existing ERV defrost art achieves.
Frost is prevented before it accumulates — no recovery loss from melting, no energy wasted defrosting passages that weren't frosted. The model identifies the locus before the criterion is crossed.
Model parameters adapt to the specific installation over time, forming a building-specific frost signature. Fleet data from networked units can further refine predictions without user intervention.
The controller targets the minimum bias sufficient to hold the critical region above the criterion, then backs off as margin is restored — minimizing any distortion to recovery while keeping the corner safe.
FAQ
Where it fits
Any building system that depends on a passive recovery ventilator in a cold climate is exposed to the frost problem Cryonil solves. The control framework adapts to the core type and the unit architecture.
Whole-home recovery ventilators in cold-climate housing. These units frost early, cycle often, and have no occupant-visible warning that ventilation has stopped.
Dedicated outdoor-air systems where recovery downtime carries real HVAC cost and potential code compliance issues. High duty-cycle units benefit most.
A sensing and control layer for core and unit manufacturers to license and embed at the design level, with per-unit royalty or design-in fee structures.
Enthalpy membranes and rotary wheels, where local moisture transfer interacts with frost onset. Cryonil's predictive model accounts for latent as well as sensible heat at the critical zone.
Intellectual property & status
Core claims on the ERV hardware assembly: sensing array, modulator, controller, supplemental actuators.
Process claims on the localize-bias-verify-fallback control loop, including model-based prediction and adaptive learning.
Networked multi-core system claims and a computer-readable-medium claim anchoring the software layer.
Pre-disclosure note
Technical content on this page is intentionally high-level. Claim scope, sensing and actuation specifics, model detail, and test data are shared under NDA with qualified manufacturers and licensing partners after a provisional is on file and employment-IP clearance is confirmed.
Licensing tracks
Sensing and control layer integrated into a manufacturer's product line. Per-unit royalty or upfront design-in fee. Includes field exclusivity options for primary product categories.
Pre-non-provisional co-development for qualified manufacturers seeking to shape the specification. Early access in exchange for testing and validation collaboration.
Complete patent assignment to a qualified acquirer. Available for a defined portfolio scope on negotiated terms.
