Please help me help my tech

[MEENag]

First, a timeline:
April 30, 2009: Tech replaces evap. coil because pan has rusted through
June 14, 2009: A/C stops cooling altogether
June 15, 2009: Tech finds it frozen up and 6 lbs (out of ~8 lbs) low on refrigerant. Replaces refrigerant. Can't find a leak
June 16, 2009: Tech comes back because of inadequate cooling. Finds obstruction in filter drier and replaces it, and cleans condenser unit.
June 19, 2009: Tech comes back because of inadequate cooling. No problems found. Adds some refrigerant, but says it didn't really need it.

The A/C hasn't been working correctly since it initially froze up, though it is blowing cold air. It functions fine from about midnight to 10AM and has a return/supply differential of 20 deg F (78-58). Starting at around 10AM it struggles to maintain 80 deg F and the house slowly heats up to 85-87 deg F, peaking in the late afternoon. The return/supply differential shrinks to ~13-14 deg F. It takes until midnight to cool back down to 80. It runs constantly from 10ish until midnight.

It is an older system (16 years) and has been trouble free until the leaking pan issue. I would've had the whole thing replaced, but I am moving within a year and it had been performing wonderfully besides the leak.

The tech is coming back tomorrow to take a look again and I want to be able to ask intelligent questions when he does. Ignoring the potential of having a leak, what could cause this type of performance issue?

My guesses so far:

1) Compressor problems (he said he checked it and it showed signs of age, but it was functioning OK.)
2) Large cold air leak in attic (I looked and didn't find anything).
3) Blower problem
4) Expansion valve problem
5) Improper charging procedure
6) Improperly sized replacement evap. coil
7) ??

Do all of these make sense for the issues I am having? Can you add any more?

I appreciate any help I get.
Thanks,
Jeff

[the dangling wrangler]

Time to call in the pros. This guy is guessing at things.

[Gunnery Sergeant Hartman]

I would've had the whole thing replaced, but I am moving within a year and it had been performing wonderfully besides the leak.

So you're going to leave the new owner with a cobbed up mess...

Nice guy.

[tinknocker service tech]

from the ammout of times refrigerant is added sounds like a leak somewhere and needs to be fixed.

if the system was evacuated and charged properly then it should not never need refrigerant added again unless it has a leak

[the dangling wrangler]

I would've had the whole thing replaced, but I am moving within a year and it had been performing wonderfully besides the leak.

So you're going to leave the new owner with a cobbed up mess...

Nice guy.

That was my first thought too. :)

[francosair]

BINGO! I found your problem..............your tech.

[Pascone10]

easy!! Purchase a new HVAC system (not from this Co.), the new owner will appreciate this! (it deff wont hurt selling your home)

2. Get a new tech!

Those are your options.

You cant be guessing like your tech... Where did you come up with that list anyway?

[hvaclover]

I would've had the whole thing replaced, but I am moving within a year and it had been performing wonderfully besides the leak.

So you're going to leave the new owner with a cobbed up mess...

Nice guy.

ROTFLMAO!!!!!!!!!!!!:D:D:D:D:D

[udarrell]

First, a timeline:
April 30, 2009: Tech replaces evap. coil because pan has rusted through
June 14, 2009: A/C stops cooling altogether
June 15, 2009: Tech finds it frozen up and 6 lbs (out of ~8 lbs) low on refrigerant. Replaces refrigerant. Can't find a leak
June 16, 2009: Tech comes back because of inadequate cooling. Finds obstruction in filter drier and replaces it, and cleans condenser unit.
June 19, 2009: Tech comes back because of inadequate cooling. No problems found. Adds some refrigerant, but says it didn't really need it.

The A/C hasn't been working correctly since it initially froze up, though it is blowing cold air. It functions fine from about midnight to 10AM and has a return/supply differential of 20 deg F (78-58). Starting at around 10AM it struggles to maintain 80 deg F and the house slowly heats up to 85-87 deg F, peaking in the late afternoon. The return/supply differential shrinks to ~13-14 deg F. It takes until midnight to cool back down to 80. It runs constantly from 10ish until midnight.

It is an older system (16 years) and has been trouble free until the leaking pan issue. I would've had the whole thing replaced, but I am moving within a year and it had been performing wonderfully besides the leak.

The tech is coming back tomorrow to take a look again and I want to be able to ask intelligent questions when he does. Ignoring the potential of having a leak, what could cause this type of performance issue?

My guesses so far:

1) Compressor problems (he said he checked it and it showed signs of age, but it was functioning OK.)
2) Large cold air leak in attic (I looked and didn't find anything).
3) Blower problem
4) Expansion valve problem
5) Improper charging procedure
6) Improperly sized replacement evap. coil
7) ??

Do all of these make sense for the issues I am having? Can you add any more?

I appreciate any help I get.
Thanks,
Jeff
Perhaps, none of the above...

It sounds like the Return Air is drawing hot air from the attic or garage areas.

When those areas are not so hot it cools better & has close to a normal indoor SA/RA temp-split.

When those areas get hot, bingo it no longer can handle that extra hot-air heatload.

First, check the Condensing Temperature (CT) verses the outdoor Ambient (OAT). The CT spread will increase during the hot part of the afternoon & into the evening.

First, check for temp changes at Return Registers, then just before air enters the blower. Much temp increase during those hot periods? Depends on how the Return Air is ducted as to where you're most likely to find those air leaks. If chamber under the furnace, air could be coming down unsealed walls into the chamber.

