Two Hundred Condensers, Not One Sensor

Walk the back of almost any garden-style apartment community and you will find rows of condensing units — one per apartment, installed over a span of years, in various states of repair.

Now list what that property measures continuously. Access control events. Camera footage. Leasing enquiries and conversion. Water submetering. Package lockers. All instrumented, all reporting somewhere.

The condensers report nothing at all. On a 200-unit property that is 200 sealed refrigerant systems operating with no instrumentation of any kind, and the property learns their condition exclusively through work orders.

Fleet-scale consequences of a per-unit problem

Everything the field research says about a single residential system applies here, multiplied. The Department of Energy's 2018 review found that field testing reveals nine out of ten systems carry a correctable installation or maintenance issue, with low airflow present more than half the time and refrigerant charge faults spanning 29–78 % undercharge across studies.

Applied to a fleet, the implication is not that a few units are bad. It is that most of them are somewhat degraded, in ways nobody has measured, and that the property has no way to rank them.

That ranking is the thing multifamily operations most needs and least has. Maintenance capacity is finite. Deciding where it goes is currently driven by which resident called, which is a queue ordered by complaint rather than by condition.

The turn cost nobody attributes correctly

There is a second-order effect worth naming. When a unit's cooling underperforms without failing outright, the resident does not necessarily file a work order. They may simply find the apartment uncomfortable, and that experience feeds into a renewal decision.

We are not going to attach a number to that, because we do not have a study quantifying how HVAC performance affects multifamily renewal rates and we are not going to invent one. But the mechanism is not controversial: a unit that is too warm in August is a worse place to live, and residents make renewal decisions partly on how the place felt.

The relevant point is that this cost is invisible in the maintenance ledger. It shows up in turnover, where nobody connects it back to a refrigerant charge that has been 20 % low since the second year.

Why commercial-grade monitoring never reached these units

Large commercial buildings have monitored HVAC for decades, through building management systems. PNNL's assessment of commercial building controls estimated national primary energy savings potential of 2.74 quads, and stated that "as much as 30 % of building energy consumption can be eliminated through more accurate sensing, more effective use of existing controls, and deployment of advanced controls."

None of that infrastructure ever reached the individual apartment condenser, for a straightforward reason: a BMS is justified by a central plant. Two hundred small split systems have no central plant to hang the instrumentation on, and running wire to each unit was never economic.

A self-contained monitor with its own cellular connection removes that constraint. It does not need the property's network, a head-end system, or per-unit wiring. Each condenser reports for itself.

Vetralis watches refrigerant pressure and line temperature per unit and alerts on drift. It cannot detect every fault, and it does not replace maintenance staff. What it gives a property is the thing it currently lacks entirely: a condition signal from equipment that has never produced one.