eclipse heat recovery ventilator - for condensation control

Installation Instructions

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How It Works

Heat recovery ventilators contain two fans. One extracts the air from the room and the other replaces it with fresh air. The two air flows pass through alternate layers of a highly efficient heat exchanger. The heat in the extracted air is passed to the incoming cooler air, but air streams do not mix within the ventilator.

The ventilators are designed to run continuously at low speed providing background ventilation. When the humidity exceeds a pre-set level the ventilator switches to boost, rapidly removing the damp stale air.

What Does It Cost?

The ventilator does cost a few pence each day to run, typically costing about 16p a week. This has to be offset against the improvement in living conditions, the reduction in damage caused by damp and condensation and the cost of replacing the lost heat if a conventional extractor fan were used.

Power Consumption Pence Per Week
On Trickle 11p
On Boost 55p
Typical (15% boost, 85% trickle) 16p

Typical running costs of the HRV based on electricity cost of 7.2p/unit

Dampness & Condensation

Improvements in building construction such as the use of double glazing, wall and ceiling insulation, cavity fill and draught excluders have all been encouraged in recent years. This has improved the insulation, but has also reduced the natural ventilation. Water generated by activities such as washing, cooking, drying clothes and breathing can not escape so easily. Condensation and damp problems have, consequently, increased.

Extractor fans remove the moist air but do not replace it. Colder replacement air is drawn through open windows and natural vents. If the heat is not replaced the room temperature drops and more condensation occurs as water vapour condenses on cold surfaces.

Reduce Dampness

The Heat Recovery Ventilator (HRV) can help solve this problem by extracting the damp air and replacing it with fresh warmed air. The internal humidity sensor switches the ventilator to boost when the humidity exceeds a pre-set level. This rapidly removes the damp air before the water vapour can condense on cold surfaces or can travel to other rooms.

The air within a room usually contains more water vapour than the outside air. Steady trickle ventilation with rapid extraction when required provides an economical and effective method of combatting condensation and damp problems in many properties.


Trickle: Low level background ventilation

Boost: High level for rapid extraction of dampness and smells

Controls Humidity Sensor
Off On
Pull Cord Switch Off Trickle Boost
Off Boost Trickle

Pull cord option on selected models

Users Guide

The Eclipse Heat Recovery Ventilator

  • Extracts damp stale air
  • Provides fresh, warmed and filtered replacement air
  • Removes nasty odours
  • No open windows, no draughts and improved security
  • Low running cost
Air flow diagram

The HRV with air flows shown

All dwellings require adequate ventilation to maintain indoor air quality and to remove moisture.

The HRV provides this ventilation. It is similar in operation to an extractor fan except that it also returns fresh filtered air to the room in which it is fitted. The heat in the extracted air is used to warm the incoming, typically cooler air. with an extractor fan all of the heat is returned to the room.

The fresh air gives a healthy living environment whilst the heat recovery ensures that little additional heating is required to maintain a comfortable room temperature.


The two front filters should be checked regularly.

If dirty they should be washed in warm soapy water and replaced once dry.

Open the front filter covers by gently pulling each cover in the direction marked by the arrow. The filters can then be reached.

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