Correct any Return Air problems. -Darrell

[MEENag]

I would've had the whole thing replaced, but I am moving within a year and it had been performing wonderfully besides the leak.

So you're going to leave the new owner with a cobbed up mess...

Nice guy.

When I said "besides the leak", I meant the rusted evaporator coil pan that I had replaced, not the potential refrigerant leak that hadn't happened yet.

When I decided to replace just the evaporator coil because of the rusted pan and not get a whole new system, my thinking was that my system had performed without flaw for 16 years and that it might well last another 4-5+ years. It wasn't about the money, well partially, but it was more about not wanting to trash a perfectly good system. Whoever buys the house will know the age of the system and will take that into account when making an offer and I won't have a problem making concessions for it. Thanks for making a judgement on my character though.

Pascone10,
Where did I come up with that list? I made it up and came here and asked if any of them made sense and if anyone had other ideas. Clearly I'm no HVAC pro. :)

Please shoot down any of my guesses that don't make sense.


If I thought this process would've been any more than a quick evap. coil swap, then I would've had the system replaced.


The tech is a nice guy and was recommended by several people. He charged me a small amount for his first visit after the evaporator coil replacement and didn't charge anything for the next two visits. He's the owner of a two truck independent business and has probably lost money because of accepting my job. I figure I'll give him another chance tomorrow and then call in someone else if he can't figure it out.

Darrell,
Excellent suggestion. That's the kind of information I was looking for. Thanks.

[Twilly]

Twilli says HVAC guys are hard on H/O's. Cause some of them used to be H/O's themselves

[udarrell]

It appears everyone is avoiding a response to my post explaining why all the symptomatic experience data points to hot air sources entering the Return Air.

Because of when the indoor split is reduced, e.g., when the attic or garage would be hot, it is an easy diagnosis. The indoor temp-split is mainly dependent on indoor Return Air temp & humidity levels.

Additionally what is the humidity levels in your attic or garage.

I have seen & solved this problem many times during my many decades as a Tech & Contractor. Smaller Return Air leaks are usually overlooked leading to costly inefficient performance.

It is possible you might learn a little HVAC by going to my Internet pages, for this month of June alone hits appear to be going over 80,000, & the HVAC pages lead all other pages by a wide margin for number of hits.

Do you want to solve the problem or just talk about it?
If you don't want to respond to my analysis, perhaps I should quit trying to help anyone solve their air conditioning problems.

Why should I spend any time & effort in an attempt to help anyone solve their problem on this forum, when I'm ignored & when there is no feed-back?

I guess I'm a spoiled child, I want a two-way communication, or it's so-long it's been good to know you.

You might spend a fortune on new ultra high efficiency equipment & end up with hot-air, pardon the pun.:D - Darrell

[zrox]

Loss of refrigerant and the tech found no leak :confused:


BINGO! I found your problem..............your tech.

Maybe the tech has a leak :rolleyes:

[MEENag]

Darrell,
I responded to your suggestion at the bottom of my previous post. Again, thank you for the input. That is exactly what I was looking for. Since I wasn't able to get to a computer until after midnight last night and I am at work now, I haven't been able to spend much time looking to see if that was my problem. I did go up in the attic after 1 AM last night to look for any obvious return air problems, but I didn't see any. I need to take a better look tonight.


Last week, it was very hot here (100+, Fort Worth) and the humidity was low. Yesterday, the high was around ninety (and it was overcast) and the system seemed to perform much better. That tells me that the problem has probably been occurring since the evaporator coil was replaced and that I just didn't notice it in the relatively mild May/early June that we had here.

The tech isn't coming until Wednesday (at my request), but I talked to him this morning and he said he has consulted with other techs about my issues and the only thing that they came up with was that it is probably a compressor problem.

[the dangling wrangler]

First, a timeline:
April 30, 2009: Tech replaces evap. coil because pan has rusted through
June 14, 2009: A/C stops cooling altogether
June 15, 2009: Tech finds it frozen up and 6 lbs (out of ~8 lbs) low on refrigerant. Replaces refrigerant. Can't find a leak
June 16, 2009: Tech comes back because of inadequate cooling. Finds obstruction in filter drier and replaces it, and cleans condenser unit.
June 19, 2009: Tech comes back because of inadequate cooling. No problems found. Adds some refrigerant, but says it didn't really need it.



Maybe it's just me but, what's up with the June 19th visit?

It either needed gas, or it didn't. Can't be both.

[zrox]

First, a timeline:
April 30, 2009: Tech replaces evap. coil because pan has rusted through
June 14, 2009: A/C stops cooling altogether
June 15, 2009: Tech finds it frozen up and 6 lbs (out of ~8 lbs) low on refrigerant. Replaces refrigerant. Can't find a leak
June 16, 2009: Tech comes back because of inadequate cooling. Finds obstruction in filter drier and replaces it, and cleans condenser unit.
June 19, 2009: Tech comes back because of inadequate cooling. No problems found. Adds some refrigerant, but says it didn't really need it.



Maybe it's just me but, what's up with the June 19th visit?

It either needed gas, or it didn't. Can't be both.

Maybe it was a "if all else fails, add refrigerant" moment :rolleyes:

The tech probably could'nt find the problem and decided to "wing" it!

[the dangling wrangler]

Maybe it was a "if all else fails, add refrigerant" moment :rolleyes:

The tech probably could'nt find the problem and decided to "wing" it!

It's really a shame, this unit has been opened as many times as it has been lately.
It appeared to be a good, tight, sixteen year old system, before the coil change out anyway.

