Chilled beams and additional air con

[r.bartlett]

Chaps

Went to look at a building yesterday and the client wishes to increase the air con of his chilled beam. However they are already max'ed out. I suggested some splits for spot cooling certain area's but he said they make the chilled beams work against it and then the beams don't work properly

Had me confused by this but this is what he believes and for all I know it is probably correct.

I don't have much experience of CB's but welcome advice from those who do

Richard

[stufus]

It depends on whether he has dual flow beams or not but it's highly likely he has ,as single beams are rare.
If you have a split throwing out air at 5,6,7c it 's going to short cycle to the beams and cause the lphw valves to drive open.
In my opinion CB's only work well in an open plan environment with an active beam set up ,passive beams and chilled ceilings don't float my boat at all ,and have had nothing but trouble with them in the past.
Google chilled beams ,I'm sure there's loads of info floating about the Interweb.
Cheers
Stu

[r.bartlett]

Thanks

I spoke to a manufacturer and he told me splits were a no no. I will try to suggest isolating them CB's in thast area and just use splits..

[stufus]

Sounds like a plan
Cheers
Stu

[MikeHolm]

How do they de-humidify?

[RSTC]

Chilled beams don't dehumidify, you will need to take care of that separately.

If your beams aren't making it you will can but in more chilled beams but make sure you have capacity in your chiller and chw pipework.

If not then, best to disconnect the chilled beams in that area and put in supplemental local cooling. Don't try dropping the CHW temperature as that will cause the beams to sweat.

If you do put in splits along side the beams make sure that the beam's control stat is somewhere out of the way (perhaps a return air duct stat) and set the temperature on the split a degree or two higher and lock into cooling only mode. Also make sure that the air flow isn't directly on to the beam - look at floor mounting or wall mounting perhaps.

[install monkey]

RB be careful of any modifications to a pfi building,without getting consent from the builders. as ive recently found out that u cant even have blu tak on walls,you cannot paint a wall another colour and they do get regularly inspected by the builders too!

[multisync]

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[Scramjetman]

Chilled beams rely on absorbing radiant heat. Radiant heat travels at near the speed of light. The concept is supposed to be really energy efficient. In practice, they can be really fickle. Dewpoint and occupant comfort are often big issues if they are not designed correctly for the load. If the beam gets below dewpoint, it will rain on your parade.

[cool_tech]

Do these chilled beams have filters/ screens. they could be blocked causing bad air flow across coil. maybe worth checking

[r.bartlett]

The onsite team check filters etc. The problem is caused with a change of use (IE the head count for that section tripled from design along with the PC's etc)

As regards the condensation in another part, some contractors accidentally swapped the CB pipes with the other chilled water circuit and the lower water temp caused the Cb's to condense and drip on the carpet.

The quotes and alternatives have gone in so we wait...

[r.bartlett]

RB be careful of any modifications to a pfi building,without getting consent from the builders. as ive recently found out that u cant even have blu tak on walls,you cannot paint a wall another colour and they do get regularly inspected by the builders too!

We won't do anything till it's signed off -in triplicate. There is a huge growing list of dilapidations already stacking up for the 25 year hand back...Shed load of rectifying works on these PFI buildings is going to cripple the good old tax payer in years to come..