Hydronics & Plant Logic | Module 304
Hydronic Air Separator Dissolved Gas Triage
Field Status: Air in a hydronic system causes oxidation (corrosion), noisy valves, and reduced heat transfer across terminal units. Coalescing air separators are designed to knock micro-bubbles out of suspension; if they fail to perform, it is almost always due to incorrect placement (velocity too high) or an fouled internal coalescing element (spongy media).
We use the following audit to determine if your air separator is performing as a true coalescer or merely a high-velocity pipe section.
SYS AUDIT: Air Coalescing Vector
COALESCENCE STATUS: —
—
Gas Separation Principles
A coalescing separator works by slowing fluid velocity down to allow tiny bubbles to attach to the media element, merge into larger bubbles, and eventually migrate to the top air vent.
| Condition | Hydronic Impact | Root Cause |
|---|---|---|
| High Velocity | Bubbles stay suspended | Separator sized too small. |
| Low Pressure Drop | Bypass | Element broken or removed. |
| Gurgling/Noise | Air-locks | Separator location or vent failure. |
Diagnostic Gateway Challenge
You install a new air separator, but air continues to lock the terminal fan coils. You note the separator is installed directly after the primary pump, where water velocity is clocked at 5 FPS. What is the issue?