Not trying to beat the tech up, stuff happens, I guess.

[MEENag]

In all fairness to the tech, my wife was the one that was home for the June 19th visit so she told me what he told her. Something could've been left out or lost in translation.
Also, his other crew did the evaporator coil swap, so the initial problems might've been with their work, but he should still be able to figure out the problem.

Since it seems very likely that he is going to diagnose it as a compressor problem after he can't find anything else when he comes back, does it makes sense that the compressor could be causing the issues that I have (seems to work fine until it gets really hot outside/in attic)?

[the dangling wrangler]

If it's still freezing up, I'd think the compressor was working.
Not seeing the "big picture" here, it's kinda hard to say exactly what the problem(s) are.

[marvin]

i have to side with darrell on the r a leak BUT if the coil was iNSTALLED PROPERLY & LEAK CHECKED the refg. drum should have never come out of the truck. we can all make a swag about what the problem may be but
with out the proper info. it is all just a guess.
have a youngster here in almost the same situation you are describing.
today he has one of my nextel ph. & a start up sheet i have used for years
tf he doesnt get in a hurry & can follow directions this problem will be solved today. one interesting aspect will be the temp. @ the filter grille & at the
air handler. dont even mention static to this guy. he thinks it is what you
get when your radio is between stations.
lots of luck but you may have to find another mech. for your repair.

[udarrell]

In all fairness to the tech, my wife was the one that was home for the June 19th visit so she told me what he told her. Something could've been left out or lost in translation.
Also, his other crew did the evaporator coil swap, so the initial problems might've been with their work, but he should still be able to figure out the problem.

Since it seems very likely that he is going to diagnose it as a compressor problem after he can't find anything else when he comes back, does it makes sense that the compressor could be causing the issues that I have (seems to work fine until it gets really hot outside/in attic)?
If the refrigerant system were grossly overcharged that could reduce capacity enough to reduce performance under those heavier load conditions.
http://www.udarrell.com/airconditioning-excessive-airflow.html

However, you don't ever want a compressor condemned when something else is causing the problem. They have a lot of compressors returned as being bad, they're tested & they were good compressors.

If it is kicking more heat off the condenser than it should be for the indoor temp & humidity, then the compressor should be okay.

The nominal condenser temp-split corresponds with its SEER Rating. What SEER is it rated at?

No gauges required, to check if your A/C is near specs! However, the temperature & indoor humidity make a big differenence in the (CTS) condenser-temp-split. Not right, Call for a Service Tech!

ARI Conditions are: 95ºF-OAT; 80ºF-IDB; 67ºF-IWB or 50%RH with -> (Airflow & proper load on evaporator!)
You can also look up the high-side condenser pressure/temp at specific ARI or ACCA (TVA) conditions.

TVA conditions are: 75-f IDB, 63-IWB, or close to 50% RH |95-f OAT with indoor airflow rates & data at three blower CFM's 350, 400 & 450-CFM per-ton of cooling.

Take the both the indoor Supply Air & Return Air DB, WB or %RH, too! If you have an accurate airflow CFM, we can Ballpark the BTUH your A/C or Heat Pump is delivering in the cooling mode.

12-SEER - Hold the thermometer & don't drop it into the fan blades!
1.5-Ton 18,000 18ºF T.Split Cond.CFM 1400 @ 50% RH, 600-CFM; 85ºF OAT
2-Ton 24,800 23-F T.-Split Cond. CFM 1400 WATTS 2659 (All below ARI Conditions)
2.5-T 30,200 20-F Temp-S Cond. CFM 2000 WATTS 3404
3-Ton 35,600 17-F Temp-S Cond. CFM 2800 WATTS 4107
3.5 T 42,500 19-F Temp-S Cond. CFM 2800 WATTS 4554
4-Ton 48,500 18.5-F Temp-S Cond. CFM 3400 WATTS 4761
5-Ton 59,000 23-F Temp-S Cond. CFM 3400 WATTS 6969

The new Goodman 13-SEER 1.5-Ton Condenser, 2-Ton Evaporator:
At 675-cfm 450-per/ton cooling | 85-F OAT | 63-IWB or 52% RH | 20-F Indoor Door Temp-split | 18,600-Btuh |R-22|201-psig 100-F = Your CT temp will be a 15-F condenser-temp (CT) split - smaller capacity compressor to larger coil areas | 80-psig suction | - Darrell

[man from trane]

It appears everyone is avoiding a response to my post explaining why all the symptomatic experience data points to hot air sources entering the Return Air.

Because of when the indoor split is reduced, e.g., when the attic or garage would be hot, it is an easy diagnosis. The indoor temp-split is mainly dependent on indoor Return Air temp & humidity levels.

Additionally what is the humidity levels in your attic or garage.

I have seen & solved this problem many times during my many decades as a Tech & Contractor. Smaller Return Air leaks are usually overlooked leading to costly inefficient performance.

It is possible you might learn a little HVAC by going to my Internet pages, for this month of June alone hits appear to be going over 80,000, & the HVAC pages lead all other pages by a wide margin for number of hits.

Do you want to solve the problem or just talk about it?
If you don't want to respond to my analysis, perhaps I should quit trying to help anyone solve their air conditioning problems.

Why should I spend any time & effort in an attempt to help anyone solve their problem on this forum, when I'm ignored & when there is no feed-back?

I guess I'm a spoiled child, I want a two-way communication, or it's so-long it's been good to know you.

You might spend a fortune on new ultra high efficiency equipment & end up with hot-air, pardon the pun.:D - Darrell

^ I'll back you up. This was the conclusion I came to as well, given the small amount of info.

