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I see your dialogue with Beenthere, but I don't fully understand. Which measurement is suspect? The supply 86% RH? I am not sure how to improve that one,please see my response to Beenthere regarding measurement methodology. It is definitely higher than return though, is that an issue?

Any other measurements suspect? I think I did a reasonable measurement on the rest but I will re-measure anything questionable. Clarification on "something is wrong" would be greatly appreciated.
The humidity is super suspect. With what you measured, you're actually only removing 14,000 btu/hr. (the moisture is adding heat) I actually ran the numbers 4 times, in 2 different apps as I thought that I was making a mistake.

With the performance data beenthere posted, and the conditioned you mentioned, you should be moving north of 40,000 btu/hr. The sensible heat removed should be around 28,000 btu/hr. (temp measurement only)

Conditions greatly effect the capacity.

Try measuring the temp and humidity right at the air handler intake. If there's a filter, remove it to give you access.

PS. MBH stands for thousands of BTUs per hour.

PPS. The heat rise method is accurate when measured carefully.
 

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Hello all,my second thread is a follow up to my 1st one:

In that thread I investigated potential airflow issue as The tech told me that there was an issue with air return restriction. That doesn't appear to be the case as measurements and Goodman suggest I should be getting about 1500cfm on this unit.

Application is for second floor condo one hour north of Tampa FL. Originally there was a 2.5T unit that wouldn't get any cooler than 76 when ambient outside was in 90s. Contractor installed a new 3.5T Goodman unit. This is a small condo that is only 1200 SQ ft but with high ceilings (10') which is mainly one large room. New unit only gets down to about 74 on a hot day but did get down to 72 today.

New air handler is a Goodman ASPT**14 while condenser is a GSX14.

Supers05 recommended that I take a bunch of measurements, they are included in this new thread as I figure it is time to start over.

Airflow appears~1500cfm per earlier thread.
Outside ambient 93 deg, 49%RH
handler return 73.2deg , 49% RH
Handler supply 60.1deg, 86% RH

Condenser measurements:
View attachment 664837
View attachment 664836

I'd appreciate any thoughts on why this unit doesn't work any better than the original unit.
When you fist start up a
Hello all,my second thread is a follow up to my 1st one:

In that thread I investigated potential airflow issue as The tech told me that there was an issue with air return restriction. That doesn't appear to be the case as measurements and Goodman suggest I should be getting about 1500cfm on this unit.

Application is for second floor condo one hour north of Tampa FL. Originally there was a 2.5T unit that wouldn't get any cooler than 76 when ambient outside was in 90s. Contractor installed a new 3.5T Goodman unit. This is a small condo that is only 1200 SQ ft but with high ceilings (10') which is mainly one large room. New unit only gets down to about 74 on a hot day but did get down to 72 today.

New air handler is a Goodman ASPT**14 while condenser is a GSX14.

Supers05 recommended that I take a bunch of measurements, they are included in this new thread as I figure it is time to start over.

Airflow appears~1500cfm per earlier thread.
Outside ambient 93 deg, 49%RH
handler return 73.2deg , 49% RH
Handler supply 60.1deg, 86% RH

Condenser measurements:
View attachment 664837
View attachment 664836

I'd appreciate any thoughts on why this unit doesn't work any better than the original unit.
Hello all,my second thread is a follow up to my 1st one:

In that thread I investigated potential airflow issue as The tech told me that there was an issue with air return restriction. That doesn't appear to be the case as measurements and Goodman suggest I should be getting about 1500cfm on this unit.

Application is for second floor condo one hour north of Tampa FL. Originally there was a 2.5T unit that wouldn't get any cooler than 76 when ambient outside was in 90s. Contractor installed a new 3.5T Goodman unit. This is a small condo that is only 1200 SQ ft but with high ceilings (10') which is mainly one large room. New unit only gets down to about 74 on a hot day but did get down to 72 today.

