Replies

1. 
   scotclarke | Mar 29, 2002 04:13am | #1

   Only if you want to run a butcher shop on the side.!

2. 
   junkhound | Mar 29, 2002 04:26am | #2

   Only way to know for sure is to get the complete specs for the 2 units from York or your dealer (don't think York has full specs on the web, IHS catalog service has them, but it's a fee) and compare the COP for typical temperatures in your area. Forget looking at Seer and that stuff.

   As an example, in the 1-5T range, the Rheem 4T is more efficient that any of the others. Other makers will vary.

3. 
   rjw | Mar 29, 2002 04:36am | #3

   Where are you located?  I don't see 3 tons until houses are around 2,500 -3,000 sq feet, in NW Ohio.  I bet you'd need more in, say, anywhewre warmer.!

   The problem with oversizing is the loss of effective dehumidification.

1. 
   TheoRichter | Mar 29, 2002 04:40am | #4

   Probably shoulda mentioned I'm in SW Florida.4 seasons here, warm,hot,hotter, hottest. My house is south facing to boot. Older house (leaky) little or no insulation. (Will fix insulation and caulk)

4. 
   TLRice | Mar 29, 2002 02:39pm | #5

   123,

   3 tons is a lot of cooling for 1000 sf (2-1/2 is too, for that matter). Modern equiment is much more efficient that something 26 years old. You will not be able to find COP info for an AC unit since it doesn't apply. The SEER rating will tell you something to compare similar units. For instance, a 12 SEER unit is 20% more efficient than a 10 SEER unit, for the same conditions.

   Does the 2.5 T unit run constantly on a very hot day? The difference between 2.5 and 3 is minor and if 2.5 is well suited for your house, the 3 isn't going to be too big. If the 2.5 is already too big, the 3 ton will be worse. Two problems with oversized AC's: the run time during "off peak, high humidity" loadsis too short to dehumidify and the space will be "clammy" and uncomfortable; and the constant cycling of the unit will be inefficient and wear out the equipment quicker.

   What is really important is what is the cooling load on your house? Without that info, nobody can tell you what size AC you need.

   Another question for the company doing the work: "Why can't you fill an order properly?" If they think there is no difference or cannot tell the difference, they have problems.

1. 
   junkhound | Mar 31, 2002 02:48am | #6

   "not be able to find COP info for an AC unit since it doesn't apply"

   HUH? -- you mean my Thermodynamics prof (and textbooks, and Trane manual, etc.) are spouting BS and last year's Rheem spec sheets were made up for AC??  The rest of your post is right on.

   IMHO, SEER and HSFC are mostly meaningless numbers for marketing people and gov. bureaucrats to tout, had a heck of a time last year finding out the specific test parameters to get to SEER et. al.  As a specific example, if you buy by SEER for cooling but need winter HP operation also, a 4T Rheem 10 SEER actually is MORE efficient than a 12 SEER in the 30 F to 52F regime, so in some areas the 10 will show better than 12 over the entire year if you run all the basic numbers yourself.

   Edited 3/30/2002 7:49:21 PM ET by JUNKHOUND

1. 
   MarkH64 | Mar 31, 2002 03:08am | #7

   Three tons is three tons, no matter what the efficiency of the unit or how old it is. I can say it sounds big enough for sure though.

2. 
   TLRice | Mar 31, 2002 06:37am | #9

   JH,

   What I mean is that COP applies to HPs not AC only units. At least not that I've seen, but I'm always willing to be educated by someone who has more than I. COP also applies to chillers, but that's not what we're talking about.

   Edited 3/30/2002 11:48:03 PM ET by Tim

1. 
   4Lorn1 | Mar 31, 2002 10:47am | #10

   I'm no expert in AC but if it was my house I would get a second opinion on the cooling load calculations and AC sizing. Check with your power company. The ones in this area will do an energy audit for free. The last audit I saw was quite detailed, they included all the worksheets, and gave an unbiased opinion for comparison.

   If necessary get another contractor. Some contractors may do the analysis for a nominal cost. Handling the second analysis on the QT may be best. I would think a reputable contractor would not be overly miffed. If he gets rude I would toss him out. I think I would rather deal with an angry AC contractor than have to live in a damp, clammy, house and pay extra money to the power company every  month for the privilege of having an oversized AC unit.

2. 
   JeffOps | Mar 31, 2002 11:06am | #11

   Onlyest time I ever saw COP applied to HP and AC was when cousin clem was hiding some of that marijeweenie stuff in the ductwork down there at wal-mart.

   You know, they almost throwed him in jail. I don't really understand why. Sales in the junk food aisles more than tripled. And nobody was fighting over shoes in the women's shoe department anymore.

   Whattaya mean, I can't be three people at once ???!!?

3. 
   junkhound | Mar 31, 2002 03:19pm | #12

   Tim:

   Wasn't trying to criticize, only trying to make the point that over the last 30 years, engineering terminology has been so badly corrupted and dumbed down by marketers and bureaucrats that it's hard to get real technical data on retail items.

1. 
   TLRice | Apr 01, 2002 02:28pm | #13

   I don't have 30 years of experience in HVAC, but I know what is available in all the engineering data that I use regularly. I do not specify Rheem products and seldom see submitals for Rheem. Never see COP listed. If you want it, you have to calculate it. I do not know the details of how SEER is determined. So are you an HVAC installer, designer, contrator, or what?

2. 
   junkhound | Apr 01, 2002 03:18pm | #14

   Tim:

   I'm an aerospace engineer. See one of Ron Teti's thread on who I used to be. You are absolutely correct in that you have to calculate COP in most cases, which was my point.

   Not in the HVAC business but have installed HVAC on volunteer basis in churches/private schools, relatives homes, etc. Have been part of teams that built Environmental Control Systems (HVAC is called ECS in the aerospace arena, everybody has a different terminology) for a few large military systems.

5. 
   lux812 | Mar 31, 2002 04:48am | #8

   What about the duct work is it big enough? is the air handler did you get a Matching indoor coil ? How bout a heat loss heat gain run on the house ? that will tell all

6. 
   billsky | Apr 15, 2002 03:46am | #15

   Hi 123,

   I got some news for you if it's not too late.  I have 1200 sq foot home.  It was always uncomfortable.  I had the thermostat set on 70 to make me feel like I had air condition.  I had a 3 ton unit with seer of 8.  It short cycled and never got rid of the humidity.  It is a older home I have 6 inches of insulation in the ceiling, and 4 inches in the floor.  No insulation in walls.  I just had to replace it because no parts are available.  The unit had a stainless steel heat exchanger.  The galv. flue box kept rusting out.  Put a new 2 1/2 ton unit in and am comfortable at 75.  The installer corrected many items that should of been done on the first installation.  They used some type of masking liquid and closed off someleaking return items.  They insulated the return. No more short cycling.  New unit is 12seer.  Hope this helps.  Larry

   
   

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   Edited 4/14/2002 8:51:07 PM ET by Larry