ReplyThe next sad thing.
if a 5 ton was able to cool your house all those years with that much attic air being pulled in.
You probably only need a 4 ton A/C.
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My house is about 17 years old. I bought the house in late '98 and replaced my AC with a York 5 ton system in March '09 based on high electric bills, inability to cool the house in the summer to temps I would like and knowing that the old AC would probably fail soon.
I had some posts here about the system I chose in '09 and to set the record straight I had all kinds of installation problems. The contractor left something in the air handler that sucked into the blower 2 hrs after they left and you can guess the rest... But much to my dismay, after fixing installation issues and at about 1 1/2 years in from my proudly owned new AC , it was getting worse, humidity skyrocketing, wife saying she is hot. I am at work during day peak heat hours so I thought she was just crazy.
We had FPL do a vent test and they said our vents were good except that the air handler suction was probably failed somehow. Something to the effect of sucking hot air out of the attic but they can't see it unless they break through walls. It is a boxed system, that is, suction duct to a big rectangular box (roughly 7'x3'x2') within the walls that the air handler sits on. So we broke through the wall and found the problem. The box was never finished by the original builder best we can tell. In between the studs is a direct path to the attic, and lots of it. We were sucking air, who knows, up to 40% from the attic directly since the house was built. Can you believe it! On top that, the new 5-ton two speed system put in in Mar. '09 has much more suction in high than my old system. Well, it sucked in the attic blown in insulation and dust to the point that the evaporator coils were basically clogged. Not sure how air was even flowing it looked so bad.
I wish I took pics but I didn't. To tell the truth, I got sick to my stomach every time I looked at it. It is fixed now including a coil cleaning. The worst part is that for 17 years semiannually this system was serviced and verified good by AC technicians. In fact, it was serviced two weeks ago and given a clean bill of health, are you kidding, no way could flow have been good, do they or should they measure flow during a test? My wife kept *****ing and that is why we had FPL come over as part of their energy audit. Thank you FPL!! You would think my AC contractor that installed the new AC would have seen it, noticed it or tested for it, but no.
It is sad to say that I have less faith in AC service than ever. And the bull about getting comfortable with them seems useless. We have had a few different companies. They are either poorly trained, don't care and then each time someone else different comes over, with some being better than others. What bothers me is that this website has folks that are competent but I can't find them here in S. Florida near me. A flow test, blank stares. Multiple suctions based on system size...naw not needed they say. Unbelievable!
But the good news, humidity is now down to normal levels. The house is cool and the unit barely goes to high speed. I can't wait to see how much my bill goes down.
So much for 17 years in the making to be fixed. Thanks again to a professional audit by FPL and the competent AC guy that repaired the box.
God Speed, Jim. We'll miss you - 2-26-23
The next sad thing.
if a 5 ton was able to cool your house all those years with that much attic air being pulled in.
You probably only need a 4 ton A/C.
Professional Member*
or less...Originally Posted by beenthere
Regular Guest
What is the square foot of the house?
Regular Guest
So why no shout out to the tech? If its so hard to find good techs, why not mention his name or company here?
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There are a lot of "black hat" AC guys out there, but a few good "white hat" ones too. Have you finally found a good one? He would likely be more toward the high price end of the spectrum but I hope you find and keep such a guy (or woman, if such a thing is possible<g>).
It was when you and FPL started measuring things that you found the 17-yo problem. I am a big proponent of measuring things. A blower door test would have shown up an abnormal amount of leakage, and a duct blaster test would have too, from day one -- but those tests are expensive and often show up bad news, which the builder would prefer not to see. The largest share of the blame I would put on that builder and his subcontractors. It is easy to imagine the biggest thing the builder cared about, was getting the job done for the lowest price possible. When you shop for lowest price and are not diligent about checking the work, you get corners cut... and you got one of the worst case scenarios. Home buyers are often scathingly criticized for caring about good looking counters and floors, but not even asking about HVAC systems. And things would be a lot different if they cared as much about those systems as superficial things.