New air handler is a Goodman ASPT**14 while condenser is a GSX14.

Supers05 recommended that I take a bunch of measurements, they are included in this new thread as I figure it is time to start over.

Airflow appears~1500cfm per earlier thread.
Outside ambient 93 deg, 49%RH
handler return 73.2deg , 49% RH
Handler supply 60.1deg, 86% RH

Condenser measurements:
View attachment 664837
View attachment 664836

I'd appreciate any thoughts on why this unit doesn't work any better than the original unit.
When you first start up a system you have to evaporate the water from the floors, carpets, ceilings, walls, insulation, and clothing in the house, this can take a day or more to do, it requires a lot of energy. The first day is never optimum. However, after running for a while your return and supply air temperature differential should be much higher. As a minimum, the supply air temp at the first register should be 55 degrees, optimally 52 to 54 degrees if your return air is 73. If you have an ECM I(Electrically Commutated Motor) indoor fan motor this requires you to go into the menu and selecting tons and or CFM per ton and adjusting the fan speed to a lower CFM. From the factory they are usually set to output 400-450 CFM per ton, it often requires lowering the CFM far below that to correctly set up the system. If you put an amp meter on the system now and then again after lowering the fan speed you will see a big drop in amperage drawn as well. The system will dehumidify and cool more quickly because of the greater return and supply air temperature differential.

If you do not have an ECM motor you will have to see if you have motor tap options to lower the CFM.

Sincerely,

William McCormick
 

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When you fist start up a



When you first start up a system you have to evaporate the water from the floors, carpets, ceilings, walls, insulation, and clothing in the house, this can take a day or more to do, it requires a lot of energy. The first day is never optimum. However, after running for a while your return and supply air temperature differential should be much higher. As a minimum, the supply air temp at the first register should be 55 degrees, optimally 52 to 54 degrees if your return air is 73. If you have an ECM I(Electrically Commutated Motor) indoor fan motor this requires you to go into the menu and selecting tons and or CFM per ton and adjusting the fan speed to a lower CFM. From the factory they are usually set to output 400-450 CFM per ton, it often requires lowering the CFM far below that to correctly set up the system. If you put an amp meter on the system now and then again after lowering the fan speed you will see a big drop in amperage drawn as well. The system will dehumidify and cool more quickly because of the greater return and supply air temperature differential.

If you do not have an ECM motor you will have to see if you have motor tap options to lower the CFM.

Sincerely,

William McCormick

Also, the addition of an inexpensive freeze stat will protect the system from any experiments and icing of the evaporator coil. They are extremely inexpensive, I buy two and leave one as a spare. They require a short piece of thermostat wire to wire the freeze stat in series with the yellow from the thermostat and the condenser for single-stage compressors.

Sincerely,

William McCormick
 

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When you fist start up a



When you first start up a system you have to evaporate the water from the floors, carpets, ceilings, walls, insulation, and clothing in the house, this can take a day or more to do, it requires a lot of energy. The first day is never optimum. However, after running for a while your return and supply air temperature differential should be much higher. As a minimum, the supply air temp at the first register should be 55 degrees, optimally 52 to 54 degrees if your return air is 73. If you have an ECM I(Electrically Commutated Motor) indoor fan motor this requires you to go into the menu and selecting tons and or CFM per ton and adjusting the fan speed to a lower CFM. From the factory they are usually set to output 400-450 CFM per ton, it often requires lowering the CFM far below that to correctly set up the system. If you put an amp meter on the system now and then again after lowering the fan speed you will see a big drop in amperage drawn as well. The system will dehumidify and cool more quickly because of the greater return and supply air temperature differential.

If you do not have an ECM motor you will have to see if you have motor tap options to lower the CFM.

Sincerely,

William McCormick
This procedure of setting the indoor fan speed can require two technicians to spend four to eight hours to accomplish the proper setting of the indoor fan speed. That is why it is rarely done. Working at a high-end job the setting of the fan speed is the most important part of the job. The mini-splits are taking over because they monitor their own fan speed, while the split systems are almost never set up properly.

