Goodman superheat chart versus fromula

Moderators: CEO1, AC480

User avatar
3rdcoast
Site Moderator
Posts: 633
Joined: Mon Oct 13, 2014 7:26 pm
Trade Experience: 29
Service History: Worked for big companies in past, currently hacking by myself
Trade Certifications: None Provided

Goodman superheat chart versus fromula

Postby 3rdcoast » Fri May 05, 2017 3:36 pm

Installed a goodman 14 SEER straight cool the other day, (R410A). Since 14 SEER is entry level now, Goodman and many other brands are using pistons on the 14 SEER stuff. Was charging the unit by the chart in the unit, and decided to check the number versus the superheat formula developed earlier by a tech.

Correct me if I am wrong, but I used the formula (3*indoor wetbulb-80-outdoor ambient)/2

It used to come pretty close to the charts on the older equipment, but on the chart in the Goodman there was quite a difference.

I will have to check it against another brands chart when I run across one in the future.

Click on the chart to make it readable.

GOODMAN SUPERHEAT CHART VERSUS FORMULA.jpg

User avatar
CEO1
Founder
Posts: 2997
Joined: Mon Feb 17, 2014 11:20 pm
Trade Experience: 30
Service History: Primarily residential, with an occasional light commercial something.
Trade Certifications: Expired NATE's, State Certified Contractor
Location: SouthEast

Re: Goodman superheat chart versus fromula

Postby CEO1 » Fri May 05, 2017 8:20 pm

That's the formula...maybe they decided to lower the piston system superheat for increased coil loading and a little more refrigeration. :? Who knows? But I suspect it's all about getting the rated efficiency, for the least amount of money.

Goodman's come a long way since the 90's...and in spite of the bad mouthing it gets, the mechanical side is probably as good as any of the "non-premium" brands. But why they keep dickin' with pistons is beyond me, other than the money. I bought the new 14 SEER condenser last year for my system, which has a piston on the outdoor unit. I had planned to convert it to a TXV, but have yet to muster the courage to do it. :mrgreen:
One of the MFIC's...

User avatar
AC480
Founder
Posts: 2074
Joined: Fri Feb 21, 2014 7:57 pm
Trade Experience: 37
Service History: Chiller Technician
Trade Certifications: LA State Lic Mechanical / MS State Lic HVAC / CRCM
Location: Southeast Louisiana

Re: Goodman superheat chart versus fromula

Postby AC480 » Fri May 05, 2017 9:38 pm

CEO1 wrote:That's the formula...maybe they decided to lower the piston system superheat for increased coil loading and a little more refrigeration. :? Who knows? But I suspect it's all about getting the rated efficiency, for the least amount of money.

I believe what you say is the reason. Trying to meet the efficiency rating is more important than adjusting the superheat for the longevity of the system.

CEO1 wrote:Goodman's come a long way since the 90's...and in spite of the bad mouthing it gets, the mechanical side is probably as good as any of the "non-premium" brands. But why they keep dickin' with pistons is beyond me, other than the money. I bought the new 14 SEER condenser last year for my system, which has a piston on the outdoor unit. I had planned to convert it to a TXV, but have yet to muster the courage to do it. :mrgreen:

Yes, I believe they have. It is a whole lot easier for me to get motivated to work on other's stuff than my own. I can always find a reason to put it off, or no reason other than I don't feel like it. I bought 2 txv's to put on my split system WSHP last year. I have a muffler that is almost rusted out, and 2 refrigerant pressure operated water regulating valves to change. I do need to order the muffler. We didn't have much of a winter and we were very busy this year as well. And we continue to get cool fronts here in May. Tomorrow would be a great day ,but I have everything but the muffler, and this just pinged my memory. I am probably going to come home from work one day in the middle of the summer to a hot house. :x
I have been fretting all day trying to find a list I have been working on of stuff I need to do and stuff I need to order. I probably should have just made another. I probably threw the dam thing in the trash can.... :x

"We do these things not because they are easy, but because they are hard"
-John F. Kennedy, Rice University, Sept. 12, 1962

User avatar
Behappy
Senior Tech*
Posts: 784
Joined: Sun May 03, 2015 7:57 pm
Trade Experience: 45
Service History: Been there, Done that and got the scar to prove it.
Trade Certifications: ID 10 T certified, NATEless for a couple of years now.
Location: So. MS

Re: Goodman superheat chart versus fromula

Postby Behappy » Sat May 06, 2017 7:12 am

Wow, that took a little time to set up that chart.. Thanks
At every school I have been to they harp on using the Mgf. charts for charging.

