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Posted: 8/20/2017 8:15:16 AM EDT
[#1]
Bump for morning crew.
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Posted: 8/20/2017 8:20:29 AM EDT
[#2]
I'd like to know how you determined the proper sizing for your system?
What made you choose the 2.5 ton unit versus the 4 ton unit? What is your air flow? Superheat, subcooling, delta T? How many CFM can your duct system handle? |
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Posted: 8/20/2017 8:20:55 AM EDT
[#3]
It's been a LONG time since I went thru hvac schooling (IBEW required class
 ) but a ten degree differential is way too low. IIRC ~ twenty was the goal.
Purging w/ nitrogen while brazing is preferred. Do you have an inline filter? If you have the means to reclaim refrigerant you could add some in small increments, wait a while between and measure the differential. If you notice the differential starting to drop due to too much refrigerant take some out via an EPA certified method 
I have no experience w/ 410, we practiced with 22 |
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Posted: 8/20/2017 8:34:03 AM EDT
[#4]
I would recover the refrigerant, replace the drier, evacuate and put the factory charge in then adjust charge,
Don't think it would take more than a pound or 2 over a factory charge with just an extra 10 feet of line |
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Posted: 8/20/2017 8:39:43 AM EDT
[#5]
Quote HistoryQuoted:
I'd like to know how you determined the proper sizing for your system? What made you choose the 2.5 ton unit versus the 4 ton unit? What is your air flow? Superheat, subcooling, delta T? How many CFM can your duct system handle? Air handler is in the basement. Ducts are in on the second floor but not on the first because I'm working on the home still, on the first floor at the moment is just a large vent installed right into the plenum. Moves some serious air. Can't imagine there's a restriction. Will get some more info shortly. Delta was only 10 degrees. Does superheat mean anything with a TXV? |
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Posted: 8/20/2017 8:40:31 AM EDT
[#6]
Wow. Where to start....
Need : Outdoor temp Suction pressure and temp @ condenser Liquid pressure and temp @ condenser Info asked for above will help size it and determine if size is a factor. I'm asking for info to diagnose how the condenser is acting and what your SC really is. Most want about 10* subcooling. "like crap" isn't a real term. Has ANYONE pulled a good vac on the system? If you bought your own tank of 410 then you'll put a pound or less in it and have a 24lb tank laying around forever if done right. It wouldn't take much to make up for 10' of line set |
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Posted: 8/20/2017 8:42:54 AM EDT
[#7]
Quote HistoryQuoted:
No manual j was done just the usual "you need this much tonage per this much sq/ft" I am only 1300sq/ft but can't remember what ton units I have. Will check when it's in front of me. Air handler is in the basement. Ducts are in on the second floor but not on the first because I'm working on the home still, on the first floor at the moment is just a large vent installed right into the plenum. Moves some serious air. Can't imagine there's a restriction. Will get some more info shortly. Delta was only 10 degrees. Does superheat mean anything with a TXV? |
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Posted: 8/20/2017 9:01:21 AM EDT
[#8]
Quote HistoryQuoted:
Subcooling is the point at which saturated vapor turns to a liquid at the condenser. Superheat is the point at which liquid turns to a vapor in the coil. I will record it anyway. |
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Posted: 8/20/2017 9:06:24 AM EDT
[#9]
Quote HistoryQuoted:
Wow. Where to start.... Need : Outdoor temp Suction pressure and temp @ condenser Liquid pressure and temp @ condenser Info asked for above will help size it and determine if size is a factor. I'm asking for info to diagnose how the condenser is acting and what your SC really is. Most want about 10* subcooling. "like crap" isn't a real term. Has ANYONE pulled a good vac on the system? If you bought your own tank of 410 then you'll put a pound or less in it and have a 24lb tank laying around forever if done right. It wouldn't take much to make up for 10' of line set I mentioned above I had a subcooling of 12. System chart called for aprox 299psi with 11-13 subcooling. That's what it had yesterday when I was done. I plan on checking again today when ambient temps get higher. Vacuum was done by an HVAC tech. I saw no micron gauge that I can remember but a vacuum pump was used. This was before I knew anything about HVAC. |
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Posted: 8/20/2017 9:07:45 AM EDT
[#10]
410a is a blend, get a leak and depending on where it is ,one component of the gas leaks at a higher rate than the other. Like someone suggested ,pulling the refrigerant out and installing a drier, recharge is probably a good start.
