Greetings to all from South Africa
I am 'almost' certain this could fall under the category of HVAC, but if I got it wrong, please forgive me and re-direct me.
Am looking to DIY a ventillation system for our home. Located east coast of South Africa, brick building, concrete tiled roof, temperatures range 10 to 40 celcius ( all year ) and relative humidity usually 70% or higher.
Problem we are having is mould. I have noticed in a few rooms where ventillation is good, the problem is less, so am guessing that a better air flow would reduce the mould presence and smell in other rooms. Due to a number of reasons, we can't leave windows wide open all the time to get the required air flow ( security, excessive winds from the sea, monkeys invade the house, etc ).
My thinking is to use a centrifugal fan ( like this http://za.rs-online.com/web/p/centri...lowers/7013586
/ ) 230v, 133 x 270 mm, 890m³/h, 86W, 0.64amp.
Since my workshop is elevated higher than the house ( floor of workshop level with top of house walls, and only 3 meters apart ) I was thinking to have a series of air filters on the input to the blower, and then the blower connected to a duct bridging to the house.
Question now is : is it better to run sheet metal duct around the outside of the house ( under the roof overhang ) and feed the air into the 3 bedrooms through the existing air ventillation bricks ( just under ceiling height, about 3 x 5 inches ), or run the ducting into the ceiling cavity, split into 3, and install a vent in each room ?
My intention is to create a slightly presurised house ( at least in the sleeping area where the problem exists ) and to create sufficient flow of cleaner ( reduced mould spore count ) air. The air should follow the path of least resistance and exit down the passageway and out the lounge / dining / kitchen area.
My thinking if this works, is later to add a return feed from the lounge end of the house, back to the workshop. A simple temperature control managed by an Arduino micro controller would determine the air temperatures and, if (for example) I set the preferred temperature at 25 celcius, and the outside incoming air ( through the filters ) is below that, and the return duct exhaust air is warmer, then divert the air through a heat exchanger to use the exhaust air to warm the incoming air.
Any advise or suggestions would be really appreciated.