SolarVenti in the Adelaide Hills

The Adelaide Hills region is a great place to live – fresh air, open space, beautiful countryside, great food and wine. I live in an old sandstone cottage (circa 1880) and this does have some definite advantages – the building design and thermal mass, along with the frequently cooler summer evenings, means that air conditioning is not needed. The flip-side is the disadvantage that the building design and thermal mass can have in winter – the house tends to be damp, and these 300mm-thick stone walls soak up a lot of heat! These disadvantages had been exacerbated by my working life-style, which involves travelling for at least six months per year, with the house closed and locked up for periods of up to 8 weeks at a time. Coming home in winter to a cold (internal ambient temperature approximately 10 degrees), damp, musty house was no fun at all. Being very much concerned with reducing my impact on the environment a ‘conventional’ reverse cycle heating / cooling unit was not even considered as an option. I was then made aware of the ‘SolarVenti’, a type of solar air heater.  Further investigation revealed that this unit used the sun’s energy to heat dry ‘outside’ air and then introduce this into the house via a ceiling vent, and the larger units (SV30) were supplied complete with a second fan to extract hot air in summer. The units looked good, are made in Denmark, appeared to be of a high quality, and appeared simple to install and maintain.  After a brief discussion with the supplier (Global Eco & Environmental Solutions) I ordered one of the SV30 units and went away to work, happily anticipating the delivery of my new ‘toy’.

Upon delivery of the unit I opened all the boxes and checked all the contents. I was impressed with the secure packaging and the quality of all items – most components were of aluminium construction and all fasteners were of stainless steel. I arranged the assistance of my brother and we got to it – a little bit of head scratching and clambering on (and within) the roof and we were done. A solid days’ work and the unit was installed – but unfortunately it was late in the day and there was no sun. So what else was there to do but have a cold beer (or two) and pray for clear skies… I’m pleased to say the  next day dawned bright and sunny and yes, the SolarVenti was up and running.

I am a bit of a ‘fiddler’ and like to ensure that equipment operates at maximum efficiency, so my installation was a bit different to that advised by SolarVenti.  This house has high ceilings (over 3 metres) and I tend to live at floor level, so that is where I wanted the nice warm air. Instead of the standard ceiling vent, I ducted the produced air through the ceiling and down a wall, to discharge approximately 300mm above floor level in a central part of the house.  Initially I used flexible ducting in the ceiling, but was disappointed in the lack of airflow. To minimise flow losses due to friction inside the duct I modified the installation several times, and it now consists of 150mm PVC sewer piping in the ceiling which is mated to a rectangular duct (manufactured for me by an air conditioning company) running down an internal wall.  I was now getting nice warm dry air supplied into my house whenever the sun shone, with the thermostat stopping the heating fan and starting the cooling fan whenever the house reached the set temperature.

The result? Quite an amazing improvement – I returned to the house at the end of one August, the house having been empty for nearly seven weeks, and was very pleasantly surprised. The house internally was approximately 17 degrees, the musty smell had disappeared, the mildew problem in the kitchen had disappeared – it was like having a window open on a warm spring day the whole time I was away. With the house now being much less damp than before, it ‘felt’ warmer and was also much easier and quicker to heat. This was an unexpected bonus but very welcome – less wood to chop!  The performance of the house in summer is also improved. I had previously fitted two ‘whirly bird’ style roof vents to reduce heat build up in the ceiling cavity, and these are now assisted by the extraction fan, which is powered by the SolarVenti in summer. During our most recent summer Adelaide experienced fourteen consecutive days with a maximum temperature over 35 degrees – at the end of this period the internal temperature of my house was around 27 degrees.

Family and friends have also noticed the improved comfort and feel of my house – so much so - that I have now fitted SV30 units to the homes of my mother, my brother, and a friend – all being older houses of sandstone and brick construction. Two of these have been ‘conventional’ ceiling vent installations with the third being ducted in a similar manner to my own. Later model SolarVenti SV30 units were supplied with larger photovoltaic panels, and to increase the effectiveness of the units installed by myself, I retrofitted additional PV panels to each. In addition, on the two ‘ducted’ installations I modified the ducting and installed the new in-line fans now available from SolarVenti. The additional PV panels greatly increased supplied air volume and temperature, and the in-line fans also assisted the ducted unit’s performance.

We have all noted the following advantages of the SolarVenti installations: lower moisture levels, leading to increased comfort with reduced need for heating and less incidence of residents ‘catching colds’; elimination of ‘musty smells’ and incidences of mildew; coming home on a sunny spring (or autumn) day to a warm house, not an ‘ice-box’; being able to secure a house with all doors and windows closed, but still achieving effective ventilation; and reduced heat build-up in summer. Definitely an improvement and well worth the cost and effort.

Peter Aberdeen