Attic Solar Space Heating System Controller Specification

Using the solar heated air in your home provides you with a secondary heating system which is 10 to 50 times more efficient, and 10 to 100 times less expensive per kWh, than all other forms of home heating.

The powerful microprocessor based Attic Heat Harvester Controller is designed to efficiently control the transfer of free solar heated attic air, or solar heated conservatory air, to living areas and to provide system performance data. An extra cost option permits the controller to automatically operate an attic cooling fan.

The Attic Heat Harvester Controller continually monitors an attic/conservatory and a room temperature sensors to determine when the heating fan should be turned on to transfer move free solar heated attic air. An extra cost option turns on an attic cooling fan when attic temperature exceeds a user pre-set maximum.

Mk1 Attic Solar Space Heating Controller, exploiting solar heated attic air
Mk1 Attic and Conservatory Heat Harvester Controller - Exploiting solar heated attic air

System input power: 230vac 50Hz (default) or 115vac 60Hz. – voltage selection made using links.
Micro Processor: Microchip PIC16F1936
Clock rate 8 Mhz

Inputs: Thermistor
1 – Attic thermistor 30K at 25°C
2 – Room Thermistor: 30K at 25°C

1 – 3 amp 230vac SPNO relay – provides 230vac (115vac) to power fan
2 – 0.5 amp max, 18-26vac SPCO relays – provides 24vac to open/close main air valve
Option: 3 – 1 amp 230vac SPNO relay – provides 230vac (115vac) to power attic cooling fan

2 line x 8 character 5.6mm high alphanumeric LCD display with LED backlight

Keypad:    3 push buttons: 'MODE', '+', '-',

1 – +5vdc on - Green LED
2 – System running – Yellow LED – flashes each second in normal operation flashes if system errors detected – see error codes in Manual
3 – Fan On – Red LED

110 x 110 x 68mm (4.35 x 4.35 x 2.7 in) with clear polycarbonate lid
Fixing holes: 4 in a rectangle spaced at 95mm (3.75 in)
Weight 0.5kg 1.1lbs

System Performance Parameter Range:

Temperatures -9.9 to 70°C in 0.1 °C increments
14.2 to 160°F in 0.2 °F increments
Current Power (CKw) 0 to 65.5kW in 0.1kW increments
Current Efficiency (CEff) 0 to 99.9 in 0.1 increments
100 to 999 in increments of 1
Total Power (kWh) 0 to 999.9 kWhrs in 0.1 kWh increments
1000 to 16,609 kWhrs
Total Efficiency (TEff) 0 to 99.9 in 0.1 increments
100 to 999 in increments of 1
Un-Used kWh
(Un-Used kWh)
1 to 65,535 kWh
Cost of running the heating fan (Heating cost) 0 to 9.99 currency units, e.g. $, £, €
10.0 to 99.9
100 to 399
Heating Fan running Hours (FHr) 0 to 999.9 in 0.1 hr increments
1000 to 6143 hours (25 days) in 1 hr increments
Average Attic-Room Temperature Difference when heat fan is running (AvTD) 0 to 99.9°C or 0 to 99.9°F
Cost of running the cooling fan (Cooling Cost) 0 to 9.99 currency units
10.0 to 99.9
100 to 399
Cooling fan running Hours (Cooling Hrs) 0 to 999.9 in 0.1hr units
1000 to 6143 hours (256 days)

System user pre-settable Parameter ranges and initial default values

Range Default
Attic Temp – Room Temp (Attic-Rm Temp) 0 to 9.9.4°C
0 to 17.8°F
Max Room Temp
(Max Room Temp)
5 to 30°C 23°C
Max Attic Temp (MaxAttic Temp) 38 to 51.8°C
100 to 125.2°F
Fan Flow
(Fan Flow cmh or cfm)
0 to 5100cmh
0 to 3000cfm
Heating Fan Power (Heat Fan Watts) 0 to 255watts 80watts
Cooling Fan Power (Cool Fan Watts) 0 to 255watts 60watts
Electricity Cost
per kWh
(ElecCost pkWh)
0.001 to 0.255 currency units  

Conservatory and Attic Solar Space Heating system, exploiting solar heated attic air