Compressor map. A maker's ten-coefficient polynomial in evaporating and condensing temperature, valid inside its envelope. Read any of the catalog's at your conditions.
A compressor map is the manufacturer's statement of what a compressor does across its operating range: capacity, power and mass flow as ten-coefficient polynomials in the evaporating and condensing saturation temperatures, published under AHRI 540 in North America and EN 12900 in Europe, each at a stated superheat and subcooling. A selection program evaluates the polynomial at a pair of temperatures; a system solver finds the pair where the evaporator, the compressor and the condenser balance, and reads the map there. The map is valid only inside the published operating envelope — the polygon on the datasheet — and a cubic read outside it answers plausibly and wrongly.
This catalog holds nearly ten thousand such maps from four makers' published data, each page sampling its map across its own envelope, and the free lookup reads any of them at your conditions. Inverter machines add part-load steps — the same polynomials at several speeds — which the solver interpolates between; without them a modulating machine's power is over-stated because its efficiency changes as it unloads. The standard also states how far a fitted map may stray from a measured point, and the tool that fits a map from a table reports each point against that limit.
Open the builder — the examples in the Design tab's sources list include a machine of this kind, and the Simulate tab runs it against a year of weather.
DOAS — dedicated outside-air system · SZVAV — single-zone variable air volume · VAV terminal box · Economiser · Waterside economiser · Demand-controlled ventilation · Face-and-bypass · Head-pressure control · Humidity ceiling and floor · Cycling and modulation · Coupling · Priority · Category · Nested system · Design point and TMY year · Superheat · Subcooling · Sensible heat ratio (SHR) · Bypass factor · Wet-bulb temperature · Dew point · COP and EER · Evaporating and condensing temperature · Range and approach · Heat-recovery (three-pipe) VRF · Typical meteorological year (TMY)