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Old 07-13-2008, 12:23 PM   #1
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Carrier rep coming to diagnose a problem


As you know from my earlier post about a new house, new system... (page two below) I am having trouble with both the GC that built the house and the HVAC installer. I contacted Carrier (hoping they would be a disinterested third party to these issues) and they contacted the HVAC installer and made an appointment to come out Tuesday with him to diagnose the system problems. Should I assume the Carrier rep will have my best interests at heart? Is it in the Carrier Rep's interest to side with the HVAC installer?

From before, the split is only ten degrees rain or shine, night or day. I am measuring at the return and at the vents in the rooms with a digital thermometer. Is this the appropriate method? Should I expect these guys to measure this also or with a different method?

This is my final shot to have the GC and HVAC installer fix my system. If the Carrier guy says it is working right and sized correctly but it still won't cool my house on a day over 92 degrees, I'm screwed.

Any help on determining if it is sized correctly would be especially helpful. 2489 square feet with nine foot ceilings in most rooms, 13 foot ceiling in two bedrooms and 16 foot ceilings in the great room. About half of the square footage is nine foot ceilings. Lots of air to cool with a four ton unit.

Any insight into what I should say to the Carrier rep or look for when he and the HVAC installer are here would be very, very useful.

As I said before, everything you have all told me has been super. I surely couldn't have come this far with the GC without your help. Thanks.

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Old 07-13-2008, 01:26 PM   #2
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Carrier rep coming to diagnose a problem


The fact that its not cooling on 92 degree days is proof of the problem, alone. go back to the original post , I beleive I told you what meseurments to ask for. These numbers and temps will not only show that you are somewhat in the know , but if you post them I or others will be able to confirm that the system is charged properly. By simple logic if the system is operating properly with an acurate charge and still not keeping up with the load of the house , There is no other option then the system is undersized .

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Old 07-13-2008, 01:38 PM   #3
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Carrier rep coming to diagnose a problem


Goe Fan,
I found out with the help of all on this chat room that it is not a heat pump but an A/C system. I put photos of the data plate on the other post. How do I get the wet bulb temp inside. I know we used to use a special measuring device when I was in the Army. Does any of that matter since I now know it is an A/C system rather than a heat pump??

Thanks for your patience
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Old 07-13-2008, 02:17 PM   #4
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Carrier rep coming to diagnose a problem


with out a digital phycometer. you take a regular alchole thermometer and use a peice of duct tape to tie a spring to the top. wrap the bulb with a small peice of a damp rag ( distilled water prefered) and swing it around your head. the rate at which the water evaporates will determine the evaporitive cooling effect and the temp shown is your wet bulb , this method is obviosly not 100% acurate but it will get you within a degree or 2. Any hvac guy worth his salt has a digital one they cost about 150 at grainger
It does matter the sub - cool and super heat targets are determined by indoor wet bulb and outdoor ambeint. there is no way to know you are putting in the right amount of refrigerent on a heat pump or straight ac with out these # 's a piston system is charged to a target super heat of the gas in the suction line , a txv system is charged to a target subcool of the liquid in the liquid line
all other methods are guess's and are not acurate , pressures alone are meaningless, a acuratly charged system will cool much better and be much more eff. There are very few acuratly charged systems out there

the carrier guy wants it fixed but he will not embarrass the company so ask these questions but dont stand around when the guages go on he probubly will be putting on a clinic for the company and wont want to do it in front of you. let me know how it works out

Last edited by geo fan; 07-13-2008 at 02:24 PM.
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Old 07-13-2008, 02:50 PM   #5
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Carrier rep coming to diagnose a problem


Ask him if he can do a Manual J load calculation for the house. That will verify the sizing and airflow requirements for each room.

Ask him if the excessive use of flex duct is having a dramatic effect on the airflow.

Did you pay for heat pumps, or was that just a misunderstanding.

I really think he will try to be unbiased. Carrier doesnt want you unhappy with thier product, and they dont need the agrevation of a poor installer.

Good luck.
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Old 07-13-2008, 03:02 PM   #6
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Carrier rep coming to diagnose a problem


Quote:
Originally Posted by 8 Ball View Post
I really think he will try to be unbiased. Carrier doesnt want you unhappy with thier product, and they dont need the agrevation of a poor installer.
Good luck.
Especially, when you tell him you've posted this on DIY and 1456 people (ok a little exaggeration) have looked at this thread and are awaiting a response to see if they're gonna tell all the people (at least 4) they know about this. 4X1456=5824 then they tell their friends and so on.
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Old 07-13-2008, 05:09 PM   #7
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Carrier rep coming to diagnose a problem


8 Ball,
There was a misunderstanding, I guess. When we bought the house, the GC told us it was a heat pump. Then all this and he says he misspoke. I would rather have had a heat pump, with the gas furnace downstairs pushing any extra needed heat upstairs, plus with a gas fireplace upstairs as well. Gas is expensive too, compared to electricity in Tennessee. So... is it worth going to the mat over? I don't know. There was nothing in writing saying it was supposed to be a heat pump. There are plenty of witnesses that listened to him say it was a heat pump during the final walk-through. At this point, I just want to get the A?C blowing cold air and I'll be happy.
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Old 07-13-2008, 08:43 PM   #8
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Carrier rep coming to diagnose a problem


So this is a "SPEC" house. Meaning that the GC built it to sell, you did not hire a GC to build your home.

