Is a Top-Off a Leak? What § 84.106(b) Makes You Do Every Time You Add Refrigerant

It's the most common refrigerant moment in the trade. Suction pressure is a little low, superheat is a little high, the customer says it "hasn't been cooling like it used to." You hook up, add three pounds of R-410A to a 50-pound rooftop unit, and everything comes back into range. Twenty minutes, one small cylinder, done.

Then the question that more than a dozen of our previous posts have mentioned in passing and none of them has actually answered: was that a leak? Do you have to log it? Calculate something? Did a clock just start?

The honest answer has two halves, and both matter. A top-off is not automatically a leak — the rule never says a small addition equals a violation. But a top-off is always a leak-rate calculation. On any covered appliance, every addition of refrigerant, however small, triggers the same math and the same record as a five-alarm loss. The calculation is what tells you whether the rule cares. Skipping it because "it was just a top-off" is the single most common way a clean shop drifts out of compliance without ever noticing.

Here's the rule text that settles it, the arithmetic that makes small additions more dangerous than they feel, the three exclusions verbatim, and the ticket the top-off has to leave behind.

The One Sentence That Answers It

The whole question lives in a single sentence of 40 CFR § 84.106(b). Here it is from the current eCFR text, not paraphrased:

Read the trigger word: added. Not "added because of a leak." Not "added in an amount that seems significant." Added. The rule doesn't have a de minimis threshold for additions, doesn't distinguish a top-off from a recharge, and doesn't ask why the refrigerant went in. If pounds went into a covered appliance, a leak rate gets calculated — unless the addition fits one of the three named exclusions, which we'll take verbatim below.

"Covered appliance" is doing real work in that sentence, so pin it down. Per § 84.106(a), the section applies to refrigerant-containing appliances with a full charge of 15 or more pounds where the refrigerant is a regulated substance (an HFC) or a substitute with a GWP above 53, and it does not apply to appliances "used for the residential and light commercial air conditioning and heat pump subsector" or to appliances containing solely an ozone-depleting substance. We drew the 15-pound line here and the residential carve-out here. If the unit you topped off is a 12-pound split system on a house, none of this applies. If it's a 50-pound RTU on a strip mall, all of it does.

Why "Just a Top-Off" Is the Dangerous Case

Here's the part that surprises people. Small additions are not less likely to trip a threshold than big ones. Under the annualizing method, they can be more likely — because the leak rate is a rate, and a rate has time in the denominator.

The annualizing formula defined in § 84.102 takes the pounds added, divides by full charge, then divides by the fraction of a year since the last addition. Three pounds is 6% of a 50-pound charge. If that's the first addition ever recorded on the appliance, § 84.106(b)(1) tells you to substitute 365 days, and the rate is 6% — under every threshold. But if the last addition was 92 days ago, the same three pounds annualizes to nearly four times that:

That middle number is over the 10% comfort-cooling threshold and over the 20% commercial-refrigeration threshold. The last one — a pound and a half, the kind of add nobody would call a leak — is already past 10% on its own. Same technician, same truck, same "topped it off" note on the ticket. The difference is entirely in the days since the previous addition, which is why the date of the last add is a required field and why a ticket that says "topped off" without a weight and a date can't be defended.

The § 84.102 definition of the annualizing method also closes the obvious dodge. Step 1 is the pounds added "to return it to a full charge, whether in one addition or in multiple additions related to same leak." Splitting one leak into three small visits doesn't produce three small rates.

The rolling-average method is gentler on any single add but unforgiving over a year: it sums every addition in the trailing 365 days and divides by full charge. Three pounds in March, two in May, a pound and a half in August on the same 50-pound unit is 13% — over the comfort-cooling line — even though no single visit looked like anything. Whichever method your facility uses (and § 84.102 requires one method for all appliances at a facility), the top-off is an input to it, every time.

Three pounds is a top-off. Three pounds ninety-two days after the last three pounds is a 23.8% leak rate. The refrigerant is the same. The calculation is what tells them apart.

The Three Exclusions — Verbatim, Because People Stretch Them

§ 84.106(b) names exactly three situations where an addition does not require a calculation. Not "the system was just a little low." Not "it's a new customer and we don't have history." Three:

1. Immediately following a retrofit. You converted the appliance to a different refrigerant and charged it. That charge is the new baseline, not a leak.

2. Installation of a new refrigerant-containing appliance. The initial charge on new equipment.

3. A seasonal variance. This is the one people reach for on spring start-ups, and it has a precise definition in § 84.102:

Read the structure: a removal you made and recorded, followed by an addition no larger than what you removed, both within twelve months. A spring top-off on a unit nobody pulled refrigerant out of last fall is not a seasonal variance — it's an addition, and it gets calculated. And if you do use the flexibility, § 84.106(l)(12) requires records "stating that they are using the seasonal variance flexibility and documenting the amount added and removed." The seasonal-variance post walks the whole thing; the short version is that the exclusion is earned by paperwork, not declared after the fact.

There's a fourth carve-out worth knowing that lives elsewhere in the section. Under § 84.106(k), "purged refrigerant that is destroyed at a verifiable destruction efficiency of 98 percent or greater will not be counted toward the leak rate." That's a purge-and-destroy configuration on larger systems, not a service-truck situation — but if the appliance has one, the destroyed pounds come out of the numerator.

That's the full list. Every other addition to a covered appliance is a calculation.

