🔎 Finding One Unit Again: Serial Number, Model, or the Tag on the Machine

A building engineer stopped me in a corridor last year and asked whether the pump I rebuilt was the one on the primary loop or the secondary. It was eight months earlier. There are four pumps in that room, three of them the same model, and the tag on the one I worked on had been painted.

Getting equipment into a system is the easy half, and it is the half every app markets. The half that decides whether the records were worth keeping is this one: one specific unit, back on screen, while somebody is standing next to you waiting.

Three Ways In, Fastest First

Scan the tag. If the unit carries a QR code you printed, a camera gets you there in a second and there is no ambiguity about which of the four pumps you are looking at. That is the whole argument for tagging.

Type the serial. This is the one that matters when there is no tag, and it is the one that connects your records to everybody else's: a warranty portal, a parts counter, a manufacturer lookup all speak serial numbers. Paste it in and you land on the unit.

Search whatever you can actually read. Sometimes the serial is gone and the model is not. Sometimes neither survived and all you have is a manufacturer and a filter size. That still narrows four pumps to one.

What Search Matches

On the phone the main search box matches a unit on the equipment name, the manufacturer, the model number, the serial number, and the filter and belt sizes recorded on the unit itself. Parts come back as their own results, matched on part name, part number, serial, manufacturer, model number and their own filter and belt sizes, so one query gives you both the units and the spare profiles.

The search box inside a building is a wider one, and it is worth knowing it exists. That one adds notes, equipment type, the location inside the building, the floor, the unit number, the out-of-service reason and the asset tag, and it returns the unit when one of its parts matches rather than listing the part separately.

Sizes are the part that surprises people. A filter size is a field on the unit and also a field on the filter recorded against it, so typing a size gives you the units that carry it and the spares stocked for it. That is a different question from "find this unit" and an extremely useful one at a supply counter. You do not have to type it the way it was recorded, either. Both sides are normalized before they are compared, so a belt stored as 4L340 comes back when you search A32, and the reverse works too. A cogged belt is deliberately kept apart from its plain counterpart, so AX32 and A32 stay two different products.

The web dashboard is not the same search, and it is worth knowing where the difference bites. The command palette on Ctrl+K or Cmd+K is a fast jump rather than a full sweep: buildings by name and address, equipment on name, serial, model and type, parts on name and part number. It does not look at filter or belt sizes at all, so a size search that works in your hand on the phone comes back empty at the desk. When a result did match on a serial or a part number rather than on the name, the row says so and shows you the value that matched, so you can see why a unit came back.

The Search That Used to Lie

This is worth telling because of what the bug taught me about search in general. Searching "Pump" in that boiler room returned two of the four pumps. Not an error, not a warning. Just two results, and the list stopped.

A short list reads as a complete list. So the honest conclusion for anyone using it was that the other two pumps were not in the app, and the natural next action is to add them, which is how you end up with duplicate records for equipment you already documented. A silent absence is worse than an error message, because an error message at least tells you not to trust what you are looking at.

The phone search and the dashboard command palette now say "N more matches, keep typing to narrow it down" whenever there are results below the fold. Same fix in both places. If you have ever added a unit because you could not find it, check for the duplicate.

When the Plate Is Gone

Half the time the reason you cannot find the record is that you cannot read the machine. A serial you cannot read is a serial you cannot search. Before you give up and create a new record, there are four or five other places the same data lives, and on an older unit at least one of them is usually intact.

The electrical disconnect enclosure beside the unit often carries a label with the MCA and MOP, and it is shaded and vertical, so it weathers far better than the plate baked flat on the cabinet. Inside the access panel there is frequently a second sticker, sometimes a full duplicate of the nameplate and sometimes a wiring diagram with the model printed on it. The compressor carries its own data plate with RLA and LRA on it, which is enough to confirm you are at the right machine even when the unit plate is unreadable. On a split system the coil section has a separate model and serial from the condenser. And the blower motor tag gives you the motor, not the unit, which is the mistake to avoid: a motor model number recorded as an equipment model number sends the next person to the wrong parts list.

For the plate that is technically still there but unreadable, a photograph and the AI scanner will often pull out what your eyes cannot resolve. It reads what is stamped on the plate, usually under ten fields depending on how much of it survived. It needs a connection, as every AI feature does.

Filter and belt sizes are worth being exact about, because two true statements about them get confused with each other. A nameplate does not normally carry either one, so a scan of a nameplate will not hand you a filter size. But the scanner does extract both, and it has two ways to get them: a data label that explicitly prints one, such as a plate reading "Filter Size: 16x20x4" or "Belt: A42", or a photograph whose subject is the filter or the belt itself. Shoot the filter frame and it reads the nominal size off the cardboard, returns it as AxBxC, and returns one entry per distinct size with a count when a count is legible. Shoot the belt and it takes the designation and stops there, so BX81 comes back as BX81 rather than dragging the cross-reference codes stamped after it along too. So you do not measure them, you photograph the part rather than the plate. More on working a corroded plate is here.

