A new system gets installed, it runs, the crew leaves, and that’s usually the last anyone thinks about it until something goes wrong. Most of what actually protects that investment — and most of what determines whether “goes wrong” happens in year two or year fifteen — happens quietly in the twelve months after the truck pulls away, on a schedule nobody hands you at closing.
The short answer
Three checkpoints, three different jobs: 30 days (catch install problems while they’re still the installer’s problem to fix), 90 days (register the warranty before the deadline, and check the system through its first full season), one year (get real numbers on how it’s actually performing, not just whether it’s still running). Miss the 90-day mark specifically and you can quietly lose years of parts coverage without ever being told.
Why the calendar matters more than it seems
A furnace, AC system, or boiler doesn’t fail the way a lightbulb fails — suddenly and obviously. It drifts. A refrigerant charge that was correct at startup can slowly leak down over months without tripping anything a homeowner would notice; a boiler that had a little air in the lines at startup can keep circulating it for a year before a radiator loop goes cold. None of that shows up as an emergency. It shows up as a slightly higher bill, a room that’s not quite as comfortable as it used to be, or a part that fails five years earlier than it should have — and by then there’s no baseline left to compare against and no clean way to prove it was ever wrong.
The checkpoints below exist to catch problems while they’re still small, while there’s still a paper trail, and — for one of them — before a real deadline closes a door for good.
What to check, on the calendar
30 days
- Nothing unusual. No error codes, no short-cycling, no noise or vibration that wasn’t there in week one. New systems occasionally reveal a minor install issue only after they’ve run through a real weather swing — catch it now, while it’s unambiguously the installer’s problem to fix under the workmanship warranty, not a maintenance call you pay for later.
- The filter. Construction dust from the install itself clogs the first filter faster than a normal one. Change it at 30 days regardless of what the box says, then start the real schedule after that.
- The startup numbers. If nobody handed you a startup report — refrigerant charge, gas pressure, temperature rise, the numbers covered in the last piece on this site — this is still a reasonable window to ask for them. Past 30 days, getting the installer back out for paperwork alone gets harder.
- The permit, if one was pulled. A permit that’s open but never inspected and closed out is a real problem at resale, and it’s much easier to chase down while the installer’s crew and paperwork are still fresh.
90 days
- Warranty registration. This is the one most homeowners lose without ever finding out. Most manufacturers extend parts coverage — often from a base 5 years to 10 — only if the equipment is registered within a window that’s commonly 60 to 90 days from install. Miss it, and the system quietly reverts to the shorter base warranty with no notice, no reminder, and often no way to appeal it later. Confirm registration happened — ideally with a confirmation email or number in hand — don’t assume the installer did it for you.
- A full season behind it. By 90 days, a system installed for cooling season has usually run through real heat, and one installed for heating season has usually seen real cold. Compare the actual utility bill against what was promised at the time of sale. A gap here is worth raising while it’s still fresh, not filed away as “probably normal.”
- Hydronic systems specifically. A boiler that seemed fine at startup can develop air pockets as the system cycles through its first real thermal swings. A radiator that’s warm at the bottom and cool at the top is trapped air — bleed it, and if it keeps recurring, that’s worth a service call, not another round of bleeding.
- Outdoor equipment. Check that landscaping hasn’t grown in around a condenser or boiler flue termination, and that line-set insulation is still intact — it’s a common target for animals in the first season.
One year
- The first real service visit. This is when a technician can recheck the original startup numbers — the same superheat/subcooling and gas pressure readings from install day — against where they are now. A charge that’s drifted down, or a temperature rise that’s crept outside its specified range, is a leak or a developing problem, and it’s far cheaper to catch at year one than to discover at year seven when the compressor or heat exchanger finally gives out.
- The real first-year cost. Twelve full months of bills is the first honest comparison against the old equipment or the efficiency numbers used to sell the new one. If it’s meaningfully off, that’s worth a real conversation with the installer, not something to quietly accept.
- The paperwork, together. File the startup report and the first annual service report in the same place. That pair is the actual baseline for everything after it — for a warranty claim, for the next technician who works on the system, or for whoever buys the house from you.
What a bad answer sounds like
“Just call us if something goes wrong” is the answer of a business that wants a service call, not a system that’s actually being watched. Nothing about drifting refrigerant charge or a missed registration deadline announces itself as “something wrong” — that’s exactly the point.
“It’s all covered under warranty” without ever confirming registration happened is a promise nobody’s checked. Ask to see the confirmation, not just hear the assurance.
“We don’t really do annual visits, just call when it breaks” describes a transactional relationship, not a maintained system — and it puts the entire burden of noticing a slow problem on someone with no gauges and no baseline to compare against.
The checklist, tacked to the fridge
The version above with the reasoning; this is the same thing stripped down to what you’d actually tape inside a utility closet door.
| 30 days | 90 days | One year |
|---|---|---|
| Nothing unusual (noise, codes, short-cycling) | Warranty registration — the deadline that quietly costs the most | First real service visit |
| Change the filter | System through a full season | Real first-year cost, from 12 months of bills |
| Ask for the startup numbers | Hydronic: check for air in the lines | File the paperwork together |
| Permit closed out, if one was pulled | Outdoor unit clear of landscaping |
Copy the dates into your own calendar reminders the week the install finishes, while they’re still easy to count from.
None of this requires expertise you don’t have. It requires knowing the three dates exist, and that one of them has a deadline attached whether anyone tells you or not.