HEG Air Circulation System, with Roof Heat Recovery and Condensation Control Module

HEG Air Circulation System

What is an Air Circulation System?

The HEG Air Circulation System (ACS) is a hybrid system that has been created over 5 years by Home Efficiency Group by a process of continual refinements. At its heart, the HEG ACS is an overgrown air transfer system, albiet with significant differences, including:

  • larger capacity fan(s) - depending on the configuration, we use a single or dual fan set-up, with fans having two fan speeds and two different diameters and air flow rates.
  • larger gauge ducting - for noise reduction and efficient heat transfer.
  • different inlets/outlets - subtle inlets and outlets, with optional filtered intake, and for minimal draughts.
  • different controller - for accessing free solar air via the Roof Heat Recovery Module, and to allow for simple access via the customer.
  • optimal ducting configurations - methods for noise/vibration reduction, developed and refined over years by our installer team members.

Modules available

  • Roof Heat Recovery Module - for accessing free solar gain in your roof cavity/void; bundled with 98% of all jobs.
  • Window Condensation Control Module - for guaranteed eradication of persistent window condensation.
  • Summer Heat Exhaust Module - to lower the heat load in the livable part of the house, as well as the roof cavity simultaneously.

Circulate air to up to 10 rooms (4 rooms shown in this diagram):

Duct up to 6 rooms (4 rooms shown in this diagram)

Our customers indicate that they have huge savings on wood and electricity. This is because they no longer need to run the heaters on "high" in order to distribute heat. Low heat settings can now be selected and the ducting system does the rest!

Ducted Air Circulation System

Does your heater keep your lounge room hot, but other rooms in your home are chilly?

A ducted air circulation system takes warm air from one room and distributes it to rooms that require heating. Not only do you warm rooms, but you also displace stale, moisture-laden air, the cause of window condensation! Look at these diagram for an illustration of how the system works:

Wasted heat through ceiling is the norm in most houses, unfortunately

With the HEG Air Circulation System, otherwise wasted heat is recycled to heat the rest of the house. This means you save on energy because you can switch off panel or oil heaters in bedrooms, and you don't need to have your primary heater set to "high" - the ducted air circulation system does all of the hard work! This often equates to a 15% to 35% saving on wood/power costs.

Inter-Room Air Transfer System

Works great with wood heaters! Increase ambient temperatures by up to 8 degrees and get rid of condensation 


Ducted Air Circulation Systems (tm) are priced based on:
  1. the number of outlets required in your home;
  2. the modules required e.g. Window Condensation Control Module;
  3. where you are located i.e. travel fees can apply in some areas;
  4. some house characteristics that increase labour time e.g. lath and plaster ceilings, low pitch of roof requiring removal of sheets of roofing iron;
  5. the method which we need to use to access ventilation for the system (only applies to jobs requiring Window Condensation Control); and
  6. miscellaneous installation aspects, such as penetrations through cupboards to reach downstairs rooms.

Extra fees that may apply:

  • Travel  (if more than 20km from Launceston or Hobart, $3 per KM one way apply)
  • Additional Roof Off work (retrofit mostly): $75 per sheet of corrugated iron
  • Cupboard penetration: $200 (assumes two internal shelves to cut through)
  • customisations (such as penetrations through cupboards to lower-floor areas or external conduit where required)
  • non-standard inlets and outlets
  • non-plasterboard or horsehair plaster ceilings. $50 fee per protrusion applies for lath and plaster, timber or double ceilings (even with plasterboard below) due to extra labour, difficulty of placing outlets, extra tooling required and extra preparation and clean-up time.
  • Removal of storage items in the sub-floor or ceiling cavity.
  • Asbestos removal (outsourced to a specialist company)
  • Difficult access to roof cavity or parts of house
  • Multiple visits required to complete job.

All pricing is subject to onsite inspection, and HEG reserves the right to alter or refuse a quotation based on this onsite inspection (although it would have to be exceptional circumstances to do so).

Did you ever think your roof was a heater?

Have you ever noticed how hot your roof cavity is on a bright sunny day? That free hot air can be filtered and used to warm your house during the day. Often the roof space will still be warm for hours after the sun goes down. Higher pitched roofs with roof sarking (foil) are better as they have a larger air volume and tend to trap the heat for longer.
Solar Roof Heat Recovery Module
For Solar Roof Heat Recovery, we simply add a module onto one of our  HEG Air Circulation Systems. This enables you to have multiple benefits, such as circulating warm air from your living room (wood heaters or heat pumps typically) to bedrooms, or offsetting your traditional heating costs using free heat from the sun.
The air is filtered via an industrial grade filter, and an adjustable thermostat controls when the air valve will open i.e. if the air is hot, the air valve will introduce the warm, filtered air into your home. If the system is switched off, or the temperature drops, the air valve will close.
When the roof space air is cold, the system only extracts air from your living room heater. The solar gain from your roof space essentially pre-heats your home, meaning that your heaters do not need to work as hard, thus saving you heating costs. During Spring and Autumn, you will often find that you can remove the need for additional heating altogether, but this does depend on the outside temperatures, your bedtime and your expected comfort levels.
Call us on 1300 96 80 60 or email info@heg.com.au for a free onsite quotation.