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Posted: 8/20/2017 9:09:52 AM EDT
[#11]
was the txv sensing bulb removed before soldering and then replaced on the suction line and insulated properly?
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Posted: 8/20/2017 9:14:50 AM EDT
[#12]
Quote HistoryQuoted:
was the txv sensing bulb removed before soldering and then replaced on the suction line and insulated properly? |
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Posted: 8/20/2017 9:15:54 AM EDT
[#13]
Quote HistoryQuoted:
410a is a blend, get a leak and depending on where it is ,one component of the gas leaks at a higher rate than the other. Like someone suggested ,pulling the refrigerant out and installing a drier, recharge is probably a good start. Was the suction line schrader. |
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Posted: 8/20/2017 9:21:55 AM EDT
[#14]
Quote HistoryQuoted:
Wow. Where to start.... Need : Outdoor temp Suction pressure and temp @ Liquid pressure and temp @ condenser Info asked for above will help size it and determine if size is a factor. I'm asking for info to diagnose how the condenser is acting and what your SC really is. Most want about 10* subcooling. "like crap" isn't a real term. Has ANYONE pulled a good vac on the system? If you bought your own tank of 410 then you'll put a pound or less in it and have a 24lb tank laying around forever if done right. It wouldn't take much to make up for 10' of line set |
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Posted: 8/20/2017 9:26:39 AM EDT
[#15]
Quote HistoryQuoted:
fixed that for you Quote HistoryQuoted:
Quoted:
Wow. Where to start.... Need : Outdoor temp Suction pressure and temp @ Liquid pressure and temp @ condenser Info asked for above will help size it and determine if size is a factor. I'm asking for info to diagnose how the condenser is acting and what your SC really is. Most want about 10* subcooling. "like crap" isn't a real term. Has ANYONE pulled a good vac on the system? If you bought your own tank of 410 then you'll put a pound or less in it and have a 24lb tank laying around forever if done right. It wouldn't take much to make up for 10' of line set Remember, the compressor is IN the condenser. The evaporator is the a coil he refers to. |
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Posted: 8/20/2017 9:30:52 AM EDT
[#16]
Quote HistoryQuoted:
Like shit would of been the proper term on any job site I've ever been on, but I was trying to be more proper for a classy place like arfcom. I mentioned above I had a subcooling of 12. System chart called for aprox 299psi with 11-13 subcooling. That's what it had yesterday when I was done. I plan on checking again today when ambient temps get higher. Vacuum was done by an HVAC tech. I saw no micron gauge that I can remember but a vacuum pump was used. This was before I knew anything about HVAC. Quote HistoryQuoted:
Quoted:
Wow. Where to start.... Need : Outdoor temp Suction pressure and temp @ condenser Liquid pressure and temp @ condenser Info asked for above will help size it and determine if size is a factor. I'm asking for info to diagnose how the condenser is acting and what your SC really is. Most want about 10* subcooling. "like crap" isn't a real term. Has ANYONE pulled a good vac on the system? If you bought your own tank of 410 then you'll put a pound or less in it and have a 24lb tank laying around forever if done right. It wouldn't take much to make up for 10' of line set I mentioned above I had a subcooling of 12. System chart called for aprox 299psi with 11-13 subcooling. That's what it had yesterday when I was done. I plan on checking again today when ambient temps get higher. Vacuum was done by an HVAC tech. I saw no micron gauge that I can remember but a vacuum pump was used. This was before I knew anything about HVAC. |
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Posted: 8/20/2017 9:32:13 AM EDT
[#17]
Quote HistoryQuoted:
I understand what they are just was under the impression superheat was not used with a TXV. I will record it anyway. Quote HistoryQuoted:
Quoted:
Subcooling is the point at which saturated vapor turns to a liquid at the condenser. Superheat is the point at which liquid turns to a vapor in the coil. I will record it anyway. |
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Posted: 8/20/2017 9:43:15 AM EDT
[#18]
Quote HistoryQuoted:
Subcooling is the |
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Posted: 8/20/2017 9:59:16 AM EDT
[#19]
Hopefully this all makes sense tried to get this info before wife rushed me out the door.
