New ac system to be installed...help on selection

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Old 12-15-13, 12:09 PM
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New ac system to be installed...help on selection

Hi, I'm starting to shop around to have a new ac system installed into my house. Currently use two 8,000 btu, 9.5 seer window ac units and have no ductwork. I have a 1800 sq foot split level house and see no need to cool the lowest level, only the bedroom level and living/dining/kitchen level. The rec room level is very cool in the summer. I have access to both above and below these floors, however I don't see a good way to run ductwork from below without lowering the already low drop ceiling in the rec room level.
I did some research on attic mounted air handlers, and find there will be significant loss just by installing the ducts and air hander up there.

Do I have any other options?
Any suggestions on the latest systems, like which system is the best to install?
 
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Old 12-15-13, 12:26 PM
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There is also mini split units. Many people hate working on these because of tight working conditions and high potentially lethal DC voltage and lack of measurable analog control signals between components, but they are very efficient.

I had a class instructor tell me that the high DC voltage to inverter compressors will stop your heart instantly instead of knocking you off like AC voltage. I hope to never test this statement.
 
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Old 12-15-13, 12:33 PM
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I was originally going to install one of those, but I like the idea of having a return with a filter for the entire house. It should reduce allergens and dust. The split system reminds me of my window units where the filter is crappy and the dust somehow gets around the filter and into the coils.
 
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Old 12-15-13, 12:38 PM
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Service calls will take longer and cost more as well.

Are you considering a heat pump for the attic or a gas furnace?
 
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Old 12-15-13, 12:43 PM
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No to both. I heat with a wood stove and a system 2000 as a backup. Radiant cast iron baseboard.
 
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Old 12-15-13, 12:46 PM
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Also no gas available, oil only.
 
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Old 12-15-13, 12:53 PM
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There should not be anymore efficiency lost for an attic system than for a crawl space. Think u need to keep reading
 
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Old 12-15-13, 01:58 PM
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Basement is cool in the summer, while the attic is very hot. Surely there is some loss due to the equipment sitting in a hot space, no?
 
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Old 12-15-13, 02:30 PM
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Most houses in the Houston area have the furnace and ductwork in an attic.
Basements are very uncommon except in some older homes in River Oaks.
 
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Old 12-15-13, 02:41 PM
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I'd say almost every new home back in coastal VA had the A/C-furnace in the attic. Very few basements unless you were on a hill somewhere. Sure there is some loss due to the heat up there, but well insulated ducts and proper installation minimized it. Small amount of warm air on initial start-up, but no big deal.
 
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Old 12-15-13, 04:24 PM
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Any suggestions on which system? I see there are 2 stage compressors an variable speed ones. Both sound really good compared to older single stage versions.
 
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Old 12-15-13, 06:36 PM
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No Pro, but I've only heard/read about issues with the variable speed fans. Might have been corrected by now.

Don't think I know anything about variable speed compressors.
 
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Old 12-16-13, 06:06 PM
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I would never go to OIL; I'd go with Propane.
I've had both & for many reasons, prefer propane.

Make sure it is installed properly & orifices feeding the manifold changed, from natural gas, to propane; and pressures; Inlet pressure to the propane gas valve regulator set according to instructions...

If you go with a split system with a duct system; Way oversize the Return-Air Filter areas...

Do a load calc for sizing the equipment: HVAC Load Calculation - Whole House Loadcalc
 
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Old 12-16-13, 06:56 PM
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I have oil heat and cannot change.
I will run the load calc and see what I come with.
 
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