[man from trane]

Darrell,
I responded to your suggestion at the bottom of my previous post. Again, thank you for the input. That is exactly what I was looking for. Since I wasn't able to get to a computer until after midnight last night and I am at work now, I haven't been able to spend much time looking to see if that was my problem. I did go up in the attic after 1 AM last night to look for any obvious return air problems, but I didn't see any. I need to take a better look tonight.


Last week, it was very hot here (100+, Fort Worth) and the humidity was low. Yesterday, the high was around ninety (and it was overcast) and the system seemed to perform much better. That tells me that the problem has probably been occurring since the evaporator coil was replaced and that I just didn't notice it in the relatively mild May/early June that we had here.

The tech isn't coming until Wednesday (at my request), but I talked to him this morning and he said he has consulted with other techs about my issues and the only thing that they came up with was that it is probably a compressor problem.

Overcast = cooler attic space. Still looking like return ducts. You're checking the returns, right?

[MEENag]

Thanks again for your input, it is much appreciated. It's going to take me a little while to digest most of your post. Lots of acronyms, but I've got some of them figured out.
I think my unit is 3 ton, 13 SEER, but I am not at all certain.


I still like the return air theory. I'll do a more thorough check tonight. Last night, I just looked at where the two, rather large, ducts terminate into the end of the unit opposite of the evap. coil/plenum(it's suspended horizontally in the attic). I don't know what all of the terminology is, but I have the flexible insulated ducts. One of the two return ducts had the insulation pulled away from where it terminates into the return plenum (if that's what it's called) and I could see the clips around the circumference. I couldn't see any gaps at the clips, so I figured it was ok. I wouldn't think the tech replacing the evap. coil would've done anything at the return air end of the unit.

Thanks again, everyone, for all of your input

[heaterman]

First, a timeline:
April 30, 2009: Tech replaces evap. coil because pan has rusted through
June 14, 2009: A/C stops cooling altogether
June 15, 2009: Tech finds it frozen up and 6 lbs (out of ~8 lbs) low on refrigerant. Replaces refrigerant. Can't find a leak
June 16, 2009: Tech comes back because of inadequate cooling. Finds obstruction in filter drier and replaces it, and cleans condenser unit.
June 19, 2009: Tech comes back because of inadequate cooling. No problems found. Adds some refrigerant, but says it didn't really need it.

The A/C hasn't been working correctly since it initially froze up, though it is blowing cold air. It functions fine from about midnight to 10AM and has a return/supply differential of 20 deg F (78-58). Starting at around 10AM it struggles to maintain 80 deg F and the house slowly heats up to 85-87 deg F, peaking in the late afternoon. The return/supply differential shrinks to ~13-14 deg F. It takes until midnight to cool back down to 80. It runs constantly from 10ish until midnight.

It is an older system (16 years) and has been trouble free until the leaking pan issue. I would've had the whole thing replaced, but I am moving within a year and it had been performing wonderfully besides the leak.




Well Jeff, my first question would be, how did he match a coil to a system that is 16+ years old? That in itself could account for reduced cooling capacity. Then there seems to be some question as to the actual charge currently contained in your system. The tech is now questioning the condition of your compressor and to be honest, at 16 years old, most of us would. Hind sight is 50 / 50 as you are well aware but it may be time to stop throwing good money after bad and just replace the system. If it was installed in "my" shop or home "I" might have been inclined to jury rig it together. I never would have suggested or have let a customer talk me into replacing a coil in a unit that old. Since the system did function properly prior to the coil change, I would lean toward a problem related to either the mismatching of the coil and condenser, or improper evacuation and charging of the system after the change out or a combination of both. Good luck, but if I was making a recommendation to you as a customer of mine, I would say change out the system.:cool:

[man from trane]

Missing important info- How did it work the first 2 weeks in June before it quit?

[MEENag]

Man from Trane,
It seemed to be working ok in May and the first couple of weeks of June, but the temperatures were pretty mild then, so I might not have noticed any problems. It froze up right as the temperature started to get really hot.

Heaterman,
When the tech first came out to evaluate the evap coil pan leak, he said it was time to think about getting a new system and gave me quotes from 3 different systems and for just replacing the evap. coil. As I mentioned before, It was cooling flawlessly when the evap. coil pan started leaking, so I thought I could get more mileage out of it. I run my cars until they die too. Why replace something that is working fine?

I'm not sure how he sized the replacement evap coil. Just looking at it, the new evap coil box looks 50% bigger than the one it replaced.

[heaterman]

What type of metering devise does the system use?

[the dangling wrangler]

What type of metering devise does the system use?

Are you thinking, x-valve and no start assist installed?

[MEENag]

Heaterman,
I don't know enough about my system to answer your question. If you have a hypothesis, I'd like to hear it if it might be something to bring up to my tech.
Thanks,
Jeff

[heaterman]

Are you thinking, x-valve and no start assist installed?


Either that or higher seer coil with piston orifice installed with a lower seer condenser.

[the dangling wrangler]

Either that or higher seer coil with piston orifice installed with a lower seer condenser.

Who knows? Even the home owner dosen't.(no disrespect)

[heaterman]

Jeff, just print out this thread and show it to your tech. Might give him some new ideas, who knows?

[the dangling wrangler]

From the information so far, I'm assuming this is a horizontal application, in the attic.

If it's a return air leak, it shouldn't be all that hard to track down.
If this is an up flow, the return could be pulling from an open wall cavity,platform not sealed, something like that.
Could be something as simple as a piece of insulation has come loose.

