How it Works
Absorption cooling uses thermal energy directly — no compressor, no electricity for cooling. The same proven technology that's been silently cooling RV refrigerators for 60 years.
Absorption Cooling
Just propane and physics. No compressor. No grid electricity.
Window Kit
Slide the adjustable panel into any standard window. Locks in place with thumb screws. Five minutes, no tools.
Propane Tank
Connect a standard 20 lb tank to the quick-connect fitting on the outside of the window panel.
Deploy Cooling
Slide the heat rejection assembly out through the window. It locks in the deployed position automatically.
Cool Air
8,000 BTU of steady cooling — enough for a bedroom or living room up to 350 sq ft. Cool air in 20-30 minutes.
Runtime is everything
Hurricane Beryl left hundreds of thousands without power for over a week. Most cooling solutions don't last past dinner.
Comparison based on 8,000 BTU load at 95°F ambient. Propane shelf life is indefinite; gasoline degrades in months. Battery runtime from manufacturer claims with optional add-on batteries.
Your Current Options
Generator
- Portable generator CO kills ~100 people/year. Beryl alone: 400 hospitalized.
- 65-78 dB — louder than a vacuum cleaner
- Gasoline sells out before the storm arrives
- Sits in your garage for months. Won't start when it matters.
Battery AC
- $5,000+ to cover a multi-day outage
- Best available: 8 hours, then nothing
- Needs the grid to recharge — the thing that's down
- Loses capacity sitting in storage every year
Hotel
- $250+/night — if any rooms are left
- Sell out within hours of a major event
- Family of four: $1,500+ per week
- Your home sits empty and unprotected
Safety
Millions of RV owners sleep feet from propane absorption refrigerators every night. This technology has a 60-year safety track record.
Sealed Combustion, Vented Outside
All combustion air comes from outdoors, all exhaust goes outdoors through the included window kit. Zero emissions in your living space — the same principle as a gas water heater or furnace.
Oxygen Depletion Sensor (ODS)
Continuously monitors indoor air. Automatically shuts off gas flow if oxygen levels drop below safe thresholds.
Flame Failure Protection
Thermocouple-driven shutoff kills the gas supply instantly if the burner flame goes out for any reason.
ANSI Z21.40.1 Compliance
Designed to ANSI Z21.40.1 — the national safety standard for gas-fired cooling appliances. Every unit will be independently tested and certified before it ships.
Technical Specifications
FAQ
$1,499 for the Founder's Edition (first 500 units). A single propane tank costs $50-65 and runs 20+ hours.
A standard 20 lb propane tank provides 20+ hours of continuous cooling at rated conditions (95°F ambient). At extreme heat (105°F+), runtime is 18-20 hours. A $50-65 tank exchange gets you through most multi-day outages.
Yes. The combustion system is completely sealed and vented outside through the window panel — just like a gas water heater. Holdfast also includes an oxygen depletion sensor, flame failure shutoff, and tip-over protection. It produces zero carbon monoxide in your living space.
Yes. Like any portable air conditioner, Holdfast includes a window kit to reject heat outside. The kit also routes combustion exhaust outdoors, completely sealed from your living space. Setup takes under 10 minutes — no tools, no permanent installation.
Portable generators produce carbon monoxide that kills about 100 Americans every year — 400 Texans were hospitalized from CO poisoning during Hurricane Beryl alone. They run at 65-78 dB (enough to shake windows), require monthly maintenance, and gasoline degrades in months. Holdfast runs at 35-42 dB, requires zero maintenance, and propane stores indefinitely.
No, and we won't pretend it can. Holdfast cools one room — a bedroom, living room, or any space up to about 350 sq ft. During an emergency, one cool room is the difference between dangerous heat exposure and a safe place to sleep.
Swap in another tank. A 20 lb propane tank provides 20+ hours of cooling. Two tanks get you through a 3-day outage. Propane is available at every gas station, hardware store, and Walmart — and unlike gasoline, it stores indefinitely. Buy two tanks today and they'll be ready in five years.
It rolls on locking casters. Think of it like a rolling tool chest or a large cooler on wheels — you roll it out of storage, set it up, and roll it back when you're done. Two people can lift it over a step.
Holdfast is in active development. Reserve above to get priority access — we'll share engineering updates and timeline milestones as we hit them.