They should be tore down to check bearings, clearances and tolerances, and as above stated, We can also say and overhaul is a good thing cause next Tuesday it may come apart on you due to a catastrophic failure.

 

Thanks for the replies...

Efficiency of the chiller (kw/ton) is still within the design specifications and it is measured / calculated all the time through monitoring.

From what I can understand now, its basically a preventive maintenance, i.e. replacements of bearings, alignment of shafts etc.

What I don't like is that the chiller manufacturers forget or avoid the talk of overhauling until its 5 years old and suddenly a good chiller now has a potential breakdown waiting to happen.

 

Yes and No, have oil samples been taken annualy, or quarterly being this thing runs24/7? Has the machine had any issues leaks mainly? if so how many times has it surged, how bad and for how long? If it's been meticulously serviced and oil samples show no plating or any other negative finds, I would say ''start budgeting and planning'' for an overhaul. Ever had a vibration check done? I would reccommend some predictive maint. Our Vibration tech can do his magic and tell me an inboard bearing is bad, and to boot he can tell me if it's the bearing or race. I am not saying 40k an teardown at all, but the mfg take into account of possible issues machine may have encountered in 40k hours. And I personally favor a machine that has run 24/7 to one that starts and stops.

 

Thanks for the feedback. Now I am have a better feel of the system and not alone when I think there should be other recommended ways before opting for expensive overhaul which may not be necessary!


GA_Frank - its a R123 chiller - a negative pressure machine - 100,000 hours should be OK for this?

Southern_mech /baitcaster Yes, I am planning to do a vibration and oil test. The chiller has no leaks, works well, maintains its efficiency and is well maintained.

Yes, I like chillers that dun 24/7 and maintained regularly on time with oil change etc done regardless of the oil condition.

This is why I feel an expensive piece of equipment should not be subjected to a general rule of overhauling at 40,000 hours or so.

Here Chiller Manufacturers should stand by their equipment or charge less than 10% of the chiller cost for overhauling at 40,000 hours and not 25 to 30%. When this is taken into account, i will rather tell my clients to wait for one their 15 year old well maintained, never overhauled chiller to burn out and replace when it does, because the maintenance cost of the new chiller overrides the operational cost savings (provided they have a standby of course).

By adding this high cycle maintenance and the related cost, so called efficiency improvements are reduced significantly in life cycle cost analysis of a retrofit for example.

 

Thanks for sharing. Exactly...scare tactics. I noticed as a business they want to see growth - chillers in buildings have a 15 to 20 year cycle. Once that cycle is over, the rate of chiller replacement reduces - and I believe to overcome this reduced rate of change is sudden need to overhaul chillers. They seem to forget that the word overhaul means a major replacement and this is usually done to make good a system to run a little longer than the normal lifespan.

I have a chiller in its 7th year, 24 / 7 except for the usual 6000-7000 hrs oil change, filters, temperature sensors (I always see them drift), tube cleaning etc - running smoothly and no major issues - performance again monitored using magnetic flowmeters (at cw and ch side), high accuracy thermistors (+- 0.05 deg C), accurate power meters and data logged every minute...

 

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It sounds good

HVAC_MY : Your maint and sensor package are far more sensitive than the factory ones. If you have been able to follow this program since the start-up you should be in great shape bearing and motor wise. As mentioned by others a steady history of oil analysis for acid levels, wear metals and moisture pretty much will tell you what is going on inside the compressor and motor. Your purge tells you about shell and vessel integrity. (no leaking air coming in, no moisture). The vibration analysis is also great non-destructive PM. What I would add in addition is eddy-current tube testing. The oil, vibration and eddy current testing are used when the chiller is still pretty new to set-up a baseline to evaluate any wear that occurs as the chiller ages. The expected life of a centrifugal chiller is based on many things other then ASHREA life expectancy. If your chiller runs 24/7 365 days a year, you already jumped the toughest hurdle. The starting and stopping of a chiller is what can do the most harm, unless the machine surges during operation. Based on most of the facts you have stated on this post, you should be able to achieve a long and excellent equipment life. Best of luck to you. Geo

 

Thanks - will add the eddy current test

Thanks for the feedback Geo!

Will add the eddy current test and use it as a baseline for future reference. I have done the rest of the test and passed with flying colors. The contract is a shared savings type and maintenance is directly my responsibility for another 4 years which means I don't need client's approval to conduct testing etc - this is a plus point as I make sure the chiller is in the best condition possible.


Again thanks for sharing.

 

maxster,

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