Common Scenario...

Kane holding a fan!



Your living room is kept warm & comfortable with your current heater, but the warmth does not effectively penetrate into other parts of the house, particularly bedrooms off passageways. Alternatively, if the heaters can warm up other parts of the house, it is after a substantial period of time and the living room becomes uncomfortably hot.

Related concerns

You may be using portable or panel heaters in bedrooms or passageways, or alternative heaters used in separate lounge rooms, adding additional expense to the household. These only have limited effectiveness and, in combination, are more expensive than the primary heater.


Warm air, in general, does not like to naturally move away from your heater unless it is blown or caught in a cross-draught. Wood and gas heaters, in particular, naturally create a strong vacuum as the hot up-draught travels up the flue, which means that recently-heated air gets sucked away before it has a chance to be of any use. If you have a combustion heater of any kind, you will probably note that all draughts in your house are towards the heater, making it very difficult for warm air to move to other rooms in the house. As the warm air does not want to move away from the heater, most people then resort to closing doors to keep heat in specific rooms and cold rooms isolated.


A ducted air circulation system continuously moves air to and from the living room to the bedrooms, bathroom(s) and other living areas of the house. Warmed air will slowly travel around the house approximately 10 times per hour, taking the chill off the thermal mass of the house (walls, furnishings and even floors) as it circulates An air inlet is placed in your ceiling near to the heater, which is connect to the other rooms via heavily insulated flexible ducting. A quiet, yet powerful, centrifugal air pump moves the air efficiently through the ducting. It is recommended that 4-5 rooms are ducting to at least, usually all bedrooms and the bathroom, so as to generate this “circulation effect”. Alternative systems that used weak fans, low-capacity ducting and incorrect positioning of the inlet and outlets are not able to capitalise on the circulation effect, which is where all the real benefits of the system are realised.

Expected outcomes

Less reliance on expensive panel heaters or other primary heaters, distribution of warmth to up to 10 rooms in the house, increase in the ambient temperature of the bedrooms and passageways by 4 to 8 degrees depending on heater type and house size, a reduction in your heating-related bills, reduced window condensation, a drier environment with better air quality and a warmer living room. The living room is warmer because the warmest air (just below the ceiling) is “folded” back into the lower sections of the room by the subtle circulation effect, and returning air  from rooms is warm instead of being cool.

Components of an Air Circulation System

Subtle Bedroom Diffuser

These are the standard air outlets/diffusers used with the HEG Air Circulation System. They distribute the air evenly around the room, and don't blow the air down onto the back of your neck. As you can see, they are ceiling white and subtle by design.

Typical bedroom outlet Diffuser shown from below

Standard vs Filtered Inlet

The standard inlet that comes with the HEG Air Circulation System is a round "jet" inlet. However, some people prefer a filtered inlet so that it captures particles that are floating in the air for additional air quality, and to minimise cleaning requirements.

Typical inlet in HEG Air Circulation System Filtered inlet, 400x400mm

Digital Controller for the Roof Heat Recovery Module, part of the HEG Air Circulation System

Polyester-Insulated Ducting

This ducting is flexible in nature so that it can weave its way through roof obstacles. It has an inner-sheaf (foil-plastic laminate) over a strong wire skeleton, which is then surrounded by safe polyester insulation (which is used in teddy bears!) to retain heat. This then has an outer protective layer of strong foil-plastic laminate. 

Mix-Flow Ducting Fans

The inline ducting fans that we use are sourced as "best of breed", and are a major differentiator of HEG Air Circulation Systems. They are designed for long-term use, coming with a 3 to 5 year warranty depending on the brand that we are using. Pictured, below, is a 200mm inline ducting fan.

HEG Easy Controller for the Roof Heat Recovery Module

The HEG Easy Controller has the following features:

  • Simple on/off switch. This control is intentionally kept separate from the main control as we can often incorporate the switch into an existing light switch to make it more subtle.
  • Allows the user to specify a "Trigger Temperature", which is the temperature at which free solar heat is obtained from your roof cavity.
  • Summer Override Function. Simply switch off the digital thermostat to disable the Roof Heat Recovery Module. This will allow you to duct cooler air around your home in summer. The source of the cooler air can either be air from a well ventilated part of your home, or an Air Conditioner.


HEG Energy - Home Efficiency GroupHome Efficiency Group
Local Call Fee: 1300 96 80 60
285 Invermay Road, Invermay TAS 7248 
1/65 Albert Road, Moonah TAS 7009