Chiller maintenance tips from a pro

May 5, 2000
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In his more than 50 years in the hvacr industry, John C. Schaub Sr. has seen and serviced more than a few chillers. He is still active as president of Schaub Consulting in Medford, NJ, while his son, John C. Schaub Jr., carries on his former business at John C. Schaub Inc., Mt. Laurel, NJ.

Schaub Sr. doesn¿t hesitate to share his experience in the field. The following are some of his primary tips for technicians.

¿The most important thing for compressors is the oil,¿ said Schaub, so the first thing he always does is check the oil. ¿Oil is essential,¿ he noted. The tech should take a small sample of the oil to check its condition.

¿Make a visual check of the oil,¿ he said. ¿The darker it is, the more problems you¿ll have.¿ Keep it clean.

On larger systems, Schaub recommends changing the oil once a year. Be sure to clean out any particles that may be in the bottom of the crankcase. ¿Over months of operation, you will pick up metal particles in the system.¿

It¿s also imperative to check the superheat. He explained that ¿Superheat is vital to the performance of the unit and to keep the compressor cool.¿ It¿s important that superheat doesn¿t rise and cause a problem with the compressor.

On larger chiller systems, Schaub recommends that the oil be changed once a year.

Give 'em some air

Schaub has also found that many companies ¿don¿t have sufficient air circulating in the compressor room.¿ They¿ll also put ¿barrels and trash in the room, so you can¿t get to the unit. And a unit not seen is a unit that¿s going to have problems.¿

A lot of chillers in the field don¿t have water gauges, stated Schaub. Usually, it¿s the responsibility of the company purchasing the chiller to install water gauges so you can see pressure drops, particularly through the evaporator.

But many companies ¿don¿t do what they¿re supposed to do. They let it slide. And then, suddenly, they give us a call.¿

If maintenance is done on a regular basis, a technician won¿t have to come to the rescue. ¿On units that have proper maintenance,¿ he said, ¿your problems are almost zero.¿

One recommendation that Schaub has long made is to put a bypass valve on the end of the pipe run going to the chillers to get the proper water flow. ¿It¿s important to have the proper flow through the chiller tube bundles.¿

He pointed out that you don¿t want to have overflow through the tube bundle because then you get vibration, which can damage the copper tubes.

Schaub suggests telling your customers to check the compressor room every day. They should:

  • Look for oil around the unit; if there is any, they have a leak.
  • Check the sight glass with the unit on.
  • Check for compressor short cycling. And if they hear rattles or any change in noise levels, they should contact your company immediately.

These daily checks ¿can save a lot of grief.¿

He also noted that ¿In the spring is when you have most of your problems with water towers,¿ particularly in the country where the farmers plow their fields, kicking up dust and dirt into the air, which gets into the towers and goes right to the condenser.

So you have to clean the condenser. With air-cooled systems as well, you have to clean to remove the dust.

¿What causes refrigerant leaks is vibration,¿ said Schaub. ¿This is the biggest problem ¿ around the compressor, on the lines, around the capillary lines.

¿You need to check that you don¿t have high vibration on a capillary line. If you do, secure it so it does not vibrate. That¿s the most popular place where leaks are found.¿

An explosive lesson

In 1967, Schaub was called to service chillers at a plastics plant. He had finished his work and was talking in the office with the plant manager. An explosion then shook the entire building.

In the rear of the plant there were tanks with a volatile liquid used in plastics production. A maintenance man had opened a tank valve and within seconds, the liquid contacted a steam pipe, causing the tank to explode.

Schaub was told to run for his life because a second explosion was imminent. Instead, he ran for his truck and $5,000 worth of equipment, because without the truck and equipment, he was out of business.

He didn¿t realize that the plant next door was a gasoline refinery. If that would have exploded, the entire area would have been leveled. Unfortunately, two men did die immediately in the explosion, and the maintenance man died later.

The lesson here, noted Schaub, is to know what you are doing or else ask to be sure.

Mistakes can be deadly. The risks are high when you¿re working with pressurized systems, power, and rapidly moving objects, such as found in compressors and fans.

Let¿s be careful out there.

Schaub can be reached at 609-654-2138; www.chillers.com/schaub.htm (Web site).

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