Ambient 75 Liquid PSI 255 Sat 85 Line temp 75 Gas / suction PSI 111 Sat 36 Line temp 74 (if maters TXV) Air after evap coil 65 deg Air at return 77 deg Bottom of evap temp probe on line after TXV 42 deg Top of evap (where TXV probe is) 73 Temp at thermostat 73 Spec on outside unit say 259-274psi 9-10 subcooling (depending on wet bulb) for 75 degree ambient |
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Posted: 8/20/2017 10:04:23 AM EDT
[#20]
2 ton units
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Posted: 8/20/2017 10:16:27 AM EDT
[#21]
Quote HistoryQuoted:
FIFY. Quote HistoryQuoted:
Quoted:
Subcooling is the |
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Posted: 8/20/2017 10:27:17 AM EDT
[#22]
Quote HistoryQuoted:
No manual j was done just the usual "you need this much tonage per this much sq/ft" I am only 1300sq/ft but can't remember what ton units I have. Will check when it's in front of me. Air handler is in the basement. Ducts are in on the second floor but not on the first because I'm working on the home still, on the first floor at the moment is just a large vent installed right into the plenum. Moves some serious air. Can't imagine there's a restriction. Will get some more info shortly. Delta was only 10 degrees. Does superheat mean anything with a TXV? 
Seriously speaking your answer is in bold. By having the ductwork open you are not creating any static pressure therefore your CFM can be 2000 instead of 800 required for a 2 ton unit. Do you know what the minimum and maximum output of your air handler are? You should blank off the outlet to the first floor by at least 50% to see if it will improve. do you have at least a 16"x16" unobstructed return air duct? Does the system have heat and if so what type? Oil, Gas, Electric? I may be able to help you figure out how much CFM you have. |
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Posted: 8/20/2017 10:41:37 AM EDT
[#23]
Quote HistoryQuoted:
Hopefully this all makes sense tried to get this info before wife rushed me out the door. Ambient 75 Liquid PSI 255 Sat 85 Line temp 75 Gas / suction PSI 111 Sat 36 Line temp 74 (if maters TXV) Air after evap coil 65 deg Air at return 77 deg Bottom of evap temp probe on line after TXV 42 deg Top of evap (where TXV probe is) 73 Temp at thermostat 73 Spec on outside unit say 259-274psi 9-10 subcooling (depending on wet bulb) for 75 degree ambient With a 57 degree indoor wetbulb and the conditions in red you should have 25F subcooling for the unit to be properly charged. With a 60 degree indoor wetbulb and the conditions in red you should have 23.5F subcooling for the unit to be properly charged. With a 63 degree indoor wetbulb and the conditions in red you should have 22F subcooling for the unit to be properly charged. With a 66 degree indoor wetbulb and the conditions in red you should have 20.5F subcooling for the unit to be properly charged. |
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Posted: 8/20/2017 10:48:36 AM EDT
[#24]
Quote HistoryQuoted:
So you have a half completed half assed installation without a manual J and are wondering why it doesn't work?
Seriously speaking your answer is in bold. By having the ductwork open you are not creating any static pressure therefore your CFM can be 2000 instead of 800 required for a 2 ton unit. Do you know what the minimum and maximum output of your air handler are? You should blank off the outlet to the first floor by at least 50% to see if it will improve. do you have at least a 16"x16" unobstructed return air duct? Does the system have heat and if so what type? Oil, Gas, Electric? I may be able to help you figure out how much CFM you have. Gas. I did see some CFM ratings somewhere. I will check. |
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Posted: 8/20/2017 10:49:33 AM EDT
[#25]
Quote HistoryQuoted:
With the assumption of a 2 ton unit with a tx valve pushing 800CFM With a 57 degree indoor wetbulb and the conditions in red you should have 25F subcooling for the unit to be properly charged. With a 60 degree indoor wetbulb and the conditions in red you should have 23.5F subcooling for the unit to be properly charged. With a 63 degree indoor wetbulb and the conditions in red you should have 22F subcooling for the unit to be properly charged. With a 66 degree indoor wetbulb and the conditions in red you should have 20.5F subcooling for the unit to be properly charged. |
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Posted: 8/20/2017 10:55:08 AM EDT
[#26]
From your superheat number you have a restriction. Superheat really should not be over about 22 degrees unless you have a fixed metering device and you have a large load, like house is 95 degrees and unit is just started after repair.
