The hottest room in most houses here used to be a garage

Sometimes, and it is the first thing almost everybody asks for, so it is worth explaining why we measure before answering. A duct carries a fixed amount of air, and the system was sized for the house before that room existed. Adding a register does not create airflow — it takes it from the rooms that were getting it, and people notice within a fortnight, usually in the bedroom furthest from the equipment. Three measurements settle it in one visit: the calculated load of the new space, what the existing equipment is actually delivering rather than what its nameplate says, and the static pressure the ductwork is running at. If the system is already at or over its rated static pressure, which in this housing stock it very often is, there is no spare air to take.

Because it is effectively a different building attached to the house. The slab was poured to take a car, so it is usually thinner, usually has no perimeter insulation and often no vapour barrier. The wall where the door was is normally the least insulated wall in the building. There is very little depth above the ceiling for insulation, so it runs hotter than any other ceiling. And the heating system was sized years before any of it existed. Equipment alone rarely fixes all four, which is why we look at the room before we look at the machine.

No, and we will say so plainly. We are a heating and cooling contractor, not a builder. In California a garage conversion is normally permitted building work, and permitted work carries its own requirements about insulation, ventilation and how the space is heated — but those questions belong to your city or county building department and to your builder, not to us. We will fit what the design needs and tell you honestly when a question is somebody else’s.

Possibly, but it is the second question rather than the first. Attic air on this corridor goes far above the outdoor temperature on a hot afternoon, and most of the ductwork here runs straight through it, so duct leakage costs more here than almost anywhere. We measure leakage, static pressure, charge and filter restriction before anybody talks about efficiency ratings, because sealing joints properly with mastic, re-supporting sagging runs and adding return capacity costs a fraction of equipment. What we will not do is quote you a percentage saving in advance — that depends on how leaky your ducts actually are, which is exactly what the measurement is for.

No, and nobody else can either in any meaningful sense. An open space with a door up or no walls cannot be air conditioned; what gets sold for it is fans and evaporative equipment under another name. We will tell you honestly what those do and do not achieve in this climate and let you decide, rather than quote for something that will disappoint you.

Rubidoux, Jurupa Valley, Riverside, Mira Loma, Pedley, Glen Avon, Norco and Eastvale.