Well... that explains a lot. Did you purchase it "as is", and get a great deal?

Dont misunderstand, the AC, plumbing and electrical should conform to set standards, I guess what I am trying to picture is a worst case scenario, lets say, for example, the flex duct needed to be replaced with insulated hard duct, and the AC changed out to a 5 ton unit. Someone is going to have to pay for that. Going to be like pulling tiger teeth.

Bad deal for everyone. Manual J. load calc..

Last edited by 8 Ball; 07-13-2008 at 08:57 PM.
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Old 07-15-2008, 12:53 PM   #9
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Carrier rep coming to diagnose a problem


All,
The Carrier rep found that the unit had a bad txv. The calculations he did showed 31 degrees rather than 10-11. I don't know what that means but he did say it had something to do with the superheat. He explained that this valve was not opening as the temperature outside rose, which in turn did not allow enough refrigerant into the coils?? He also found a 19 degree split when taken at the unit in the attic. When asked about a Manual J load calc the GC and the HVAC guy both said it was done for the house before the system was installed.

So, will replacingthe txv make the unit cool better? If the split is 19 degrees at the unit, why is it 10 degrees where it sucks and blows into the house? Where do those other nine degrees go?

The valve will be replaced on Thursday so we will see what kind of a difference it makes.

BTW, the Carrier Rep complimented the HVAC installer on his "great ductwork" inthe attic.

Again, all comments will be helpful.

Thanks

Last edited by Faulknertw; 07-15-2008 at 12:59 PM.
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Old 07-15-2008, 06:00 PM   #10
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Carrier rep coming to diagnose a problem


A manufacturer will never burn a contractor in front of a cust. its just bad business . A high super heat can mean low charge or less likely a restriction in the txv. a restriction is caused by something in the pipes that shouldnt be . I can not beleive you are at 19 with that high of a superheat. just be glad you got somebody on the job that knows what he is talking about . even though I doubt he's being straight with you . I hope the repair is taken care of
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Old 07-16-2008, 09:14 AM   #11
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Carrier rep coming to diagnose a problem


If you actually have that high of a split at the unit in the attic, I would then look at how well the ducts were sealed. You are losing it somewhere. You might be drawing hot attic air into the return or losing cold supply air into the attic, or both.
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Old 07-16-2008, 08:44 PM   #12
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Carrier rep coming to diagnose a problem


Are you serious about the ductwork comment, or was that sarcasm?

Did you get a copy of the Manual J calculations?

Would you put the photos up again.

Last edited by 8 Ball; 07-16-2008 at 08:47 PM.
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Old 07-16-2008, 09:30 PM   #13
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Carrier rep coming to diagnose a problem


I did not ask for the Manual J load calc. They said they did it prior to building the house. they also said this was the standard HVAC system for this particular house, as if they do not take any additional considerations into account. for instance, my house is on a finished basement. I find it hard to believe that the split could be 19 at the unit and only 10 inside the house...or is this common? At any rate, they are coming to replace the TXV tomorrow. Do you think that could make enough difference to keep my unit from running nonstop?

Here are the photos. If you want to see others let me knwo and I'll take them and post them.
Attached Thumbnails
Carrier rep coming to diagnose a problem-20080621-015.jpg   Carrier rep coming to diagnose a problem-20080621-023.jpg   Carrier rep coming to diagnose a problem-20080621-009.jpg   Carrier rep coming to diagnose a problem-20080621-021.jpg   Carrier rep coming to diagnose a problem-20080621-022.jpg  

Carrier rep coming to diagnose a problem-20080621-020.jpg  
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Old 07-16-2008, 09:57 PM   #14
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Carrier rep coming to diagnose a problem


Theres got to be a contractor out there from Tenessee. Lets hear from one.

Is this the norm?
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Old 07-17-2008, 12:25 AM   #15
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Carrier rep coming to diagnose a problem


Looking at the pics, again I gotta go with airflow problems. Of course, you may have 19degrees diff at the furnace but with all that flex and roller coaster ductwork, the air is bound to slow down and pick up some heat along the way...I think that is where your 9 degrees is going. Call a reputable sheet metal company to look at your system....I think they will definitely find some issues.

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