Sincerely,

William McCormick
 

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When you fist start up a



When you first start up a system you have to evaporate the water from the floors, carpets, ceilings, walls, insulation, and clothing in the house, this can take a day or more to do, it requires a lot of energy. The first day is never optimum. However, after running for a while your return and supply air temperature differential should be much higher. As a minimum, the supply air temp at the first register should be 55 degrees, optimally 52 to 54 degrees if your return air is 73. If you have an ECM I(Electrically Commutated Motor) indoor fan motor this requires you to go into the menu and selecting tons and or CFM per ton and adjusting the fan speed to a lower CFM. From the factory they are usually set to output 400-450 CFM per ton, it often requires lowering the CFM far below that to correctly set up the system. If you put an amp meter on the system now and then again after lowering the fan speed you will see a big drop in amperage drawn as well. The system will dehumidify and cool more quickly because of the greater return and supply air temperature differential.

If you do not have an ECM motor you will have to see if you have motor tap options to lower the CFM.

Sincerely,

William McCormick
52°f is too cold for the supply. The target is 55-60 depending on your location and humidity.

Most units do not have any menus at all, or even a screen. It'll be through DIP switches or jumper pins. The OP has neither. They have a PSC, and speed taps.

400 cfm/ton is nominal for cooling. 350 cfm/ton is only when dehumidification is really needed. You shouldn't be dropping below that.

It really shouldn't take a single tech more then an hour to setup a resi unit.
 

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52°f is too cold for the supply. The target is 55-60 depending on your location and humidity.

Most units do not have any menus at all, or even a screen. It'll be through DIP switches or jumper pins. The OP has neither. They have a PSC, and speed taps.

400 cfm/ton is nominal for cooling. 350 cfm/ton is only when dehumidification is really needed. You shouldn't be dropping below that.

It really shouldn't take a single tech more then an hour to setup a resi unit.
We usually don't do anything to them and leave if it seems ok, but on high-end jobs, we get out all the equipment and charts, and you would be surprised at how many systems come over-charged, some are extremely over-charged, and some extremely undercharged. After you get done playing with that, which often no one bothers to do if nothing is really screaming trouble, you then have to check the fan and if you have to alter the speed, then you might have to dump or add charge, so if you really want to do it right it could take four hours to a whole day. I know from the calls on really hot days how many systems are not set up properly 90 percent of them or I wouldn't be there. We used to take cardboard and put it around the condenser to simulate a hot day and truly get the charge right. But today no one wants to go there and who can blame them no one is going to pay for it, and it is another service call or a new unit down the road in todays thinking.

Do you know how many Trane fan motors I have been called to replace because the coil was throwing water with the factory settings? I go and lower the fan speed by one tap and the customers tell me of savings and better quality air. Do what you like but after working in estates and with really good people I got a whole new education.

We were installing some new American Standard systems about twenty years ago, two-stage systems, and right from the factory the systems were outputting a 22 degree supply and return differential in the first stage. The unit never left first stage cooling. You couldn't hear it run and the customer gave everyone on the job two and three hundred dollars as a tip when we went back to do another job. He was saving a thousand a month on cooling. It was things like that which made me rethink my strategies.

Sincerely,

William McCormick
 

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We usually don't do anything to them and leave if it seems ok, but on high-end jobs, we get out all the equipment and charts, and you would be surprised at how many systems come over-charged, some are extremely over-charged, and some extremely undercharged. After you get done playing with that, which often no one bothers to do if nothing is really screaming trouble, you then have to check the fan and if you have to alter the speed, then you might have to dump or add charge, so if you really want to do it right it could take four hours to a whole day. I know from the calls on really hot days how many systems are not set up properly 90 percent of them or I wouldn't be there. We used to take cardboard and put it around the condenser to simulate a hot day and truly get the charge right. But today no one wants to go there and who can blame them no one is going to pay for it, and it is another service call or a new unit down the road in todays thinking.