HVAC techs work in a field with a low bar to entry, and find themselves faced with pressure to be the low bidder all the time. As a consequence of this pressure there is a tendency not to load up with expensive tools for testing. Tools that they absolutely need if they are going to diagnose a sick HVAC system such as yours. Most homeowners see them as a person to maintain an APPLIANCE, while in reality the central AC is part of a rather complex SYSTEM. I think this difference of perspective is the cause of a whole lot of problems.
It would help if the industry tried to build more self-diagnosis into their systems. And it would help if diagnostic tools could be made both simpler, cheaper and more reliable (e.g. less need for calibration). That would encourage more technicians to own and use the tools they need to diagnose a problem like this. Duct systems are the sleeper problem that so many houses have, and very few homeowners appreciate the payback from investing in a good duct system. Very glad to hear of your eventual success story! And I wish you had taken pictures too.
Count yourself fortunate that you live in FL where the state actually cares about getting things right for all homeowners. I am a homeowner in TX and the state does not act like FL: what few rules we have are often violated. There is a reason so much good research comes out of the FSEC (Florida Solar Energy Center) and not "TSEC".
Best of luck -- Pstu
Professional Member*
He said "inability to cool"
So let him be happy and stop planning seeds in his head about junks crap with Manual J, K, L, M, N, O, ...
Regular Guest
Well it seems that now that some of your problems have been rectified,you now have a new set to deal with.
I don't have a problem with a 5 ton unit in S.Fla.,however I do believe your ductwork is too small.You would need the equal of 20 6" runs on the supply side .
With your discription of the return air (suction duct),I believe that much suction could only happen with too small a duct ande probably too few return air griiles.You would need the equal of 11 8" returns or two 20x10 independant ducts one to each side of the furnace or air handler.
Of course these measurements would be smaller for say a 3.5 or 4 ton unit.
Professional Member
Installation and repair/measuring are 2 completely different careers. The installation guys aren't there to solve 17 year old problems. Getting the old system measured instead of direct replacement might/would of saved alot of aggravation. Air filters weren't needing to be changed way too soon with strange items being found?
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OK, I am happy as can be right now. Perhaps a 4-ton would work but I expect that based on 2,300 sq ft, as I recall, under air that the house design came with the 5-ton so it is needed. Now when I was receiving quotes one gentlemen said that it would have been best to have duel AC systems and not one 5 ton based on my heat load. Nobody even hinted that I could get away with a 4 ton.
I have learnt my lesson big time - not to go with the cheaper installer, go with the better one. I too, thought AC systems/install was simpler than it is.....
As to the tech, he works for the same company that did the install in early '09. He was great but the early '09 install was a disaster that took me over 6 months to settle. If anyone wants more information I will PM them. The company is a big one in S Florida. I will let the company know how good the Tech was IMHO.
Great post PTSU. And yes, the FPL thing saved me. I paid $35 for it and received a $90 rebate for work since they found an issue that needed to be fixed. I have not found a great contractor yet, currently looking. Any recommendations in Palm City, FL let me know. And you are right on. This issue was found by measuring. I am an ex-engineer and believe in the science behind decisions.
Believe it or not, It was getting so bad that I put foam insulation between many of my sun facing windows and blinds for the summer to help with the heat load. All the while thinking my AC system could not take the heat load, especially since this summer has been much hotter than average. My wife even bought into it.
Let me know your thoughts on the 5 ton unit, not that I am going to change it out anytime soon.
REP, my suction is one, a ~28" x 15" that my filter sits in. I am sure I have some issues here. But this is nothing compared to what I had.
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At 2300 you are borderline either way depending on house insulation and tightness.
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KNEIL - I don't disagree but I will say that I learnt a lot from this site and you folks here know more than 99.9999999999% of the population. If I knew how or who did measurements prior to my new system I would have had it done. Anyone I asked detailed questions just got sketchy and said stuff like " oh this is fine" or " no changes are needed, just another 5 ton", etc. They provided virtually no science. They were kind of like, I am the expert, trust me.The installation guys aren't there to solve 17 year old problems. Getting the old system measured instead of direct replacement might/would of saved alot of aggravation
I do believe that the recent installer should have seen the faulty box with the airhandler removed. If he had pointed it out I would have gladly paid for the fix, no questions asked. I think the installer just wanted to get the job done and go home on the Friday it was. Plus they were going to put in a HEPA filter than got botched plus they left somethig in the air hander, on and on it went....
