Ductless Mini-Splits and Age
jackofalltrades777
| Posted in General Questions on
Do ductless mini-splits becomes LESS efficient with age? If the filters are cleaned regularly, does a mini-split lose it’s efficiency with time due to wear and tear?
Also, what is a good temp coming out of a unit when cooling? Let’s say inside air temp is 75F. What should the cooled air be coming out? Around 50-55F or lower?
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Replies
Only if the refrigerant leaks out.
Flare fittings are usually not zero leak so there is a very slow small leakage over the life of the unit which does effect performance eventually. Otherwise, they don't "wear" out, as long as coils are clean, you'll get the same cooling or heat out of them.
In general, no not without a leak.
Long before the compressor gets worn out and become inefficient and ineffective the coils tend to develop small expensive to repair leaks. The lazy servicemen give the unit a shot of gas and go leaving the home owner cool temporarily. After a few gas and go call the home owner decides to buy a new unit.
Yes a leaky system is both inefficient and ineffective the more it leaks the less efficient it becomes.
The only way to be sure the charge is correct is the remove it and weigh what get removed and recharge. Any loss of charge is 100% a leak.
If your unit is operating at full speed because the room is a few degrees above the set point the discharge air should be 15-20° cooler than the return air. If the room is at or near the set point the compressor speed slows and the unit will blow warmer air.
Walta
My Mitsubishi 1-ton minisplit is about 7 years old. It's cooling a 730 sqft guest house (R-30 walls/R-40 ceiling). It's been very hot outside (100-105F) and I have it set to 71F inside so the unit is in full speed. Air discharge has been around 53F. It seems to be running in full speed more this summer than it did last summer. I'll have it looked at next week but that's why I was wondering if it's age starting to take it's toll.
Maybe it leaked a little refrigerant but I'll have the AC guy check that. I know car AC systems can leak refrigerant through the seals and I usually just buy a can of refrigerant with "stop leak" and inject it and watch the gauge to make sure it's not over-full. It works and the car AC runs great for a few more years, until a seal starts to leak again. Just buy a can for $30 and recharge it and it's good for a few more years. Not sure if the same applies to household minisplits?
Like I said before the only proper way to check the charge is to recover the charge and weigh what is recovered.
Given the 18° delta and assuming the room is at the set temp, it seems unlikely there is anything wrong.
Note, your mini splits motor is located inside a hermetically sealed steel dome eliminating the troublesome shaft seal and rubber hoses found in cars. Blindly dumping more refringent into a highly tuned system based solely on your feeling that it is running more than your recall it running in the past would be foolish at best.
With that said if your delta falls below 15° and the room gets a few degrees above its set point after 7 years of service you may well have an undetectable leak and need to have the unit recharged.
Walta