Chiller Efficiency: Testing, Inspection and Upkeep


Complete chiller upkeep can lengthen the life of kit, enhance its reliability, save scarce refrigerant, and scale back power and different working prices whereas shopping for you time to work out a long-range plan.

Testing and inspection

You will want design specs, gear manuals and restore historical past for every part, and a value historical past for buy, repairs and operation. Are some elements getting extra repairs and costing greater than others? Are annual power prices rising quicker than price will increase? Have latest prices exceeded previous prices? Are your prices greater than prices at different related amenities? Are they greater than averages out of your skilled affiliation? You will wish to do that testing yearly or two, so arrange a recordkeeping system if you do not have one. Resolve if you wish to check in-house or use an inspection company with the instrumentation {and professional} know-how.

For those who resolve on an expert, your upkeep workers should activate and set the system for the inspector, change drive ratios, add dampers if wanted, substitute worn components, and present the inspector the place panels and gear are situated. Inform your gear vendor and consulting engineer in regards to the inspection to allow them to present design details about the unique system.

You will must conduct air steadiness, water steadiness and sound testing. The elements examined are:

• air-moving gear

• provide and exhaust followers

• diffusers and grilles

• water-balance components

• circulating water pumps

• cooling towers

• chillers

• air- and water-cooled condensers

• ducting.

A steadiness check on a packaged unit takes a couple of day; on built-up items, at the very least two or three days or extra for multi-zone or multi-unit techniques. All testing devices needs to be calibrated inside six months of testing.

Air-balance testing

You will must do air-balance testing first as a result of system air have to be in steadiness for water-balance testing to proceed correctly. Particular instruments and instrumentation used are:

• scorching wire anemometer

• rotating vane anemometer

• self-timing velocity counter

• pitot tubes 18-60 inches

• velocity meters

• clamp-on ammeter

• static ideas

• a number of 8-inch stem thermometers

• motorized psychrometer

• hand sling psychrometer

• micromanometer

• inclined gages 3-inch and 10-inch

• multi-point floor pyrometer

• combustion check units

• electrical drill motors

• balancing hoods

• pyrometer

• recording thermometers

• smoke gun

• and two-way radios.

The method contains testing and adjusting blower rpm to design; motor precise vs. full load amps; pitot tube traverse of provide ducts and design CFM of followers; system provide and exhaust static pressures; design vs. precise recirculating air; design CFM of out of doors air; getting into moist and dry bulb air temperatures; exiting moist and dry bulb air temperatures; adjusting all provide and return air ducts and zones to design CFM; adjusting every diffuser grille and register to inside plus or minus 10 % of design necessities; FPM velocity at every diffuser, grille and register; and changes to reduce drafts. Additionally, all controls have to be checked for correct calibration and settings.

Water-balance testing

Water-balance testing needs to be accomplished solely after air-balance testing is full and the air system is correctly balanced. Along with the beforehand talked about instruments, you may want water-pressure gages, a differential gage set for studying orifice and venturi stations, and meter units for studying velocity and circulate. You will additionally want vibration analyzers, and air and water air pollution check gear.

The water-balancing course of contains:

• beginning and setting all controls to correct settings

• eradicating and cleansing strainers

• analyzing water for correct remedy and cleansing

• checking pump rotation

• verifying that enlargement tanks are charged and never air or water sure

• checking air vents at high of water system to make sure that they’re put in and dealing

• setting temperature controls to full cooling

• checking working temperatures of chiller and boilers

• ensuring that chilled water pumps are calibrated for correct GPM supply

• checking present and return water temperatures

• checking chiller water circulate strain

• monitoring water and steadiness temperatures at inlet facet of cooling coils

• monitoring strain drop via coils and circulate price

• monitoring pump working suction and discharge pressures.

Checklist all pump mechanical specs, motor rated and operating amps and water metering gadget readings.

Sound testing

Previous techniques loosen up, get misaligned or maybe weren’t accurately sound insulated when put in. Thorough sound testing utilizing decibel meters and vibration evaluation is part of the testing and inspection. Sound checks embrace background sound stage with gear off, complete sound stage with gear on, and correction of sound stage to gear solely. Sound ranges are in contrast with constructing specs utilizing readings in decibels. Gear vibration absorbers and insulation are checked for effectiveness.

Chiller restore

Earlier than finishing repairs, ensure you’ve complied with all security precautions, comparable to carrying private protecting gear and performing lockout and tagout procedures. The commonest repairs required on account of check information are cleansing and minor changes. All techniques want filter and duct cleansing on the air facet at the very least annually. If the filters are tight and duct joints are correctly sealed or taped, cleansing will not be an enormous job, and the air system can be extra environment friendly. Water, oil and refrigerant pattern checks point out the gear’s situation. If there’s water within the refrigerant, seals needs to be changed. If there’s refrigerant, rusted steel or steel filings within the oil pattern, examine the seals, piping, bearings and rotary or reciprocating components for put on.

Drive gears, bearings, belts and couplings will final for years with PM plan. They need to be checked at the very least yearly, even when fluids do not point out an issue. V-belt drives needs to be tight on the underside and slack on high between the sheaves for extra arc of contact and fewer slipping. If the sheave groove bottoms are vivid, the V-belts are bottoming out and can slip. Both change the V-belts in the event that they’re worn or change the sheaves if they have been slipping and the V-grooves are worn. Worn sheaves will rapidly break new V-belts.

