When people hear their water heater runs on propane, the kitchen LPG tank comes to mind. Fair. So let's compare them properly — because the comparison is the answer.
Start with the amount
A Karnot R290 heat pump carries a refrigerant charge of typically under 1 kilogram — factory-sealed into a welded copper circuit, leak-tested before it leaves the line, never opened in normal service.
The LPG cylinder under a Philippine kitchen stove holds 11 kilograms — more than ten times as much gas — indoors, beside a flame, on a rubber hose, connected and disconnected by hand every few weeks.
The honest framing: if propane in the house worried us as a country, we'd have stopped cooking years ago. The heat pump holds a tenth of the gas, welded shut, standing outside.
The three layers of engineering
- Small charge. R290 is classified A3 — non-toxic, flammable — so the design rule is simple: keep the charge small. Under 1 kg means even a total release outdoors disperses below ignitable concentration almost immediately.
- Sealed and outdoors. The refrigerant never enters your rooms. The circuit is hermetically sealed in the outdoor unit; what travels indoors is water in a pipe. Outdoor installation is Karnot's standard practice — and where outdoors is genuinely impossible, we'd sooner fit a non-flammable CO₂ system than force R290 inside.
- Hard standards. IEC 60335-2-40 sets the appliance rules — charge limits, ventilation, separation from ignition sources. EN 378 governs the refrigeration system safety. Karnot designs to both. These aren't aspirations; they're the pass/fail criteria the equipment is built against.
Why accept any flammability at all?
Because the "safe" synthetic alternatives carry quieter problems. The common HFC refrigerants score 675–3,922 on global warming potential against propane's 3. Many break down into PFAS — 'forever chemicals' that accumulate in water and blood. And all of them sit under a legal phasedown that pushes their service prices up through the life of your equipment.
Propane's risk is visible, small, and engineered down with seventy years of practice. The synthetics' risks are invisible, large, and growing. We chose the one you can see — the full three-way comparison is here: R290 vs CO₂ vs HFC.
The track record
Millions of R290 systems run worldwide — domestic fridges have used hydrocarbon refrigerants for decades, and R290 heat pumps are now the mainstream choice across Europe. Natural refrigerants were the original refrigerants, a hundred years before the synthetics; the engineering playbook for handling them is mature.
Who's telling you this
Karnot Energy Solutions Inc. is a Philippine company in Mapandan, Pangasinan. We build natural-refrigerant systems only — R290 heat pumps (AquaHERO, iHEAT) and CO₂ refrigeration (iCOOL) — for the Philippines, the UK, the US and Canada. Our installers are trained for hydrocarbon refrigerants; outdoor-first placement is our default design rule.