Help, Underfloor Installation!

[knighti]

I have a customer that has bought an old building and has converted one floor into open plan offices, 420 metre sq, it has a new raised floor 250mm above the old existing stone floor. They are insisting on having air conditioning installed under the new floor. Does anybody have any advice/info regarding this type of installation as opposed to that of a normal anbove ceiling ducted system? The provision for return air will also have to be in the floor!

[The Viking]

There has been various manufacturers playing with these type of systems. We look after one site with a Hiross system working this way.

Honestly, it is c##p.

First, every time someone pulls a new cable under the floor the skirts are damaged and needs repairing (separation between supply and return air).

Then, even if the system works OK, who wants cold air blown up under their desks/bums/skirts/trouser legs and so on.
And all sorts of dust and rubbish is collected in the grilles.

Nah sorry, don't like it.

[Brian_UK]

It would need to be fully ducted, modular and to prevent draughts would need to be directed above desk level for the supply.

I would suggest that you stand back from it and suggest that they employ a design consultant; that way any failings will not be your responsibility.

[hendry]

you can follow that of a dance floor.

we did plenum air supply for dance floor. you could have non-ducted return.

you might have space problem of 250mH, if you use low velocity duct may be ... [duct joints are thinner]

250mmH is internal dimension?

you have to consider the needs of fire protection system for such enclosed space/s.

furthermore the intermittent supports to the raised platform may pose additonal design hindrances to you ...

hope that helps. good luck!

[AcidSlasher]

how are you supposed to put an indoor unit in a space of 250mm?? unless theres something im missing....

there are many other problems this poses as well, what about the floor joists? how can u move ductwork around with them in the way?

i dont think its possible mate, tell them to put it in the ceiling

[grump]

Stay well clear,computer rooms only they don,t mind cold
air up em.

[knighti]

The new floor is on stilts or something above the old stone floor, they say they've had the same kind of install done elsewhere?! I'm going to try and go see it next week I'll post back on here and let you all know what the previous guys have done...

[Tesla]

I went to an AIRAH talk a few years ago and there were a couple of companies in Europe installing underfloor supply systems. Looked like CRAC to me with more and bigger than normal outlets. Common in industrial processes where fumes or excess heat needs to be removed.

[John MacK]

Hi-Ross as mentioned before do units for this type of installation, they used to do a VAV (Variable air volume) cassette that fitted in the floor tile space in a similar way to a ceiling cassette, and the floor void was used as the supply air plenum etc.

Most commonly used in computer suites etc.

Maybe you could look at a chilled floor system, without blowing the air, i.e an underfloor heating system on a reverseable heatpump..?...?

[PRESS]

You can access from Trane's website www.trane.com engineers news letter achive there is one very good article with excellent insight on underfloor air conditioning. I have done installations as well as several maintenance work on typical installations like that.