Either you have trash plugging the screen in the liquid line or your TXV is not functioning. Remember SC and SH are like gas gauges. High SC means refrigerant backing up in the condenser, high SH means not enough refrigerant coming through the the cooling coil and back to the condenser. It sounds like you have it charged to correct SC but you are being fooled because it is not feeding and refrigerant is backing up in the condenser making it look like normal subcooling. The 38 degrees superheat is telling you are not flowing correctly. A second possibility is that you have a restriction in the condenser, the refrigerant is being metered before it leaves the condenser resulting in the normal looking SC reading. A restriction in the condenser is pretty rare but it is a possibility. Either way I bet you have a restriction and are under charged due to the restriction. If you have a vacuum pump first recover refrigerant and vacuum the system and weigh in the charge according to condenser data plate. Most systems have enough charge for 25' of lines and the coil. If you weigh in the charge and end up with high subcooling and high superheat that confirms restriction external to condenser. If the subcooling /superheat look similar to what you have now you probably have a restriction in the condenser. Remember a pressure drop will equal temperature drop, look for sweat or icing in the condenser coil/liquid line. If you have access to infrared thermometer you might be able to find a cool spot on the condenser coil. Odds are your TXV is malfunctioning. Make sure the equalizer line on your txv has a valve core depressor or the valve core is removed on your equalizer port on the suction line. |
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Posted: 8/20/2017 10:56:54 AM EDT
[#27]
Quote HistoryQuoted:
With the assumption of a 2 ton unit with a tx valve pushing 800CFM With a 57 degree indoor wetbulb and the conditions in red you should have 25F subcooling for the unit to be properly charged. With a 60 degree indoor wetbulb and the conditions in red you should have 23.5F subcooling for the unit to be properly charged. With a 63 degree indoor wetbulb and the conditions in red you should have 22F subcooling for the unit to be properly charged. With a 66 degree indoor wetbulb and the conditions in red you should have 20.5F subcooling for the unit to be properly charged. |
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Posted: 8/20/2017 10:58:45 AM EDT
[#28]
Use this to find your actual subcooling. My gauges do it in real time.
Oops. Wrong image. http://www.hvactechsupport.com/ac-pressure-chart.asp  Attached File |
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Posted: 8/20/2017 11:12:57 AM EDT
[#29]
Quote HistoryQuoted:
Will try. Gas. I did see some CFM ratings somewhere. I will check. What you wan to find is efficiency, BTU input, BTU output. Can we start out by making the assumption that the gas installer properly adjusted the burner or did you DIY the furnace also? Subcooling is not a fixed value. it is dependent on 2 factors ambient temp and load (wet bulb). Here are a couple of examples. Outdoor Drybulb, Indoor Wetbulb, Subcooling 115, 73, 2 115, 70, 5 115, 67, 8 115, 64, 11 115, 61, 13 115, 59, 14 115, 57, 15 105, 73, 6 105, 70, 9 105, 67, 12 105, 64, 15 105, 61, 17 105, 59, 18 105, 57, 19 95, 73, 10 95, 70, 12.5 95, 67, 15 95, 64, 17.5 95, 61, 19 95, 59, 20 95, 57, 21 85, 73, 14 85, 70, 16.5 85, 67, 18 85, 64, 19.5 85, 61, 21 85, 59, 22 85, 57, 23 75, 73, 17 75, 70, 18.5 75, 67, 20 75, 64, 21.5 75, 61, 23 75, 59, 24 75, 57, 25 |
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Posted: 8/20/2017 11:18:08 AM EDT
[#30]
Quote HistoryQuoted:
