Step 1 – Known airflow Start with the supply/exhaust airflow Q (m3/h). For balanced AHUs, Q_supply approx Q_exhaust. Step 2 – Temperature difference Find the outdoor design temperature T_out and the exhaust (room return) temperature T_exp. The available temperature lift is DeltaT = T_exp – T_out. Step 3 – Effectiveness Choose an effectiveness epsilon (typical […]
Waste-Heat Recovery Case Study: Stack & Exhaust
The opportunity A metal-finishing plant exhausted 18,000 m3/h of 160C air from curing ovens to atmosphere – pure lost energy. The brief was to recover it for winter make-up air heating and preheat a process water loop. The solution A high-temperature plate air-to-air exchanger (stainless, rated to 200C+) transferred exhaust heat to incoming fresh air. […]
Wastewater Source Heat Recovery: Reusing Drain-Water Energy
The hidden reservoir Showers, wash-down, and process drains leave buildings at 25-40C – warm enough to be a valuable heat source. Wastewater (drain-water) heat recovery captures it before it disappears down the sewer. How it works Drain-water heat exchangers wrap a coil around or sit inside the greywater stream, pre-warming incoming cold water. Heat pumps […]
Supermarket Heat Recovery: Refrigeration + Ventilation
Two loads, one building Supermarkets and big-box retail bleed energy in two ways: refrigeration rejects heat constantly, while fresh-air ventilation (bakery, deli, entrances) demands conditioning. Heat recovery bridges them. Ventilation recovery Exhaust from the sales floor is warm and can pre-heat incoming make-up air in winter via a rotary wheel or plate exchanger. In cooling […]
Geothermal and Ground-Source Air Pre-Heating
The earth a few meters below the surface stays near constant temperature all year. That stable thermal mass can be used to pre-condition ventilation air before it reaches a building, cutting heating and cooling loads. How Ground Coupling Works Outdoor air is passed through a buried pipe loop (ground heat exchanger) or across a ground-coupled […]
Pharmaceutical and Cleanroom Exhaust Heat Recovery
Pharmaceutical plants and cleanrooms move huge volumes of HEPA-filtered air. Codes generally forbid recirculating exhaust that may carry contaminants, but the energy in that air can still be recovered using physically separated exchangers. Why Separation Is Mandatory GMP and HVAC codes require exhaust from containment areas to be discharged, not reused. Cross-contamination could compromise product […]
Commercial Kitchen Heat Recovery
Commercial kitchens run powerful hoods that throw away large amounts of hot, greasy air. Replacing it with conditioned make-up air is a major cost. Kitchen heat recovery captures the sensible heat while keeping grease and smoke out of the supply. Why Separation Matters in Kitchens Exhaust carries grease aerosol and odors, so any recovery device […]
Heat Exchanger Cleaning and Maintenance Guide
Heat recovery equipment only delivers its rated savings if it stays clean. Dust, grease, and moisture film raise pressure drop and lower effectiveness. A simple maintenance plan protects the investment. General Inspection Schedule Environment Inspect Clean Clean office air Every 6 months Annually Dusty / industrial Quarterly When dP +15-20 % Greasy (kitchen, booth) Monthly […]
Air-to-Air vs Air-to-Water Heat Recovery
Heat recovery comes in two broad forms. Air-to-air exchangers move heat directly between two air streams. Air-to-water devices (like run-around coils or exhaust water heaters) transfer heat into a fluid loop that can serve distant or mixed loads. Side-by-Side Factor Air-to-Air Air-to-Water Streams Two air ducts Air + water/glycol loop Distance Short (cores co-located) Long […]
Frost Protection in Heat Recovery Systems
In cold climates, exhaust air can be warm and humid while intake is far below freezing. When that exhaust cools below its dew point inside the core, frost forms. Left unchecked, ice blocks the airflow entirely. Why Frost Happens Frost appears when exhaust outlet temperature drops near 0 C and the core surface is below […]