Carrier Infinity 4 Ton - will I ever be happy

[rogressem]

I've been complaining about my 4 ton Carrier Infinity (24ANA748 condenser, Infinity thermostat) for years. Basic complaint - its just doesn't seem as cold as the old Goodman R22 system that it replaced, but I don't have any facts to back that up - I didn't obsess over the old system, it seemed to work fine, until I had to have it replaced.

I've had a couple of different companies come out, but I guess I'm being stubborn.

Had someone come out yesterday on a good hot day, and I asked for a good check and that I wanted to record the numbers.

Outdoor dry bulb: 92.7F
Outdoor humidity: 55%
Evaporator return air temp: 79F
Evaporator supply air temp: 65F
Indoor wet bulb: 64F
Indoor humidity: 53%
Suction Pressure: 158psig
Hi side Pressure: 360psig
Suction Line Temp: 71F
Liquid Line Temp: 94F
Vapor Line Temp at the outlet of the evaporator: 66.5F
1400 CFM (from the infinity Thermostat)
Blower RPM: 1400 (from the Infinity thermostat)
Static Pressure: .77 (from the Infinity thermostat)

Required subcooling for this unit: 15F

Calcuations based on figures above:
Subcooling: 15
Superheat (system): 16F
Superheat(at the evap): 10F

He took evaporator return/supply air temps near the air handler.

So, as usual, he said everything is right on, but I can't understand the following:

1) I guess that evaporator delta T is OK based on what he told me and from what I've read, but my downstairs R22 system sure does better
2) That liquid line temp has always been at or just above outdoor ambient. This is subjective, but it just bugs me that when I reach over and "feel" the suction and liquid lines on my R22 condenser (downstairs unit), the liquid line is very warm and the vapor line is very cold (and sweating much more than the Carrier). Is that just a function of R22 vs R410a.
3) Lastly should they be measuring air flow instead of just looking at the Infinity thermostat? I don't think I've ever seen anyone take a CFM measurement. More than one has said that the Carrier Inifinity adjusts blower RPM to maintain proper CFM.
4) I've been told that these high efficiency units are designed that way (not as cold), but that just doesn't make sense either.

Bottom line, if they are getting good subcooling and superheat values, is that the best I'll get out of this thing?

[comfortdoc]

What is the model number of the indoor unit? What are the diameters of the refrigerant lines and the length? Is the indoor unit above / below the outdoor unit and how far?

Let's start there.

[rogressem]

(Subject should have been: "Carrier Infinity 4 Ton - will I ever be happy)

Air Handler/Furnace: 58VA110-1-20
Evaporator: CNPVP4821ACA

7/8 Suction Line
3/8 Liquid Line
(these were previously used for the R22 system, installer seemed to do a proper install job in 2008)

Indoor unit about 25-30 feet above. I've estimated the lineset length to be about 60 feet.

I've had concerns about the lineset:
1) Two short radius 90degree elbows
2) Two 45 elbows
3) One mild kink. My main HVAC contractor said it probably wasn't hurting anything, but would fix for about $$$$. (I posted pictures of that kink here a few months ago - I think most said don't worry about it)

Suction line is insulated well, I've check that (at least where I can see it).

[comfortdoc]

Couple more questions - During the hottest days what is the temp difference of the liquid line where it leaves the condenser VS where it enters the TXV?

What was the room temp on the User Interface when he took the readings and is the system maintaining setpoint?

[second opinion]

I've been complaining about my 4 ton Carrier Infinity (24ANA748 condenser, Infinity thermostat) for years. Basic complaint - its just doesn't seem as cold as the old Goodman R22 system that it replaced, but I don't have any facts to back that up - I didn't obsess over the old system, it seemed to work fine, until I had to have it replaced.

I've had a couple of different companies come out, but I guess I'm being stubborn.

Had someone come out yesterday on a good hot day, and I asked for a good check and that I wanted to record the numbers.

Outdoor dry bulb: 92.7F
Outdoor humidity: 55%
Evaporator return air temp: 79F
Evaporator supply air temp: 65F
Indoor wet bulb: 64F
Indoor humidity: 53%
Suction Pressure: 158psig
Hi side Pressure: 360psig
Suction Line Temp: 71F
Liquid Line Temp: 94F
Vapor Line Temp at the outlet of the evaporator: 66.5F
1400 CFM (from the infinity Thermostat)
Blower RPM: 1400 (from the Infinity thermostat)
Static Pressure: .77 (from the Infinity thermostat)

Required subcooling for this unit: 15F

Calcuations based on figures above:
Subcooling: 15
Superheat (system): 16F
Superheat(at the evap): 10F

He took evaporator return/supply air temps near the air handler.

