valance heating and cooling systems

m slocum

We have an AAOn ERV for make up air and a wheel to control the humidity.
It started out as a 4 pipe system but it was value engineered to a 2 pipe system.We are using basic controls with outdoor resets on the boilers and chiller.
We oversized the coils in the erv to help on the in between cooling and heating days.
We are 3 hours above the Mason-Dixon line and I have not heard of any of these systems this far north.
I can't wait to see how well it will work.

m slocum

valance systems

Has anyone installed a valance heating and cooling system?
We are about to start hanging the coils and covers,which took over 3 months to get from the manufacturer.
Our supplier feels this will be the way of the future.
We will be installing it a church.The engineer promised that it would be a quiet and draft free system.It should be being there are no moving parts.
My biggest concern is if the temps are set back, how long will it take to recover.

Brad White_149

You will need a lot

of surface area compared to other systems. These have very low delta-T's so require area to make up the load.

Bear in mind these are sensible cooling devices and do nothing (thankfully!) to remove moisture. If they did they would rain in the space. Your ventilation system should do the dehumidification.

The systems are fine for stable predictable sensible heat gains. High population spaces need other means for latent heat removal.

FredR

Valance Systems

Brad, refering to the last paragraph, could you please elaborate. Thanks for your input.

FredR

Valance Systems

Brad, refering to the last paragraph.
"The systems are fine for stable predictable sensible heat gains. High population spaces need other means for latent heat removal."

Could you please elaborate. Thanks for your input.

Brad White_149

Fred

These systems (AKA "Chilled Beam" systems") work by imposing a cooler surface in the space served, over which cooler air convects downward and toward which radiated heat from bodies can be emitted.

Because these surfaces do not want to have condensation upon them, the chilled water temperatures run through them are up-tempered (blended) to be at least a degree or two above the space dewpoint, sometimes more. This means a valance or beam within a 75F/50% RH space with a dewpoint of 55.1 degrees, wants to be maintained at a temperature at least 56 to 57 degrees, sometimes more as a margin of safety.

Because the surfaces are never below the space dewpoint, their absorbtion of heat is entirely sensible (temperature-based) rather than sensible plus latent (moisture-based).

The surfaces, even if cooled to say, 57 or 58 degrees, tend not to be large for these devices (radiant cooled ceilings having more surface area and a better shot at cooling an entire room). The size of these beams would overpower a room visually in my opinion and of many architects who want HVAC to disappear.

By "stable, predictable sensible loads" I would place in first order an interior space with lights, some people of course and a fairly steady fixed amount of equipment; an open office for example.

Put the same room on a north exterior exposure and you still have a fairly steady heat gain. Put the same room on the east, south or west exterior exposures and you will have a peak load significantly above the base load depending on the time of the day.

The small relative areas of these devices would be hard pressed to catch up to a sudden influx of solar gain. If sized for that, the controllability and response time would have to be huge, tailored not to over-cool the room when in shade but ready to cool a burst of sun.

Take the same interior room and impose a large mobile sensible and latent gain. Our example office is met with an impromptu baby shower, retirement party, or Fastow and Lay giving bad news.

Large numbers of people with their latent load could quickly raise the space dewpoint well above the beam/valance temperature. Beads of sweat would apppear on the valance surfaces in less time than it takes to read about it.

Thus you can see if these were applied in a space with expected high populations in ordinary use, the means of moisture removal would have to be separate.

The poster's AAON unit and wheel is one such way.

Does this help?

I like the use of chilled beam/valance systems, but you just have to know their limitations.


Brad

Wild West

www.edwards-eng.com
home in n.j.

Wild West

www.edwards-eng.com
home in n.j.

Brad White_150

Nice, thanks

I had not seen these before, apparently with drains. Not the type I was refering too, these being indirect coils and convective/reverse-convective. Still, a good application.

Always learning something new here on The Wall.

Thanks!

Brad