FCU Selection Software — Bringing Engineering Rigor to Terminal Units

Walk into any HVAC contractor's office and you'll find a beautifully maintained AHU spreadsheet — and an FCU process held together with hope. Terminal units are too small to justify a "real" tool, the thinking goes, so they're sized off vendor catalog tables and a quick rule-of-thumb correction.

That works until it doesn't. A four-pipe system with under-spec'd FCUs in 30% of the rooms means a building-wide comfort complaint that lands in the engineering team's lap two months after handover. The contractor pays. The brand pays.

What FCU selection actually requires

A correct FCU selection involves more variables than a catalog page can hold:

• Sensible vs latent capacity at the room's actual entering air conditions — not the 27°C / 50% RH catalog point.
• Coil rows and fin density that hit capacity without crossing the noise budget.
• Fan speed selection that gives you future reserve without sitting in a low-efficiency corner of the curve.
• Connection sizing that doesn't introduce a pressure drop the central plant didn't budget for.

A good FCU Selection Software does all of those in one pass, against a certified performance set, for every unit on every project.

How MileSoft handles it

The MileSoft FCU Selection Software shares the same certified-curve engine as our AHU and Chiller tools — which means three quiet wins for engineering teams:

1. One library, one source of truth. When R&D updates a coil family, FCUs benefit at the same moment AHUs do.
2. Project-level consistency. AHU + FCU selections live inside the same project. The hand-off between central plant and terminal selection doesn't drop bytes.
3. Branded submittals. Performance sheets, dimensional drawings, and BOMs export in your branding — no more pasting screenshots from a vendor catalog into a contractor's submittal.

The features that quietly save deals

• Bulk selection. Drop in a Revit/Excel room list; the engine selects the correct unit for every space and flags the ones that need engineering judgment.
• Acoustic guardrails. A configurable noise budget prevents the engine from "successfully" selecting a unit that will get a comfort complaint on day one.
• Quick re-runs. When the architect moves a wall and the room load changes, re-selection across the project takes a minute, not an afternoon.

Where it fits

FCU selection rarely lives alone. The strongest deployments wire it next to:

• AHU Selection Software for the central plant,
• Chiller Software when the chilled-water plant needs sizing too,
• and Lifecycle Cost Analysis when the customer is comparing two-pipe vs four-pipe TCO.

A practical takeaway

If terminal-unit selection is a weak link in your engineering workflow today, that weakness will surface as warranty cases and reputation damage years from now. A purpose-built FCU tool is the cheapest insurance policy in the HVAC stack.

Book a 30-minute demo and bring a recent project — we'll re-do the FCU selections with you and show where the catalog-table approach was leaving margin (or risk) on the table.