Yes, I did do some research into low speed large diameter fans of the type you
mention
http://www.breezepower.com.au/breeze_power_2a4.pdf but they were fairly
expensive and there was a bit more installation work required. I would point out
that by installing ceiling vents in all rooms a roof mounted exhaust fan will do
a similar job to the above unit. However, my main objective is to reduce the
temperature of the air trapped in the roof space so that it does not overload
the insulating properties of the ceiling insulation, so I do not plan to install
ceiling vents initially. I will install a number of vents around the eaves to
allow the intake of cooler air to the ceiling space. By having only a single
exhaust hole in the roof for the fan I anticipate that warmer air will not leak
out too quickly during the cooler months because the fan will never be turned
on.
:
::>
:> :Ross Herbert wrote:
:> SNIP
:> :>
:> :>
:> :> Large retailers/companies whose enterprise relies heavily upon export
:> negotiate
:> :> with the various freight providers for special rates. If they care to
:> pass on
:> :> the freight savings to customers then buying goods from the other side
:> of the
:> :> continent can be wothwhile and you can even save money over a local
:> purchase
:> of
:> :> the same item. For smaller companies who don't have such economies of
:> scale
:> :> freighting items across the country can be expensive.
:> :>
:> :> Australia has a population of only 22M so the possibility of buying
:> from
:> :> interstate at low freight costs are not usually the norm. For example,
:> I
:> :> recently wanted to buy a rooftop mounted, mains powered,
:> thermostatically
:> :> controlled roof space evacuation fan. None of the locally available
:> solar
:> :> powered items would do - they were all like high priced gimmicky toys.
:> I
:> :> couldn't find anyone in Western Australia who could supply what I was
:> after
:> so I
:> :> had to go interstate to NSW
:> :>
http://www.skydome.com.au/images/pdf/ventillation_brochure.pdf
:> :>
:> :> The manufacturer quoted me a cost of $90 in freight to have it sent
:> across
:> :> Australia from the east to the west (roughly the same distance as your
:> dog
:> food
:> :> purchase). ...
:> :
:> :
:> :Yikes! That's a rather small item. It seems to me that there must also
:> :be a large tax burden on freight in Australia. We also have sparesely
:>
opulated areas like Nevada or nearly the whole midwest, areas where
:> :it's almost like every farmer has his own freeway exit.
:>
:> When it comes to being sparsely populated anywhere west of Adelaide is
:> hard to
:> beat - and that takes in almost two-thirds of the land area of Australia.
:> Adelaide is 2793km by road from Perth and you might come across a man and
:> his
:> dog if your lucky. It's not quite that sparse, but you get the idea.
:>
http://en.wikipedia.org/wiki/Geography_of_Australia
:>
:> :
:> :
:> :> ... And I dare say that this was a bit cheaper than if I had gone to
:> a
:> :> freight specialist locally and obtained a price to bring it across. One
:> off
:> :> freight costs for an individual customer are not cheap out here and
:> often are
:> :> more expensive going from west to east than the other way. It's all
:> about
:> :> economy of scale...
:> :
:> :
:> :If you bought the attic fan because of heat build-up in the house, ever
:> :thought about an evaporative cooler? I put in this one, broke through a
:> :wall and did a fixed installation, works like a charm:
:> :
:>
:
http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053
:> :
:> :They had an Australian model as well but seem to have discontinued it
:> :after just a few months.
:>
:> I have a 27 degree pitch corrugated colorbond roof
:>
http://www.colorbond.com/
:> with sealed eaves. Last summer we had a long run of hot days around the 40
:> deg C
:> or above mark and after a few days of this heat the ceiling insulation
:> becomes
:> overloaded by the stored superheated air in the roof space and it begins
:> to make
:> it very uncomfortable in the rooms below. I measured the air temperature
:> in the
:> roof space at 55deg C and I think it would be even hotter than that if I
:> had the
:> right measuring thermometer. Since I don't want to go down the
:> refrigerative air
:> conditioning path due to expense and power requirements, and there are
:> relatively few days when it is absolutely necessary, I am hopeful that by
:> evacuating the hot air and replacing it with cooler air from lower down
:> the
:> temperature in the rooms below will be cooler by several degrees C. For a
:> few
:> hundred $$$ it is worth a go.
:>
:> Evaporative air conditioning has been used extensively in Australia mainly
:> in
:> the form of whole-of-house ducted systems (eg. Breezair etc). They are
:> cheap to
:> run and can be effective where humidity is low. Once relative humidity
:> gets
:> above 35% their efficiency declines rapidly (by approx 50% and more).
:> There are
:> portable evaporative units available but they are not really worthwhile
:> imo.
:> Many homes here have removed evap and installed refrigerative ducted ac.
:> Evap
:> should work well in Nevada and similar climates.
:
:We opted against any sort of aircon, instead we bought a thing called
:'silent breeze' over 25 years ago. It's a large electrically driven fan,
ver a metre in diameter, which has been fitted into the ceiling of a room
:that's at the other end of the house from the sleeping area. At nighttime
:when it cools down we open some windows and turn the fan on, it sucks cool
:air into the entire house, and vents out through the tiled roof, exhausting
:the heated air from the roofspace at the same time. For all but a handful of
:horror periods of a few days through summer, it enables us to hold the
:interior of the entire house to a thoroughly comfortable level day and
particularly) night, there'd be few nights during summertime when we don't
:have a blanket on the bed.
:
:The thing has required zero maintenance throughout its entire life, and
:total power is just the fan motor, way less than an aircon. Best investment
:we've ever made IMHO.
:
:
:
