Heat recovery: Overview

Basic concepts

A heat recovery unit allows the internal air renewal of the premise, maintaining and recovering the energy used for air conditioning.

What is a heat recovery unit?

The main objective of a heat exchanger or heat recovery system is the recovery of the energy by transferring the heat of the air that is extracted from the inside of a premise to the air that is driven outside.

How does it work?

A heat recovery unit is basically composed of a directly driven fan, an exhauster and a heat exchanger, all perfectly assembled and joined inside a thermal and noise insulated structure. The internal extraction air circuit pass by the exchanger without mixing with the circuit of the external driven air.

Through heat exchanger ventilation it is possible to recover a high percentage of the energy used for the premise acclimatization that otherwise would waste.

Heat recovery units advantages and benefits

By the use of heat recovery units in buildings we obtain:

• Optimum internal air renewal
• Clean and comfortable ambience
• Better climate control
• Energy efficiency improvement
• Energy saving
• Lower acoustic pollution
• Contribution to the environment protection

Heat recovery units are designed according to the type of installation:

• Heat recovery unit for horizontal installation
• Heat recovery unit for vertical installation
• Heat recovery unit false-ceiling installation (horizontal)

The efficiency of a heat recovery unit is directly related to the exchanger. The most common are:

• Back flooding aluminum plates exchanger with efficiency between 52%- 55%
• Crossed flow plates exchanger of high efficiency (54%-75%)
• Rotary exchanger of high efficiency (70%-77%)

The exchanger as well as the fans are the most important parts of a heat recovery unit. The technical characteristics of the fans that are necessary are calculated according to the air volume to be moved and the number of daily renewals.

The performance of the heat recovery unit will also depend on the fan type:

• Double inlet, low pressure centrifugal fans
• Double inlet, low pressure centrifugal fans with external rotor motor
• Double inlet, medium pressure forward curved belt-driven centrifugal fans
• High efficiently back curved motoimpellers
• High performance back curved EC motoimpellers

The most efficient fans are the ones that use the new technology EC.