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Author Topic: A/C questions  (Read 1462 times)

Offline Xiaopig9

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A/C questions
« on: July 16, 2016, 05:34:02 PM »
It's new system, in order to get rebate, sale select a big case coil,
There are the module numbers:
Furnace gmvc96040
A/C.     Gsx16018
Coil     capf3636b6+txv30

Usually coil is half ton large than outdoor unit, but this one is double.
And salesman said that is suggested by goodman.

Question is
How do they decide txv is 2.5 ton?
How to setup cfm, coil? Outdoor unit? Or txv.

Thanks

Offline JobarcoAC

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Re: A/C questions
« Reply #1 on: July 16, 2016, 07:52:47 PM »
From what I can see at the Air-Conditioning, Heating, and Refrigeration Institute's website... it looks good to me. See Attachment I provided. The salesman should have done this.
https://www.ahridirectory.org/ahridirectory/pages/home.aspx

The manufacture decides the txv is 2.5 ton along with how to setup cfm, coil, outdoor unit and txv along with many other things. Please see and follow the manufacturer's installation instructions.

Jabs

Offline Admin

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Re: A/C questions
« Reply #2 on: July 16, 2016, 07:58:30 PM »
To get the $400 OPA rebate you need to achieve 15 SEER.  In your case because you have an ECM fan motor in the furnace, it's easier to achieve the higher SEER.  With that furnace you could install the GSX13018, 13 SEER AC, and achieve 14.5 SEER and qualify for the $250 OPA rebate.

You don't need a TXV or a 3 ton coil with the GSX13 or GSX16 to qualify for rebates.

You would achieve 16 SEER using a 2 ton coil and TDR (Time Delay Relay).  A TXV is just one more thing to fail so I wouldn't install one if it's not required.

You can search the AHRI database here,

https://www.ahridirectory.org/ahridirectory/pages/ac/defaultSearch.aspx

In the Outdoor Unit Model window type,
GSX16018

In the Furnace Model Number window type,
G*vc96040

Most TXV's can be used on 1.5 to 3 ton coils, or 3 to 5 ton coils and there's really nothing to setup besides the placement of the TXV bulb on the suction line.

Offline Xiaopig9

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Re: A/C questions
« Reply #3 on: July 16, 2016, 08:46:16 PM »
Thanks JobarcoAC, Admin.

I will read manual about the setting for cooling.

So it doesn't matter txv24 or txv30 even txv36, may suit for this case?
And about TDR, I'm not familiar with it, may you talk more detail about it? Thanks Admin.

Offline Admin

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Re: A/C questions
« Reply #4 on: July 16, 2016, 09:33:14 PM »
The time delay relay isn't anything to worry about when applying for the OPA rebate, as they don't ask for any information about it.

It's a built in or add-on control that will prevent the AC from short cycling.  Most digital thermostats incorporate a 5 minute compressor protection delay, which would qualify as a TDR in my opinion.

Offline Xiaopig9

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Re: A/C questions
« Reply #5 on: July 17, 2016, 12:55:28 PM »
Thanks.
I'm not familiar with SEER rate,
You said "would achieve 16 SEER using a 2 ton coil and TDR (Time Delay Relay).  A TXV is just one more thing to fail so I wouldn't install one if it's not required."
In my mind if we need get high SEER, should use TXV as metering device. And non bleeding TXV would benefit to high SEER.
So in this case, gsx16018, with 2 ton coil and piston would get 16 SEER and rebate?

Offline Admin

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Re: A/C questions
« Reply #6 on: July 17, 2016, 01:16:06 PM »
Yes, search the AHRI database for reference #7443417.  The furnace you have will matchup with the GSX16-018 and CA24 coil and will achieve 16 SEER.

Offline Xiaopig9

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Re: A/C questions
« Reply #7 on: July 17, 2016, 01:21:03 PM »
Yes,
I just searching the website, it make sense.
Thanks again

Offline Xiaopig9

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Re: A/C questions
« Reply #8 on: July 17, 2016, 01:25:30 PM »
Sorry about lots questions.
So in our case, to select TX valve, it doesn't matter use 1.5 ton or 2.5 ton?

Offline Xiaopig9

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Re: A/C questions
« Reply #9 on: July 24, 2016, 06:19:33 PM »
After installation, got readings:
Sc: 6f
Sh: 4f
Delta T: 20f

Set cfm to 600, bulb tighted and well insulated.
Is it txv too big?

Thanks.

Offline Admin

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Re: A/C questions
« Reply #10 on: July 24, 2016, 09:15:19 PM »
What were the system pressures, indoor wet bulb, indoor temperature and outdoor temperature, when you did your tests?

If you installed a 2 ton coil, increase your indoor airflow between 700 and 1200 CFM.

If you installed a 3 ton coil, increase your indoor airflow between 1050 and 1800 CFM.

That should increase your superheat and lower the Delta T.


Offline walker

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Re: A/C questions
« Reply #11 on: July 26, 2016, 01:07:05 AM »
After installation, got readings:
Sc: 6f
Sh: 4f
Delta T: 20f

Set cfm to 600, bulb tighted and well insulated.
Is it txv too big?

Thanks.

What were your pressures and RA?

Offline Xiaopig9

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Re: A/C questions
« Reply #12 on: July 26, 2016, 06:30:46 PM »
Didn't record indoor wb, and ambient temperature, because it's TXV.
It was a hot day, inside RA 76f, didn't remember excactly pressures, low side around 130 to 140,

Tried to set higher CFM, but it doesn't increase SH, according to above website link, the CFM is 623, if I remember right.