Air Circulation systems and HEAT PUMPS

Some notes on retro-fitting ducted air circulation systems with heat pumps (aka reverse-cycle air conditioners):

• The air coming out of a heat pump is 12-25 degrees warmer than your temperature setting on the heat pump remote control, depending on the model of the heat pump and at which stage the heat pump was turned on. This means a surprisingly warm layer of hot air naturally accumulates below the ceiling. Typically this air is 8 degrees warmer than ground-level air, often a lot warmer.
• The living room at sitting level actually gets warmer after the ducted system is introduced as the top layers of warmest air are mixed in with the cooler lower layers.
• A HEG ducted air circulation system will slowly circulate warm air around your house 10-15 times per hour. This will help maintain a uniform temperature throughout the house. The living room will always be warmer, but the chill will be gone from the rooms that are ducted to. No draught is felt, but you will experience the warmth. Even your passageways will be heated as air travels from the bedrooms back to the inlet near the heat pump.
• The air outlets that deliver air to bedrooms are very subtle in appearance, being "matt ceiling white" in colour. The inlet is typically placed 1.5 to 3 metres from the heat pump. We try to place the outlets away from the bedroom doors, usually half-way between the light fitting and the window.
• You should expect an ambient temperature increase of 4-5 degrees throughout your house, which nicely takes the chill off the house. The results do vary in houses according to your patterns of use with the heat pump, the degree of insulation in your ceiling and/or sub-floor, the amount of draughts, etc.. These temperature increases can be much higher with a thermally efficient house.
• The fan is designed to be very quiet, and we suspend it from roof bearers or trusses so as to shock absorb it even further. The flexible ducting that is used is very well insulated with polyester insulation, losing minimal heat as it transfers warm air to bedrooms, bathrooms, en suites and/or other living rooms.
• As the heat from a heat pump is relatively mild (as compared to a gas or wood heater), it is particularly important to have effective insulation in your ceiling. This will improve the effectiveness of the ducting system as it means that the air going into the inlet will be a lot warmer and less heat will be lost as the warm air circulates around your home. Home Efficiency Group can install insulation more cost effectively than most people can self-install due to our bulk-buying power and installation expertise, so please ask for a competitive quotation.

Air Circulation Systems and WOOD HEATERS

The ducted air circulation system dramatically improves the efficiency of your wood heater, and can be used with either heater depending on your preference and convenience. With a wood heater, you should expect:

• An 8 degree ambient temperature increase throughout the house;
• The hot ceiling-based layers of air being mixed with cooler, ground-level layers air, resulting in a much warmer living room;
• 50% less wood consumed (as you will be forced to turn the wood heater down when the living room warms up);
• Eradication of any serious condensation

Some interesting facts on wood heaters:

• Most modern wood heaters are the equivalent of a 12-14 KW heater.
• Wood heaters generate two main types of heat: radiant (the "glow") and convective heat (the warm air).
• Wood heaters inherently create a strong vacuum as a strong up-draught is created in the flue. The bigger the fire, the bigger the vacuum. This is why draughts in a house are towards the wood heater, and this also explains why the warm air generated by a wood heater generally does not travel to the far side of the house (the bedrooms!).
• Due to the inherent vacuum of a wood heater, a large portion of the convective heat (warm air) that is created by the wood heater is sucked back into the heater itself and exhausted out of the flue. This makes the convective aspect of wood heaters particularly inefficient.
• With a wood heater, air at ceiling level level is often 15-25 degrees warmer than ground level. This changed depending on how the wood heater is being run, how much insulation is in the ceiling and how high the ceiling is.
• Wood heaters can inadvertently cause window condensation at the far end of the house because they create hot and cold temperature fluctuations between different rooms of the house.

The Air Circulation System allows the wood heater to become MUCH more efficient with its convective heat by creating a counter-vacuum that tries to take the warm air before it is sucked back into the wood heater and wasted (exhausted out of the flue). As a bonus with wood heaters, our Air Circulation System allows the wood heater to effectively control window condensation. This is because large air temperature variances between rooms are eliminated, and the vacuum created by the wood heater allows the house to be ventilated as dry air from outside is "sucked" into the house via 100's of small air leakage points throughout the house (such as power points, vents, cracks around windows and doors, skirting boards, etc...).