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ARI tests are done at certain temperatures to compare units apple-to-apples. You can also check with the manufacturer on the EER performace characteristics. You may be able to get the exact performace given the temperatures you are using. This will be different from ARI, as it will be giving...

Thanks for the responses thus far. There is a lot of piping for the building, as this is a geothermal project of about 1500 tons. We are sizing the piping up from 12" to 16", and the branch piping is typically 4" for as little as 27 GPM. It seemed a little arbitrary to size all of the...

Currently we are designing condenser water piping (40-90 degrees F water) to be flowing at 4 feet per second or less. Sure it is great for acoustics, but the piping ends up being upsized a lot along the way, and it will cost more. Another senior engineer is insisting this method of design...

Will there ever be a problem with primary pumps overwelming the secondary pumps? The only condition I can think of is that the bypass isn't large enough and there is little demand on the secondary.

I've been looking at HP's Dynamic Smart cooling. Any thoughts on using this to control each rack to what you need or equipment requirements? www.eypmcf.com

Gepman is right, you shouldn't be worried about treating the latent loads in a locker room, you should be exhausting it. If you increase the exhaust rate by increasing the fan speed (if it can do it) and rebalancing the system to exhaust more from the locker room. You might consider ducting an...

And a good Thanksgiving to you too! www.eypmcf.com

For this system, I would place structural supports for the frame to be connected to. You don't want it to just rest there, as it will drift away. Slopes can be deceiving, and I wouldn't trust one just because it is underwater. To drop it down slowly I would use a crane. Provide connections...

Yeah, thought I'd get more attention from the Comp Eng group on the air temperature here. Good to know that a leaving temp of 95 from the server/room would not be a major problem. I know that at a certain point elec equipment runs less efficiently due to temp, and it only gets worse as it...

In short, yes, you can have a surface that is too slick. As you probably know a film will develop to prevent transfer that would be as good. While it can be a good thing for things such as sterile environments, it can be not-so-good for heat exchangers. www.eypmcf.com

Hey, does a warmer operating data center make you nervous? We are looking at providing a data center with a 75 degree supply temperature and a 95 leaving temperature from the servers. This increased temperature difference allows for an HVAC system with a better configuration, but what does...

Instead of passive chilled beams you may want to look at radiant panels. No ugly mess to sell to the architect, less engineering hassle, and less maintenance issues. The ventilation requirements remain the same - you can use a dedicated OA system to serve directly to the spaces you need...

As others have stated, humidity is what is going to drive the load. You should see if they are having a designer resizing the load, and if not ask for the load calculations to prove a correct sizing. Commercial sizing is closer to 350-450 CFM/ton, or up to 1 CFM per SQFT. With the amount of...

Hmmm... there seem to be a lot of info missing. I'd lot at your application... you say you are making ice cubes, so you might want a mechanical system that can sense when the cubes are frozen and remove them from a tray. The heat exchanger might be an additional step that takes away some of...

Hey, thanks. As you mentioned decreasing the velocity isn't an option, but the nature of the prevailing winds may be the biggest problem. The only thing even close is a stair pressurization fan about 30' in one direction; everyone wants to know whether the diesel fumes will manage to get...

I think the International Mechanical Code lists a minimum of 75 CFM per fixture. I have always designed at 100 CFM per fixture to allow for future expansion, fan rebalancing, etc. Over-designed? Nah, it works as separate as a relief of OA and allows the bathroom to remain negatively...

A Z duct is NOT an air-to-air heat exchanger. A Z transfer duct is often used between full height walls above the ceiling to transfer air from one plenum or area to another. The Z bend is to eliminate noise - sound gets absorbed when having to bounce through two 90-degree angles. You will...

You will probably need to get more involved with this... include the CFM, how far away you are from the fan(s), whether you are using a return grille, and if are looking for a sound attenuator or something else. www.vanderweil.com

Hey, so I was leafing through my ASHRAE manuals and found that I am missing my 2003 Applications. I'm looking to calculate the plume from generator exhaust; does anyone have any spreadsheets or even just the equations needed to find acceptable dilution? www.vanderweil.com

You may want to put heat tracing on the piping to prevent it from freezing. If you have a condition where the water stops flowing in -5C it will eventually freeze... prevent that from happening overnight by adding the heat tape inside the insulation and a simple temperature sensor...