From your superheat number you have a restriction. Superheat really should not be over about 22 degrees unless you have a fixed metering device and you have a large load, like house is 95 degrees and unit is just started after repair. Either you have trash plugging the screen in the liquid line or your TXV is not functioning. Remember SC and SH are like gas gauges. High SC means refrigerant backing up in the condenser, high SH means not enough refrigerant coming through the the cooling coil and back to the condenser. It sounds like you have it charged to correct SC but you are being fooled because it is not feeding and refrigerant is backing up in the condenser making it look like normal subcooling. The 38 degrees superheat is telling you are not flowing correctly. A second possibility is that you have a restriction in the condenser, the refrigerant is being metered before it leaves the condenser resulting in the normal looking SC reading. A restriction in the condenser is pretty rare but it is a possibility. Either way I bet you have a restriction and are under charged due to the restriction. If you have a vacuum pump first recover refrigerant and vacuum the system and weigh in the charge according to condenser data plate. Most systems have enough charge for 25' of lines and the coil. If you weigh in the charge and end up with high subcooling and high superheat that confirms restriction external to condenser. If the subcooling /superheat look similar to what you have now you probably have a restriction in the condenser. Remember a pressure drop will equal temperature drop, look for sweat or icing in the condenser coil/liquid line. If you have access to infrared thermometer you might be able to find a cool spot on the condenser coil. Odds are your TXV is malfunctioning. Make sure the equalizer line on your txv has a valve core depressor or the valve core is removed on your equalizer port on the suction line. You are making an assumption that his airflow is correct. His subcooling is low and superheat is high because his airflow is most likely more than double the spec due to the wide open duct on the first floor. The first thing that must be established is proper airflow. Without accurate and proper airflow all the advice in the world will not get this system running properly. Once he posts the nameplate from the furnace we will be able to do a temp rise test to determine cfm. |
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Posted: 8/20/2017 11:22:38 AM EDT
[#31]
Quote HistoryQuoted:
The manufacturers desired subcooling is always right on the rating tag. Post a pic. It will be right there. It's typically 8-15* depending on the make model seer and size. It always says on the tag. Anything more is a waste of gas as I have learned it. I`m a mechanical contractor with 30 years experience. His first problem is excess airflow due to open ductwork. if he has 12 or 14 degrees of subcooling in 75F weather with a 57F drybulb he will have 0 subcooling inn 95F weather with a 70F wetbulb. An app such as HVAC Buddy is very useful. |
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Posted: 8/20/2017 11:50:34 AM EDT
[#32]
Here are the charging calculations for his conditions with various wet bulbs.
He goes from undercharged to severely undercharged   
  
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Posted: 8/20/2017 12:03:02 PM EDT
[#33]
Quote HistoryQuoted:
Subcooling rating on condenser is at maximum conditions. I`m a mechanical contractor with 30 years experience. His first problem is excess airflow due to open ductwork. if he has 12 or 14 degrees of subcooling in 75F weather with a 57F drybulb he will have 0 subcooling inn 95F weather with a 70F wetbulb. An app such as HVAC Buddy is very useful. |
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Posted: 8/20/2017 12:12:13 PM EDT
[#34]
Quote HistoryQuoted:
I have that app! I'll actually open it. Thanks. Return air Wetbulb temperature is the most underutilized variable in determining system operation. |
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Posted: 8/20/2017 12:25:13 PM EDT
[#35]
Haven't made it back home yet. The system always has moved a lot of air. Sounds like it may be the problem.
Also seems like I do need to measure wet bulb. Any tooling recommendation for that? |
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Posted: 8/20/2017 12:31:06 PM EDT
[#36]
Quote HistoryQuoted:
Haven't made it back home yet. The system always has moved a lot of air. Sounds like it may be the problem. Also seems like I do need to measure wet bulb. Any tooling recommendation for that? You can actually make your own wet bulb thermometer using a cheap digital thermometer and a piece of cotton shoe lace. Cut a piece of cotton shoe lace and place it on the sensing tip of the thermometer. Wet the shoelace and put the tip in the return air stream. The water evaporating will cool the thermometer providing the wetbulb temperature. 