[udarrell]

Man from Trane,
It seemed to be working ok in May and the first couple of weeks of June, but the temperatures were pretty mild then, so I might not have noticed any problems. It froze up right as the temperature started to get really hot.

Heaterman,
When the tech first came out to evaluate the evap coil pan leak, he said it was time to think about getting a new system and gave me quotes from 3 different systems and for just replacing the evap. coil. As I mentioned before, It was cooling flawlessly when the evap. coil pan started leaking, so I thought I could get more mileage out of it. I run my cars until they die too. Why replace something that is working fine?

I'm not sure how he sized the replacement evap coil. Just looking at it, the new evap coil box looks 50% bigger than the one it replaced.
It appears there may have been numerous problems created when the old evaporator was replaced.

Sounds like a seriously mismatched coil.
Perhaps a high SEER higher tonnage coil, in anticipation of soon installing a new system.
The coil may have a piston sized for that tonnage coil, which means it would overfeed big-time when pressures went up.

It would be bad enough, even if it had a TXV metering device.

Even at the same tonnage, those higher SEER coils have a lot more liquid refrigerant capacity compared to the lower SEER condenser; not a particularly good situation with this kind of mismatch.

I don't want to make any negative comments here. - Darrell

[davefr]

It appears there may have been numerous problems created when the old evaporator was replaced.

Sounds like a seriously mismatched coil.
Perhaps a high SEER higher tonnage coil, in anticipation of soon installing a new system.
The coil may have a piston sized for that tonnage coil, which means it would overfeed big-time when pressures went up.

It would be bad enough, even if it had a TXV metering device.

Even at the same tonnage, those higher SEER coils have a lot more liquid refrigerant capacity compared to the lower SEER condenser; not a particularly good situation with this kind of mismatch.

I don't want to make any negative comments here. - Darrell


^^^ +1. If the old system was operating properly and all the problems started when the coil was replaced due to a rusty pan, then that's what I'd focus on as the likely root cause of the problem. (vs. the compressor or air return)

[tinknocker service tech]

just wondering here
6lb refrigerant and did he find the leak
plugged filter dryer and replace it and charge system
add refrigerant even tho could not find a problem

you say it isnt cooling so yes there is a problem and he can find it so add refrigerant why? If it is charged correctly then adding or removing will do nothing but cause a differant problem


i tend to think with the ammount of refrigerant just has been put into this system you compressor is working but for how long

have him find and fix the leak and evacuate and charge the system

also keep in mind you just opened a 16 year old system. This imo can be like playing with fire and getting mad because you got burnt

[Twilly]

It appears everyone is avoiding a response to my post explaining why all the symptomatic experience data points to hot air sources entering the Return Air.

Because of when the indoor split is reduced, e.g., when the attic or garage would be hot, it is an easy diagnosis. The indoor temp-split is mainly dependent on indoor Return Air temp & humidity levels.

Additionally what is the humidity levels in your attic or garage.

I have seen & solved this problem many times during my many decades as a Tech & Contractor. Smaller Return Air leaks are usually overlooked leading to costly inefficient performance.

It is possible you might learn a little HVAC by going to my Internet pages, for this month of June alone hits appear to be going over 80,000, & the HVAC pages lead all other pages by a wide margin for number of hits.

Do you want to solve the problem or just talk about it?
If you don't want to respond to my analysis, perhaps I should quit trying to help anyone solve their air conditioning problems.

Why should I spend any time & effort in an attempt to help anyone solve their problem on this forum, when I'm ignored & when there is no feed-back?

I guess I'm a spoiled child, I want a two-way communication, or it's so-long it's been good to know you.

You might spend a fortune on new ultra high efficiency equipment & end up with hot-air, pardon the pun.:D - Darrell


Twilli loves to read your post and has your web pages book marked, so don't be discouraged that they don't listen, they don't listen to Twilli either.......Colerman

[Twilly]

It appears everyone is avoiding a response to my post explaining why all the symptomatic experience data points to hot air sources entering the Return Air.

Because of when the indoor split is reduced, e.g., when the attic or garage would be hot, it is an easy diagnosis. The indoor temp-split is mainly dependent on indoor Return Air temp & humidity levels.

Additionally what is the humidity levels in your attic or garage.

I have seen & solved this problem many times during my many decades as a Tech & Contractor. Smaller Return Air leaks are usually overlooked leading to costly inefficient performance.

It is possible you might learn a little HVAC by going to my Internet pages, for this month of June alone hits appear to be going over 80,000, & the HVAC pages lead all other pages by a wide margin for number of hits.

Do you want to solve the problem or just talk about it?
If you don't want to respond to my analysis, perhaps I should quit trying to help anyone solve their air conditioning problems.

Why should I spend any time & effort in an attempt to help anyone solve their problem on this forum, when I'm ignored & when there is no feed-back?

I guess I'm a spoiled child, I want a two-way communication, or it's so-long it's been good to know you.

You might spend a fortune on new ultra high efficiency equipment & end up with hot-air, pardon the pun.:D - Darrell



Twilli loves to read your posts and Twilli has your web page book marked and reads it all the time, don't feel bad that they don't listen to you, they don't listen to Twilli either........

Coleman

[HVAC_James]

I love reading this stuff it helps new guys in the industry

[Some Dude]

Valves

[MEENag]

I made another midnight trip into the attic. I looked again at the return air portion of the unit, and everything seemed ok still. There didn't seem to be any air being sucked into the pulled away insulation that I mentioned earlier. I used a very thin sheet of plastic wrap to test to see if attic air was being drawn in at various areas of the return end and didn't find anything.

