A/C unit is too small for my house.


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Old 06-03-10, 06:27 AM
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A/C unit is too small for my house.

So I recently purchased my first home in Sept. 09'. We hadn't really tried the A/C until about a month ago when it started warming up, we live in Oklahoma.

I bought a home warranty with the house. It's through Old Republic. The A/C unit runs constantly trying to cool the house down to 74 degrees or so. I had the warranty people come out and they determined that the A/C unit is too small for my house. It's 1972 square feet, built in 1958. He said it is a 3 ton unit and should be 3.5 probably 4 because of the age of the house. He also said he's pretty certain the home warranty company will not cover this. I had new EnviroView windows installed last year which I'm sure is helping, but not enough.

As purchasing a new unit out right would be expensive I am sure, and I don't have alot of money, I'm looking for what options I have. Does anyone think if I complain enough I could get the home warranty company to install a new larger unit?

Any suggestions would be helpful, thanks!
 
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Old 06-03-10, 07:09 AM
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Well, let's start with the big question. No, I seriously doubt anyone would cover that under a home warranty program. Possibly it could have been caught during a presale inspection, but I think even that is unlikely.

How's the attic insulation? Possibly you could add some for a little less heat loss there? Fresh system filter? Check all accessible ducting for leaks?

I have to ask, why are you trying to get the house down to 74 degrees? I'm not sure I could get our house down that far and it's 1/3 the age and with a 5 year old ac system.

One of the ac pros should be along with more info; in the meantime you might try testing to see what kind of temperature drop you are getting out of the system (this will help the pros). Measure the temperature at the warm air intake (where the ac draws the air from inside the house). Next measure the output temperature at a vent and compare the two figures. A really good figure would be in the 18-20 degree range if I recall from other discussions here. Your older unit is unlikely to be that high, but the figure might be revealing.
 
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Old 06-03-10, 07:16 AM
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Originally Posted by the_tow_guy View Post
Well, let's start with the big question. No, I seriously doubt anyone would cover that under a home warranty program. Possibly it could have been caught during a presale inspection, but I think even that is unlikely.

How's the attic insulation? Possibly you could add some for a little less heat loss there? Fresh system filter? Check all accessible ducting for leaks?

I have to ask, why are you trying to get the house down to 74 degrees? I'm not sure I could get our house down that far and it's 1/3 the age and with a 5 year old ac system.

One of the ac pros should be along with more info; in the meantime you might try testing to see what kind of temperature drop you are getting out of the system (this will help the pros). Measure the temperature at the warm air intake (where the ac draws the air from inside the house). Next measure the output temperature at a vent and compare the two figures. A really good figure would be in the 18-20 degree range if I recall from other discussions here. Your older unit is unlikely to be that high, but the figure might be revealing.
Ok, that sounds like a good idea of something to check for sure.

I agree that I seriously doubt they will warrant a new unit replacement.

I was told by the A/C guy that came out that at 95 degrees outside you can expect on "average" for it to cool the house down to 75 degrees. As I've been unable to cool it at 74 when it's in the 80s I kinda figured there is something not right.

They even said themselves the reason appears to be that the unit is too small though.
 
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Old 06-03-10, 09:42 AM
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I don't think a bigger unit is your best or first option. the size of the unit go hand in hand with the insulation of the house. I agree with tow-guy.., get the temperature split first, and then check all your insulations,-- ceiling, door, window, wall, duct.... (a 1958 house's insulation may be only 30% effective compare to today's new house.)
 
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Old 06-03-10, 10:23 AM
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I'm going to be odd man out on my suggestion but putting on my flame proof suit I'm going to suggest you look for a used 12000 BTU window unit and put it in the room you use a lot and are uncomfortable in.
 
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Old 06-03-10, 06:44 PM
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I live in a 1928 house with 1600 sq ft with poor second floor insulation. My a/c is 2.5 tons and has trouble cooling when it is in the 90's. My thermostat is set to 75. As things are, a 3 ton unit would probably do the trick.

My experience is similar to yours. We moved into this house in April and when the hot weather came in June we had tremendous trouble with the a/c. Had some joker from the home warranty come and check it out. He did a botched job. Said I had too much freon and took it out. Well that didn't fix anything. They were a real pain in the a$$ about coming out again so I just got someone that had nothing to do with the warranty. They came out and the tech did a really good job at investigating the problem.

It turned out I did not have enough return air flow so I had them add a small return register to the system. Even though it still doesn't perform perfectly, it made a HUGE difference in the performance of the system.

I recommend you do two things. First, check your filter to make sure it's clean. If you have flex duct on your return, make sure the bends aren't too sharp and restricting. Next, blow off the warranty company and get your own guy in that knows what they are doing to troubleshoot the system. You may just need to add another return.

Even though the temp in my house will rise 2-3 degrees on a 95 degree day, it is bearable. I don't find it worth buying a larger unit. At some point on plan on getting the upstairs insulated better which is a far better investment.
 
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Old 06-05-10, 12:50 AM
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Get a REAL hvac tech to check the refrigerant charge, condition of the air handler/evap coil, blower speed/airflow, and ductwork.

3 tons should be plenty for 1972 sq ft unless there's no insulation in the attic or the outdoor design temp is well over 100F; do not assume that the existing system is actually delivering 3 tons of cooling.

Slapping a larger unit in isn't a good solution - chances are that the ductwork is undersized as is.
 
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Old 06-05-10, 07:51 AM
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I agree. Get your system serviced by a separate HVAC contractor. A static pressure measurement can help determine ductwork problems, if they exist.
 
 

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