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Posted: 8/20/2017 1:06:26 PM EDT
[#37]
Quote HistoryQuoted:
Maybe you didn't see where he wrote that his ductwork is incomplete. You are making an assumption that his airflow is correct. His subcooling is low and superheat is high because his airflow is most likely more than double the spec due to the wide open duct on the first floor. The first thing that must be established is proper airflow. Without accurate and proper airflow all the advice in the world will not get this system running properly. Once he posts the nameplate from the furnace we will be able to do a temp rise test to determine cfm. Is there a properly sized return to it? The air out can only be equal to the air in to the blower regardless of where that air comes from. Supply air leaks outside of the conditioned space result in negative pressure of the space, return air leaks outside of the conditioned space result in positive pressure of the conditioned space. |
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Posted: 8/20/2017 2:42:20 PM EDT
[#38]
Quoted:
A year ago I personally installed an A-Coil, outside unit, and lineset. I had a certified tech braze the lines in and do a start up. Line set is aprox 24ft long. Tech did not add any 410a. System works like crap runs all the time to maintain 74 deg. Fast forward to this year. I start educating myself. Outside unit only has enough 410 for 15ft of lineset so system is most likely low. I try to get same tech but never can get him to come back out. Get new tech. He replaces leaking schrader valve and adds some 410. Still runs like crap if not worse. Now I really get educated. Buy my own tools. Do stupid EPA crap. Acquire 410. Charge is really low. I bring the system up to spec as far as I can tell. Charge by subcooling (has txv). Chart says 83 ambient temperature aprox. 299psi with 12 deg sub-cooling. I get it dialed in about perfectly. Charged with bottle upside down on liquid line throttling the valve slowly to restrict refrigerant from liquid to gas. I do not have a means to check indoor wet bulb yet but chart shows very little variation in values based on wet bulb. Is this a bad assumption? As for my problem. It does cool better but I don't think it's still up to snuff. Temp split from return to first outlet is only 10 degrees. Should this not be 18-20 degrees? Filter is clean. A Coil is clear. Coil is only cold half way up. If I temp probe the coil from top to bottom there is over a 20 degree split. Reading on this I'm understanding it should not range more then 10 degrees. I'm concerned it's still undercharged slightly or the txv is not working correctly. Also concerned the original tech did not bring the microns down low enough. Also did not braze with nitrogen in the line. Any ideas? I plan on checking the charge again tomorrow with it having plenty of time to balance out. Thanks ahead of time. I enjoy reading posts by folks who are highly motivated... GOOD WORK OP! You will figure this out. 
You can do your own brazing, get a Turbo Torch on eBay and a Presto lite [acetylene] cylinder, spend a bit extra to get high % silver alloy filler stick or wire. Won't cost much. Or bite the bullet and get a basic oxy-acetelene setup, the major cost are the tanks, but that is possible to be worked around. Get a vac pump from Harbor-F... You will be set for refrig work for life and this experience makes you more 'powerful' eBay will have most anything you need, new and used, at great $. Don't let the folks spewing 'you're on my' TURF NONSENSE ---distract you. Or make solving your issue overly complicated. |
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Posted: 8/20/2017 4:32:08 PM EDT
[#39]
Coil is model MC35B3XH1H
Handler/Furnace model G8T10016UHB11A Outside unit model TCGF24S41S3A From what I can tell the evaporator is rated at 1200cfm I'm having a hell of a time trying to figure out what the handler is rated. This tech sheet does list cfm ratings but not sure which it is. http://www.upgnet.com/Site/InformationCenter/Luxaire/Documents/Archive_CDs/0500/PUB/65074/OUT/TG5L.pdf TXV is S1-1tvm4f1 |
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Posted: 8/20/2017 5:20:38 PM EDT
[#40]
Just add frezone until line is beer can cold.
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Posted: 8/20/2017 5:48:58 PM EDT
[#41]
For temp/humidity/wet bulb stuff, I recommend this -
 
I think I paid $60 a couple of years ago, and it's still working great! And if you really want to get a great manifold, I have this one - 
I LOVE this thing!!! Reads subcooling/superheat directly! I can be inside measuring wet bulb and air flow and get SC/SH/pressures on my phone via bluetooth! Buy the Yellow Jacket hoses with the valves, they're worth it! I paid over $300 a few years ago, now it's cheaper! |
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Posted: 8/20/2017 5:53:05 PM EDT
[#42]
Quote HistoryQuoted:
For temp/humidity/wet bulb stuff, I recommend this - www.amazon.com/dp/B00HJ12YU2I think I paid $60 a couple of years ago, and it's still working great! And if you really want to get a great manifold, I have this one - www.amazon.com/dp/B00W94NETOI LOVE this thing!!! Reads subcooling/superheat directly! I can be inside measuring wet bulb and air flow and get SC/SH/pressures on my phone via bluetooth! Buy the Yellow Jacket hoses with the valves, they're worth it! I paid over $300 a few years ago, now it's cheaper! |
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Posted: 8/20/2017 7:51:44 PM EDT
[#43]
what fan speed do you have set?