Here are a few pictures that may or may not be helpful.

First, a look at the whole (almost) unit:
http://home.swbell.net/jspock1/img_0826.jpg

Now for the new evap. coil. I didn't notice until tonight that the new one is not quite as wide as the old one, so there is a gap that had to be filled.
http://home.swbell.net/jspock1/img_0828.jpg

Close up of the tag seen on the left of the previous pic. Has detail of the original cooling section:
http://home.swbell.net/jspock1/img_0831.jpg

Other side of evap coil:
http://home.swbell.net/jspock1/img_0835.jpg

Close up of evap coil label. Sorry it is so blurry. I didn't realize it was that bad until I got back down and uploaded the pics to the computer
http://home.swbell.net/jspock1/img_0837.jpg

The two tags have different pressures specified, but they don't seem to be talking about the same thing (Test pressure vs. Design pressure)

Thanks again for all of your help. It's too late for me to address all of the newer posts, but I've read them and appreciate the info.

[Some Dude]

enough said

[the dangling wrangler]

enough said

:D


Not my coil of choice either.

[udarrell]

My concern is the other end of the Return Air duct that there's no pic of.

Does it exit into the ceiling, & is there any chance whatever that there is a path within the ceiling structure where attic air could be sucked into he Return?

Check the temp going into the Return air grille, then find a way to check in the duct just above the ceiling.

The fact that when the attic gets hot the SA/RA split is greatly reduced tells us that either the Return air is taking on attic heat, or the condenser could be grossly overcharged.

Or, the condenser is way over charged & can't handle the extra exterior & interior heat load.

Check indoor airflow, then Check Subcooling & Superheat. You can use a good mercury TH to check the condenser-temp (CT) discharge air compared to the Outdoor-Ambient-Temp (OAT).

Therefore, you need a low cost (mine is a) MA-Line digital pocket TH use the tubing bend as it goes into the indoor plenum. Use a piece of tubing insulation & you can monitor the Subcooling with temp synchronized THs. With these new digital's always keep & read the instructions, HOLD, RECALL, etc...

I had two - a sensor bulb/dial read I initially bought for low temp work, & a bulb sensor digital read, both designed for taking SH & SC, they are both gone, so a year ago, I bought the low cost substitute & it seems to work.

I may have overlooked it, but I didn't see any pressures listed; always have them leave all the test data they collect!
It could just be badly over charged, view both linked pages.

http://www.udarrell.com/ac-trouble-shooting-superheat-subcooling.html
http://www.udarrell.com/airconditioning-excessive-airflow.html
-Darrell

[troyorr]

Since the replacement coil can be used on 22 or 410, make sure the proper metering device is installed.

[Some Dude]

Looks like a wall of shame to me.

[hvaclover]

FYI that York you have is actually a Consolidated Ind. Furnace.

There was a class action suit brought against them as the heat exchangers and other components would cause fire. You can still look it up on the net.

The Meridian ac coil marries up to the old Consolidated because Texas Furnace assumed all of Consolidated's fabricating machinery and rights to design.



BE VERY CAREFUL WIT THAT FURNACE> THE COURT ORDERED THEM ALL SHUT DOWN AND REPLACED>

[udarrell]

It would also not handle a larger heatload if it were losing refrigerant & the liquid is flashing into the TXV; a TXV that is verified correct for the that refrigerant & tonnage.

Ask them for a record of pressure readings & both Subcooling & Superheat data. - Darrell

[man from trane]

How do you Texans survive in the HVAC industry?! No wonder it doesn't work. :D I'll bet it's 120 degrees in that attic, nowhere to stand, working by flashlight, wow. I wouldn't want to be up there for more than 5 minutes. In the midwest I always had a nice comfy basement to hang out in and contemplate the issue.

I was in an attic for 20 minutes a week ago to fix a duct in an office and it was torture.

[the dangling wrangler]

How do you Texans survive in the HVAC industry?! No wonder it doesn't work. :D I'll bet it's 120 degrees in that attic, nowhere to stand, working by flashlight, wow. I wouldn't want to be up there for more than 5 minutes. In the midwest I always had a nice comfy basement to hang out in and contemplate the issue.

I was in an attic for 20 minutes a week ago to fix a duct in an office and it was torture.

I'll get back to you on that, when I figure it out. :D

Ya just do it,wipe your brow, and go to the next one.

[joey83]

It's good that homeowners want to be informed and educated on their HVAC equipment, but it's not so good that you feel like you have to find out the problem of your unit and pass it on to your tech. If 6 of the 8 pounds of refrigerant was gone, then there is a BIG refrigerant leak. It could be low again. It could have air in the lines. The clogged filter drier is a little bothersome to me.

Here's what I usually tell people that don't want to replace the unit because they're about to move. When you put that house up for sale, the first thing the inspector is going to say is "the HVAC equip. is X years old and past the average life of like equip." The new buyers will get you to pay for the new unit after that so why not get it now and enjoy it for yourself a couple years before you sell? You'll benefit from lower utility bills which will be a nice return on your investment. And in your case, you won't have to worry about the furnace blowing your house up.....

[ticotech cayman]

he changed the coil and few days later he found a obstruction in the dryer, if he service it right the first day that would not ever happend . that seens to me just a bad installation and the tech created the problem.