Do you know how many Trane fan motors I have been called to replace because the coil was throwing water with the factory settings? I go and lower the fan speed by one tap and the customers tell me of savings and better quality air. Do what you like but after working in estates and with really good people I got a whole new education.

We were installing some new American Standard systems about twenty years ago, two-stage systems, and right from the factory the systems were outputting a 22 degree supply and return differential in the first stage. The unit never left first stage cooling. You couldn't hear it run and the customer gave everyone on the job two and three hundred dollars as a tip when we went back to do another job. He was saving a thousand a month on cooling. It was things like that which made me rethink my strategies.

Sincerely,

William McCormick
I agree that units do need to be setup right. However, we try not to overload the OP with walls of technical text. Most of the OPs here are DIY'rs with extremely limited technical knowledge on the subject they are asking about. It's best to take them one step at a time, at their pace and comfort level. Open your own thread and we can discuss and debate at length over the details. I think it could very well be interesting and fruitful.
 

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Discussion Starter · #48 ·
The humidity is super suspect. With what you measured, you're actually only removing 14,000 btu/hr. (the moisture is adding heat) I actually ran the numbers 4 times, in 2 different apps as I thought that I was making a mistake.

With the performance data beenthere posted, and the conditioned you mentioned, you should be moving north of 40,000 btu/hr. The sensible heat removed should be around 28,000 btu/hr. (temp measurement only)

Conditions greatly effect the capacity.

Try measuring the temp and humidity right at the air handler intake. If there's a filter, remove it to give you access.

PS. MBH stands for thousands of BTUs per hour.

PPS. The heat rise method is accurate when measured carefully.
Thank you for the clarification.

Based on your, Beenthere and others inputs, I am starting over.
a) Just found out that tech wired condenser to wrong electrical panel:(. They didn't connect it properly to the unit that they connected it to. Final straw. Called corporate and complained.
b) electrician is coming out Friday to fix electrical.
c) told tech that he needs to adjust TXV, the low SH could ruin my compressor over long term. At first he said it wasn't adjustable, but after looking into it, he says it might be. Looking at the manual, my unit is not on list of non-adjustable TXVs. The implication is that it is adjustable. He is coming out on Friday to make this adjustment.
d) tech promised to bring 'anometer to check static pressure'. He doesn't have a manometer.
e) I am planning to borrow a professional humidity gauge from someone else for Friday.
f) I will be there to monitor all work on Friday.
g) I'll re-measure everything after they complete and then post back here.

Thanks again!!!!!!!!!!
 

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I agree that units do need to be setup right. However, we try not to overload the OP with walls of technical text. Most of the OPs here are DIY'rs with extremely limited technical knowledge on the subject they are asking about. It's best to take them one step at a time, at their pace and comfort level. Open your own thread and we can discuss and debate at length over the details. I think it could very well be interesting and fruitful.
Wasn’t my intention to overwhelm infact I was trying to abbreviate the whole process by highlighting a 13 degree TD (Temperature Differential) as being way too low. The TXV is doing its job by asking for more Freon with only a 13 degree TD. He needs to lower fan speed by whatever means.

Sincerely,

William McCormick
 

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Wasn’t my intention to overwhelm infact I was trying to abbreviate the whole process by highlighting a 13 degree TD (Temperature Differential) as being way too low. The TXV is doing its job by asking for more Freon with only a 13 degree TD. He needs to lower fan speed by whatever means.

Sincerely,

William McCormick
At 2.3°f SH (if that's even accurate) it's over feeding, and needs to be adjusted.
 

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How the heck is he going to check static pressure with an anometer? They check air speed/velocity, not pressure.

