zoned hvac vs add'l unit

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  #1  
Old 04-21-01, 01:05 PM
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I have an all-electric 1 1/2-story house with an uncomfortable (hot in summer) upper floor. Upper has half the square footage of the bottom floor. I dutifully got 4 HVAC bids: 2 suggest buying an additional unit for the upper floor, 2 say create 3-4 thermostat-controlled zones using just the existing unit (which is big enough for the entire house's square footage). They're all pretty set in their beliefs (and think the other way is plain wrong).
The costs are near equal, so I need to decide which way to go. What are pros and cons of zoning the heating/cooling with one unit versus adding an additional unit? Are there situations where you would definitely go one way or the other?
Thanks for any help you can give. It's not the kind of decision I want to make a mistake on.

appreciate it,
itzjack
 
  #2  
Old 04-21-01, 03:21 PM
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itzjack

Keep in mind that a/c does two things.It cools BUT also dehumidifies.About 2 months ago some contacted the forum.Problem...house cool but clammy.Seems a/c install was too large for application.Althought temp was at 72 the unit did not run long enough to dehumidify.SINCE YOU AND THEY STATE unit is large enough to cool your home I would go with the zone set up.PDF
 
  #3  
Old 04-21-01, 03:51 PM
fjrachel
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Extra input

Zoning a home should cost about half the price of installing a new system. We're talking sheet metal, low voltage control panel and electric dampers.
Adding a new system is adding a new system. Condenser, air handler/furnace, vents, sheetmetal,etc.
Also remember, if all zones are calling your house should cool. Since you say it does not, then zoning is not an option.
What is the sq. ft. of the house and what is the a/c size? Is all the ductwork exposed, i.e. basement? Give us some technical information.
 
  #4  
Old 04-22-01, 05:00 AM
PDF
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I missed something,somewhere

Itzjack.You stated unit is large enough to cool entire house.Do you at this time have supply vents upstairs?Do they supply a/c?Like I said from your original it sounds as if your upstairs has no cooling supply.Please advise.PDF
 
  #5  
Old 04-22-01, 01:42 PM
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Smile zoning hvac vs add'l unit, thx/clarification

Appreciate the replies, fjrachel and PDF. PDF's point about lack of time to dehumidify is a great one. Thought about an oversized system cycling on and off a lot more, but not the lowered dehumidifying. Thanks!
You'd asked for some technical info . . .
Home is on a slab in central Arkansas; conditioned space on 1st floor = 1500 sq ft, 2nd floor = 700 sq ft, bonus room above garage = 300 sq ft for a grand total = 2500 sq ft. ALL OF THIS is being cooled (to varying degrees) by a 5-ton, 10 SEER Lennox unit. (BTW, the electric furnace (strips in the air handler, no heat pump) ate my lunch this past winter, too . . . average $350-$400/month!)
In the current set-up there is no zoning AT ALL, just one thermostat on 1st floor. So, 2nd floor (with some walls bordering attic) can get too hot to sleep even when vents are fully open. 2nd floor and bonus room ductwork also runs thru the unconditioned attic.
If I added a new unit, it would be a heat pump largely using existing ductwork for the upstairs and bonus room; the current unit would become for 1st floor only.
FYI, I'm also adding some insulation on the 2nd floor walls that border the attic to help with heat gain/loss there.
Hope that this info clarifies my situation. BTW, fjrachel, the best zoning bid came in only about 20% cheaper than buying a new unit for the upstairs -- unfortunately for me far short of the 50% difference you mentioned. My bad luck I guess.
Thanks again,
itzjack
 
  #6  
Old 04-24-01, 03:38 AM
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2 ideas

Sanyo,Goodman and other companies make a split ductless heat pump unit.These units mount TO THE WALL and supply heat and cooling.An other option is a thru the wall incremental unit.It can be purchased as a heat pump.These units are used alot by motel and hotel chains.The best thing about these units,you can control individuals temp settings in both areas.Stay in touch and let us know what you decided and how your "added" system worked out.Somewhere down the line someone may ask the same question and we can refer him to you.PDF
 
 

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