need advice on new ac unit with existing gas furnance


Old 12-28-00, 08:39 AM
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I have an approx. 10 year old gas furnace with an a/c unit. I had the inside a/c coils replaced 3 years ago because of leaks. It was a makeshift job because the repair company did not have or could not find the replacement coils for that particular unit (and it was early summer). This set of coils sprung leaks this fall (luckily in late September). We are in East TN (not a lot of snow, but it can be cold in the winter and very hot in the summer). This is a one-level brick house on a concrete slab (approx 2450 sq ft). I have a 4 ton Carrier unit. The venting is in the attic. The inside unit is in the back of the house in a tight interior space.

I have several questions/problems. I am planning to replace the entire a/c unit in late winter/early spring, but I am wondering if that would solve my problems with the heating/cooling. I am looking for an optimal and reliable solution at a reasonable cost.

1) With heat or a/c, the back of the house seems fine, but the other end is not warm or cold enough. From my views of the venting, I don't think that there are any adjustment valves.

2) The blower has started squeaking a little when it is running.

3) When the outside unit is running, it makes a lot of noise (especially when it starts or stops). Are there any brands/units that would operate more quietly?

4) Is 10 years old for a furnace? Should I be looking to replace it? I was told about a combination heat pump/gas furnace (???). With energy prices/availability being somewhat hazy in the future, would this be a better bet or would it be worth the current cost? Or should this wait until the furnace really gives out before going to the expense of replacing it? (I love gas heat. We had a heat pump at the old house.)

5) When replacing the a/c, what should I be asking about/looking for when I am comparing estimates? I will ask about quieter outside units (but I wanted some information from people who were not trying to sell me something).

I want whatever solution I choose to last for next 10-20 years. Any advice?
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Old 12-28-00, 04:11 PM
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Sounds as though you may just have alot of minor problems that need to be adressed by a pro.
1. Is your duct work in the slab or in the attic?
2. When was the last time blower motor was oiled? If it's squealing do to non-service, replace it.
3. Noise may just be a loose rain sheild that covers outdoor fan motor. They tend to slip when they get old and make noise. Or could be compessor noise to, but check the simple stuff first.
4. Most heat exchangers in furnaces are under warrenty for at least 10yrs.
5. You need to find a reputable company. Not the ones who did the bad coil. When you talk to companies about the equipment they sell be informed. Go to the web sites of Carrier, Trane, Rheem, etc. for info.
In the past ten years how often do you have your system serviced? Not including when something is wrong. Going high effeciency will require knoledgable service, just like your car.
Old 01-03-01, 07:18 AM
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The duct work is in the attic.

I think that the blower motor was serviced at least two years ago (probably three). As you can guess, the same company who did the a/c repairs serviced the unit. Since everytime they came out for maintenance they always found something big wrong, I quit calling them as often.

The guy who built the house never serviced the system as far as I know (he did not even have any kind of filter in place at the intake). I bought the house in 1993. I know that it was 3 to 4 years before I had it serviced (lack of knowledge and experience on my part).

After I posted my query, I went searching further on the web and found some specific information on heat and cooling units (I happened upon this site first).

I found a list of questions/requirements for the company who would replace/service the unit. One of the questions/comments is that any company that is giving an estimate to install an a/c unit should inspect the venting (for holes, leaks, is it adequate). It makes sense to me. Comments? Any other suggestions about things to ask?

I recognize the need to find a reputable and reliable company to service the unit on a regular basis. (I have been asking around, but gas heat is not as common here.) Thanks for the info!
Old 01-03-01, 03:30 PM
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First and foremost, require the installing company to do a heat load calculation on your home and you'll want to see it. That is the only way to do a job correctly. Yes you are in heat pump, oil country.

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