If belt plies are separated, change the belts. In the event that they’re unfastened sufficient in order that urgent them within the middle between the sheaves strikes them a couple of thickness of the belt, realign them with a straight edge; then tighten them. Loosen the motor anchor bolts, again the motor away from the pushed sheave by turning the motor body adjusting screw underneath the motor till the belts are correctly tensioned.

Bearings and gears protected with the correct quantity and sort of fresh lubricant can run hotter than you possibly can contact — greater than 110 levels — for years with out issues. Even new lubricant isn’t completely clear, so in-line oil filters are funding. Common filter inspection and alter will uncover issues earlier than they turn into critical. Pillow block bearings shouldn’t be greased too usually. Normally, just a few photographs as soon as each three to 6 months is sufficient. Seals will be broken by overlubrication. Take away the aid plug earlier than including grease, and permit the bearing to run awhile to discharge the surplus. Verify the colour and texture for indicators of rust, steel, water or different contamination. Rubber gloves and security glasses or full face safety needs to be worn the place acidic refrigerant could be current.

Security checks

Common PM security and electrical checks are an vital a part of your annual check and inspection course of. Your system documentation will present:

• the place these units are situated

• what checks to carry out

• tips on how to carry out them, and the way usually

• what instruments you want.


Begin by speaking to the requester or tenant to get an outline of the issue. For instance, if the issue is in a bundle heating and A/C unit, discover out if it is a cooling or heating drawback, or each. At all times begin with the plain:

• Is energy attending to the system?

• Are the fuses and fused swap contacts good?

• Are circuit breaker contacts clear and tight?

If the heating works however the cooling would not, this in all probability eliminates the heating circuit controls. Observe operation to substantiate this. Whenever you’ve narrowed the chances, hop-scotch {the electrical} circuit within the space of the issue with a voltmeter, set to the circuit’s voltage vary. Hold the circuit diagram helpful — often inside {the electrical} panel door or within the working and repair handbook. Typically a microswitch or relay sticks open. For those who discover an open swap — no voltage the place a voltage needs to be current — which needs to be closed when the circuit is energized, faucet it just a few occasions with an insulated screwdriver deal with. If this causes the system to renew operation, flip off the system, flip it again on, and repeat the check.

If this confirms that the swap is defective, substitute it. Then attempt the system once more to ensure it is the one drawback, and that the alternative was carried out correctly. When utilizing a tester, it is good apply to make use of an alligator clip on one lead. Just one hand is required to do the testing with the opposite probe.

Damper leakage

Many hassle calls from improper temperature are from too excessive a temperature within the duct or temperature time lag. Too excessive a temperature could also be because of delivering combined air at, say, 62 levels, when it needs to be 54-58 levels. Temperature time lag is simply too lengthy a time to chill the air throughout the modulating interval leading to a sense of discomfort. As a lot as 35 % of month-to-month working prices will be because of compensation for leakage. To right this drawback and decrease your working prices on the identical time, examine the zone mixing dampers for leakage. Gentle foam plastic on the main edges of blades seals them higher when they’re closed. Leaking dampers additionally improve the noise stage.

Guide dampers needs to be put in off the face of multi-zone items; it’s going to present precise adjustment of complete circulate. Diffuser, facet wall or computerized dampers are solely meant for effective adjustment. Verify their linkages and vary of movement. You can not discipline air steadiness your system with out the suitable variety of dampers in the suitable place.

Preventive/predictive upkeep

Routine PM for many continuously used chillers — electrical centrifugal, electrical reciprocating and absorption — contains annual lube oil, oil filter aspect and refrigerant filter-dryer cartridge adjustments. Oil sampling and inspection for bearing or gear put on particles is completed in addition to checking magnetic plugs within the oil reservoir.

Rust particles originate within the condenser and point out air and moisture within the refrigerant system. Chemical evaluation of each the refrigerant and oil yield priceless details about the presence and supply of contaminants. Fluid leak checks are made twice a yr, until low fluid ranges point out the necessity to check extra continuously. Leaks within the refrigerant system of air and non-condensable gases are greatest dealt with by common purges. Clear tubes after each season and examine for corrosion, erosion, stress corrosion and fatigue brought on by thermal stress. At all times use a water remedy specialist for preliminary charging of a brand new system and for steady monitoring. Present testing devices can detect tube cracks early; substitute the tubes as quickly as they’re found.

The water resolution of lithium bromide used as a refrigerant in absorption chillers could be very corrosive. It assaults metal, copper and copper alloys in 300 F air or greater. Use corrosion inhibitors within the manufacturer-recommended vary; examine it twice a season. Additionally examine alkalinity and presence of ammonia, copper or iron which can be current in small (components per million) portions. Water strainers and traps needs to be checked, cleaned and adjusted yearly.

Vibration evaluation of rotating gear on the bearings needs to be accomplished throughout operation to examine for bearing and kit put on, bent shafts, imbalance in fan and blower blades, and coupling or different misalignment in air dealing with gear, water pumps, chillers and motors. Infrared scanning {of electrical} switches, circuit breakers, motors and kit containers will detect overheating circumstances and assist determine unfastened or corroded electrical contacts, scorching motor windings, dangerous bearings and gears and low oil ranges. These predictive upkeep inspections needs to be carried out at the very least yearly after establishing a baseline or regular studying at every level — and do them earlier than the main shutdowns so findings will be analyzed in time to resolve what repairs are required. This method permits lead time for acquiring spares, particular instruments and gear and planning the work.


Source by Julian Arhire