An air conditioner is a machine that moves heat from one location to another and produces an additional amount of heat depend on its (in)efficiency.

I’m definitely not saying that it’s OK to have these cooling towers in close proximity with a network station, I just saying that not everything that appears to be related to A/C is “blowing hot air” on the temperature probes, and people should understand what’s going on before predicting how mechanical equipment will affect temperature readings. I think Judith Curry would make a comment about understanding the underlying physics’ if this were her area of expertise.

I think this episode brings into focus the comments that Steve M has made about the observations from these sites to date and that is that while we cannot estimate any quantitative correction (or even direction of the correction) from these findings, it does certainly point to a lack of quality control on the part of the scientists responsible for and using these measurements. It also places some uncomfortable amount of uncertainty around the accepted measurements and elicits some interesting comments from those with a stake in the published error margins.

While my comment may be considered stroking Steve M, I could say the same about Jim Edwards stroking Judith Curry; however, when it comes to quality control, I’ll take Steve M every day of the week.

First, my #24 was directed to your #22, not my own 19 – but I’m sure you’re smart enough to have figured that out.

Second, you said:

at least in the temperate air of the SoCal coastal region, where that employer was located, the exiting air of our towers was typically above outdoor ambient. However, in Wickenberg AZ during summer, that probably would not be too likely.

You could be right on both counts, it will all be dependent upon the heat load that is being moved. The thing about these units is that they’re designed to remove A LOT of heat. They will be oversized, the question is how much will they be oversized ?

It’s essentially a big swamp cooler that pulls in hot dry air and emits cool wet air. As you allude, they will be especially effective in places like Arizona. The process heat load is on top of that. So the cooling tower will give you a constant 150-tons of effective cooling, and that cooling will be divided between whatever variable heat load you produce as you turn your various processes off and on, and cooling of ambient air. You don’t typically buy a 106.5 ton cooling tower to match your process, so there’s usually quite a bit extra cooling capability in the tower to cool ambient air. If you’re working in wafer fab or magnetic disk production, however, where new processes are being constantly being added / upgraded or you have to move more 72 degree air through the HEPA systems b/c your clean room had to be upgraded from class 1000 to class 10, then you could easily start to approach the maximum cooling load available from the tower. You could then expect to be emitting relatively warm wet air until the cooling tower got replaced with a larger one.

More of the newer installations attempt to save operating costs by using variable frequency drives on the fan motors. The air flow gets throttled back, but not the water flow. This will reduce the cooling capacity and increase exhaust temp – so that’s another important factor, but I wouldn’t care to guess on it unless Mr. Watts’ volunteers start looking for slow-spinning fans and/or installed VFDs near the fan motors.

You’ll note that in the above photo there are two cooling towers. That implies that they actually maxed out on [or came close to it, or planned to come close to it with a plant expansion] the one to the left at some time in the past and replaced it with the one on the right. They could also have parallel or staged systems.

Lots of Qs, but insufficient data to come to a conclusion. Maybe the easiest thing to do is just measure exhaust temp and ambient temp for all HVAC equipment.

Yes, you’re right, that’s a very good point. [And a very good memory...] These are going to be belt-driven, too, so the motors aren’t directly in the airstream like they would be with many direct-drive fans. These motors definitely will emit a good amount of hot air, but from the position of the towers it appears that the motors are situated between the towers and the wall behind. What’s going to happen to that heat ? Will it rise up between the tower and the wall ? Will it be drawn by the relative low pressure on the side of the unit created by the fans and enter the cooling tower ? Or will it snake past the low pressure zone and enter the network station ? I wouldn’t care to guess, but the third option seems least likely to me, as the wind entering these units is fairly strong.

http://www.baltimoreaircoil.com/english/info_center/pubs/DUTYMOTORPRD.pdf

These definitely produce a bit of heat. Also, now that I recall a bit more, at least in the temperate air of the SoCal coastal region, where that employer was located, the exiting air of our towers was typically above outdoor ambient. However, in Wickenberg AZ during summer, that probably would not be too likely. You’d be above the safe operating area if exiting air was that warm …. I think??

Thanks Jim! see what an army of davids knows!

The A/C heat exchangers shown in the picture do not emit hot air like most condensing units that people are used to seeing. They emit relatively cool, wet air.

The ‘BAC’ you can see painted on the units stands for Baltimore Air Coil. BAC makes cooling towers; these are essentially evaporative coolers [or, swamp coolers, if you're familiar with that term] that discharge outside. You can see two 5-gallon buckets of what appears to be algaecide in between the units, as well as a hose bib to service the units. The two big pipes coming through the side of the unit are the insulated inlet and outlet pipes filled with either refrigerant or a chilled water brine. The smaller black pipe is for makeup water. The installation could be for A/C, refrigeration, or chilled water for some or other industrial purpose.

These units always have water percolating through them, and the fans are designed to have as high as 100% duty cycle. They push ambient air straight up through condenser tubes and percolating water, then through a ~2″ thick baffle on top. Most of the air goes up, but some doesn’t. The baffles can get filled with moss and it’s not impossible that a unit can have baffle plates removed – they lift right off.

Cooling towers are the things that can become sources for Legionnaire’s Disease, if the water is untreated and they are too close to an outside air intake. It can feel noticably cool when you get within a few feet of one.

I’m definitely not saying that it’s OK to have these cooling towers in close proximity with a network station, I just saying that not everything that appears to be related to A/C is “blowing hot air” on the temperature probes, and people should understand what’s going on before predicting how mechanical equipment will affect temperature readings. I think Judith Curry would make a comment about ‘understanding the underlying physics’ if this were her area of expertise.