But, you bring up a good point. After the installation when you go to service the unit and the chart is missing...
What ca gonna do?

Your chart shows the "rule of thumb formula" to be 30 to 75% off (for most reasonable temps).
I have an app on my phone that uses this, so I am guilty. I guess the horse shoe/atomic bomb principle works here.

That being said most of the "High SEER" systems (2 speed and variable speed) we have been putting in...
Across the board, after using the charts, are ending up with a 7~8* SC (xvlv).
I haven't the time to apply the "Jim Bergman" formulas, but I would bet they are close.

User avatar
MITTS
Senior Tech*
Posts: 1186
Joined: Mon May 18, 2015 6:33 pm
Trade Experience: 21
Service History: HVACR
Trade Certifications: None Provided
Location: Up Yonder

Re: Goodman superheat chart versus fromula

Postby MITTS » Sat May 06, 2017 8:03 am

Could it be the difference between copper and aluminum coils?

Since aluminum doesn't transfer heat as well there would be less SH as it leaves the coil all things being the same.
I don't know
karate
but I know
ka-razy

User avatar
CEO1
Founder
Posts: 2997
Joined: Mon Feb 17, 2014 11:20 pm
Trade Experience: 30
Service History: Primarily residential, with an occasional light commercial something.
Trade Certifications: Expired NATE's, State Certified Contractor
Location: SouthEast

Re: Goodman superheat chart versus fromula

Postby CEO1 » Sat May 06, 2017 9:28 am

Behappy wrote:Wow, that took a little time to set up that chart...I haven't the time to apply the "Jim Bergman" formulas, but I would bet they are close.


Does anyone (besides me) ever wonder if service people outside the arena of "professional forums" even know what superheat and subcooling are, what they imply or how to determine the values? ..or even care? I'll bet, not many...

That's probably the reason so many service company owners kept selling R-22 systems when 410A equipment was available...they knew 22 systems needed to be 70 psi and beer-can-cold, but didn't know what psi value went with beer-can-cold on 410 systems... :roll:

I've been referring replacements to another company, whose owner I know and trust...he's honest, after-the-sale service conscious and does a lot of work, compared to me. I went behind him (an employee) recently on a system they had topped off with R-22 (I guess) while the HO ponders replacing the old POS equipment. There was still a problem with the condensate running in the floor. The HO thought the problem might be a frosting coil, wondering if the top-off had already leaked out. At some point, I suspected frost and set the system (heat pump) to "heat" for defrosting and the OD unit would only run a couple of minutes and shut down...it was tripping on high head pressure. And in the cool cycle, it was <70 psi and "beer-can-cold"...measured superheat was 2 or 3 degrees. They had charged the HO $400 for 3 lbs of 22 and it probably needed a pound and a half. :roll:

The owner of the company has been doing HVAC longer than me... :?

You can go to the 'other place', read stuff posted by techs who have some kind of HVAC degree, all kinds of certifications and they post something like "My pressures are 'spot on', but the superheat is high", or low or whatever. Even when I was very green, didn't fully understand what the numbers were supposed to be or what they meant, I knew high superheat and 'spot on' pressures didn't go together.

I did seminars a while for Johnstone...I'd be talking to 75 people, explaining saturated conditions or boiling point or superheat/subcooling, and see most of the 75 with 'deer-in-the-headlights' expressions on their faces. And a lot of those guys go out every day and charge equipment owners good money to mal-adjust the equipment... :roll:

I do my fair share of 'mal-adjusting', but am conscious of what I'm doing and why...there are cases where we 'do what we have to do'. Still, it's always refreshing to see a 'professional' bring up an intelligent topic accompanied by accurate data, that deserves a thoughtful reply. :)
One of the MFIC's...

User avatar
Behappy
Senior Tech*
Posts: 784
Joined: Sun May 03, 2015 7:57 pm
Trade Experience: 45
Service History: Been there, Done that and got the scar to prove it.
Trade Certifications: ID 10 T certified, NATEless for a couple of years now.
Location: So. MS

Re: Goodman superheat chart versus fromula

Postby Behappy » Sat May 06, 2017 2:47 pm

CEO1 wrote:
Behappy wrote:...I'd be talking to 75 people, explaining saturated conditions or boiling point or superheat/subcooling, and see most of the 75 with 'deer-in-the-headlights' expressions on their faces.

