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remp (Mechanical) (OP)
17 Dec 03 17:21
I have just been speaking to a mechanical engineer in the UK and he has told me that VAV systems are no longer in vogue there. He told me that its all ceiling mounted fan coil units and chilled beams for commercial buildings. Can you believe it....?? and this is in London.
Personally speaking I think 4-pipe fan coil units are extreemly expensive not to mention difficult to maintain when it comes to filter changing and coil cleaning.
As for chilled beams all the manufactures data I have seen indicates very low cooling effect with chilled beams(w/m2) and would truggle to cope with internal zone air conditioning loads unless quite a lot are installed.

Anybody, anywhere particularrly UK readers anything to say??
Please dont tell me ye dont use VAV anymore.
Helpful Member!  imok2 (Mechanical)
17 Dec 03 18:38
How many of you are familier with the cooling vests issued to HVACR mechanics who work on hot roofs or attics. It's said that they can work up to 4 hours in a 130/140*f atmosphere with out having to take a break. Well why don't they issue these vests to all those who work in office builds. and eliminate all air conditioning systems except ventilation? Maybe the UK could take the lead!
remp (Mechanical) (OP)
17 Dec 03 18:45

Jezzz, dont be given them new ideas mate!!! Im heading there in the new year, im going to have enough to content with, with their current practices.
imok2 (Mechanical)
18 Dec 03 20:48
Sorry billie, I lost my mind there for awhile...but i'm OK now...I think!
SAK9 (Mechanical)
19 Dec 03 21:03

Chilled beams and ceilings can be applied only in places with a mild climate like UK.The maximimum loading they can take is about 110 watt/sqm.As for FCUs,they are still in use in low end office buildings where the building owner tries to push maintenance issues to tenants.
paulkeating (Mechanical)
19 Jan 04 1:18
have a safe trip, billyQ !!!!!  PaulieK
Cooky (Mechanical)
19 Jan 04 7:56
I regularly see specifications for HVAC systems which have 100, 200 and sometimes 300 fan coil units.  I may only see one VAV system every couple of months.  I work for Carrier and we offer both fan coil units and VAV systems (Carrier call them Moduline), so we are not biased to one particular system.

There is no doubt that the VAV systems are the best solution for many commercial office applications, they are quiet, very low maintenance, good temperature control, good air distribution and very energy efficient.

There are various reasons VAV has fallen from popularity over the past few years, I think a major reason is the changing role of the consultant.  Why should they spend weeks designing a complex VAV systems, with hundreds of meters of ducting and large AHU's, when they can send a schedule of fan coil units to a few manufactures and get them to select the correct unit?.  The same principal is used to for the design of the chilled water and hot water piping systems.

The second major reason is cost.  With the constant pressure to lower the cost of a new office development, the fan coil system offers a lower installation cost versus the VAV system.  It seems the lower maintenance costs and running costs of the VAV system are not taken into account.

I know there are other reasons for this move away from VAV towards fan coil units, but these are my thoughts.....


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