How Many CO2 Cartridges Does an HVAC Tech Actually Go Through?
June 24, 2026
If you clear AC condensate lines with a CO2 drain gun, cartridges are a running cost you can plan for. Here’s a realistic look at how many a working tech goes through — and the point where buying singles stops making sense.
Per call
One 16g threaded cartridge clears a typical 3/8″–1″ condensate line in one or two shots. So:
- Routine maintenance / light clog: ~1 cartridge
- Moderate clog or longer run: 1–2 cartridges
- Stubborn or neglected line: 2+ (or step up to a 45g for ~3× the gas per shot)
Call it ~1.5 cartridges per drain-clearing call as a planning average.
Per week and per season
In cooling season, a tech doing several AC calls a day adds up fast:
| Calls/day with drain work | Cartridges/day (~1.5 ea) | Per 5-day week | Per 4-month season |
|---|---|---|---|
| 2 | 3 | 15 | ~260 |
| 4 | 6 | 30 | ~520 |
| 6 | 9 | 45 | ~780 |
Even a modest route burns through a few hundred cartridges a season. A two-truck shop can clear a thousand.
When to buy by the case
Buying 16g cartridges in tens is fine for a homeowner. For a working tech or a shop, the math changes quickly:
- Lower per-unit cost — case and pallet pricing drops the per-cartridge cost meaningfully.
- Fewer orders — stock a season at once instead of reordering monthly.
- No mid-season stockouts — the worst time to run out is a 95° afternoon with a backed-up line.
If you’re going through 300+ a season, request bulk pricing — that’s the threshold where case and pallet rates kick in.
Stocking tips
- Keep 16g threaded as your standard, with a few 45g on the truck for the bad ones.
- CO2 cartridges don’t expire (the gas is stable for years); the limit is rust on the steel, so store them dry.
- Confirm your drain gun is threaded before stocking up — see threaded vs non-threaded cartridges.
FAQ
16g or 45g for drain work? 16g handles the vast majority of residential lines. Keep 45g on hand for long runs and stubborn commercial clogs.
Can I leave cartridges on a hot truck? Brief heat is fine, but avoid prolonged storage in extreme heat — they’re pressurized. Keep working stock in the cab, bulk stock in the shop.
I’m new to this — how do I clear a line? Our step-by-step on clearing an AC drain line with a CO2 gun covers it.
Stocking a truck or a shop for the season? Get a bulk quote on 16g and 45g threaded cartridges — ships fast from Minnesota. Browse drain guns and refills.