2.5 ton with 3 ton coil


  #1  
Old 07-30-08, 08:33 AM
A
ADF
ADF is offline
Member
Thread Starter
Join Date: Jul 2004
Location: Canada
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
2.5 ton with 3 ton coil

my neighbour's getting a new unit. they told him it was a 2.5 ton unit with a 3 ton coil. does that mean that the coil that goes above the furnace cools as if it was a 3 ton? or is it something else?

does this cool the house faster? what about removing heat?

pros? cons?

i'm curious to see how to compares with a straight 2.5 ton unit.

thanks in advance.
 
  #2  
Old 07-30-08, 02:07 PM
Beachboy's Avatar
Member
Join Date: Nov 2006
Location: Northeast Kansas
Posts: 704
Upvotes: 0
Received 1 Upvote on 1 Post
It is pretty common to price out an AC system with the next larger coil. The main reason is for slightly better efficiency. I have the exact situation in my house as you mentioned...a 2.5 ton AC with a 3 ton coil. You won't notice any improved performance, but the SEER of the total system will be somewhat improved. I think my contractor said my nominal 13 SEER system would be rated more like 13.5 SEER with the larger coil. The main benefit is marginally improved overall efficiency. I know of no downside, unless the larger coil costs slightly more. The cooling capacity is governed by the condensing unit, so you will get 2.5 tons of cooling, NOT 3 tons.
 
  #3  
Old 08-04-08, 11:19 AM
B
Member
Join Date: Jul 2008
Location: johnson county, ks
Posts: 317
Upvotes: 0
Received 0 Upvotes on 0 Posts
Yeah, it is normal. It just means your designer better know what he is doing or there can be problems.

My 3.0 ton heatpump is installed with a 4.0 ton coil and TXV.
 
  #4  
Old 08-04-08, 12:29 PM
T
Member
Join Date: Jul 2008
Location: Kansas
Posts: 264
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by badtlc
Yeah, it is normal. It just means your designer better know what he is doing or there can be problems.

My 3.0 ton heatpump is installed with a 4.0 ton coil and TXV.
I would be wary of anyone that wanted to increase the size by a ton differential....we install many with .5 ton diff and have had no problems...it should be txv controlled, which all 13 seer that we do, are. The theory that my old boss taught me was that as long as it was txv, the larger coil had more surface area for greater humidity removal and can push up the energy effeciency by a half point. Never tested it with real numbers, but never had a complaint either.
 
  #5  
Old 08-04-08, 01:00 PM
B
Member
Join Date: Jul 2008
Location: johnson county, ks
Posts: 317
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by tinmantu
I would be wary of anyone that wanted to increase the size by a ton differential....we install many with .5 ton diff and have had no problems...it should be txv controlled, which all 13 seer that we do, are. The theory that my old boss taught me was that as long as it was txv, the larger coil had more surface area for greater humidity removal and can push up the energy effeciency by a half point. Never tested it with real numbers, but never had a complaint either.
I don't think 3.5 ton coils are all that common.
 
  #6  
Old 08-04-08, 01:14 PM
T
Member
Join Date: Jul 2008
Location: Kansas
Posts: 264
Upvotes: 0
Received 0 Upvotes on 0 Posts
Can't speak for all brands but Rheem (I install) has an 042 series coil....that's 3.5 ton
 
  #7  
Old 08-04-08, 03:16 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 9,500
Received 68 Upvotes on 62 Posts
I agree that a larger evaporator coil will increase efficiency somewhat because of higher suction pressures.
The downside of this is in a humid climate this efficiency gain comes at the expense of moisture removal.

Lots of ifs as to whether it is worth doing.
 
  #8  
Old 08-04-08, 04:39 PM
Jarredsdad's Avatar
Member
Join Date: Oct 2002
Location: Troy, VA
Posts: 1,392
Upvotes: 0
Received 0 Upvotes on 0 Posts
2.5 with 3 ton coil is not uncommon. I've seen 4 ton Tranes with an option of 5 ton coil.

Bottom line is when designing a system you have to consult manufacturer guidlines and use condenser, evap combos Approved by manufacturer to get the results you need for the specific job.

I wouldn't sweat it too much.

Tell the guy to ask contractor, I suspect he/she will not have any problem providing the spec sheets.

I think this one goes into the "keep a sharp eye out, but don't automatically assume your getting the shaft" file.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: