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Daikin=Overated
07-08-2008, 09:29 PM
I wondered from your experience what the longest duration you've known an Inverter driven air conditioning system (any guise) run for before component failure. By this I mean it could be PCB issues, power supply, compressors etc.

From my own experience I'd say around 1-3 years approximately before something goes bang:rolleyes:

Why is this? Teething problems, or poor design maybe?

Let's face it. Fixed speed systems in comparison are more reliable, albeit less sophisticated and obviously more power hungry. So pro's and cons with either. However most fixed speed systems I've known, have run for the manufacturers recommended service life of 10 years and more with regular maintenance. The amount of PCB's I've changed with (all manufacturers Inverter systems) just isn't right! Maybe it's a big con to keep us forking out for spares???

Your comments welcomed.

J.

hendrag
08-08-2008, 11:55 AM
ive got to say i think the inverter units are miles more reliable than the hideous old non inverter units of old. modern tehnology has made all electrical and mechanical devices more reliable look at cars as an example. i know of old inverter units installed in the early ninetys which are still plodding on reliably but before you analyse too much bear in mind that a vrf system in 1995 would have cost 2-3 times what you pay now so it bloody well should last forever.

regards

Hendrag

paul_h
08-08-2008, 03:30 PM
I think the older bigger units that have "oil recovery" features seem to be better than the cheaper newer ones.
The cheaper, newer ones seem to have a lot of compressor failures. Whether that is because of cheaper compressors, or because inverters spend too much time at low speeds and lose too much oil and no longer have oil recovery, I don't know.
But other than that, more circuits and components obviously mean more chances of things going wrong.
Besides the compressor and condenser fan, what's a conventional dumb outdoor going to do? Stuff up a relay (be it soft starter or contactor etc) is the most likely.
What's an inverter going to do? IPM, AFM, control PCB or mains filter PCB.

Daikin=Overated
13-08-2008, 10:49 PM
[quote=paul_h;116116]I think the older bigger units that have "oil recovery" features seem to be better than the cheaper newer ones.

Interesting you should mention that Paul, I fitted a new Hitachi Inverter the other day from their 08 range that boasted gas injection. Whether this is to relieve stress on the compressor to allow quicker temp achievement, or to aid in cooling the compressor similar to oil return in some way I don't know, but I'm always interested to see what manufacturers make improvements with their own kit.

This model also had a dip switch setting (RPK commercial range) that allowed the system to reconfigure in the event your using pipe runs of less than 5 meters which could have come in handy in the past.

We'll see how long this one lasts........

paul_h
14-08-2008, 05:06 PM
The oil return I speak of wouldn't be helped by stress relief or other cooling. I'm talking about the sumps running dry and compressors seizing. They all have accumalators on the suction, and inverters are programmed to run at a low RPM for a long time before cutting out, and when they start too.
Most of the time they aren't effectively circulating the oil back, hell they are sold on the principle that they use less power and run at low speeds most of the time, but the new mass market inverters have no oil recovery control.
When you have an accumalator plus random filed installed pipe work, how can they expect oil return?

Daikin=Overated
14-08-2008, 07:12 PM
The oil return I speak of wouldn't be helped by stress relief or other cooling. I'm talking about the sumps running dry and compressors seizing. They all have accumalators on the suction, and inverters are programmed to run at a low RPM for a long time before cutting out, and when they start too.
Most of the time they aren't effectively circulating the oil back, hell they are sold on the principle that they use less power and run at low speeds most of the time, but the new mass market inverters have no oil recovery control.
When you have an accumalator plus random filed installed pipe work, how can they expect oil return?

You could always revert to the old practice of oil traps I guess? I've yet to experience a compressor on a Inverter fail due to oil recovery issues, though I've had that contribute toward many fixed speed compressor failures over the years. Then again I do work mainly on commercial inverter splits so hopefully this aspect has been considered in the design regarding oil return on this advanced kit?

Husky250
14-08-2008, 10:22 PM
You could always revert to the old practice of oil traps I guess? I've yet to experience a compressor on a Inverter fail due to oil recovery issues, though I've had that contribute toward many fixed speed compressor failures over the years. Then again I do work mainly on commercial inverter splits so hopefully this aspect has been considered in the design regarding oil return on this advanced kit?

Its my belief an Inverter unit is an engineered system. The ones I have dealt with call for no oil traps. My take on that is as long as you don't exceed the manufacture's piping requirements you should be OK. Once you start to push the limits, you are begging for trouble.