Replacing AC unit, 2 questions

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Old 03-30-05, 07:42 AM
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Replacing AC unit, 3 questions

House is 1850 sq feet total, built 1993. AC is Trane XE1000, furnace is Trane XE78.

Also a finished (2 years after house built) walk out basement, 500 sq ft. In summer I turn basement vents to a whisper for dehumidifying since basement is naturally cool, so not much of AC load. In winter I open the vents more for heating and also use a electric wall heater since thermostat is on main floor and basement can be cooler.


I had my AC unit checked under the service contract with a company down here. They told me the freon was low by 2.5 lbs. Last year they told me it was low 1 lbs and added freon. The tech also told me that the coil was 21 degrees and would ice up if we tried to use it this summer as it currently is. This time they recommended I get the unit replaced. It is a 12 year old Trane. I told him to skip adding coolant while I look into replacing the unit as I have another month until things get hot down here in NC.

I called another company and the person there said that at the outside temperature of 55 degrees this AM that the tech would not have been able to get an accurate reading on the coolant and that the temperature needs to be 65 degrees or more for this kind of check. The second guy is coming out to check the unit this PM when the temp should be 70 or more. He said that he would explain how everything should work.

What's the scoop here?

Also, we have single zone AC & heat. The heat works ok, but the AC is somewhat uneven in the summer. I adjust a big manual damper at the blower that I had installed about 9 years ago. This damper controls the flow between 2 ducts, one for the main floor and the other for the upstairs which goes all the way up into the attic. Prior to this damper being put in, getting enough cold air all the way to the top of the house was a no go without freezing the main floor. Now the cold air distribution is a lot better, but still somewhat uneven. I have some concern that the unit is not operating at good effeciency by having to set the damper so that the main floor has a small opening to its duct while the second floor is wide open.

If I need to replace the AC unit, can I get dual zone AC while retaining the single furnace (gas) unit? Or does this damper system not affect the operation efficiency of a single zone unit?

Would a 2-stage AC unit be compatible with the current furnace/blower? This has one level of operation. Or will I need to make other replacements?

Any comments?
 

Last edited by padkison; 03-31-05 at 11:11 AM. Reason: Add Info
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Old 03-30-05, 09:26 AM
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Wink

First 2.5 lb then 1 lb of freon why didnt he look for and fix the leak. Thats what he should have done for sure.
Now you dont say how big the home is just 2 floors. So yes you can put electric dampers in the duct for up and down. To work off just one unit. but I dont think you will be happy with it. The best way to go for a two story home is with two units one for each floor heat and cool. You will save money in the long run and also have a back up if one goes down.

Oh and I have worked out in the snow to put freon in an AC unit that had a big people load on it. That was before they came out with power saver dampers that took outside air in the unit if it needed cooling.

ED
 
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Old 03-30-05, 10:29 AM
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Red face

Let me recap your situation. First you have issue on diagnosing and correctly repairing your AC unit. And second, you live in a two story home and cooling the second floor is a problem.

Ed is correct on both counts. You need another HVAC dealer to properly repair what seems to be freon leak. Now to the larger problem. You do not mention size of your home nor the age of your ductwork,brand, model, size of your HVAC equipment. You need a reputable dealer experienced in zoning solutions for two story homes. Obviously mechanical dampers have their own problems as far as attempting to manually adjust and equalize air flow between the floors. Two separate units are usually the preferred method for heating and cooling a two story home. But a properly designed ductwork system, properly sized equipment, and electric dampers can be a satisfactory and less expensive solution if provided by a dealer experienced in this area. You may want to check with neighbors/friends who have 2 story homes for suggestions on dealers. And I would recommend authorized dealers. Any other suggestions would be guesses and unproductive. Good Luck!
 
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Old 03-30-05, 06:25 PM
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A good tech fixes any leak before charging, it's a must and more important it's the law, If I see a tech juicing a unit I always ask him why not fix it the right way, I always get some type of reaction
 
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Old 03-30-05, 06:32 PM
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Three of a kind

I'll go with both Ed & TigerDunes on the 2 floors, 2 systems. I'm told there are zones systems out there that work well but I've not yet seen one.

Regarding your service person: (1) I would GUESS your system is overcharged which is just as bad as being undercharged, maybe worse. (2) How this person could tell you you need 2.5# of refrigerant, without putting it in, is beyond me. (3) I will not attempt to check the charge on your typical residential system when the outdoor temperature is below 75, I much prefer 80 or higher.
 
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Old 03-31-05, 11:05 AM
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Specs on the house and Unit

House is 1850 sq feet total, built 1993. AC is Trane XE1000, furnace is Trane XE78.

Also a finished (2 years after house built) walk out basement, 500 sq ft. In summer I turn basement vents to a whisper for dehumidifying since basement is naturally cool, so not much of AC load. In winter I open the vents more for heating and also use a electric wall heater since thermostat is on main floor and basement can be cooler.
 

Last edited by padkison; 03-31-05 at 11:13 AM. Reason: add info
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Old 03-31-05, 11:29 AM
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Wink

1850sq ft total Id stay with the dampers you have now for up and down and move them around as you need.Might try 24/7 on the blower when on AC or heat.

ED
 
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Old 03-31-05, 01:16 PM
Thomas W.
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replace it

replace your system it's 12 yrs old and you plan on staying, I agree he should of looked for a leak but if it's that old you benefit more by replacing it.
Have a good company do the load and then design a system that doesn't have you changing dampers yourself there are many that can do controlled.

At this point replace everything and have them look at the carrier Infinity system that may work real good for your need
 
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