So, as usual, he said everything is right on, but I can't understand the following:

1) I guess that evaporator delta T is OK based on what he told me and from what I've read, but my downstairs R22 system sure does better
2) That liquid line temp has always been at or just above outdoor ambient. This is subjective, but it just bugs me that when I reach over and "feel" the suction and liquid lines on my R22 condenser (downstairs unit), the liquid line is very warm and the vapor line is very cold (and sweating much more than the Carrier). Is that just a function of R22 vs R410a.
3) Lastly should they be measuring air flow instead of just looking at the Infinity thermostat? I don't think I've ever seen anyone take a CFM measurement. More than one has said that the Carrier Inifinity adjusts blower RPM to maintain proper CFM.
4) I've been told that these high efficiency units are designed that way (not as cold), but that just doesn't make sense either.

Bottom line, if they are getting good subcooling and superheat values, is that the best I'll get out of this thing?

Your system is not performing anywhere near its capacity. Can you re-post the kink?

Running low airflow your delta T should be with 53% rh closer to 18 and you suction line is picking up 6 degrees of SH

[rogressem]

Today:
Outdoor ambient: 91.5
Liquid line temp @ condenser: 92-93
Liquid line temp @ evap (just before entering casing): 92

Used my old k-type, which seems to be accurate when compared to the fluke that the tech used because we compared them yesterday.

Room temp yesterday on the User Interface when he took the readings was about 79-80. As far as holding set point, on those hot days, I would say no. Set to 78 and it drifts up to 79/80 and holds all day.

I try to keep the downstairs thermostat set 1 degree below upstairs (very open area - both thermostats are in line of site of each other). It does a good job.

Couple more questions - During the hottest days what is the temp difference of the liquid line where it leaves the condenser VS where it enters the TXV?

What was the room temp on the User Interface when he took the readings and is the system maintaining setpoint?

[comfortdoc]

As second opinion posted the system does not seem to be operating at capacity. If the measurements are accurate, it is not at capacity. Are the LL temps you posted while the system is running? Does not make sense to me that the insulated suction line absorbs 5-6°, but the un-insulated LL does not change at all.

I would be looking for leaking ducts - probably return, and temp increases in the LL. It is a long run not insulated.

[beenthere]

1400 CFM on a 4 ton should have a lot higher delta across the indoor oil.

1400RPM? Its running on the governor. Not sure your control is giving accurate info.

[tipsrfine]

Required subcooling for this unit is 15 degrees f?

Where did you get this number? The charging instructions should be on the condensing unit, so I would double check that 15 degrees sub-cooling. The sub-cooling required may vary depending on various conditions.

[rogressem]

Yea, good catch, I typo'd that. RPM was 1036

1400 CFM on a 4 ton should have a lot higher delta across the indoor oil.

1400RPM? Its running on the governor. Not sure your control is giving accurate info.

[rogressem]

I'll double check those line temperatures tomorrow afternoon after the outdoor ambient warms up. Yea, those were running temps (I've questioned that LL temp at the condenser for a long time)
I double checked my notes from what he got yesterday. (but he didn't get the LL temp up at the evap).

I'll get LL and suction line temps at both places and post.

As second opinion posted the system does not seem to be operating at capacity. If the measurements are accurate, it is not at capacity. Are the LL temps you posted while the system is running? Does not make sense to me that the insulated suction line absorbs 5-6°, but the un-insulated LL does not change at all.

I would be looking for leaking ducts - probably return, and temp increases in the LL. It is a long run not insulated.

[rogressem]

Yea, thats what he told me, and I see it here (attached)

Required subcooling for this unit is 15 degrees f?

Where did you get this number? The charging instructions should be on the condensing unit, so I would double check that 15 degrees sub-cooling. The sub-cooling required may vary depending on various conditions.

[rogressem]

Here are the three pics from the original thread:
1. http://hvac-talk.com/vbb/attachment....1&d=1330740981

2. http://hvac-talk.com/vbb/attachment....1&d=1330740991

3. http://hvac-talk.com/vbb/attachment....1&d=1330741003


The contractor that installed this system (they didn't create the kink), said it was probably not worth fixing, but would do it for about $

Got another quote, he would not fix it (its in the crawl space), but would run a new line set up the side of the house into the attic for about $ or so. That was reasonable, but I wasn't excited about the downspout dressing on the side of the house.

Your system is not performing anywhere near its capacity. Can you re-post the kink?

Running low airflow your delta T should be with 53% rh closer to 18 and you suction line is picking up 6 degrees of SH