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Squeaky Clean

GSH130181AB Goodman 1.5 ton heat pump charging chart

12 posts in this topic

  I'm looking for a specific manufacturer charging chart (not the generic ones offered all over the net). This is an 06 unit with a fixed orifice and I understand these heat pump units are very finicky about charging. I would say I'm looking at about 7-9 degree superheat (+ or-5) on 90 F degree day. ( it seems like my thermostat is stuck on 90 these days!)  I found an installation manual and it has a performance data chart, but I don't see anything concerning super heat / sub cool. Any help would be appreciated.

Edited by Squeaky Clean

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Did you check behind the condenser access panel? Sometimes they have a charging chart on the backside. I usually just a sliding charging ruler. You measure like outside dry bulb and inside wet bulb. Then match it up to get superheat. I don't do much hvac but I've never had trouble using those on heat pump or straight a/c.

Edited by BryanS

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yes I checked, it had gotten wet and peeled off.... I was told I should not use those slide rules for these small heat pump units as charge is critical, both heat and cool.

Edited by Squeaky Clean

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http://hvaccharts.com/products.html

Something like these which I also own. Works just fine.

Ah. No idea. Our HVAC instructor had us buy them in school. Never heard of them being an issue for small heat pumps. The only critical thing I know about heat pumps is charging during a/c because you can only really weigh in during the winter.

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Those slide rules you provided a link to,  help you calculate the super heat on the specific unit your working on, but I'm looking for the actual manufacturer specifications as an comparison , so I have a value to shoot for......correct? or am I missing something?

Edited by Squeaky Clean

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Yea they are just general. I believe they are based off of enthalpy charts which is typically how a manufacturer would figure it up if I'm not mistaken. I don't know how to read an enthalpy chart myself because we never actually covered that section in school.

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I could be wrong though. I've been out of school since 2010. I don't see the sliding rules being wrong. Typical superheat is 8-12. If the dataplate doesn't say otherwise. I just go by the chart or 8-12 degree superheat. You may want to verify you airflow is good if your superheat is 7-9 already. You have a delta T? Temperature going into the return minus temperature coming out the supply vent. I believe it should be around 15-20 degrees difference.

Edited by BryanS

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No, I agree that they are not wrong.......but they only help you determine what your currently working with as far as calculating the super heat or sub cool , but they can not tell you what the specific numbers should be for that specific unit your working on....and that's what im looking for in this case. I know based on the generic charts what my goal numbers should be.....but I would like to see the chart for this specific unit.  I hope that makes sense.  

Edited by Squeaky Clean

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I just uploaded the file that I think will help you. I labeled it Goodman HVAC numerous models.I put it in Pot Luck Supper side.  Page 58 has SH charging chart. Also, look up Efficient comfort.net. He has some of the generic charts but he also has several other charts and troubleshooting pages too. He also lists evaporator leaving temperature charts and evaporator delta T charts. You can also put your data in his A/C analyzer and see what it suggests. It's more of a troubleshooting tool but it's more detailed than generic charts. 

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I could be wrong though. I've been out of school since 2010. I don't see the sliding rules being wrong. Typical superheat is 8-12. If the dataplate doesn't say otherwise. I just go by the chart or 8-12 degree superheat. You may want to verify you airflow is good if your superheat is 7-9 already. You have a delta T? Temperature going into the return minus temperature coming out the supply vent. I believe it should be around 15-20 degrees difference.

Bryan, yes you are wrong.

The sub cool can be anywhere between 8-20.

The superheat is only done off the slide rule, the sticker or the formula.

In south florida it's not uncommon to have 20-35 super heat.

I think the lowest I ever had was around 15

Stefan

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Pretty sure my slide rule has subcooling and superheat calculations. It hasn't been an issue yet.

And thats depending on the metering device obviously.

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A fixed orifice uses superheat. A txv uses subcooling and superheat.

If you use the sub cooling method on a txv and don't also make sure you have the proper superheat, it can be off.

If you use the sticker it will be right because they did the proper calculations.

By the way to figure superheat, take the indoor wetbulb temp

multiply by 3 take away a constant of 80 and then take away the outdoor dry temp.

Divide by 2+ plus or minus 5

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