The technology
One water loop. Two coils. Both loads drop.
HEDS performs the same sub-cool step as any typical dehumidification system — but sources the reheat from the chilled-water return of its own cooling coil, through a second energy recovery coil. Every BTU the recovery coil pulls out of the return water is a BTU that doesn't have to be purchased as reheat and doesn't go back to the chiller — dropping both heating and cooling loads.
The core idea
One move cuts two loads at once.
HEDS meets real-world dehumidification and reheat loads — small, medium and large. The live operation screen shot from the Timken Museum example below shows the effects of HEDS. The other screens beneath it are also real projects.
| Configuration | Cooling load to chiller | Reheat load (BTU @ meter) | Total Cooling + Heating BTU |
|---|---|---|---|
| Standard sub-cool / reheat AHU | 15.5 tons / 186,000 BTU | 91,700 BTU | 277,700 BTU |
| HEDS energy-recovery AHU | 10.1 tons / 121,200 BTU | 0 boiler energy required — uses recovered heat | 121,200 BTU |
| Coil-load reduction due to HEDS (Savings) | 5.4 tons / 64,800 / 34.6% | 91,700 / 100% | 156,500 BTU / 56.4% |
Real-world savings run higher than any textbook example — every demonstration project has exceeded 50%; several average over 60% annually.
State point by state point
The process, on the air side and the water side.
Filtration & fan wall
4″ MERV 11 pre-filter + MERV 16 secondary (≈95% of virus-sized particles), optional HEPA final stage, UV-C at the coil and drain pans. Direct-drive ECM fan arrays — no belts, no VFDs — improve fan efficiency 8–15%.
Cooling coil
Air is sub-cooled to roughly 46–57°F at near-100% RH, condensing out moisture. The oversized, slow-velocity coil lets the chilled water leave warm — 63–75°F instead of the conventional ~55°F.
Cooling Recovery Coil
That warm return water flows through a second, sensible-only coil that reheats the cold saturated air to ~55–65°F, as needed by the loads — dropping supply RH to 65–80% with no purchased reheat for most of the dehumidification season.
Back to the plant, lighter loads
The now-cooler water returns to the chiller carrying less load. One loop, two coils: the chiller load and the reheat load drop together, and diverse zones take only small trim reheat where needed.
NREL Thermal Test Facility measurement (Shoukas 2025): 80.0°F entering air delivered at 63.7°F supply · chilled water supplied at 43.8°F, returned at 60.9°F after the recovery coil — a 17°F+ differential from one water loop.
Part-load behavior
Where competing systems fall apart, HEDS gets stronger.
Buildings run at part load the overwhelming majority of the year. Sample selection data for a 10,000 CFM tropical HEDS unit at 45°F CHWS — leaving dewpoint holds steady while the recovered fraction grows as load drops.
Holds steady to deep part load
The cooling-coil leaving dewpoint is continually optimized from peak design down through low part load — the failure point where wheel, desiccant and heat-pipe systems lose control of the space.
The recovered fraction grows
As airflow falls, the chilled-water return runs warmer and a larger share of the cooling load can be recovered as reheat — the opposite of conventional coils, which can lose ΔT at off-design conditions.
Pressure drop falls with load
With VAV systems, air-side pressure drop declines as load drops, so fan energy falls with it — compounding the chiller and reheat savings across the hours buildings actually operate.
Conventional coils lose ΔT and stack condensate at part load; low tube velocity slides into laminar flow and heat-transfer effectiveness collapses. HEDS' redesigned circuiting and optimization-driven flow keep the heat transfer effectiveness and the ΔT high across much of the load range. The measured part-load dataset — dewpoint, ΔT, recovered fraction and pressure drop across the operating envelope — ships with the complete selection matrices in the Design Assistance Guide under NDA.
The hydronic payoff
HEDS is the cure for Low Delta-T Syndrome.
A 100-ton chiller designed for a 12°F ΔT delivers only 67 tons at 8°F ΔT — a third of the plant capacity is unusable and stranded. Because HEDS coils run a 20–30°F chilled-water ΔT at peak, they attack the syndrome directly — cutting chilled-water flow rates and allowing the chillers to load up fully. Stranded capacity is recovered.
- Frees stranded plant. Recovers 18–28% of chiller capacity owners already paid for — often enough that an undersized loop starts meeting its loads.
- Halves the flow. The same cooling load at >2× the ΔT means less than half the GPM — effectively doubling the BTU-carrying capacity of existing piping.
- Cuts pump energy 50–>70%. Flow has a ~cubic relationship to pump HP. At Naval Base Guam, HEDS cooling coils generated 19°F+ differentials driving >75% pump-energy savings.
- Defers the next chiller. Load reduction plus recovered capacity lets plants downsize — or skip the replacement entirely.
The optimization layer
Every unit ships with an HVAC-system optimizer, not just a control panel.
The recovery coil saves energy during dehumidification calls. HEDS saves all year because every controller ships factory-programmed and factory-commissioned, continuously resetting seven setpoints: supply-air dry-bulb, dewpoint and static pressure; chilled-water supply temperature and loop ΔP; hot-water supply temperature and loop ΔP.
Chillers and boilers, off entirely
The HEDS HVAC optimization "Thermal Flywheel" strategy compares conditions to the prior day and floats the building on its thermal mass — at a fine-arts museum, chiller and boiler runtime was nearly eliminated across a five-day-long 47–80°F outdoor swing. No internet connection required.