[udarrell]

It's good that homeowners want to be informed and educated on their HVAC equipment, but it's not so good that you feel like you have to find out the problem of your unit and pass it on to your tech. If 6 of the 8 pounds of refrigerant was gone, then there is a BIG refrigerant leak. It could be low again. It could have air in the lines. The clogged filter drier is a little bothersome to me.

Here's what I usually tell people that don't want to replace the unit because they're about to move. When you put that house up for sale, the first thing the inspector is going to say is "the HVAC equip. is X years old and past the average life of like equip." The new buyers will get you to pay for the new unit after that so why not get it now and enjoy it for yourself a couple years before you sell? You'll benefit from lower utility bills which will be a nice return on your investment. And in your case, you won't have to worry about the furnace blowing your house up.....

I'm in agreement with your statements, including concerning the equipment.
Also, agree with the preceding comments.

When they show the homes on TV they never say boo about the air conditiobning or heating, - I'll never understand that.

After the sale the inspector shows them (many-times) the junk they bought.

A good updated central air ought to be a major selling point. I check the past utility bills of any home of interest to me, or for others I was looking out for.

My all electric home, except for oil heat, - electric bill was only $42.30 for the month of June & we had some real hot humid days when I had it real cool at all times in here. - Darrell

[fenian]

what's the bucket for?
gotta love when a furnace becomes a shelf.

:)

[MEENag]

I talked to my tech a little while ago and I mentioned a few things that y'all have posted. He is coming back this afternoon. I thought it was supposed to be yesterday, but that was an assumption on my part. He had previously checked for a return air leak and didn't find anything.
He said he was going to try one more thing before recommending replacing the outdoor unit. He was going to put in a TXV. He said it currently has a fixed orifice for R22. Thoughts?

Darrell,
I asked about pressure readings and he said he doesn't write them down. He said the superheat was "10". I don't know enough to know what that means.

Fenian,
The bucket was underneath the unit to catch the rusty water dripping off before the evap.coil was replaced. I should probably move it.

hvaclover,
Had I known about the furnace issue, this thread probably wouldn't exist and I'd be enjoying a whole new system. Thanks a lot for pointing it out. The deadline for claims is just a couple of months away.

Ticotech,
It was actually 1.5 months after the replacement that the obstruction was found, but I'm sure it was still related. However, changing the drier didn't have an effect on the performance.

Joey83,
My thoughts about replacing the system prior to selling differ a bit. If I know I'm about to move out of a house, I wouldn't be inclined to spend more for a higher SEER, more efficient system that I won't ever get the benefit of. I would've put in the cheapest of the three RUUD/RHEEM systems that I was quoted before replacing the evap coil, all of which were still better than my current system.
If the age of the system comes up a closing time, I'm ok with giving an allowance up to the cost of that lower level system. If the new owner wants to upgrade, he can make up the difference. I'd prefer that if I were the buyer too.

Thanks again for all of the advice. I'll let you know what happens.

[man from trane]

Superheat = 10. That means that the liquid refrigerant has boiled off and the vapor that is left at the outlet of the evap has gained 10 degrees of heat. You don't want liquid refrigerant going back to the compressor, which would be idicated by a very low superheat, say 2-3 degrees or less. 10 is good, more than 15-20 means the coil is not receiving enough refrigerant.

I don't think a TXV is going to make a huge difference, but it's a good idea. It should help mask the fact that the coil is mismatched. I just can't help but think he's missing something.

I was thinking of this post today while I was working on a similar unit above an office in a warehouse. HOTTTT!!! Return duct was leaking hot air into the system, but the holes were very obvious; I could stick my entire arm inside. I got done pretty fast to get the heck out of there.

[HARD HAT AREA]

install a txv

[joey83]

I'm going to agree with the Trane Man. A TXV is a good idea that maybe should have been done with the coil change out, but isn't going to make the difference he's hoping for. Maybe it's time for a new tech. Is this guy a contractor?

[davegreenlee]

Enough said.

[udarrell]

Simple Way to Ball-Park Operating BTHU
For anyone, - to Ball-Park Operating BTUH, you need the diameter size of each duct & a way to check the velocity from each run. A low cost anemometer to check the velocity in FPM will work. (If you want a more precise BTUH; There are also some great uses for a thermometer & a low cost humidity gage.)

Check & record the temp rise off the outdoor condenser against OD ambient.

Check & record the temp drop of the supply outlets, record indoor relative humidity. Record Dry bulb & Wet bulb of both the Supply Air & Return Air along with CFM airflow & I’ll tell you the BTUH it is delivering.

Let's say you have a 1.5-Ton 18,000-BTUH Rated A/C. All the 5 ducts are 6" dia., & they all average 688-FPM velocity, a bit high. You need the sq.ft. of the duct; 6X6= 36 *X's .7854= 28.2744/ by 144= 0.19635sq.ft. area *X's 688-FPM = 135-CFM *X's 30= 4,050 *X's 5= 20,250-BTUH.

A 1.5-Ton Goodman Data with 2-Ton indoor E-Coil; 95-F outdoors; at 75-F IDB, a high humidity 71-F IWB; at 600-CFM delivers 20,500-BTUH.

NOT close to nominal BTUH Rating, Call a Tech; call one anyway they need to be busy, ha!

Just remove one diffuser & check the velocity in FPM, it’ll be close enough for Govt., work.;) There are also other options...
============
The easiest way is to use Hart & Cooley Engineering Data (P-16, deflection A).
A 10x4 adjustable fin register at 700-fpm delivers140-CFM; Pres. Loss is .031”; with a 13-ft throw.