You have an ECM blower, have him set the air flow between 350 and 400 CFM per ton. And he or you can check that by temp rise with the electric heat. Then the TXV can be adjusted.

Personally, if I was going to your place. First, I would check static, and adjust air flow for the condenser. Then I would recover the entire charge. Then weigh back in the factory charge. Then run the system and after 15 minutes of run time. Add refrigerant to get the SC where it belongs, if needed. And then adjust the TXV to get proper SH.
 
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How the heck is he going to check static pressure with an anometer? They check air speed/velocity, not pressure.

You have an ECM blower, have him set the air flow between 350 and 400 CFM per ton. And he or you can check that by temp rise with the electric heat. Then the TXV can be adjusted.

Personally, if I was going to your place. First, I would check static, and adjust air flow for the condenser. Then I would recover the entire charge. Then weigh back in the factory charge. Then run the system and after 15 minutes of run time. Add refrigerant to get the SC where it belongs, if needed. And then adjust the TXV to get proper SH.
I hate it when they upgrade the model but don't change the model number much. I was looking at the wrong pdf......I thought it was a PSC.
 

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I hate it when they upgrade the model but don't change the model number much. I was looking at the wrong pdf......I thought it was a PSC.
Yeah, got burnt on that a few times already myself.
 
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At 2.3°f SH (if that's even accurate) it's over feeding, and needs to be adjusted.
I live in the northeast and I get to set up systems that are starting up in 90-degree outdoor air and inside temps near 90 degrees with 88 percent humidity. I have seen pressures that make me wonder about the charge even after running for 20 minutes. Some of these houses have already developed black mold in the short time the old AC system was down. But I see similar pressure readings as the OP posted, I almost always also install an Aprilaire dehumidifier but often do not get it installed before setting up the AC system. After the dehumidifier is installed it also changes the performance of the AC unit. Imagine trying to heat your house to 72 degrees with 85-degree air it would take all day or you might never get there. The same is true of AC it is all about the temperature differential between the return and supply duct. When I lower the fan speed the pressures become more normal. The OP as someone pointed out might be suffering from a contaminated charge. Or believe it or not, the system could be undercharged. But my bet is the fan speed. I always check the amperage as well if the amperage is high it is probably the fan speed. The TXV's are usually dialed in nicely.

Because many of the air handlers and furnaces have to be set for tonnage and CFM per ton anyway I always start with standard 400 CFM per ton and then work downward. And I have noticed by tracking results with the ecobee thermostat graphing system that by lowering the fan speed getting more dehumidification that the unit runs less, draws less power and the humidity stays low even between cycles. These things do not happen when I go with factory fan settings. So for friends and family, I do these things. The ecobee lets you look at indoor, outdoor temperature, humidity, as well as the set temp at any given moment in the past as well as what equipment was running at any given moment.
I do not blame other HVAC guys for not wanting to fool around with these options each unit has specific rules for programming. Some of the boards in furnaces are actually two inches above the floor when mounted in the up-flow position. That means we are kneeling on the same knees, that were getting cooked on the roof the day before trying to cycle through choices on the LED readout. If you just ate lunch and you're on your knees with your head on the ground you might taste your lunch while cycling through LED menu choices. Or you might be in a hot attic or drop ceiling trying to wipe the sweat out of your eyes as you struggle to read the LED and the wet install sheet with the codes.

From installing a lot of EWC zone damper control boards and bypass dampers I had the opportunity to see what is and what is not important about setting up a system. The EWC comes with a SAS (Supply, Air, Sensor) that protects the air handler from icing, so I was able to push systems to the extreme and then document the effects with the ecobee thermostat graphing system.
 

