Shower Heat Recovery: How does it work and how much energy can you recover?

Every time you take a hot shower, you use energy to heat the water. But the moment that warm water disappears down the drain, most of that valuable heat is lost.

Shower heat recovery changes that.

A shower heat recovery system captures heat from the warm wastewater and transfers it back to the incoming cold water. Instead of letting the heat literally go down the drain, the same energy can be used again.

The principle is simple. The technology behind it is surprisingly effective.

What is shower heat recovery?

Shower heat recovery, also called shower wastewater heat recovery or a shower heat exchanger, is a system that recovers thermal energy from shower wastewater.

When you shower, two things happen simultaneously:

1. Cold water enters your home and needs to be heated.

2. Warm water leaves the shower and carries a significant amount of heat with it.

A shower heat exchanger brings these two streams together — without mixing the water.

The heat from the outgoing wastewater passes through the heat exchanger walls and preheats the incoming cold water.

This means your water heater, boiler or heat pump does not have to provide as much energy to bring the water up to the required shower temperature.

You heat the water once — and recover the heat before it is lost.

That is the basic idea behind shower heat recovery.