Water cooled condensing in hard water areas

[Iceneck]

I'm wondering...I know that water cooled condensing is much more efficient than air cooled (I can't quantify it, but that's what I've been taught). Anyway, I also know that in areas where the water has lots of dissolved minerals, there can be major scale build up in condensers and cooling towers. I guess my question is...does the increased efficiency of water cooled condsing make up for the eventual costs and headaches associated with removing the lime scale build up?

[Bseliger]

If your using a cooling tower you should contact a company and have chemicals added to the holding tanks. They will help prevent lime scale build up. Ive had to try to remove lime scale build up in cooling towers and it isnt very fun. You also have to consider that the lime build up insulates the condenser piping making it harder to reject heat. If you treat the water correctly you will not have any headaches. They do make a cooling tower cleaner, however it is quite costly, around 500 bucks for 50 gallons. Also attacks the metal.

[Bseliger]

Also should look at a water softning system to help alleviate the hard water problem.

[Iceneck]

Also should look at a water softning system to help alleviate the hard water problem.

If you're going to go to all that trouble, why not just use air cooled condensers? What I mean is, after the water softener is installed (with all its' added cost) wouldn't a business just be better off choosing an the air cooled option?

[Bseliger]

If were talking a cooling tower than were talking alota heat. The water is reused and yes some evaporates. How big of a system are you talking? The one I worked on was a 60,000 lb ammonia system.

[Russ57]

There are pros and cons to anything. You just have to decide what makes sense for you and your equipment. Big chillers are almost always water cooled. When you consider how big an air cooled condenser would be and factor in the increased risk of leaks and how much refrigerant you are talking about it makes sense. I have a lot of water cooled ice machines at work. It makes sense as they are stuck in small kitchen areas on hospital floors that were never intended for the heat load that an air cooled machine would add. They are too small to warrant remote condensers.

Water quality directly impacts water treatment. The right water treatment can protect the equipment from any quality of water. It just becomes a matter of what is in your water and what it is going to cost to treat it. The basic idea is to use chemicals which allow the concentration of minerals to "cycle up" and still prevent them from causing scale.

For example a common set point for a cooling tower would be a conductivity around 1,800 microsiemens. Now you could be in Vancover and have city water down around 3ppm or you could be in parts of southern cali and have water upwards of 1,000 ppm (of calcium carbonate). Needless to say you aren't going to have to cycle the water up much in south cali but you could run a lot higher cycles when water comes from glacier feed lakes.

Bottom line, if you have scale you have a poor water treament program and/or parts of it are broken. It should be mentioned that not all water cooled condensers for refrigeration equipment are suitable for use with "tower water". Anytime water leaving the heat exchanger is over about 95 degrees you are going to have problems.

[misternash]

OP: there's a lot to consider when looking at water. as you reject heat into the water, you will evaporate some of it, leaving the minerals in your sump. you'll have to "blowdown" (dump) a little sump water to prevent conductivity from rising too high, which will require more make-up water. it's pretty standard to utilize an automated controller to control chemical and the blowdown valve, thereby controlling water quality. chemicals to prevent scale and corrosion are needed. softened water sure wouldn't hurt as you can remove minerals, giving you a higher starting water quality. for why, as was previously mentioned, it comes down to how much surface area it takes to reject the heat from your load. water carries away more heat than air does.