Need HVAC upgrade, trying to decide between split and central options


Old 05-12-14, 06:07 PM
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Need HVAC upgrade, trying to decide between split and central options


I'd like some advice on whether it would be better to replace my current central AC and furnace combo with a newer, more efficient model, or to switch to mini-split/ductless units. Our current unit is about 10 years old (manufactured in 2003), just depending on when the owners had it installed. Both AC and furnace are single-stage systems. Our house is 2-story and 2037sq ft, with 4 bedrooms upstairs and kitchen, dining, and living rooms downstairs. The first floor has doorways but no doors downstairs, so it's one big open area from a HVAC perspective.

We had a local company come out for a tuneup and they said the contactor was getting pitted and would need replacement soon (supposedly a $290 repair if I joined their monthly membership club, or over $400 if I didn't), that the compressor motor's insulation was deteriorating, and that the overall airflow was very poor due to dirt and debris clogging up the system. The company also said my system was probably originally a SEER 10 but might be operating at SEER 8 or less due to wear and age. They said the ducts still looked ok.

The options I'm looking at now are to replace it with a newer 5-ton SEER 16, 2-stage AC and variable-speed furnace, costing approx $12K installed, or else simply install 3-4 mini-split units in the rooms we use the most (no clue how much that would cost, haven't found a contractor that installs those yet). Living in southern CA, we try to simply open the windows and use fans as much as possible, but it can get very warm in the summer. We moved in last summer, and I remember some very uncomfortable nights as we tried to tough it out in August. Running the AC for only 1 night would add about $10 to our electric bill, and I can only imagine that running it in the daytime would be even more.

That said, I'm not sure we really need central AC/heating as the downstairs remains cool or at least bearable. Instead, we could simply install mini-splits in the 3 upstairs bedrooms and maybe one more downstairs on the off-chance it actually gets that hot. Also, the office bedroom gets sun all day long and is much hotter than the other rooms, so it could really benefit from having its own unit. My understanding is that central AC is much more efficient when cooling the entire house, but I don't think we would do that very often. In our case, where we're simply trying to get one or two rooms cooled, do you think split units would save us money in the long run? What about overall cost, including buying the units and installing them? Is there some way to figure out where the break-even point is between mini-split and central units?

Thanks in advance!
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Old 05-12-14, 08:11 PM
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10 year system is not that old, unless you have extra money that you want to burn, I would not replace the current system now. don't know what brand it is, but usually the average AC life is about 17-18 years in CA. It can be easily cleaned/maintained to boost the performance. 2003 system should be 12 or 13 SEER. To replace contactor is very easy. Its a $20 part which can be put in in less then 30 minutes. I don't like your AC company, call some one else for second opinion. $400 for a contactor or 12K for a 5T AC is simply to high. To answer your question about mini-split. NO, can not compare to central AC, plus you already have the duct in your house for central AC. If you only want to cool part of the house, consider a zoned central AC system. And 5T is too much, for a 2000 sq ft house in LA, 3.5T is enough. ( Also believe me, 4 mini-split is not cheap.)
Old 05-13-14, 04:46 AM
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I dont think 12k is to high. We have know idea whats involved. 1800-2500 a ton here. falls in-line. again dont know whats involved but just put in a 3 zone 9000btu each ductless for 12
Old 05-13-14, 05:30 AM
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Somebody is selling swamp land as prime real estate.

The contactor is $25 bucks, a few screws and it's changed.
Coil cleaner, available at your local big box store is $5/can. You might need 2 or 3.

Total parts $40
Total time 1 hour

The smile on your face when you're done $priceless.
Old 05-19-14, 06:20 PM
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Thanks, everyone, the reason I put in the quoted costs is because I felt like they were way too high, and you guys have confirmed it for me.

I just had another company come out to quote me, and the salesman did say that the $12K system the first company quoted me was a reasonable price, BUT that that system is overkill and I don't need it. In fact, the salesman actually spent most of his time telling me that he didn't think it was worth it for me to upgrade since my current system was still running fine. He even spent the time to calculate out what I might expect to save each year vs how much I would have to spend to upgrade, and yeah, definitely not worth it. I'm very pleasantly shocked at his integrity.

Ok, so anyone here have a good rule of thumb to know if using a portable floor AC is a good way to save money over central if you're only trying to cool one area in your home? When I'm at work during the week, my wife is hardly ever upstairs, so we're thinking about using a 12.5KBTU unit to just cool the kitchen area during the day. The unit costs $370, though, so I'm wondering how long it'd take (how many hours of usage) to actually save back that investment.
Old 05-19-14, 06:44 PM
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Downsides of a portable unit when compared to central is the portable is obnoxiously noisy and far less efficient. If you use a portable you really need to use a two-duct model or you are exhausting a fair amount of conditioned air while drawing in unconditioned air from the outside. Further, the ducts need to have additional insulation or they will radiate heat into the area.

Will you save money running a portable instead of the central? maybe, but definitely at the cost of comfort throughout the rest of the house. In a huge mansion it may be worth it but in a reasonably sized single family house it is doubtful the savings will amount to much.

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