168 hours becomes ~60
In continuous-dehumidification (unoccupied) mode, HEDS positively pressurizes the building with a small volume of very dry air — cutting effective main-equipment runtime by up to 100 hours per week for 40-hour occupancies forced to run 24/7.
Built for mission-critical loads
Cascaded failover: HEDS is built for mission-critical loads in locations that may not have adequate maintenance manpower or funding. HEDS software can keep the HVAC system running even when multiple sensors/systems have failed. This example shows the failure recovery pathway when sensors, or multiple sensors fail, but the loads still need to be served. Supply-air sensor → room → return-air → mixed-air → outside-air → reset table → safe default. The unit keeps running rather than losing the space. Proven live when an FDA lab lost 3 of 4 chiller modules overnight — and stayed in spec.
No DDC rewrites
The factory-programmed HEDS controller reads existing sensors and feeds new ones into the existing DDC system. First-year results at Naval Weapons Station Seal Beach: HVAC electric down 59%, gas down 76% — $927,000 saved.
As can be seen below, the boiler was not running when it was 47°F ambient, and the chiller was not running when it was 80°F ambient. The boiler only ran at about 50% load for 2.25 hours and the chiller only ran for 6.5 hours 15% load during the entire 120-hour period.
From the control screen
Live data, not brochure data.
Two snapshots from operating HEDS systems — the same screens we share on a live walkthrough.
Guam-grade humidity, FDA Laboratory held at 40% RH.
The cheapest runtime is off.
The five-day chart · chiller and boiler nearly eliminated across a 47–80°F swing — see the 120-hour Thermal Flywheel chart in the optimization section above.
Electrification
The enabler of cost-effective heat-pump conversion.
HEDS slashes peak cooling loads and can eliminate purchased reheat — letting plants downsize enough to make heat-pump swaps feasible, and funding the transition from the energy savings.
Geothermal, in one sentence
HEDS can cut geothermal heat-pump compressor runtime by 500 to 1,000+ hours per year — further increasing lifecycle cost savings on top of the validated 50–80% HVAC reductions.
Versus the alternatives
Fewer moving parts. More recovered energy. Year-round energy savings.
HEDS trades a larger coil bank for the elimination of every moving, failure-prone component in competing recovery approaches — while recovering up to 100% of required reheat.
- Annual HVAC savings
- 50–80%
- New reheat purchased
- Near 0% — recovered
- Moving recovery parts
- None
- Exhaust air stream required
- No
- Total coil air ΔP
- <1.0″ WC
- Cooling-coil CHW ΔT
- 20–30°F
- Cross-contamination
- None
- Validated optimization software
- National-lab and Navy tested
Competing-system savings ranges reflect Conservant's positioning — worth confirming against your own experience. HEDS figures are independently measured; see Validation & Results.
Straight answers
Where HEDS does — and doesn't — make sense.
A document an engineer can trust states its limits. HEDS is not universal.
Climate
HEDS pays where there are meaningful latent loads — applicable in all but the driest locations on Earth. In dry climates the coil-pairing advantage shrinks to the optimization-software savings (which can still be meaningful). Exception: indoor agriculture and other internally humid loads make HEDS compelling regardless of the weather outside.
Chilled-water temperature
Serving 48°F dewpoint loads generally requires 42–45°F water at the unit — a constraint of physics, not of HEDS. Where the loop can't deliver, the design uses larger coils or a small booster heat-pump chiller. HEDS has held spec delivering 58°F dewpoint air on 54°F water during a chiller plant upset.
Retrofit economics
Tearing out a healthy AHU purely for energy savings can run 8–10-year paybacks. HEDS economics are strongest retrofitting coil banks in existing AHUs, in new construction, at end-of-life replacement, or bundled with chiller-plant or mold-remediation projects.
Space & first cost
HEDS requires smaller mechanical rooms than desiccant and ER-wheel, run-around-coil and heat-pipe systems — and will frequently net the lowest installed cost by eliminating DOAS units and downsizing the plant.
FAQ
Frequently asked questions
+What does a HEDS HVAC system cost compared to a standard air handler based HVAC system?
+Is this just a sub-cool/reheat AHU with a second coil?
+What maintenance does it need?
+Does it work in extreme humidity? In winter?
+Does HEDS improve air quality too?
+Can it be modeled in EnergyPlus?
+Is HEDS code-compliant?
+Does HEDS work with 2-pipe and 4-pipe systems?
+What can hospitals and operating rooms expect?
+What savings should 24/7 facilities expect versus standard-occupancy buildings?
+Does HEDS scale down to smaller equipment?
+What payback should I expect — retrofit versus new construction?
+What configurations are available?
Patents & intellectual property
Protected engineering: 19 issued patents, 9 pending.
The HEDS portfolio covers six layers — the coil configuration, the hydronic piping bridge and valves, the control logic and optimization, multi-AHU scaling, failsafe operating modes, and UV-C/DX integration — with clean title held by HEDS Holdings LLC. A 2024 patent-landscape analysis places HEDS in command of the heat-transfer-coil cluster.
Alongside the issued claims sits trade-secret know-how — the HVAC optimization logic, Thermal Flywheel strategy, fault-tolerant cascade and coil-selection methodology — the parts you can't reverse-engineer from a field unit.
Walk the physics with the inventor.
Scot M. Duncan, P.E. — 30+ years as HVAC SME to the U.S. Army Corps of Engineers and NAVFAC — will connect you to a live project during the call.