Three things shipped in v4.2: live virtual meters, ratio-based threshold alerts, and a much faster trend engine. Notes follow.
Virtual meters
You can now compose any two physical meters into a virtual one. The virtual meter behaves exactly like a physical meter for trends, alerts, exports — but its value is computed live from the underlying meters.
Ratio alerts
You can now set thresholds on derived values, not just raw ones. Want an alert if your make-up-water-per-kg-steam goes above 1.4? You can have it.
Heads up: ratio alerts respect a minimum-throughput floor. If steam flow is below 50 kg/h, the ratio alert is suppressed — otherwise weekend tea breaks would page you about a 5000% efficiency anomaly.
Trend engine
Roughly 3× faster on charts with more than 30 days of data. The old engine recomputed each chart on every interaction; the new one caches the trend output and incrementally updates when new data arrives.