Browsing Instead of Searching

Sometimes you do not have a search term, you just want the list of what is in this building to look like the building. Equipment sorts alphabetically by default now, on the phone and on the dashboard, with a visible sort control offering Name (A-Z), Unit then name, Floor then name, and Unit then floor then name. Your choice is remembered, and both platforms sort the same building the same way.

The old default sorted by floor and unit first, which is a reasonable order for a high rise and a baffling one for anything else, and neither key was visible in the list. Sorting is also digit aware, so Unit 2 comes before Unit 10 rather than after it, which is a small thing until you have thirty units.

What You Get When You Land on the Unit

The point of the lookup is not the specifications, which you could read off the machine if you had to. It is the history, which nobody can read off the machine.

Each service record carries the date, the type of work, a description, the technician who did it, the vendor company they work for, the parts used, and before and after photos if somebody attached them. Technician and vendor are separate fields, so "Apex Mechanical" and the individual who turned up are both recorded rather than crammed into one line, and both print separately on a report.

That is the answer to the question in the corridor. Not "there is a pump on the primary loop", but "the primary loop pump, seal kit replaced, 14 March, and here is the photograph of the old seal".

The Record Has to Be Current, Not Just Findable

Finding the right unit and being shown a stale copy of it is only marginally better than not finding it. Changes now arrive on the screen you are looking at rather than the next time you happen to reopen the app: rename a unit on the dashboard and the phone in your hand updates itself.

That also applies to what an outside contractor sees. An edit on the phone publishes to the tag, and so does printing or downloading a Link tag from the dashboard, or approving a guest service report. Anything else you correct at a desk is picked up when somebody opens the page: it draws the stored copy, then folds a freshly assembled version of the record over the top, so your correction is what the next person to scan the sticker reads. The parts card and its sizes, and any field you cleared rather than changed, still wait for a phone to republish. The full behavior, and why the refresh is deliberately read-only, is here.

Can I look up HVAC equipment by serial number?

Yes. Search matches the serial number field on equipment, parts, tools and stock rows, so pasting a serial from a warranty portal or a parts quote lands you on the unit. On the web dashboard the result row also shows which serial or part number it matched on.

What fields does the equipment search look at?

The phone's main search box matches a unit on equipment name, manufacturer, model number, serial number and the filter and belt sizes recorded on it, and returns parts as separate results on part name, part number, serial, manufacturer, model number and their own sizes. The search box inside a building is wider: it adds notes, equipment type, location inside the building, floor, unit number, out-of-service reason and asset tag, and it returns the unit when one of its parts matches. The web dashboard's Ctrl+K command palette is narrower than either: buildings by name and address, equipment on name, serial, model and type, and parts on name and part number.

Can I find every unit that takes a particular filter size?

On the phone, yes. A size is held on the unit itself and on the filter recorded against it, so typing the size returns the units that carry it along with the spare profiles stocked for it. The web dashboard's command palette does not search sizes, so do that one in the app. You do not have to match how it was typed in: both sides are normalized first, so searching A32 also returns a belt stored as 4L340. Cogged belts stay separate on purpose, so AX32 will not answer a search for A32.

Why did search used to return fewer results than I expected?

The result list was capped and the cap was silent, so a search that had more matches than would fit simply stopped, which reads as "that unit is not in the app". Both the phone search and the dashboard command palette now say how many more matches are hidden.

How do I identify a unit whose nameplate is unreadable?

Check the electrical disconnect enclosure label, the sticker inside the access panel, the compressor data plate for RLA and LRA, and the separate plate on the coil section of a split system. Avoid recording the blower motor tag as the unit model. A photograph run through the AI scanner will often recover what your eyes cannot, though that needs a connection.

Does the app keep a repair history against each unit?

Yes. Each service record holds the date, work type, description, technician name, vendor company, parts used and before and after photos, attached to that specific piece of equipment rather than to a job or a ticket.

How is equipment sorted in the list?

Alphabetically by name by default, with a sort control offering name, unit then name, floor then name, or unit then floor then name. The setting is remembered and the phone and the dashboard sort the same building the same way.

Jonathan Curtis

HVAC Technician & Founder · Equipment Tracker Pro

Jonathan Curtis is an HVAC technician and the founder of Equipment Tracker Pro. He built the app to solve real problems he encountered in the field, including the daily frustration of faded nameplates and administrative double-entry.