House ventilation/cooling fan

[journeyman Mick]

I finally got around to something I've been thinking about for quite some years. About ten years ago I was fitting skylights and other products for a home improvement company. One of the products they sold was a whole house ventilation system by this mob. I was impressed and decided I'd fit one to my house (when I owned one). They wanted a few grand for the system though and I wasn't prepared to spend that much money. I toyed with the idea of using a normal ceiling fan and building a shroud around it, but it remained an idea only. In December '08 I was getting some tyres fitted when I spotted a large workshop fan that looked suitable. I found out where they got it from and ordered one in, which I picked up on 31/12/08.

I mucked around for some time in the shed trying to build a grille out of timber venetian blind slats. I wanted the grill to fall closed by gravity and to open when the fan drew air through it, like the commercially made unit I had fitted. After a few weeks of on and off sketching and building mock-ups I gave up on it and decided that a set of timber louvres mounted on commercially available louvre galleries would be adequate. I got busy trying to make money and the project was shelved, although the fan was certainly welcome to aid in cooling my shed.

A few months ago I supplied and installed a stack of timber (Surian Cedar) louvre windows and the supplier gave me quite a few lineal metres more than I required or paid for. Enough to replace all the metal louvre blades under the sliding windows in the two front bedrooms as well as for the fan system.

This last Saturday I went down to the shed for a couple of hours in the afternoon and built a platform to mount the fan on. Sunday I spent about 5 hours finishing the platform and prepping the fan. This involved removing the wheels and re-routing the power lead. I also managed to cut a hole in the ceiling of the laundry and carted the fan and the platform up to the house.

Today I got the system up and running. I ended up having to remove a set of storage shelves and all their contents in order to make room, as well as spinning the chest freezer around to make more space. The fan was too heavy to lift so I used my manual "forklift" doohickey (courtesy of Commonwealth Rehabilitaion Got it up as high as I could and then dragged it into the ceiling cavity whilst rotating it to sit flat. Of course once I'd done this I discovered that I couldn't turn the platform through 90deg like I need to as the fan was in the way so there was about half an hour of grunting, groaning, sweating and swearing as I moved everything around, down, up and back.

The fan is in position and it runs, but it still needs a bit of work. I need to fit some rubber padding between the fan and the platform to reduce vibration and noise and I still need to fit the louvre blades and some architraves. It draws an amazing amount of air into the house, venting it into the ceiling cavity and out through the vents in the gable ends. Running it for half an hour or so tonight made an appreciable difference to the temperature and comfort levels. There's some noise, a bit more than one can effectively tune out. Some of the noise I can get rid of by fitting padding between the fan and the platform, some of the noise is generated by the fan belt and I may get a link belt to minimise this. The balance of the noise is generated by the air movement which nothing much can be done about.

Mick

[apricotripper]

looks good Mick.

[bitingmidge]

Tell me more about the surian louvre blades!
Did you build a replacement set for existing glass ones or what?

(I like this installation BTW)
P

[Honorary Bloke]

Does it have different speeds? Can you slow it down? Fan speed can make a big difference in noise and sometimes you don't need the full draw to cool the house down.

[Joker]

That sucks Mick.

Nice work.

[journeyman Mick]

Tell me more about the surian louvre blades!.............

(Not sure if that was meant seriously, but in case it was....) Surian cedar is closely related to our Toona Ciliatra (Australian Red cedar) but doesn't have the same beautiful deep red colour. I get it from the importer at a good price.

Does it have different speeds? Can you slow it down? Fan speed can make a big difference in noise and sometimes you don't need the full draw to cool the house down.

There's two speeds: Gale force and cyclonic . No actually, the fan doesn't run at a really high speed. The blades have a really aggressive angle and they run reasonably slowly, via a belt drive, so slow speed, high volume. From memory though, the commercially made unit ran slower and it had six blades as opposed to four and the blades were more rounded. No doubt, all this helped to reduce the noise. I'm confident that I can reduce the noise to an acceptable level.

Mick

[Ray]

Great idea that we have all contemplated at some stage but good onya Mick you've done it. For those still nights when it is 34 inside the house and 20 outside.

Signed
Yet another big fan of Micks

[Ray]

Hey Mick
Hows the fan going? Is it doing the job?

[journeyman Mick]

Hey Mick
Hows the fan going? Is it doing the job?

It does the job, but still needs some work to dress it up (architraves and timber louvre blades), to increase efficiency (larger gable end vents) and quieten it down (link type fan belt, rubber padding between fan housing and platform). All in all, I'm very happy with it. At the moment the sound it creates is comparable to having the dryer on with the laundry door open, a bit annoying but we can put up with it.

I reckon if the fan had a greater pitch but spun at a lower speed it would be far quieter and if I can't get it quiet enough with the measures I've planned then I may end up adding an idler shaft with some reduction pulleys on it and bending the blades for more pitch. I'm reasonably confident I can get it quiet enough without having to resort to an engineering type solution. Will let you know when I manage to get some more work done and post some pics of the finished timberwork.

Mick