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Posted: 8/20/2017 8:12:25 PM EDT
[#44]
looks like that air handler can push up to 2000 cfm. you have a 3 ton coil and a 2 ton condenser which only needs 800 cfm
you have too much cfm to get a delta t. you can't transfer enough heat into the coil at that cfm. 4 tons of air cfm on a 2 ton CU |
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Posted: 8/20/2017 8:27:58 PM EDT
[#45]
OP. You are getting some tier 1 advice. Listen to them.
Forget the Super Heat and focus on airflow. If you want to work it backwards, remove all existing refrigerant. Evacuate unit 500 microns and it HOLDS there. Weigh in the factory recommended charge plus 1 pound. Let run for 20 and then throttle/restrict your temporary duct until you have 10 Degrees of Sub Cooling. Go have a beer and forget it. |
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Posted: 8/20/2017 9:36:53 PM EDT
[#46]
Quote HistoryQuoted:
looks like that air handler can push up to 2000 cfm. you have a 3 ton coil and a 2 ton condenser which only needs 800 cfm you have too much cfm to get a delta t. you can't transfer enough heat into the coil at that cfm. 4 tons of air cfm on a 2 ton CU 0 for 3 on "professionals". I wouldn't even be trying to figure this shit out if these guys would of done what they were paid for. Is there a tool that will measure what cfm the handler is pushing? |
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Posted: 8/21/2017 11:56:52 AM EDT
[#47]
If you're looking for a Youtube channel about HVAC and refrigeration, I like this guy -
https://www.youtube.com/channel/UCrfnfhxVZbB0lLAJr7F80zQ And if you need a portable torch set, check out this Victor set - 
That includes tanks. $315 is Harbor Freight Chinese junk prices for first name American equipment. Free shipping with Prime! |
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Posted: 8/21/2017 12:28:48 PM EDT
[#48]
Quote HistoryQuoted:
How did you figure out the tonnage of the coil. If it really is a 3 ton unit I'm going to be pissed. Supposed professionals supplied the equipment knowing what existing handler I had. I relied on these people. 0 for 3 on "professionals". I wouldn't even be trying to figure this shit out if these guys would of done what they were paid for. Is there a tool that will measure what cfm the handler is pushing? Quote HistoryQuoted:
Quoted:
looks like that air handler can push up to 2000 cfm. you have a 3 ton coil and a 2 ton condenser which only needs 800 cfm you have too much cfm to get a delta t. you can't transfer enough heat into the coil at that cfm. 4 tons of air cfm on a 2 ton CU 0 for 3 on "professionals". I wouldn't even be trying to figure this shit out if these guys would of done what they were paid for. Is there a tool that will measure what cfm the handler is pushing? 35 equals 35,000 btu/hr Handler/Furnace model G8T10016UHB11A 100 equals 100,000 btu hr the 16 part is 1600 cfm @.5 inches of static with no duct work the furnace pushes 2200 cfm Outside unit model TCGF24S41S3A the 24 is 24,000 btu\hr when you move too much air past the coil you lose the ability for the heat to transfer into the coil |
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Posted: 8/21/2017 12:33:02 PM EDT
[#49]
Quote HistoryQuoted:
How did you figure out the tonnage of the coil. If it really is a 3 ton unit I'm going to be pissed. Supposed professionals supplied the equipment knowing what existing handler I had. I relied on these people. 0 for 3 on "professionals". I wouldn't even be trying to figure this shit out if these guys would of done what they were paid for. Is there a tool that will measure what cfm the handler is pushing? Yes you could measure cfm. Just use your magnehelic gauge and pitot tube, and remember your equivalent diameter formulas for round and rectangular ducts. Make sure you're at least 8 diameters downstream of any bends. Don't forget to correct for density. You are getting in the weeds. OP |
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Posted: 8/21/2017 1:23:43 PM EDT
[#50]
the 3 ton coil is not the problem, it's the 1600 cfm through it. we put 2 ton variable drive condensers on 3 ton variable drive air handlers all the time to get 22 seer but the air handler is running at 780 cfm
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