Laundry Heat Recovery: Reusing Wash and Dryer Exhaust

Laundries are heat hogs

Commercial laundries heat vast volumes of water and run dryer exhaust hot and moist all day. Up to 70% of their energy can leave as warm water and humid air. Recovery is the fastest payback in the sector.

Two streams to catch

• Wash water – drain water at 40-60C feeds a water-to-water heat exchanger or heat pump to pre-warm incoming cold water. See wastewater-source recovery.
• Dryer exhaust – warm, humid air gives up heat to make-up air via an enthalpic wheel or plate unit.

Hygiene and fouling

Lint and detergent demand cleanable, accessible cores. Plan a rhythm from our cleaning guide and use a hair/trap filter upstream of any water exchanger.

Retour sur investissement

High hot-water demand means recovery often pays back in 1.5-3 years, cutting water-heating energy 30-50%. Validate with a payback calculation. Leisure sites with on-site laundries (see sports facilities) benefit most.

Water side: the bigger prize

Wash water leaving at 40 to 60C carries the largest share of a laundry energy, so the water-to-water exchanger or heat pump on the drain is usually the fastest payback. A plate or coil unit pre-warms incoming cold water, directly cutting the boiler or electric load needed to reach wash temperature. Where the drain is continuous, a heat pump can lift that warmth to an even higher supply temperature.

Air side: dryer exhaust

Dryer exhaust is hot and humid, ideal for an enthalpic wheel or plate unit that returns both temperature and moisture to the make-up air, reducing the heating needed to replace it. Because dryers run in batches, the recovery should handle part-load gracefully, since a coil or wheel sized only to peak batch flow wastes effectiveness between cycles.

Keeping it clean and measurable

Lint and detergent make the air and water sides fouling-prone, so accessible, cleanable cores and an upstream strainer protect performance and hygiene. Trend the temperature recovery on both sides and the water-heating energy saved, so a falling trend flags a fouled coil before it hits the utility bill. The 30 to 50 percent water-heating saving depends on keeping both streams clean.

Questions fréquemment posées

What are the two laundry heat streams?
Wash water at 40 to 60C handled by a water-to-water exchanger or heat pump, and hot humid dryer exhaust handled by an enthalpic wheel or plate unit.

Which gives the fastest payback?
The wash-water side usually, because it is the largest energy share. A heat pump can lift it to an even higher supply temperature.

What hygiene issues matter?
Lint and detergent demand cleanable, accessible cores and an upstream strainer. Plan a cleaning rhythm.

What payback is typical?
Often 1.5 to 3 years, cutting water-heating energy by 30 to 50 percent. Validate with a payback calculation.

Questions fréquemment posées

What are the two laundry heat streams?

Wash water at 40 to 60C handled by a water-to-water exchanger or heat pump, and hot humid dryer exhaust handled by an enthalpic wheel or plate unit.

Which gives the fastest payback?

The wash-water side usually, because it is the largest energy share. A heat pump can lift it to an even higher supply temperature.

What hygiene issues matter?

Lint and detergent demand cleanable, accessible cores and an upstream strainer. Plan a cleaning rhythm.

What payback is typical?

Often 1.5 to 3 years, cutting water-heating energy by 30 to 50 percent. Validate with a payback calculation.