4 ton unit VS. two 2 tons units

Old 11-21-04, 03:21 PM
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4 ton unit VS. two 2 tons units

I have a two story home , with approximately 2500 sq.ft. I am thinking about replacing the old 4 ton heat pump unit.
Question........ Will i be better off if i installed one 2 ton unit for the upstairs , up in the attic and then one 2 to 2 1/2 ton unit downstairs in crawlspace or shall i just stick with the 4 ton unit that is already there?

Thanks in advance and Happy thanksgiving to all.

Old 11-22-04, 04:18 PM
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you would have better temp control with 2 units, however a zone system may be the answer

2 tstats, one up one down to contol the unit and dampers for each floor. much cheaper than 2 units, we do it all the time, good setup
Old 11-24-04, 07:29 AM
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4 ton Vs 2 2ton units

Thanks for your reply. Any recommendations as to what brand and possibly what SEER i can go with the two zone system?

Thank you again and Happy Thanksgiving
Old 11-24-04, 08:47 AM
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Put 2 units in for sure. Much better control over the temp .
Im not to hot for zone dampers. Why have a 4 ton running when its just for one zone, yes there is a bypass damper. Could go to a two strage compressor. But when you have 2 units and one goes down you till have some back up till its fixed. Put out lets and a return in the crawl space. poly down on the ground and insulation on the wall .Put a R19 in each joist space all around the home on the sill plate close all vents to outside.

Old 11-24-04, 03:22 PM
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Two units will be more expensive upfront, but long term energy costs will be lower.

There will be ductwork required for the new system, and that cost could be substantial.

Don't forget, the additional unit will require an air handler, indoor coil, lineset, condensate drain, etc.....

It may be slightly more cost effective to retrofit the ductwork in the crawlspace, if the first and second floor systems can be somewhat easily separated. In any case, the crawlspace ductwork will need to be modified so that it does not supply air to the second floor if an attic system is installed.

If you do not have temperature issues between the first and second floor, then I would stay away from the zoning stuff.

Improper air delivery and poor duct design and installation are usually the cause of temperature differences.

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