Pick the Right Refrigerant for the Job — A Contractor's Field Guide: Charge Tables by System (Split / VRF / Chiller / Cold Room / Ice Plant / Auto) + R-22/R-404A Replacements + How to Source Cylinders Fast

Every job site brings the HVAC/R contractor the same questions: "Which refrigerant does this system need? Can I use a substitute? Where do I source it in time?" A single wrong choice can mean a burned-out compressor, a repeat leak, an unpaid invoice, or a free return trip to fix the job.

This is a field guide for contractors and service teams — a complete set of refrigerant-selection tables organized by the real system types you meet in Thailand, plus drop-in/retrofit options for the R-22 and R-404A that are being phased out, the compressor oil you must change alongside them, and how to source cylinders so they're in stock, on time, at fleet pricing.

This is the "pick-it-right-on-site" overview — each section links to a dedicated deep-dive article if you need to go further on a specific refrigerant.

Three rules before you choose

1. Choose by system and nameplate, not by habit — each unit is engineered around a specific refrigerant's pressure and oil. Always read the nameplate on the condensing unit.
2. A leaked blend must be fully recharged by weight, never topped up — glide makes the composition drift.
3. Changing refrigerant always means thinking about compressor oil — HFC/HFO require POE, not mineral oil.

Master table: refrigerant by system type

Always read the nameplate first — this table gets you to the right family, but the actual unit may specify a particular grade (e.g. some 2024+ VRF brands have moved to R-454B).

Retrofit / drop-in table — when the original is scarce or expensive

R-22 and R-404A are where contractors hit "expensive/out-of-stock" most. These are the substitutes actually used in service work:

See a deep comparison of the low-GWP HFO options (R-449A / R-454B / R-513A) in the HFO comparison article, and the R-22 transition path in the R-22 phase-out guide.

The compressor-oil trap contractors fall into

This is the single most common reason a retrofit ends in a dead compressor:

• Legacy R-22 uses Mineral Oil (MO) or Alkylbenzene (AB) — the oil mixes with R-22 and returns to the compressor normally.
• All HFC/HFO (R-32, R-410A, R-404A, R-448A, R-134a, R-513A) require POE (Polyol Ester) — MO does not mix with HFC, so the oil stays trapped in the system and never returns → the compressor runs oil-starved and fails within 6-12 months.
• POE is strongly hygroscopic — it absorbs moisture fast, so you can't leave the can open; pull a deep vacuum (below 500 microns) and change the filter-drier every time.
• Some drop-ins (R-422D, R-438A) tolerate residual MO, so an incomplete oil change still works — but the cleanest retrofit flushes and converts to POE.

Charge it right — by weight, not by pressure alone

For blends with glide, the correct charging procedure is:

1. Recover the old charge fully — never vent to atmosphere (illegal + high GWP).
2. Fix the leak and evacuate deep enough (below 500 microns for POE work).
3. Charge as liquid from the cylinder by the specified weight — not as vapour drawn off the top, which gives a skewed composition.
4. Estimate the charge / cooling load with the refrigerant / cooling-load calculator, then confirm against the actual unit spec.

Systems with a history of repeat leaks should have a gas detector per ASHRAE 15 / EN 378 / ISO 5149, especially in machine rooms and enclosed spaces.

Safety and law contractors must know (in brief)

• R-32 and A2L refrigerants are mildly flammable — work in well-ventilated areas, keep ignition sources/flames away during charging, and use appropriate tools (see the R-32 A2L handling guide).
• R-717 (ammonia) is B2L — toxic, needs dedicated ventilation/detection — large systems only.
• HFC refrigerants are classed as hazardous substances under Thai law — suppliers must be licensed and ship with full SDS (Safety Data Sheet), UN Number labelling, and Hazard Diamond.
• Never vent refrigerant — recover and send to a licensed reclaim facility (see refrigerant reclaim in Thailand).

For contractors: how to source so cylinders are ready, on time, at fleet pricing

The biggest profit leak for contractors isn't "picking the wrong grade" — it's "out of stock, late delivery, swinging prices." Fix it by planning purchasing with a supplier who carries every grade:

Sahawatthanakit (1988) Co., Ltd. supplies the full range of refrigerants — R-32, R-410A, R-22, R-134a, R-404A, R-407C, R-448A/R-449A, R-507 and more — built for contractor and service-fleet teams:

• ✅ In stock, all grades — no running between shops
• ✅ Fleet pricing + lock pricing ahead for the year
• ✅ SDS + tax invoice + CoA on every order
• ✅ Delivery nationwide, express in Bangkok / Nonthaburi / Pathum Thani

Order and request a quote (contractor pricing)

Tell us the grades + your typical volume + delivery location and get a quote within 24 hours:

• 📞 Call: 02-096-2118 / 061-541-6939 (Khun Nawin)
• 💬 LINE: @406rrgvm
• 📧 Email: info@sahawatthanakit1988.com
• 🌐 Request a refrigerant quote (fleet pricing) →
• ⏰ Mon–Sat 08:30–17:30 | 🚚 nationwide delivery

Contractor tip: include your rough annual volume and we'll set steady fleet pricing and delivery cycles for the whole year — so you're never chasing refrigerant during a rush job.