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-   -   New House, new system, poor cooling (http://www.diychatroom.com/f17/new-house-new-system-poor-cooling-22919/)

Faulknertw 06-28-2008 05:59 PM

New House, new system, poor cooling
 
Hello all,
I have a new house in Tennessee that is three months old. We have had trouble cooling the house since the temps began to warm up. The system is a split system with the heat pump outside and the air handling unit and all ductwork in the attic. The attic is insulated satisfactorily. The house is east facing and has no shade whatsoever. The windows are low-e and all have blinds or shades. The system runs non stop from about 11:00AM until after dark with the thermostat set on 74. Also, during the day, the temp in the house rises so we have to actually adjust the setting on the thermostat in order to get the system to shut down and take a breather. I have measured the temparature of air at the return and the air at all of the registers in the house (for at least 15 minutes each) and there is anywhere from a 5-11 degree difference depending on whether it is the hottest part of the day or at night.
The guy who installed the system has been out several times and says the system is running correctly. I was told by this guy there should be a 14-18 degree difference in the return and register but I don't think he has spent the time like I have to actually check these temps with a digital thermometer. He told me the difference was 17 degrees before I actually began checking them myself.
Bottom line, the system runs all day on a nominally hot day to keep the temps in the house at around 74. When it gets really hot, it runs all day and the inside temp climbs to around 77-80. Not cool at all.
Any help is appreicated.

geo fan 06-28-2008 08:16 PM

20
 
the temp should be a 20 split on a standard system operating correctly. call them back again and ask these q's is this a txv or piston what is the super heat and subcool what is the wet bulb inside the house and the ambiant out door . fallow him around (good techs dont mind) if he cant answer one correctly he can not charge the system properly . if you have a txv your subcool ( the temp of the small line suctracted from the satruration temp of the liquid )should be 10-13 if you a piston it can vary allot but 8-26 depending on conditions . ask for another tech and if your state requires licences check them write down the number on the card and every answer they give you . you system is most likely under charged and if the realy are not working with you call out another comp to diagnose and bring the list of recomended work to the company dont let the second party do any work though it could void the liability of the first company obviously only consider this if the first step leads nowhere

8 Ball 06-29-2008 01:03 AM

When you say new home, does that mean a new build? Or have you upgraded the equipment in an existing home? Something is not right. A properly sized and installed system should be able to maintain setpoint.

If it is a new home, talk to your GC, and review your information with him. He can help getting the problem resolved, and should be involved in an issue that may impact his reputation.

If you have upgraded an older home, it wouldnt hurt to get an unbiased evaluation from another contractor.

There are several scenarios that could be applicable to your description, from a refrigerant leak to undersized equipment. Something is not right. Ask to see the heat load calculations from the installer, and make sure the equipment is sized properly. If the equipment is sized properly, then we can give you some direction re. instalation issues.

Look forward to hearing more.

Faulknertw 06-29-2008 07:46 AM

Specifics on the new system
 
Yes, the house is a new build. The upstairs (the downstairs is a completely finished basement with a separate two ton heat pump) is approx. 2600 square feet with a four ton Carrier 13 SEER heat pump. I have some issues with the guy that installed the system because he doesn't seem interested in diagnosing a "problem that doesn't exist". He has plenty of work where he will make money. The GC is going to have the installer come out this week with a "probe" to stick in my ductwork in the attic because they don't think my readings from the return and the registers with a digital thermometer are accurate. Will doing this leave holes in my ductwork that can leak cool air? I measured all day yesterday and last night after it cooled off and the difference is still no more than 10 degrees. Also, I don't know if this matters but the air return is positioned in the attic 31 feet from air handling unit with a 24" line running from the return to the air handler. Basically opposite sides of the attic.

biggles 06-29-2008 09:12 AM

take you split temps at the air handler(filter/top of supply duct...18F) not on the return register compared to the supply register...you should have a 10F rise outside on the air into the condenser and whats blowing up and out.that return seems too long usually they are rigth into the return connectionin in the attic...take the grill temp on the return then into the back of the air handler see if you get any heat rise from that attic on that return.

Faulknertw 06-29-2008 10:14 AM

Additional info and photos
 
2 Attachment(s)
I went into the attic while the system was running and found several leaks. The main leak blowing the most air was here in this photo. Should it be leaking cool air? I also found leaks where the air return duct attaches to the air handling unit. It was not taped well. Also, the system is supposed to be a heat pump. This unit looks like a gas unit. Am I right?

statman 06-29-2008 10:18 AM

thats a gas furnace, not a heat pump. I assume your outdoor unit is strictly ac as well. What is up with the flex duct being used as return air for your furnace? How long is that flex? Not up to code where I live.

Faulknertw 06-29-2008 10:29 AM

Photo of outside unit
 
2 Attachment(s)
Here are photos of the outside unit and data plate. Heat pump or A/C. The GC says it is strictly a heat pump HVAC system but he doesn't go into the attics. HELP!!

8 Ball 06-29-2008 10:29 AM

Good Morning.

