Seer is a measure of energy efficiency, i.e., how much electricity is being used.

Temperature drop does not depend upon SEER. I'll let the professionals comment further.

Veesubotee

I retired before the ultra high SEER units came on the scene, however, one of the ways they got more sensible cooling was to oversize the condenser & evaporator coils & then using a smaller Btuh compressor.

That works okay at the SEER Rating outdoor temp of 82-F, however when the temp gets to 95 or 100-F plus, what do you think is going to happen to that already high pres/temp evaporator?

In my humble opinion those ultra high rated seer units will lose Btuh at possibly an alarming rate.

One way you can make up for that is to up-size the system's equipment a half to a full ton & then slow the blower CFM to 350-cfm Per Ton. Even then, - will that setup get the humidity down into the 50 to 55% level.

In my opinion, the SEER should have been Rated at 95-Ambient & 75-F with 50&% Relative Humidity indoors & then see how they stack up in differing dry & humid climate zones.

Most central units are NOT even cycled on when it is only 82-F outdoors because the interior is still easily within the comfort zone!

You buy an air conditioner to keep you comfortable in high temp &/or both high humidity & temperature. Therefore, why do the seer seasonal averaging at a non applicable temperature? To me that Rating is illogical!

Just go to the equipments' EER Rating which is at least at 95-F outdoors, of course it is 80 indoors & at about 50% RH, where we size them for the their Summer Design Zone at 75-F & 50% RH at the lower temperature. As you reduce the temperature the percent of humidity goes up & is more difficult to bring down to 50 or 55%.

Would the goverment have stopped the production of 10 & 12-seer units if they had used my Rating Criteria?
I think NOT!

Let the HVAC contractors & the consumers decide what is best for their budget & their particular climate zone application!
There is a lot more but my messed-up fingers say, stop.
udarrell _ 2007

Here is a link that might be useful: udarrell.com

Thank you udarrell. My reason for asking: Yesterday afternoon it was 96 to 98 & one of my 4 units wasn't keeping that part of the house cool. I am a retired engineer, so I have temperature sensors at the return, supply, and suction line leaving the evap on all my units such that I can sit at my computer and read them or log the data at select time intervals and automatically plot it on a graph to easily spot trends/changes.
Beats crawling around in a 130 degree attic sticking thermometers in dirty equipment!
Back to my question.
My observation was that I had only an 11 deg evap on the weak unit and it's suction was 76. So I connected my manifold/gauge set and found the superheat to be 21 deg whereas the charts for this Trane SEER 13 unit showed that for the conditions, it should have been 5 deg. So I added charge & observed SH drop to 16. Good. So, being retired, no clock, no boss, etc., I incrementally added small amounts at a time, let stabilize, again & again over more than an two hours time, until I finally got the SH down to 5. By this time I had the area served by this unit down to 72. Wife's happy, but I'm not. Most everything looks good. Discharge press, suction press/temp, room temp, line current, BUT the evap delta is only 13 degrees. Well, now I have to get hot. So I crawl into 130 attic inserting known good thermometers to verify the electronic stuff. The electronics is healthy! Soooo, now I'm am thinking about this unit being the only SEER 13 that I've touched and begin to wonder if these high SEER units maybe run with a smaller evap delta than the 10s do.
Having slowly walked it through from SH 21 to 5 over a long time interval & never seeing the evap get better than 13.4, leads me to believe that maybe that is just where this unit is supposed to be. I even lowered the evap blower speed 1018CFM to 876 CFM at one point but this only changed the delta to 13.7. But, I haven't been able to locate definitive data to verify that. So that is why I asked. I really need to talk with a Trane engineer, but we both know the likelihood of getting that far past the switchboard!!
By the way my SEER10 units at this same time were running evap delta Ts of 20, 18, & 16.5 deg.

JMOR:

Here are some figures for my new 14 SEER Goodman heat pump with external TXV on the air handler:

Liq line pressure: 215 psi
Liq line temp: 99F
Suction line pressure: 80 psi
Suction line temp: 54 F

Subcooling = 6 degrees
Superheat = 6 degrees.

Other info:
Outside air temp: 92 F
Supply air temp: 72 F
Air temp after evap: 53 F
Split = 19 degrees.

Good luck.

Thank you garyg for sharing the data with me.
JMOR

Put all the test data in a column like garyg did, it makes it possible to see what is going on. It is too time consuming for me to sort it out tonight.

I take it this a 2.5-ton condenser?
Is there a high humidity problem with a high latent load?

A real heavy latent load could drop the Delta-T to 13, even 10.

On the data charts the Goodman 3-Ton 13-SEER goes from 20 to 10 delta T, depending on the Relative Humidity latent heat load on the E-Coil.

Goodman 13-SEER 3-Ton: At 95 Ambient, 75 indoor dry bulb & 63 Wet Bulb & 1350-cfm 450-cfm per ton - the E-Coil delta T is listed at 18.

Pulling the temp down to 72 sounds extra good to me.
Is the unit oversized?
What is the normal runtime at EER test conditions.

When it is hot out & a good indoor load - take the condenserÂs delta T & post it.
Post the indoor humidity percentage.

I must say GarygÂs Goodman unit is doing a-okay.
Though the usual Superheat TXV setting is 10 or 12 SH. There might be a much lighter latent load on the Goodman unit.(?)
udarrell _ 2007

Darrell:

Goodman's install manual for the condensor states that superheat should be 7 - 9 degrees so I am a little low and I'll probably tweak the TXV when I get a chance and can borrow a set of gages from a co-worker.

Where did you get the data charts for Goodman? Are they general charts or specific to Goodman?

Thanx.

OK,udarrell, here is tabular data from today.

1.5T, Trane w/exp orifice (FCCV), R22, SEER13, 100 deg outdoor,4 PM, full sun

Liq press: 242 psi (115 deg)

Liq Temp: 105 deg F

Suction press: 85 psi (50 deg)

Suction Temp: 55.4 deg

Subcooling: 10 deg

Superheat: 5.4 deg

Air on cond: 100 deg

Air off cond: 116 deg

Out DB: 100

Out WB: 76

Out RH: 33%

Evap IN: 72 deg

Evap OUT: 59

Evap Delta: 13

Room DB: 72

Room WB: 63

Room RH: 61%

Quote: Posted by garyg on Wed, Aug 15, 07 at 10:48

Darrell:
Goodman's install manual for the condenser states that superheat should be 7 - 9 degrees (Don't touch it, 9-SH is close enough! udarrell) so I am a little low and I'll probably tweak the TXV when I get a chance and can borrow a set of gages from a co-worker.

Where did you get the data charts for Goodman? Are they general charts or specific to Goodman? Thanx.
===========================
I down loaded the off the Internet, & now I can't find the original link.

They are specific to Goodman & most that I downloaded are 13-SEER.

I will try again to re-establish the link where that data is. I want to see more of "Goodman's 13-SEER & up Expanded Performance Data," too!
--------
jmor, I just now saw your data but have to fix & eat lunch, as did not hae any breakfast.

It will take a while for me to get everything sorted & analyzed. Be with you a few hours later. Sorry I did not check back sooner but have been posting heavy in several forums at HVAC-Talk -

udarrell

I don't have time to reread your initial post. Is this the best or poorest performer?

I compared all your data with a GOODMAN 13-SEER, orifice metering device, at those temps & pressures, WB & humidity & the DATA is very close, except for two areas, the Indoor SA RA Split, the Goodman shows 16-F split for an aproximate 72-db indoors with a 63-WB, your Trane had a 13-F split, a 3 degree differential.

The condenser split at that low indoor load is only 12 to 13 for the Goodman & it is 15-F split for your Trane.

Less E-Coil Split a Higher Head pressure air temp discharge split. It appears your Trane has a higher heatload through the evaporator coil.

The Goodman data was with 675-cfm or 450-cfm per ton of cooling which is normally the top end for CFM.

The published general reference indoor airflow split at 72-db & 63-wb is 17-F, however that can never be correct for differ engineered systems. It is rather meaningless.