Still, it's always refreshing to see a 'professional' bring up an intelligent topic accompanied by accurate data, that deserves a thoughtful reply. :)[/blue]


10-4

Totally agree!
But I see trucks running around with those big old yellow electronic thing-a-ma-jig's hanging in the back that they hook up to a unit.
And I wonder if they put 'em on enough, will they look at the numbers. Maybe if they see those numbers enough, a light bulb will go off.
So, I think those electronic gizmo's may be a blessing in the long run.
Besides, I am getting to the point when I can't see the little spaces under the needle on analog's... :geek:


FWIW.. I just watched Nordyne's microchannel series and they impressed me on (IMHO) how they are targeting the audience that CEO is talking about. Also they use ALL digital tools in the presentation.

http://www.microchannelfacts.com/training-sweepstakes/

User avatar
AC480
Founder
Posts: 2074
Joined: Fri Feb 21, 2014 7:57 pm
Trade Experience: 37
Service History: Chiller Technician
Trade Certifications: LA State Lic Mechanical / MS State Lic HVAC / CRCM
Location: Southeast Louisiana

Re: Goodman superheat chart versus fromula

Postby AC480 » Sat May 06, 2017 3:24 pm

CEO1 wrote:I did seminars a while for Johnstone...I'd be talking to 75 people, explaining saturated conditions or boiling point or superheat/subcooling, and see most of the 75 with 'deer-in-the-headlights' expressions on their faces. And a lot of those guys go out every day and charge equipment owners good money to mal-adjust the equipment... :roll: [/blue]


I know exactly what you mean. I think they missed the basic foundations of the physics behind mechanical refrigeration, and when you try to explain these things many just don't care to know. If you try to explain something to someone who does not have a the basic understanding of how refrigeration works you are wasting your breath. I was in a supply house a while back, and there was a tech in there from another company, one of those that are in the business simply to make money. The tech was complaining that the service manager showed up and was complaining because he was spending too much time waiting on a deep vacuum. He was no doubt, using 1/4" hoses going through a manifold like I did for so many years. I tried to explain to him he needed to ditch the manifold and get the 1/2" megaflow hoses straight to his pump. He thought I was nuts so I just gave up and walked out.

"We do these things not because they are easy, but because they are hard"
-John F. Kennedy, Rice University, Sept. 12, 1962

User avatar
JCtech
Senior Tech*
Posts: 80
Joined: Sun May 17, 2015 9:01 pm
Trade Experience: 8
Service History: service tech, learned all I know on protech;)
Trade Certifications: None Provided

Re: Goodman superheat chart versus fromula

Postby JCtech » Sat May 06, 2017 7:00 pm

AC480 wrote:He was no doubt, using 1/4" hoses going through a manifold like I did for so many years. I tried to explain to him he needed to ditch the manifold and get the 1/2" megaflow hoses straight to his pump. He thought I was nuts so I just gave up and walked out.

I can SO relate. But I had the good fortune recently to pull vacs on multiple systems that were pretty much identical along with all the other guys in my dept. I was doing 4 to their 1. A couple of guys were questioning the accuracy of my BluVac :mrgreen: So I put their Mic guage on my rig, with predictably similiar results :D Two guys ordered 1\2" hoses the next day!! Theres no proof like the pudding ;)

User avatar
CEO1
Founder
Posts: 2997
Joined: Mon Feb 17, 2014 11:20 pm
Trade Experience: 30
Service History: Primarily residential, with an occasional light commercial something.
Trade Certifications: Expired NATE's, State Certified Contractor
Location: SouthEast

Re: Goodman superheat chart versus fromula

Postby CEO1 » Sat May 06, 2017 9:09 pm

Behappy wrote:FWIW.. I just watched Nordyne's microchannel series and they impressed me on (IMHO) how they are targeting the audience that CEO is talking about. Also they use ALL digital tools in the presentation.

http://www.microchannelfacts.com/training-sweepstakes/


I think I saw that...was a banner ad at H-Talk. Or is that where you got it?

I was hoping it would get into the 'charge sensitive' discussion. :mrgreen:
One of the MFIC's...


Return to “Topics Of Interest”

Who is online

Users browsing this forum: No registered users and 1 guest