Cooling tower repair and service

Where the chiller's heat goes

Inside a water-cooled chiller, refrigerant gives up its heat to condenser water. Pumps carry that warm water up to the tower, where it spreads over the fill in a thin film while a fan pulls air through. A small share of the water evaporates, and that evaporation cools the rest. The cooled water drops into the basin and heads back to the chiller to do it again.

The chiller cannot work any better than the tower lets it. When condenser water comes back a few degrees too warm, the chiller's head pressure climbs, its efficiency drops, and on a hot afternoon it trips. Plenty of calls that start as "the chiller is down" end at the tower, which is why our chiller repair work and our tower work are really the same job.

Cooling tower faults we find most

What you see	What is usually behind it
Chiller trips on high head pressure	Condenser water too warm: a fan or motor down, scaled or clogged fill, low water flow, or bypass valves out of position.
Fan vibration or a new noise	A loose or damaged fan blade, a failing gearbox or motor bearing, a worn belt or sheave, or a bent drive shaft.
Oil around the gearbox	A leaking seal, a low oil level, or a gearbox running hot on worn bearings.
Basin overflowing or running dry	A stuck or waterlogged float valve, a failed makeup solenoid, or a bleed line left wide open.
Water spraying off the tower	Drift eliminators missing, broken or out of place, or a distribution problem flooding one section of fill.
Pump alarm or low condenser flow	A plugged basin strainer, a cavitating condenser water pump, air in the line, or a stuck valve.

Tower problems tend to stack. Scale reduces flow, low flow leaves dry spots on the fill, dry spots collect more scale. We look for the first link in the chain, not just the loudest one.

Fans, gearboxes and belt drives

The mechanical side of a tower lives in the wettest, most humid spot on the building. Gear-drive towers have a right-angle gearbox under the fan, fed by a motor through a drive shaft and couplings. Belt-drive towers use sheaves, belts and bearings instead. Either way, we check oil level and condition, look for leaks at the seals, measure motor amps, feel for bearing heat, check belt tension and wear, and look at the blades for cracks, pitch and tip clearance.

Vibration switches and fan motor starters or drives get tested too, since a vibration trip that nobody can explain usually means a blade, bearing or coupling is on its way out. Condenser water pumps, basin strainers and float or makeup valves are part of the same visit, because the tower and its loop fail together.

Hard water and the tower

Because a tower evaporates water, it leaves the minerals behind. Without a steady bleed of concentrated water and a real treatment program, those minerals turn into scale on the fill and inside the chiller's condenser tubes, where they quietly cut capacity. Middle Tennessee's water is moderately hard, which hands every tower a steady supply of minerals to leave behind:

We are not a chemical company, and we do not pretend to be one. We work alongside your water treatment vendor: we keep the bleed, makeup and chemical feed equipment working, report the scale and fouling we see on the fill and in the basin, and flag condenser tube fouling on the chiller side so the program can be adjusted before it costs capacity. That matters on towers from Nashville office and hospital buildings to the industrial plants of Clarksville and Montgomery County.

Winter freeze protection

A tower that runs through winter to cool a process, a data room or a building's interior zones has to survive nights well below freezing. Basin heaters, heat trace on makeup and drain lines, bypass valves that send water straight to the basin, and fan controls that avoid icing the fill all need to work on the first hard freeze. Towers that shut down for winter need to be drained, with the basin, lines and pump casings emptied so nothing splits. We handle both, and a fall visit on a cooling tower maintenance agreement is the time to test heaters and controls before the weather does it for you.

Repair or replace a cooling tower?

ASHRAE's median service life estimate for galvanized metal cooling towers is about 20 years, and much depends on water treatment. We rebuild before we replace: fill, drift eliminators, gearboxes, motors, bearings, float valves and basin repairs will carry many towers well past that point. When the casing or basin is corroded through, we give you an honest look at the numbers and help plan an equipment replacement during the cool months, when the chiller can spare its tower.

Cooling tower questions