Winter Cooling Tower PMs

Spring Cleaning Done Early

Not all cleaning should be done in the spring. Wintertime is the perfect time. Your cooling systems will be shut down for several months and will need some tender love and care if you want to prevent breakdowns during their peak run times. Get ahead with a few key procedures.

Wintertime means less stress on your cooling towers. You are likely running fewer chillers, a lower speed on its VFD or possibly running on a chill plate. This lack of a load on your cooling tower(s) means either entire towers are offline or maybe only a few cells in the tower are currently active. This is the time to do a deep clean on your offline towers.

Cooling Tower Break Down

Be aware that cooling towers can be a breeding ground for legionella, the bacteria that causes legionnaires disease. One way to help mitigate the risk is to increase your bromine, chlorine, or whatever chemical you use for microbe control for a few days before shutting down and opening her up. Be sure to exercise caution when adjusting chemicals and follow all SDS and manufacturer's guidelines. Your health comes first always, so wearing a respirator during the following procedures may be a good idea. If you have multiple towers, lock out the offline ones and prepare them for a few days of annoying but necessary work. Depending on the size of the towers, you may need dozens of locks. Each fill valve, balancing valve, and electrical disconnect will need its own lock.

Once you've confirmed all sources of energy are secured, drain the tower and perform an initial visual inspection. Take note of anything obvious. Address those problems now if you're able, if not, order the parts needed. Next, you need to start taking the tower apart if possible. Starting with the diffuser panels one by one. Even with a good softener and chemical treatment, they will have some amount of scale build-up. It's inevitable with any type of evaporative cooling system, even with a proper automatic blowdown system.

Now's the time to bring out your pressure washer, or rent one if your company doesn't own one. The higher the PSI the better, though too high can damage the diffuser panel fins. This is where having one with an adjustable pressure is best overall. If you don't have access to an adjustable one, you can experiment with different tip angles to find one that will knock off the scale without damaging the fins. The angles lower the pressure overall, so it's the safest solution if you can't get an adjustable model.

Washing off the scale is going to be messy if your blowdowns and water treatment aren't up to par. Likewise, if you live in an area with hard water. Make sure to get both the inside and outside of every panel. The more scale you remove, the more efficient the towers will run. This means a longer life for the towers as well as a reduced energy bill, which we all know skyrockets at the time the towers are on full blast.

Now that the panels are clean, you can move on to cleaning the inside of the tower. This is going to be miserable. It is going to be wet, slippery, and cold on top of it. Wear your best rubber clothing. Scale builds up everywhere and is especially detrimental when built up on fill valves and spray nozzles. If you can take the spray nozzles off and clean them inside your building, even better. Let them soak in a product like CLR or vinegar before brushing them clean. If you can't, then power wash them as best you can while being careful not to damage them. 

After cleaning the diffuser panels and the inside of the tower, it's time to take apart and inspect the mechanical portions. This would be your pumps and fan motors primarily. If your fans are belt-driven, check the condition of the belts. Replace them if needed, though I strongly suggest replacing them regardless of condition. The last thing you need come summertime is a belt snapping during peak season and scrambling to fix it. It is always easier to make a repair when everything is in pieces and you have plenty of downtime. 

After replacing your belts, move on to your pumps. Take apart your pumps housing to inspect your impellors. If there is any sort of pitting, you may have a cavitation problem caused by air getting into the suction side of your pump. If that's the case you need to track down and repair whatever is causing you to suck air during operation. It could be as simple as having your floats being set incorrectly. If the water level goes too low before the tower makes up water, air will get trapped when the pump tries to suck up water to feed your sprayers. You may not be able to track this issue fully until the tower is filled back up. If time allows it, fill the tower up while the panels are still off and run it. track down the issue and repair it. If time doesn't allow it, replace that impellor and order a few spares. Since you've treated the symptoms but not the root cause, the new impellor will also accumulate damage over time from cavitation, but a new one is less likely to break as fast as the already damaged one. Address this as soon as feasible.

Button Up

Once you've finished doing all you can with your pumps, check everything one last time. After a day of drying out you may be able to spot additional scale that can be cleaned. Clean everything again if needed. If not, button up the tower and give it a test run. If everything sounds good, your gauges look good, you should be good. Your power draw should be noticeably lower and your pressures may have changed since everything is clean. Less restrictions mean the pumps and fans are running much happier than they were prior to this procedure. Repeat this procedure for each additional tower you have.

Congratulations, you've ensured one of the most critical pieces of equipment in your facility is in tip-top shape and will be much less likely to break down when it's working hard come summertime. The savings on the power bill alone will allow you to justify further PMs when you point out to the bean counters just how much money they save on energy bills.