Filter dryer question.

[wingman]

Hi guys,


recently (read last october2008) I was asked to do service on a MTA chiller unit.

I noted that there was a refrigerant leak in the evaporator and the unit needed repair. After long discussions who was going to pay for the repair, 5 other techs detected the same thing.

Now we are may and still nothing is done. (long story though so I am skipping the rest) In the meantime two other companies have seen the unit claiming there is no leak in the unit. One company claimed the filter dryers have never been replaced. Something they claim that has to be done every 3 years.

According to what I know, once you start up a system you do not touch the filter dryer unless ofcourse you had to change something on the refrigerant system. Or whenever you have done an oil change (when the oil is acidic or marginal of quality)

Can someone either confirm or deny this, if it is indeed neccesary to change out FD's after 3 years if nothing is wrong with system.

[Brian_UK]

That's a hard one to be specific on Wingman.

If the compressor operates at high compression ratios, for whatever reason, then system oils and refrigerants can break down and begin the onset of internal damage.

It might, therefore, be argued that the filter/drier may be approaching overload and should be replaced to maintain system cleanliness.

A case study by Sporlan some years back may be of interest.

http://sporlan.jandrewschoen.com/40-176.htm

[chemi-cool]

From my experience, I would change a filter \ dryer on two events:
1. The system was open for any reason.
2. Temperature difference between inlet and outlet of
the dryer. [ 2°C indicate a partial blockage]

[wingman]

Brian,

the system runs under normal conditions, so no high condensation temperatures.

Chemi cool,

Just as I would do, I would not change a filter unless the system has been opened for a reason or when I have a temperature difference between inlet or outlet.


Thanks for the answers guys, realy appreciated