Expected A/C Splits/performance in 110F?

[BrandonV]

I agree - but since I have two units, and both are exhibiting the same loss in delta T, it seems really unlikely that BOTH units have the exact same leak...since I had the house units installed I got the 608 license, installed my own mini split in a different room and have a little more experience so I'm going to get the subcooling checked regardless as I'd like the practice. Just ordered some thermocouplers to get a better reading.

It does seem odd, but there likely isn't much more going on. If the ductwork was damaged, it would have occurred during some type of work. If you haven't had duct cleaning or other attic work that could disrupt the ducts, it seems unlikely the issue would appear out of nowhere.

Units leaking at the same time could be due to manufacturing defects in the coils or other equipment (produced at the same time) or identical installation errors (improperly tightened flares, etc.).

 

[ps2cho]

It does seem odd, but there likely isn't much more going on. If the ductwork was damaged, it would have occurred during some type of work. If you haven't had duct cleaning or other attic work that could disrupt the ducts, it seems unlikely the issue would appear out of nowhere.

Units leaking at the same time could be due to manufacturing defects in the coils or other equipment (produced at the same time) or identical installation errors (improperly tightened flares, etc.).

thanks appreciate it. I'll get a subcooling check done and that should help with some better details, prior to doing anything.

 

[brewchief]

The difference in temp splits doesn't necessarily mean a problem, if one was done in the morning when attic temps were much cooler it will be different then one done in the evening when the attic is just below the temperature of the sun. Flex duct in the attic could have an r value of 4.2 up to maybe 8 depending on what code required at time of original install. That means you will have a lot of heat gain from the attic into the ductwork.

Temp splits at the unit would be more accurate although they will still vary a bit depending on humidity.

A 3 ton unit doesn't necessarily mean an actual 36,000 btus, it can vary a bit based on coil match up, an AHRI match up will show what that specific combo should actually output, entirely possible that it could only be 34,000 btus.

What kind of warranty did the installing company give? We start at 5 years parts one year labor but keep extending labor each year the customer does maintenance, we also register the equipment with the manufacturer so in most cases our customers can be covered up to 10 years parts and labor, refrigerant is not covered but a unit with a problem at 1 year old we are taking care of period.

 

[karoc]

A 3 ton unit doesn't necessarily mean an actual 36,000 btus, it can vary a bit based on coil match up, an AHRI match up will show what that specific combo should actually output, entirely possible that it could only be 34,000 btus.

Like this thought brewchief, but he never did say if this is new problem or same problem after installation. Wonder if return on both is duct board sucking attic air on bottom side ? We always use sheet metal return cans with S drive on bottom so that wouldn’t happen. Checking psi won’t matter if system is in attic and sucking air. But I didn’t see location.
Wanting check charge reminds me of Carrier cls I went to for solid week. During cls all time on on his work sheets, his comments to techs were “ Leave drum on truck” I’ll always remember that statement. Back in 80’s

 

[pcmeiners]

Just because a minisplit is rated at 3 tons does not mean it is equal to other 3 ton units.
Just looked up Trane's minisplits, the BTUs spec out at 36000, but have little extra headroom; one 36k unit only outputs 32k during cooling compared to a Fujitsu 36k which outputs 9,600-39,000 BTUs in cooling .
Likely your units are operating to spec. With temperatures at 114° I sure you need more insulation in the ducting area. I would not survive near that temperature.

 

[ps2cho]

The difference in temp splits doesn't necessarily mean a problem, if one was done in the morning when attic temps were much cooler it will be different then one done in the evening when the attic is just below the temperature of the sun. Flex duct in the attic could have an r value of 4.2 up to maybe 8 depending on what code required at time of original install. That means you will have a lot of heat gain from the attic into the ductwork.

Temp splits at the unit would be more accurate although they will still vary a bit depending on humidity.

A 3 ton unit doesn't necessarily mean an actual 36,000 btus, it can vary a bit based on coil match up, an AHRI match up will show what that specific combo should actually output, entirely possible that it could only be 34,000 btus.

What kind of warranty did the installing company give? We start at 5 years parts one year labor but keep extending labor each year the customer does maintenance, we also register the equipment with the manufacturer so in most cases our customers can be covered up to 10 years parts and labor, refrigerant is not covered but a unit with a problem at 1 year old we are taking care of period.

Thanks this is helpful. I guess I didnt consider that attic temps might influence this. After cleaning the condenser a second time with foaming cleaner, I got the Delta T back up to ~18F so that is very close now. I am actually shocked that a brand new unit would be so impacted from only a year of use? Is that normal? (the unit isnt by any trees etc - the only thing is we have dust storms but thats about it).

The handler is in unconditioned space in the attic that probably gets up to 120-140F depending on the day.

The unit DID output 20F Splits when new as I have an image, so it shocked me it was down to 10-11F after 1 year of use.

 

[danski0224]

Closer fin spacing, more junk trapped.

 

[Boostingaz]

I was in Phoenix early this week. While I was there I went up to see if I could help get a neighbors system back running as they were out of town and it was off when I check on the house for them. This was the attic temp and still climbing fast!! Id spend my money on better insulation rather than throwing money at the unit in the hopes it "works better". There is no way it can keep up or work properly in these conditions.



Spray foam is your friend in this situation. My Phoenix house has about 9" of foam between the top side (flat roof with 4" polyiso panels) and 5" under the roof roof deck. No unconditioned attic it's all inside the envelope. 6" of foam in all the walls. Detached is built the same way.

3500 sqft house with 4 trane units, 3100sqft shop with 1 trane units. I don't have a schedule set, just A/C on, all the time. So 5 units cranking. Just paid this bill yesterday.

 

[Aileron]

Does it cool and cycle when its cooler oa temps? is the condensor matted, are they double row coils, outside clean but sandwiched inside dirty? usually low on refigerant issue is noticed when the outdoor air temps are cooler as the refigerant wants to stack in the condensor when it cooler. You are also be asking it to do somethings its not desihned to do, many talk here on "maintining the temp" which that is what it seem to be doing. You askjing it to drop the loadd in the house colder during a high outdoor load, to cool the inside any cooler , it has to be able to get rid of the heat its now collecting, which would be to the outside which is now a firepit.

 

[Aileron]

- the only thing is we have dust storms but thats about it).

The handler is in unconditioned space in the attic that probably gets up to 120-140F depending on the day.

The unit DID output 20F Splits when new as I have an image, so it shocked me it was down to 10-11F after 1 year of use.

dust turns to mudd in the rain.