A rule of thumb is 1 ton of AC for every 600 sq.ft of living space, so if your sure that it is indeed is a 4 ton unit that seems OK..

Next would be airflow, approx 400cfm per ton. If there is not enough airflow, this would be reflected in a lower than normal supply temp, which should be 20 deg. lower than the return temp at the coil, after the system has run at least 15-20 min.

While your up there, there are two refrigerant lines going into your airhandler, and a condensate drain. One of the refrigerant lines is larger than the other, and insulated. Any exposed copper on the insulated line should sweat, if it appears to be frosting, there could be a system problem with airflow, charge or refrigerant feed to the evaporator. Make sure the filter is clean, and the outdoor unit is clean, if you can see the coil when you check the filter, make sure there is no debris on it.

Yes there will be small holes in the ductwork, but they will be plugged with rubber plugs when they are finished, these same holes can be used for airflow readings also, if it comes to that.

Just saw your photos...thats NOT a heat pump. I will check the Carrier website.

That IS a standard efficiency (80%) gas fired furnace, with a 13SEER 4 ton AC.. Refered to as the builders grade. No heat pump here. No condensate eighther.

Can we see photos of the basement "heat pump" ?

8 Ball 06-29-2008 11:06 AM

Hey STATS... we should be selling "heat pumps" in Tennessee!!






Sorry... thats not funny.

Faulknertw 06-29-2008 11:25 AM

Basement system photos
 
4 Attachment(s)
Here are photos of the basement system plus another few of the attic unit including the main line flex going to the far end of the house where the air return is located. The length of this line is approx 31 feet. Not up to code? I could use any help on what is not up to code so the GC can get the installer to fix the system.

8 Ball 06-29-2008 12:04 PM

Basement unit is NOT a heat pump eighther. It does appear to be a high efficiency (90+) gas fired furnace, with a standard eff. AC..

I am not up to speed on code rquirements in Tenessee, but your GC would not allow a contractor to instal a mechanical system without a permit. Once a permit is pulled, the system would have to be inspected and passed before the GC can get an Occupancy Permit approved. Chances are, and by the looks of your photos, it probably meets the absolute minimum requirements, and there should be an approval sticker on or very near the equipment.

Im almost going to guarantee you have airflow issues due to the excessive use of flex duct- good for the installer-bad for you. Appears to be what we call a SLAMMER. Slam it in, and get gone.

If you truly paid for heat pumps you may have some recourse with the GC. Expressing your dissatisfaction with the system to the GC, may be the only way to have it made right.

I really dont think your issues are simple fixes, and doubt they can be resolved on a chat line on the internet. Maybe an attorney may be in order.

Your not going to get 90% efficiency from the basement unit drawing indoor air for combustion.

Im am truly sorry if I sound rather negative about all this, and hope your opinion of all mechanical contractors does not end up being a poor one.

statman 06-29-2008 08:30 PM

What a HACK job!!!!!!! I'll be very surprised if that system had a permit pulled on it...either that or the inspector was asleep on the job. There is no way that would pass here...not sure about tennessee but I can almost guarantee that is where alot fo your problem is. Not to mention that it is def not a heat pump. I would check with your city permit department to see if an HVAC permit was ever pulled for your site and if they could send out an inspector to verify this system meets current code.How is your airflow? Does it feel strong at the supply registers? Does the return air draw from all levels of your house?

8-ball....I need a vacation..and i have never been to tennessee. Could bang out 3 of these jobs a day if that is up to code.

8 Ball 07-02-2008 06:25 PM

Any follow up? Any progress with the GC?

Faulknertw 07-08-2008 06:40 PM

GC is fighting with me now.
 
The GC is doing everything in his power not to fix the problem. He sent out a guy to measure temps in every room in the house with what looked like a meat thermometer. It was a 91 degree day and the thermostat was set on 72. The temps in the house were from 71-73 degrees. But the unit never stopped running all day. And he never checked the split between the return and the vents in the house. GC calls me today and says the unit is running fine, proven by the temps in the house being within one degree of the set point. The split is still only ten degrees morning noon or night, rain or shine. Ten degrees. We ended up in a pissing contest.
My electricity bill also went up over $100 in June. That seems very excessive, given there were ten days of mild, low humidity weather in June.
Then he calls and says he had his employees call HVAC specialists and ask them if it is good for a system to run nonstop. Of course the answer was yes, they are much more efficient when they don't have to shut down and power on. All of this sounds crazy to me, but I'm no HVAC guy.
It is currently 96 degrees outside. The set point is 72 and the thermostat reads 76 degrees as the temp in the house. The system has been running non stop all day long to keep it this cool. Obviously something is wrong.
One last thing. The part of the house we are talking about is 2489 square feet with nine foot ceilings in most rooms. The great room has 16 foot ceilings and two bedrooms have 13 foot ceilings. The A/C unit is a four ton. Sound undersized?
I plan to contact Carrier tomorrow to talk to the Rep for this area. Maybe I can get some help that way.

By the way, thanks for all of your help with this.


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