What the Ticket Has to Carry

The first clause of § 84.106(b) is aimed at you specifically: the person adding refrigerant "must, upon conclusion of that … service … provide the owner or operator with documentation that meets the applicable requirements of paragraph (l)(2)." Here's what (l)(2) requires, for each time a covered appliance is "installed, serviced, repaired, or disposed of":

Notice that (viii)'s "not applicable" list is the same three exclusions from paragraph (b), plus disposal. The rule is internally consistent: if the addition is excluded from calculation, the record doesn't need a rate; if it isn't, it does. There is no version of a covered top-off that gets a ticket without a leak rate on it.

Two of the eight are where top-off tickets die. (vi) the amount — "topped off system" is not a number, and it's the second most common documentation mistake we see. Weigh the cylinder in and out and write pounds and tenths. (vii) the full charge — the denominator. If nobody has determined and recorded the full charge under § 84.106(l)(1), the rate on line (viii) can't be computed, and a top-off you did in good faith becomes a service event that can't be made compliant later.

The Sequencing Trap: A Top-Off After a Repair

One more place a routine add goes wrong, and it's about order rather than arithmetic. If the refrigerant is going in because you just fixed something — a Schrader core, a flare, a braze joint on an appliance that had already tripped its threshold — § 84.106(e)(1) governs when the initial verification test happens:

• (e)(1)(i) — for repairs that don't require opening or evacuating the appliance, the test is performed "after the conclusion of the repairs and before any additional refrigerant is added";
• (e)(1)(ii) — for repairs that require evacuation, "before adding any refrigerant to the refrigerant-containing appliance."

Test first, then charge. Charge first and the test can't distinguish a held repair from a fresh charge masking a bad one, and the record shows it. The verification-test post covers both tests and the follow-up window; the point here is that "top it off and check for leaks" is the reverse of the sequence the rule requires when a repair is in play.

Who Actually Owns the Calculation

The sentence in (b) splits the job. The person adding refrigerant provides the (l)(2) documentation. The owner or operator calculates the leak rate. Read literally, the building owner does the math.

In practice, on a small commercial account, the owner has never heard of § 84.106 and is relying on you to either run the number or tell them they need to. If neither happens, both of you have a problem — theirs is the violation, yours is the customer relationship and the record you're supposed to hand them. The workable answer is the one most compliant shops have landed on: the tech runs the calculation on the ticket at the point of service, and the ticket the owner receives already carries line (viii). It costs thirty seconds and it means the 30-day clock, if one starts, starts from a date everyone can see.

Because that's the other thing a top-off can do. If the rate comes back over the appliance's threshold — 10%, 20%, or 30% depending on category — § 84.106(d) requires the leak to be identified and repaired within 30 days "of when refrigerant is added." Not 30 days from when the office gets around to the math. From the add. Here's what that clock looks like end to end. A top-off calculated on Friday afternoon at the shop is a top-off whose repair deadline has already been running since Tuesday.

What You Top Off With

A short, honest note on the cylinder in your hand, because it comes up in the same breath.

Virgin R-410A is still legal to add. The Technology Transitions rule under Subpart B restricts what new equipment can be manufactured and installed; it does not prohibit servicing existing equipment with the refrigerant it was designed for. Topping off an existing R-410A unit with virgin R-410A is fine under both subparts.

Recovered refrigerant has a sales restriction. § 84.104(a) prohibits selling or transferring recovered regulated substance to a new owner unless it has been reclaimed by a certified reclaimer to the Appendix A specifications — or is transferred solely to be reclaimed or destroyed. Refrigerant you recover from a customer's own appliance and put back into that customer's own appliance isn't a transfer to a new owner; refrigerant you recovered from one account and want to sell into another one is.

A reclaimed-refrigerant servicing mandate is coming — but not for comfort cooling. § 84.112(e) provides that as of January 1, 2029, servicing and repair "must be done with reclaimed refrigerant" meeting the 15%-virgin standard, for equipment in exactly three subsectors: "(1) Supermarket systems; (2) Refrigerated transport; and (3) Automatic commercial ice makers." If your top-off is a rooftop unit or a chiller, that provision does not reach it. If it's a supermarket rack, it will. The reclaimed-refrigerant post has the rest.

The Sixty-Second Top-Off

Everything above collapses into a sequence a tech can run standing at the unit. None of it is new; it's the order that keeps a routine add from becoming a finding.

1. Confirm coverage. Full charge ≥ 15 lb, HFC or GWP > 53 substitute, not residential/light-commercial AC-HP, not solely ODS. If no, you're outside § 84.106 (check § 82.157 for ODS at ≥ 50 lb).
2. If this add follows a repair, test first. Initial verification per (e)(1)(i)/(ii) before any refrigerant goes in.
3. Weigh it. Cylinder in, cylinder out. Pounds and tenths, plus refrigerant type — that's (l)(2)(vi).
4. Pull the full charge and the last-add date. (l)(2)(vii) and the annualizing denominator. If either is missing from the appliance file, that's the real problem, and it's fixable today.
5. Check the exclusions honestly. Post-retrofit, new install, or a documented seasonal variance with a prior recorded removal? If yes, record it as such (and (l)(12) if seasonal). If no — and for a top-off it's almost always no — go to 6.
6. Calculate, using the facility's one method. Compare against the appliance's category threshold.
7. If it's over, the clock is running from today. 30 days (120 for an industrial process shutdown) to identify and repair, then verification tests.
8. Hand the owner a ticket with all eight fields, including the rate and the method on line (viii). Keep your copy three years.

That's the whole obligation. It doesn't require the top-off to be a leak. It requires you to find out.