Air conditioning ceiling cassettes

I quite rarely get involved with the installation of ceiling cassettes as I'm a service engineer, and deal with quite a bit of refrigeration as well as air conditioning. The thing that I always seem to take quite a while with is hanging ceiling cassettes. Usually I remove the tiles etc, put the threaded rods in and make a frame from channel before hanging another four rods to hold the cassette, but I'm sure there must be better ways than this as I seem to take quite a while to get the cassette centred. I know this probably sounds a bit trivial but any better ideas would be gratefully received.

Why the intermediate chanel frame and second set of drop rods? Get the manufacturers installation instructions for the spacing requirement ie details of their hanging brackets / fixing requirements and locate the drop rods to suit.

Most cassette units are well balanced so anti vibration shouldn't be a problem unless the rods are extremely long (over a metre). This would be the time to use an intermediate frame just for dampening purposes.

Iceman, I think you are probably using the normal method; that's the same as the install guys used at my last firm.

I have recently seen a cassette suspended using eye-bolts and crimped wire-cable supports, so I suppose anything is possible as long as it takes the weight.

You might find that the extra time you think you are taking is not actually that long. Your install guys will probably rib you about it because that's what they do ;) After a while I expect that your time will improve, at the moment you daren't make a 'bad job' of it as your service tech. comments about the install are coming back to roost.

Thanks for the replies. I used to be an install engineer when I started in the business, and worked mainly on large industrial and commercial ducted systems, chillers etc, where we were under quite alot of time pressure to turn the job around. I've always used the method above because it's just the way I was shown all that time ago, using the extra rods to enable adjustments to the position, but had just wondered if there was a quicker way that someone else may employ in order to get the cassette centred quickly without having to make adjustments to the frame.

the extra channel isn't really needed -it's just to make you feel 'safe' it's like they aren't too sure of their marking out so need adjutment in all directions

some like it as they feel it's more 'professional' looking
i feel it just spends more time/money on the job

i don't see quite get the vibration aspect either
i just looked at a job to replace 2 cassettes and they were on rods of about 8 metres length-no one mentioned vibration

take out the tiles and from your centre (say where the bars cross) from the cardboard template mark out where the fixing points are on the ceiling grid. (do the same on the opersite side)

the use either a sprit level and project up to the ceiling
or use one of these http://www.screwfix.com/app/sfd/cat/...67061&id=29941

you should have 4 dots on the ceiling to mark two lines-this is where you fix your channel.

you don't need any movement in that plane but the channel will allow you to slide the rods back and forth to align in the other plane

complex to describe but easy and cheaper to perform


cheers

richard

We do it like drawn in this raw sketch. We need 4 standard channels (omega channels we call it) of 2 m.

The 2 channels whereon the unit is attached is not fixed on the 2 upper channels. They're just laying on the upper 2.

With this system, you can slide almost 60 cm in each direction, enough to fit in a tile ceiling of 60/60 (cm)

The threated rods are parallel fixed so you can regulate the height very easy (just release the parallel 'nuts' movng up, adjust the height of the 2 rods a little bit and slide the parallel nut down again)

how do you 'do' attachments?

click the post reply button, takes you to a more advanced reply screen with more options. one of them is to attach a file :) limit of 10mb i think.

hi guys ,

you are late online so I'm always on the next day.

so many ways to hang a cassette, my way is a bit different,

I mark the ceiling with a plumb bob from four corners of the lower ceiling, the rods (concrete) or cables (wood) or weld (steel construction)

this way the four rods are a bit bigger then the holes on the cassette.

when connecting, it forms a piramide like shape and two nuts from each side securing it .

this way it can not swing and easy to adjust in place.

chemi :)

richard,

when you scroll down, at the bottom right you have the "post reply" icon.
click it and it will take you to another page where you can add smilies, attachetments - watch the size!

chemi












'

Hey,
perhaps a good tip for some of you:
we use a not very expensive pneumatic lift (a sort of a piston) to lift loads from +/- 250 kgs (or 500 pounds )t o a heigght of +/- 5 m (or 15 ft)
You only need an air compressor or nitrogen.
We even use it to mount cold room panels (ceilings)

Was not able in previous post to post the picture.

Yes, the good old Genie hoist, we have also used CO2 as the lifting gas.

marc,
out of curiosity, how much do customers pay in the UK for cassette instalation with pipes, run up to 60 feet?

your idea looks good on paper but you will need in practice quite a few sizes of these H frames.

if it is wood construction, why not cables

chemi

chemi -i don't think anyone would let you use wood for these installs

marc's idea still uses one more length of unistrut than my idea with no advantages as far as i can see..


cheers

richard

richard,
I did not mean to use wood!?!?

in many places, there is a wooden construction over the ceiling which holds the roof.

what would you do if you had to install a cassette in such situation?

chemi

sorry chemi my mistake...;-)

i would still use my method of attaching the unistrut channel to the wood with coach bolts

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=16973

of course there is an idea that we only use channel because we can't mark out accurately...


cheers

rihard

hi richard,

this is what I use for marking.

what do you call it in the UK?

chemi

it's called a plumb bob

like this-

http://www.screwfix.com/app/sfd/cat/...89283&id=10856

cheers

richard

Isn't there a drill pattern in cardboard delivered with each indoor unit?
Mitsu's have this .
Do you guys use the parallel nuts, like you can see in this picture;
You hold the 2 rods together and sldie the nut over it. You can turn both rods or remove the nut, position the rods in another position and slide the nut over it again. Very easy.

pICTURE

And who knows this products

http://www.erico.com/products.asp

The wire suspension system that Brian mentioned is called Gripple. www.gripple.com We have used it on a few jobs and found it easy and quick to use. Here is a link to a case study where they mention hanging fan coils with a 65% saving in labour costs. http://www.gripple.com/casestudy/cas....cfm?StudyID=6

We only use the double unistrut hanging method when we install cassettes in a building where the suspended ceiling is not yet in place as in a new build project. We can then have upto 150mm adjustment available to align the cassette with the ceiling once it has been installed. As we all know - suspended ceiling contractors are a law unto themselves, fixing the grid where they think it should be installed with no regard for other trades or agreed datums :D