upstairs AC not cooling very well - need 2nd opinion


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Old 08-14-02, 09:02 AM
jcd
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upstairs AC not cooling very well - need 2nd opinion

Instead of fixing the AC myself (or waiting for my husband to do it), I called a service company.

This is what the service guy wrote on the invoice:

"Upstairs not cooling good. Inspected attic ducts and equip. - all O.K. Outdoor unit is worn out - heat pressure is 285 at 88 degrees ODAT Condensing Coil has lost its ability to effectively transfer heat in turn causing poor cooling effect and runs continuously - replace equipment.

Current unit: Tempstar 2 ton split A/C horz in attic. Also need attic fan"

So the service guy didn't fix anything (yes, I paid $80 for nothing) and he recommends that the unit be replaced (for around $2300).

I am not sure if I am getting fooled here. The A/C doesn't produce enough cool air during the afternoons when it's really hot but it does cool enough in the evening.

Any suggestions from the members here? Do I really need my whole A/C unit replaced? How/what do I check to make sure this guy is not trying to rip me off?

Thanks a lot!
 
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Old 08-14-02, 10:50 AM
CHuntMD
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So for another $160 get two more HVAC folks to come and for a diagnosis. As the attic fan, do you mean one that looks like a mushroom that is on top of the shingles? You could also add a gable mounted fax at one end of the roof. Don't go cheap/undersized on they fans and it is a real bear to change a worn-out moter (which I did last summer


I'll be installing one/two of these the next time!


http://www.fan-attic.com/

Chris
 
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Old 08-14-02, 04:37 PM
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a/c replacement

285 at 88 degrees means squat. he did not list the suction pressure. it may be overcharged, it may have a dirty condenser, etc. get another opinion, hge may have been on commission. the facts he lists do not tell me replacement is necessary. attic fan is a good ides, though. this alone may deter the problem
 
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Old 08-14-02, 05:54 PM
bigjohn
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Allow me to bore you with a little theory and then you'll understand why I tell what to look for. Refrigeration is a process of moving heat from point A to point B. When you hold your hand over the hot air blowing out of the outdoor section of your a/c unit, the heat you're feeling is the heat that's been removed from the inside of the house and then it's dumped into the outside air. Now, the freon is the heat transfer fluid. When the outdoor unit gets rid of the heat, it [the heat] goes from the freon in the coil, to the tubing of the coli to fins of the coil to the air passing over/thru the fins. [I mean the air that the fan on the outdoor unit is circulating thru the coil] When the coil becomes inefficient at getting rid of the heat AND the cause is NOT a dirty coil, what usually happens is the fins start to crumble away from the tubing. This is what you want to look for on the outdoor unit. Do you see deterioration of the fins? If you run your fingers across them, do they flake off in your hands? Look especially at the bottom of the coil. The guy is saying that you have a 39 degree temperature difference between the outdoor air and the freon temperature in the coil which is a lot. After the unit has been running for at least 30 minutes on a hot day, feel the small pipe at the outdoor unit. Does it feel warm to hot or cool?
 
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Old 08-15-02, 05:59 AM
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Attic fans

Originally posted by CHuntMD
So for another $160 get two more HVAC folks to come and for a diagnosis. As the attic fan, do you mean one that looks like a mushroom that is on top of the shingles? You could also add a gable mounted fax at one end of the roof. Don't go cheap/undersized on they fans and it is a real bear to change a worn-out moter (which I did last summer


I'll be installing one/two of these the next time!


http://www.fan-attic.com/

Chris
Powered attic fans are a waste of money, use the $$$ to PROPERLY install passive vents.

They work just as well BUT you MUST use enough of them, go with 1 sq ft of free air for every 150 sq ft of attic space instead of the normal 1/300 ratio used primarily for preventing condensation and ice dams in the winter.

Very few attic even have the 1/300 ratio, including most new homes.

Those attic fans use more power than they save in most cases when compared to proper passive venting.
 
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Old 08-15-02, 06:31 AM
CHuntMD
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Hey 54regcab, what do you think about whole house fans? Mostly for spring/fall temps. There is one that uses two smaller fans in a rectangle instead one one big square type one you ususally find at the home improvment store. If I upgrade my passive cooling and scrap the powered attic fan I could use the 110 for the whole house fan.
 
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Old 08-15-02, 02:54 PM
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whole house fan

Great idea
It looks like a great product but I have my doubts about the $400+ price tag ...
(you are talking about the HRV1000 right ?)
The ones at the home centers are 1/4 the price and have a higher CFM rating ...
 
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Old 08-15-02, 03:44 PM
CHuntMD
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That is the one but others have it for lettle less than MSRP. Two main bennys I see are install easy (no cutting of roof support), easy wiring and operational speed can vary (meaning noise) I agree about the CFM but then I don't have a 2,00sf+ house either
 
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Old 08-15-02, 05:11 PM
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Red face Price

So how much and where ??
So you have a cracker box like me LOL (I'm just shy of 900 sq ft)
Wiring is teh same for both types of fans, most are 2 speed also
I do think the HRV would be considerably quiter considering the lower CFM rating.
Do you have an attic fan installed now ??
 
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Old 08-15-02, 07:16 PM
CHuntMD
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From Lowes:

Calculate the interior square footage of your home's living area. Do not include the garage, attic or basement.


Multiply this number by 3 to obtain the fan size.

Example: 2,000 sq. ft. x 3 = 6,000 CFM (Cubic Feet of air moved per Minute)
Because a whole-house fan exhausts stale, warm air into the attic, a properly sized attic ventilation system is also required to exhaust that air out of the attic.

To determine how much attic ventilation you need, divide the fan's CFM by 750.

Example: 6,000 / 750 = 8 sq. ft. attic ventilation needed


MSRP on the HV1000 is $619 and up depending on insulation and remote

Others that sell for less and other neat stuff:
http://www.wholehousefan.com/ordernow.html
http://www.efi.org/products/ventilat/tama003.html
http://www.rewci.com/hvwholhousfa.html
http://www.positive-energy.com/pages...oleHouse3.html

Still not cheap but it looks well insulated. Those monster whole-house fan can suck down th juic at least the one my inlaws have.
 
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Old 08-16-02, 05:34 AM
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Arrow Juice

$619.00 will buy a LOT of juice !!!
Remember they are all quoted at high speed as fan for CFM/Watts
A bigger fan will use more power, duh LOL
How big is your house BTW ??
 
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Old 08-16-02, 05:53 AM
CHuntMD
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It's a 1600sf two story. I look at certain projects as improvements that will make my house different then all other ones in this community and hopefully add to the resale

The HV1000 might be a good end-of-sept project. I'll post here how it goes.
 
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Old 08-16-02, 07:18 PM
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Unhappy Recovery of costs

I have seen people take perfectly good whole house fans and block them up

These are the same ppl who run the A/C when it is 60 outside instead of opening he window ...

But if it is a project that YOU like, go for it !!!
 
 

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