You don’t have to do this procedure below.
Depends on how close you want your ballpark figure to be, Ha.

Compare ratio of register sq.ft., open area to duct sq.ft. area.

Area Measure only the area where the blades are to get sq.ins., divide by 144 to get the net free area sq.ft., (or get mfg'ers data) area of the grille *X's FPM velocity = CFM *X's 30 = BTUH. - Darrell

[MEENag]

This update is long overdue. My system has been fixed for a few weeks now.

After tech #1 narrowed it down to the compressor (as he had suspected for a while, but wanted to make sure by trying other potential solutions (all the while charging me nothing)), he recommended that I replace the outdoor unit. Before doing that, I had another tech come out to get a second opinion. He was pretty thorough, but he still wasn't sure what to make of my situation. He was getting conflicting indicators. He asked if I minded if he talked to tech #1 (I didn't) so that he could get a full background of what was done. He then involved an HVAC guru, who teaches locally and had actually taught tech #1.

Below is his email to the guru. You're welcome to make your own diagnosis for fun before reading the guru's thoughts.

Notes from my visit on Thursday
July 9, 2009 2:30PM – 5:30PM

When I arrived, indoor temp was about 81.
102 degrees outdoors (inlet temp at condensing unit) on shady side of house

I inspected the attic area and found no fault with the recent evaporator coil installation.
I wrote down coil information and notes on what I saw.
Meridian Evap Coil Model # ASH 60T 4C Ser # 08E03739S (R-22/R-410a)
TXV = Emerson PT NO R0730 (R-22) [RP31074] Chatlif fittings
Aux drain pan with float switch
Refrigerant lines 3/8” and 1-1/8” (about 40-45 ft long)

When I went outside, I found the condenser fan running, but not the compressor.
I attached my gages and found static pressure of 150#+
Within a few moments, the compressor started and I noted pressures at 110# suction and 255 # head pressure.
At that time, I quickly closed the liquid line service valve to pump down the condensing unit. (testing the valves)
The unit pumped down completely, and in good time. I shut down the compressor and watched the pressures for more than five minutes and saw NO bleed through from the compressor valves.
I released the pumped down charge and restarted unit.

On restart, I monitored pressures temperatures and amperages.
61 degrees on suction line (just before service valve) later went up
214 discharge line temp
119 condenser discharge air temp
119 liquid line temp (just outside service valve before new Sporlan C-083 sweat drier)
Pressures after 15 minutes: 95 & 265
Compressor has a rough sound/feel to it (as if the compressor were bolted in with NO rubber isolator feet)
COMPRESSOR ONLY PULLING 16.93 to 17.53 amps (Rated 31.5 at Full Load)
Condenser fan pulling 1.15 (rated 1.4) 850 RPM

INDOORS: stat says 82 (my meter says 80 at one R/A grill near floor) there are several returns and some have wall chases)
IN THE ATTIC: Return air temp 82.5 (in R/A plenum) Supply air temp 65.4 (in supply air plenum) = 17.1 across evap coil

Went back outside to check further.
Shut down cond unit and then waited for about 8 minute before restarting (pressures STILL only equalized to 225 &125. Compressor would not start and after a few more minutes and a couple of tries, the compressor shut off on internal overload.
This compressor had an insulating ‘blanket’ (until I removed it)

I removed the OEM ‘start assist spool’ AND the kick-start (2 wire) start kit and installed a new ‘5-2-1 Compressor Saver’ start kit.
After 40 minutes, the compressor cooled enough to restart (I restarted it multiple times in succession to test new start kit (started every time)

I monitored the system for about 30 more minutes and the only changes were that the pressures ended up at about 87/268 AND the suction line temp was now up to 71 (was 61 earlier with 92# suction ??)
The compressor itself was 126 degrees on side top near suction inlet.

After buttoning up the system I talked with home owner about the previous findings and actions. More freon added when not sure if needed. TXV installed just last week (replaced OEM piston)

My thoughts:
Over charged?
Air in the lines? Was system evacuated fully after each time it was opened to make changes?
Drier too small? (no indication at this time)
New coil to big (higher efficiency design?) maybe slow down air flow is an experiment for clues to that possibility

After talking to Jeff (customer) on Sunday evening, he has seen no noticeable improvement since I was there on Thursday.

I also talked to tech #1 and he is eager to be of help finding and solving the problem.




NOW FOR THE REPLY FROM THE GURU:

Sounds like weak pumping compressor from all the info I see. The drier plugging was likely caused by debris from the failure process of the compressor. The evaporator replacement should have no effect on the "poor" operation in the cooling mode. The high suction/ low amp draw indicates the compressor is unloaded and thus raising the evaporator temperature resulting in increased supply air temp and thus poor capacity. The problem is compounded during higher temp days as the head pressure rises and causes a decrease in volumetric efficiency and an even higher evap temp. Basically you have about a 3 ton compressor on a 5 ton heat load. The quantity of refrigerant you are boiling off is higher than the compressor pumping volume and that results in the evap temp rise. The pump down is not a very good test because the volume of gas being pumped during that process is relatively small and as long as the comp pumps somewhat, it will pull down, just at a reduced rate that may go undetected.

Just my 2 cents, change the comp or unit.

Good luck all.

END GURU REPLY.

I had the outdoor unit replaced and all is well.

Thanks again for all of your thoughts and advice.

My wife and I are closing on a lot this week and should start building a new house in the next few months. When it comes time for making decisions on the HVAC system, I'll be back here with lots of DIY and pricing questions.:)