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JOKER - I think my house has a high heat load for its size based on high ceilings, sliders and windows. I could be wrong but that is what I think.At 2300 you are borderline either way depending on house insulation and tightness.
Since it has not been brutally hot in the two days since the fix I need to see how it does in the blaring sun and 90's....
God Speed, Jim. We'll miss you - 2-26-23
If it was pulling in as much attic air as he said it was, and still cooling the house. 4 tons would cool it with no problem now.
400 CFM of attic air, would take about 2 tons of cooling capacity.
Regular Guest
Being florida you kinda wonder about moisture removal.
I guess only time will tell. I have seen plenty of over sized units that gave low bills and cooled the house perfectly. Life is strange at times.
God Speed, Jim. We'll miss you - 2-26-23
Good chance those oversized unit were on uindersized duct work that reduced their actual capacity to much closer to the house load.
Regular Guest
Floridaman, you got that FPL testing at a really subsidized rate. Were it not for the subsidy you might add a zero to estimate the market price of these services. Be thankful that FPL takes seriously the idea that reducing load, is equivalent to buying a chunk of power at a certain price. "Negawatts" they call it, and in theory a utility commission may allow a rate of return on the utility's dollars invested in this way for the public good.
As an ex-engineer, you might appreciate the complexity of central HVAC requires an engineering approach to diagnose your problem, or to design it right in the first place. I consider that either is actually a job of engineering, although HVAC professionals rarely get the prestige or the pay of engineers. You probably worked on much more complex and subtle engineering in your career, but I submit HVAC such as yours deserves a place on the spectrum.
Regards -- Pstu
Regular Guest
The 40% was my guess, I could be way off. I can't wait to be in the house during peak heat, sun and 90's to see if this thing goes to high speed. I am not sure what the difference in tons is between high and low but before the fix, high speed could not hold temp until about 83F or so.
You know what, just as I was typing this I realized one more thing. I have a heat strip for heating and last winter was really cold down here for Florida, in the 30's many days, upper 20's for a few. I thought I had the worst heat strip man ever made in my old air handler and my new one. Now I realize that I was pulling in a huge fraction of cold air as I ran my heat strip. Last winter was when I first insulated my windows, thinking the heat strip was next to useless. I used to stand by a vent while the cold air poured out of it shaking my head..... I was actually thinking of buying a kerosine heater to augument the heat during the colder days.
Regular Guest
PSTU, I went to a merchant marine school that put a lot of focus on large AC systems, keeping holds of ships cool, etc. In fact, I look up on my bookshelf as I type this and can see "Refridgeration & Air Conditioning" by Langley, second edition from the early 80's, my textbook in school. Later I became a nuclear engineer and now I am a business guy.
I agree that HVAC can be very complex and I find it extremely interesting. One of my favorate classes was thermo, heat transfer and fluid flow in school. This is what AC is all about. When I got my system I was just dying for a techno person that would do all the calcs, equations and walk me through it, but I did not find one. I believe I was a little rushed by the time of year in that huge incentives were ending. As I recall for the system I got, $1,500 tax credit, $1,500 York rebate and $1,300 FPL rebate. The York rebate and others were expiring so I had to pull the trigger. If not, I would have waited and might have found the really good contractor.
Professional Member*
The sad part about this whole mess is that it should have been discovered before the equiment was even turned on day #1. The problem is that when the house was sheetrocked, the sheet rock company forgot to cut out the return opening. Then to compound the error, the installing HVAC company had no clue there was a major return box missing!!
Back when we did new construction, we always counted the number of supplies and returns so we'd know immediately if one or more (often more was the case) holes hadn't been cut. We always ended up cutting them out. The sheet rock companies NEVER guaranteed their work and NEVER were responsible to find all the boxes. Imagine how many electrical boxes are out there, covered by sheet rock but wires not capped!! The whole construction industry is a mess and all because it's the low bid winner. People get what they pay for and let the buyer beware!
If YOU want change, YOU have to first change.
If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!
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