Sub-soil heat exchangers

Zehnder ComfoFond-L Eco

Employing renewable energy sources to improve indoor comfort.

The Zehnder ComfoFond-L Eco sub-soil heat exchangers are designed to complement our heat recovery units. When connected to a Zehnder ComfoAir 350 Luxe or 550 Luxe system, it augments the optimum comfort of the supply air to the dwelling throughout the year – even when the temperature falls below zero. This can help improve the efficiency of the heat
recovery units as the incoming air requires less energy to meet the desired comfort temperature. By saving energy and providing an optimised indoor climate, benefits are felt by the building, the homeowner and the environment.

ComfoFond L-350

Zehnder ComfoFond L-350

to the product
ComfoFond L-550

Zehnder ComfoFond L-550

to the product

Sub-soil heat exchangers

How does it work?

The Zehnder ComfoFond-L Eco earthbrine sub-soil heat exchanger uses the relatively constant annual temperature of the earth at a depth of one to one and a half metres. This ‘passive store’ of energy remains at a temperature of 8-12ºC all year round and can be used to pre-heat or pre-cool incoming supply air in winter and summer months.

  • A brine filled ground loop is buried one to one and a half metres below the surface of the ground
  • The integrated water pump moves the brine through the ground loop at 8 l/min
  • The temperature of the brine is then modified by the temperature of the surrounding earth
  • The brine loop is connected to the ComfoFond-L Eco which draws in air through an external wall
  • The incoming air is filtered and passed through a liquid-to-air heat exchanger
  • The tempering energy of the brine loop is passed to this air which is then delivered into the ComfoAir heat recovery unit for further tempering before being supplied to the habitable rooms of the home