The General Target Super Heat at 92 Ambient(Not 100) & Return Indoor air at 63-wb is 5.4 on the nose, or what you got at 100-F ambient. I can't find the chart that goes above 92-F, but will later.

Could there be a hot air source leaking into the Return Air? I don't know or forgot what design you have for Return Air.

If it sets oven an air chamber, attic air could be coming down behing the sheetrock into the blower chamber, I have found leaks into the Returns' on many occasions.

There appears to be an unidentified extra load on that AC system. However, getting it to 72 when it is 100 outdoors seems awfully good!

Garyg, I will have upload those Goodman pdf files to my website & later, I will provide you with a link.
udarrell _ 2007

Here is a link that might be useful: udarrell.com

Okay garyg, I uploaded those two pdf files that I have, & am linking the page with those two pdf pages below for all who want them. We should be able to find the other Goodman SEER levels' Expanded data somewhere, I could not get any hits to them on the search engines.

Slow downloading for dailups & wait until they are completely loaded before using them. Then download to your hardrive for quick viewing. I have good virus & spy protection. See link at the bottom.

Jmor, sorry got you mixed with a guy with more than one unit acting up. I've been working on too many posts!

Regarding the E-Coil delt T, it probably varies some between the same SEER & capacity units, therefore you would need all the performance data on your unit.

The Superheat is off the chart that I have here for 100 Ambient & an Indoor RA 63-WB. It shows a 3 degree for 64-WB & then jumps to none for an Indoor 62-WB @ 100 Ambient.

Let me know what you think!
udarrel _ 2007

Here is a link that might be useful: udarrell.com

OK, no air leak, they really did a good job sealing it up with the wipe on mastic and the return duct goes directly to the return grill & the 4 inch wall thickness is caulked all the way around. Tightest duct work of my 4 units (different installers).
But I think, about 10 minutes ago, while looking in the envelope with User's Guide that I very likely found the installers short coming and the reason for the low 'split' and to me at least a little too high suction pressure. In the bottom of this envelope is a #51 FCCV with #51 sticker still in package. The condensing unit is 18,000 BTU, the evaporator is 25,000 and it has sticker on it indicating #55 FCCV. The condensing unit paperwork calls for #51.
Don't you think that might do it?
JMOR

Well JMOR, it is perhaps good that you posted the data, as the superheat being off the chart does indicate too large orifice metering device. Put the smaller #51 in it, that should bring the suction pressures & temperatures in line.

This Goodman data is at the highest 450-cfm perton of cooling or, 675-cfm.

I don't have a 100-F scale on the Goodman chart however, @95-ambient 70-IDB -(Indoor Dry Bulb) at your 61 %RH it says 76-psig suction; @ 105-ambient it says 80-psig which equals about 78-psig, maybe 79-psig suction.

Therefore at 100-ambient the suction with the #51 will probably be @ or around 78-psig for a 46-F E-Coil, - which should adjust the Superheat up enough to be okay.
View the Superheat Subcooling Trouble Shooting page below.
udarrell _ 2007

Here is a link that might be useful: udarrell.com

Darrell, how applicable is this Goodman GSC 13 seer expanded performance data to GSH 13 seer heat pumps? Is there a .pdf document available specific to the GSH series?

I do not have the Expanded Performance Data pdf document on the GSH 13-SEER, but hope someone else can finish it for us.

However, in the meantime looking at the GSH 13 Specification sheet (below) they are similar enough in the cooling mode to ballpark cross reference to the GSC 13 Expanded Performance Data. udarrell _ 2007

Here is a link that might be useful: goodmanmfg.com

Thanks for all your input, udarrell, I switched to #51 from the #55 that my lazy or careless installer left in the 2T coil on the 1.5T cond unit, and finally I have a cold evap, correct superheat, and proper dehumidification!
Thank again.

P.S. It is just GREAT when someone like your self answers the question asked instead of saying something like 'go read a book, you don't need to know, or you ought to know that already', or some other useless posting. I appreciate the directness.

Good job, JMOR.