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Discussion Starter · #56 ·
Bill McC said:
my bet is the fan speed.
The current tech only cared about deltaT and SC. I was trying to explain to him that I wouldn't let him off the hook unless we can prove BTUs were within spec. Currently SC is good but deltaT isn't. I told him we could fix deltaT by lowering the fan speed but that wouldn't fix btus. Since BTUs is a function of cfms and deltaH, lowering cfms would raise deltaH and BTUs wouldn't likely be affected much. He ignored btu discussion and got excited about fixing deltaT by changing cfm. We ultimately called Goodman and they said to leave fan speed alone. However, they didn't ask for test data.

Am I incorrect?
 

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The current tech only cared about deltaT and SC. I was trying to explain to him that I wouldn't let him off the hook unless we can prove BTUs were within spec. Currently SC is good but deltaT isn't. I told him we could fix deltaT by lowering the fan speed but that wouldn't fix btus. Since BTUs is a function of cfms and deltaH, lowering cfms would raise deltaH and BTUs wouldn't likely be affected much. He ignored btu discussion and got excited about fixing deltaT by changing cfm. We ultimately called Goodman and they said to leave fan speed alone. However, they didn't ask for test data.

Am I incorrect?
The lower the coil temp, the less efficient the ac will be, thermodynamically. The BTUs moved will be lower. (current draw will also be lower, but by a lesser amount.) The real benefit is the greater dehumidification.

Need to set the airflow to the correct level. The goodman guy probably suspected a problem with the airflow measurements. That was probably the reason why he said not to change the airflow.

You still haven't posted any pictures of the indoor unit and the ductwork setup. We are missing something. I think you have a sizable fresh air intake, fully open. If so, all measurements need to be taken closer to the unit.

Measuring the heat moved by the unit isn't hard. It's disappointing that not all techs carry what's needed, but it's far too common to see. They are not free and most don't see the benefit. I'm really disappointed that he can't borrow/ buy the right tools to verify the performance on a return visit. Hell, you can measure thermodynamic efficiency only using temp measurements if you really needed to. (it's far easier when you can measure humidity/enthalpy and airflow though.)
 

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Almost none of that directly helps the OP. It only serves to confuse them. High Fan speed alone isn't going to prevent them from reaching set point.

It's not about temp difference. It's about total energy removed /added over the specified timeframe. (BTU/hr) That's mass × enthalpy change here. It has to be a greater change then the heat loss /gain in that same timeframe.

We have targets for temp difference because systems are designed to the same framework of numbers. However, the situation is never textbook, so those numbers are only guidelines.

We'd be happy to talk at length on it, in your own thread. I really don't want to derail this one and not help the OP.
 

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Discussion Starter · #59 ·
The lower the coil temp, the less efficient the ac will be, thermodynamically. The BTUs moved will be lower. (current draw will also be lower, but by a lesser amount.) The real benefit is the greater dehumidification.

Need to set the airflow to the correct level. The goodman guy probably suspected a problem with the airflow measurements. That was probably the reason why he said not to change the airflow.

You still haven't posted any pictures of the indoor unit and the ductwork setup. We are missing something. I think you have a sizable fresh air intake, fully open. If so, all measurements need to be taken closer to the unit.

Measuring the heat moved by the unit isn't hard. It's disappointing that not all techs carry what's needed, but it's far too common to see. They are not free and most don't see the benefit. I'm really disappointed that he can't borrow/ buy the right tools to verify the performance on a return visit. Hell, you can measure thermodynamic efficiency only using temp measurements if you really needed to. (it's far easier when you can measure humidity/enthalpy and airflow though.)
Thanks again for your feedback. I am really embarrassed that my temp measurements are likely wrong, I really thought I did a decent job there. I am not there today. I'll take your advice on placement and I'll take pictures of unit, ducts and temperature measurement setup when I am there on Friday.

Goodman was given almost no data (I only recall deltaT), so it was strange that they voiced a recommendation at all.
 

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Is the return air temp actually being measured in the return duct, at inlet of air handler?

I suspect there's a return leak somewhere based on the numbers posted.
Even txv over-feeding, in my opinion isn't enough to have a 50f coil with low 70s return air.
 
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