Shops, offices, clinics, restaurants and small industrial. Mostly rooftop packaged units, mostly on buildings where nothing has ever been written down.
Spring before the cooling load and autumn before the first cold night. Coils cleaned properly rather than rinsed, charge verified by superheat and subcooling, belts and drives checked, economiser dampers opened and proved to travel, drains cleared, electrical connections torqued, and on the autumn visit combustion tested on the gas section with the figures written down.
The readings go against each unit, not against the building. That is the difference between a maintenance record and a pile of invoices, and it is what makes a drifting machine visible before it stops.
Free cooling from outside air, which in this climate is available for a great deal of the year, especially at night. It is also the part that seizes, and because the unit still cools nobody notices. We open and prove them every visit and tell you what a dead actuator costs to replace rather than quietly leaving it.
A kitchen hood or a big restroom fan running with nothing bringing air back in holds the whole unit at negative pressure. The front door pulls hard, the building is never warm in winter, and the conditioned air you pay for is dragged straight out through the roof. We measure it rather than guess.
Not the wrong grade — the wrong size, or a rack that no longer closes. Air takes the easy route, the coil gets dirty anyway, and the capacity drops each year until somebody condemns a unit that was only ever being starved.
A coffee shop going into a unit that was a phone shop is a different heat load, a different extract requirement and often a different gas supply. Finding that out during the fit-out is expensive. Finding it out before you sign is a negotiation.
We will give you a written note either way. If the honest answer is that the building is fine and you should stop worrying, that is what it will say.
Chiller plant, building management systems on proprietary protocols, and anything that genuinely wants a controls engineer rather than a mechanical contractor. We will say so at the survey rather than after the second visit, and where we can we will tell you who does take it on.