Attic Heat Harvester
attic heat harvesting system, installation instructions


Attic Heat Harvesting System - Installation Instructions

Before you order and install an Attic Heat Harvester System you must first consider:

using heat in hot air - buy now a) The area you would ideally like to heat - the Attic Heat Harvester is generally, but not always fitted in this area. The best location to heat is a frequently occupied room on a lower floor or a cool room that receives very little passive solar heat. It is better to heat a room at a low level because the attic heat harvester system will move solar heated attic air throughout your home and hot air rises. For the system to operate air will need to be able to escape from the heated room into other areas of your home. To achieve this air flow your may need to install air vents in the heated room doors or walls.

b) Which is the hottest side of your attic - this is often the direction of the sun around 1pm. The open end of the flexible duct should be close to this point and approximately 300-600mm (1 to 2 ft) below the attic apex.

c) Answers to a) and b) will determine the route that the flexible duct will take. The duct length should ideally be minimized, this generally determines the location of the ceiling air vent which should be between 2 ceiling joists.

d) If your home is not a single storey you will also need to decide where the duct is going to pass through the upper storey(s). Note that for maximum system efficiency the duct run should be as straight as possible. Gentle curves in the ducting will have minimal impact of system efficiency but tight curves can considerably reduce the system efficiency.

In order to get the best solution to steps a) through d) you may have to compromise somewhat.

e) The location of the Attic Heat Harvester - The controller is generally fitted to a wall in the heated room around about 5 feet from the floor. Another thing to consider is the location of a suitable electrical supply power as it is easier to connect to an adjacent supply.

When you have determined the locations for the above items your can determine the minimum length of the cables you will require, you will require these dimensions to choose the cable lengths to order. The cables are shown in the diagrams on the Attic Heat Harvester system page.

We generally do not supply all the items your need for your system as you can easily obtain them at a lower cost and obtain items that suit your home's decor. The items we do not supply include:

a) The system fused ON OFF switch and mounting box

b) the electric cable from the main supply to the On Off switch

c) the electric cable from the ON OFF switch to the Attic Heat Harvester

d) the air vent or air vents

e) the hoze or jubilee clips that secure the ducting to the fan and one way air valve.


Installation Instructions for a One Floor Home

Ensure that the Attic Heat Harvester voltage links are set to suit local power. If the system is to be powered from 200 to 240vac link B only should be fitted, links A and C should not be fitted. The Attic Heat Harvester is initially manufactured with link B made on the PCB. If the system is to be powered from 115volts link B should not be fitted, links A and C should be fitted. The links are on the bottom right of the controller PCB next to the blue transformer.

1. If you are installing a 12 inch diameter system a 12 inch diameter hole need to be made in the attic floor between 2 attic floor joists.   Before cutting the hole ensure that there are no cables or pipes in the area and that there is sufficient height above the hole, generally at least 3 feet and preferably more, for the air valve, the fan and the ducting.

2. Make a support for the air valve. This can be a 20 x 20 inch sheet of plywood that has a 12 inch hole in it for the air valve. This support will be fitted to the top of the attic floor joists.

3. Determine the length of ducting that you require. The ducting goes from the top of the fan unit to a point ideally within 2 feet of the roof apex on the most sunny side of the attic. Cut the ducting to length.

4. Fit the ducting supports to the roof trusses using wide webbing loops. Minimize bends in the ducting as bends impair air flow and reduce the system efficiency. Gentle ducting bends can be accomplished by using a flat flexible piece of wood or plastic beneath the ducting to support it attaching the end near the fan to a vertical support.

5. Mount the attic temperature sensor cable so that it is near the center of the open duct end near the attic apex and run the cable back along the ducting to the hole in the attic floor.

6. We recommend that the Attic Heat Harvester power be fed via a separate fused isolating switch located near the controller.

7. Remove the front of the Attic Heat Harvester. Make cable and mounting holes for the controller.

8. Run the cables to the cable holes preferably inside the walls so they will not be visible.

9. Wire the system up as shown in the wiring diagram. We recommend that the Attic Heat Harvester power be fed via a separate fused (2 amp) isolating switch located near the controller. The motor cabling should be rated for at least 2 amps. The air valve power cable(s) should be rated for at least 1 amp.

10. Carefully check all system connections to ensure they comply with the wiring diagram.

11. Temporarily remove the 6 way connector for the initial test. Only the main power, attic sensor and room sensor connectors should be connected.

12. Turn on the power to the Attic Heat Harvester. If the controller is connected correctly the green Power On LED should be on and the LCD display should show the 'Sign On' messages.
The unit will perform a self test, then after a short delay the current room and attic temperatures will be displayed.

13. Turn OFF power to the system.

14. Connect the 6 way connector.

15. Turn on power to the system.

16. Before any parameters are set, or after a Performance Memory Reset, an option of 'Test Installation' is given during the Attic Heat Harvester Controller power up sequence - this option is selected by pressing the '+' key.

The installation Test sequentially operates the Fan, and Air valve outputs as follows:

a) Open Main Air Valve - as the main air valve is opening a green LED on the main air valve unit will illuminate, then 30 seconds later:

b) Turn Fan On, then 30 seconds later

c) Turn Fan Off, then 30 seconds later

d) Close main Air Valve - as the main air valve is closing a red LED on the main air valve unit will illuminate

e) If the attic cooling option is not fitted the sequence repeats at a) above

f) As the attic cooling option is fitted the controller Opens the attic cooling air valve - as the attic cooling valve is opening a green LED on the attic cooling air valve unit will illuminate, then 30 seconds later

g) Turn Fan ON, then 30 seconds later

h) Turn Fan Off, then 30 seconds later

i) Closes the attic cooling air valve - as the attic cooling valve is closing a red LED on the attic cooling air valve unit will illuminate

j) 30 seconds later the sequence repeats at a) above

The installation test sequence is ended by pressing the '-' key.

17. When the system is working correctly you should setup the system parameters to meet your needs - see Attic Heat Harvester Controller manual page.

Installation Instructions for an Attic Heat Harvesting System in a two or more Floor Home

If you will use the system in a two floor home and need the heat in a lower floor, including a basement, you will need to pass the ducting through the upper floor(s). The system will be much more efficient if the duct run is straight or nearly straight as the air flow will be greater.

You will have to locate somewhere to pass the duct, this can often be through a closet or cupboard.

Make holes between the floor joists in the floors to pass the ducting through and install the system as detailed in 'Installation in a one floor home' above.