New packaged unit could it be under sized? - http://www.hvacmechanic.com/ Forums
Original message
| yatwing
 |  "New packaged unit could it be under sized?"
, posted Sun 13 Jul 03:17:  
Hi, I'm in Sacramento CA. And I just had my HVAC package unit replaced. My house is 1080 Sq Ft and I replaced it with a 2 ton Amana 15 seer unit. The problem I'm having is the unit doesn't cool the house too good. It does ok if outside temp is below 95 but if it goes above that it has trouble keeping inside temp at 80 - 81 degrees. Shoot a few days ago when it was 109 the temp in the house was 84. I think the unit is a APG15. Anyone familiar with this unit? Another funny thing is that the installer told me it has 2 stages but the Amana website states that the only 3 ton and up has the 2 stage option. Could they have wired it wrong or is it undersized? Any help would greatly be appreciated..
[this message was edited by yatwing on Sun 13 Jul 03:18] |
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| mechacc
| "Re(1):New packaged unit could it be under siz" , posted Fri 25 Jul 07:08:
Have the installer measure the return air temperature at the unit and at the return air grilles. If there is a 5 degree or more rise between the grilles and the unit there is duct leakage or radiant temperature gain if the return duct work is located in the attic. If there are no duct leaks then the ducting is picking up the heat from the attic and needs to be insulated.
Has the installer measured the static pressure? Possible that if ductwork is insulated on the inside that a piece has fallen and is restricting air flow.
If your installer is sharp they can measure and ensure that the unit is in fact delivering the required CFM per ton airflow. The wet bulb temperature in and out can then be measured and using the difference determine the actual btu output capacity of the unit. As you state this is a 2 ton unit. The blower speed may be set too high and is not removing humidity.
MechAcc
[this message was edited by mechacc on Fri 25 Jul 07:20] |
| sbrooks157
| "Re(1):New packaged unit could it be under siz" , posted Sun 13 Jul 18:43
1 cfm per sq ft of conditioned space,you need1080 cfm,400-500 cfm per ton, so 2- 2.75 tons of cooling would be good for your house,3tons would not have been out of the question for sac where sometimes it gets 115 degrees or more,best to start looking for leaks in duct, and heat infiltration into the house,add insulation etc,
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| theduke03
| "Re(1):New packaged unit could it be under siz" , posted Sun 13 Jul 08:56:
When you say "I just had my HVAC package unit replaced" Does that mean last week or last year? Is your filter clean?
Is there any attic ducts? If so then inspect the return ducts in the attic for a broken/open connection.
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Sun 13 Jul 08:59] |
| | yatwing
| "Re(2):New packaged unit could it be under siz" , posted Mon 14 Jul 23:20
I had a leak test done because I guess it's a law now in CA if you replace a HVAC unit. In order to pull the permit it needs to pass. And it pass with room to spare. As for insulation windows were replaced wit dual pane a few years back. Half the walls are insulated. I'll be working on the others soon. And according to the installers the ceiling insulation is okay. I can't believe I spent $6k to get 83 degrees of cooling. #$@$#@^
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| | yatwing
| "Re(2):New packaged unit could it be under siz" , posted Sun 13 Jul 11:52:
The unit was replaced 6 months ago. I had the installer come out 3 - 4 times now but he still thinks it's running fine. Well, that's because he's not around when the house is 85 degrees. As for the filter it's one the you'd clean and I clean it every month or so. One other thing is that I have a pre-cleaner (that's what the installer told me during the replacement) which was disable but not removed. Could that have an affect? A few other notes: I measured the temps coming out of the registers and it really fluctuated. examples: outside temp 87, Inside temp @ return 79, living rm reg 59, master rm 66, rm A 70, rm B 66, kitchen 62, bathroom 65.
[this message was edited by yatwing on Sun 13 Jul 11:54] |
| | yatwing
| "Re(3):New packaged unit could it be under siz" , posted Sun 13 Jul 23:50
Anyone else with any ideas?
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| | allen1980
| "Re(4):New packaged unit could it be under siz" , posted Mon 14 Jul 12:08
next time when it begins to get a little warm in the house check the return air temp and then check the temp out of the register and se what the diference of the two is.i wouldnt say the unit is to small how well is the house insullated?
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| | yatwing
| "Re(5):New packaged unit could it be under siz" , posted Mon 14 Jul 23:21
I'll report next stat the next time it gets upper 90's. Please scroll up the see my insulations.
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| | pntballgunz
| "Re(6):New packaged unit could it be under siz" , posted Thu 17 Jul 12:19:
I have the same unit and lately my problem was that it did not cool the house. I also live in Sacramento. It ran fine until a few weeks ago, which the inside of the house was over 92 degrees. The problem was fixed by the installer, which he adjusted the thermalstatic expansion valve (TXV). He further stated that if the problem continues, then the alternate solution is to change the TXV since it was discovered that the TXV in these units (as well as other branded units that used this particular TXV) would freeze up. To change out the TXV would be around $650. He preferred to not take that route since it is expensive. Well, after the fix I got the house down to 73 degrees, but that was on a cool evening and I need to wait on a hot day to see if it works for sure. Although he did set the termostat to 76 and when I got home from work on a 90 degree day, the house was cool. I also noticed that when the TXV froze up, the compressor would make this tinging sound like ball bearings rattling. You could check the TXV by pulling the panel off where the circuit board is located and you'll see all these small copper tubing routed to an central fixture. See if it has frost on it. Good Luck!
[this message was edited by pntballgunz on Thu 17 Jul 12:25] |
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