Interesting extractor fan

I am looking at a bathroom extractor from a block of flats (30 years old). It's an Aidelle Loovent twin fan model (feeding into a negative pressure building-wide extract duct system).
I'd had a quick look at their products and found a wide range of fans with dual speed for things like continous running and boost with occupancy or humidity, so I had assumed one fan was going to be the continuous running and the other for boost, although their current products look to be just one fan with dual speed working.
The thing was only working intermittently, and noisy. On taking the vent off the front, it was solidly packed with 30 years of dust, and difficult to see anything. I could feel one fan ws jammed, and the other one was stiff. I couldn't find the mounting screws or where the cable came in due to the dust, so had to schedule a second visit with a compressed air can.
Having got the thing down, and opened it, and got a buckload of dust out (which strongly resembled soot), I worked out its design. This model has only a single feed and runs continuously. The circuit board has tracks for a run-on timer, but no components are fitted except the mains fuse, which bizzarly covers only one of the two fans, the one that is jammed. Fuse is not blown but winding is open-circuit, so that one's had it. The other fan works, just. I disassemble and clean and re-oil the sleeve bearings, reassemble and spin up. Strangely, one fan is using 29W, but the whole unit claims to be 30W. I then try to work out the switching of the fans. The dead one has an air-flow switch which cuts in the working one when the flow is low.
So it looks like this unit is designed to run with just a single fan at once. When the primary dies (no air flow), it then switches over to the secondary fan. After 30 years, the second fan is on it's last legs. Interesting that they have designed an extractor fan which is intended to have the life of two motors consecutively, and not something I've seen before in an extractor fan. I suspect it was a high priced option, which fits with what I'm finding with other original fit items in the flat.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 6 Jul 2013 23:48:34 +0000 (UTC), snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote:

A RAID fan. Better than built-in obsolescence.
--
Graham.

%Profound_observation%
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Also I have seen a lot of fans that went open circuit and the only issue was that the winding was terminated by some form of rivet or similar and this got corroded and wnt open circuit. Howeve as has been said, the age would suggest its had its best days by now! Brian
--
From the Sofa of Brian Gaff Reply address is active
"Graham." < snipped-for-privacy@privacy.net> wrote in message
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yep, dual redundant fans used to be a building regs requirement where there was no natural ventilation.
--
fred
it's a ba-na-na . . . .
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.