Line Size for replacement

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  #1  
Old 07-14-06, 05:02 PM
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Line Size for replacement

Hi,

I'm replacing a 10 SEER 2.5 ton HP/handler with a 13 SEER 3.0 ton unit. The lineset runs ~55 ft and is currently 3/4 and 3/8. The new unit calls for 3/4 and 3/8 if 25-50' and 7/8 and 3/8 if 51-75'. The height differential between the HP and handler is about 20'

So technically, I should increase the lineset size. However, this will be a bit of a pain to run up the side of the house, run through the attic, etc.

I think I have the following options:
1 - replace the existing line set with the proper size
2 - use the existing line set
3 - use a combination of old / new

For #3, I am thinking of running the new 7/8 line about 30' under the house (from the HP to the wall where it goes up), then using the exiting 3/4 line up the wall. In the attic, I would again use the 7/8 from the wall to the unit.

Any thoughts on this?

Thanks.
 
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Old 07-14-06, 05:12 PM
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If you're gonna keep any of the 3/4" you might as well keep it all. It will do you no good to only do part of it properly. I don't think you'll lose much efficiency by staying with the 3/4" anyway.

Are you having a pro do the evac and release of the charge ?
 
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Old 07-14-06, 10:53 PM
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Wink

You say the lines are 55 ft. My chart calls for 7/8 and 3/8 for 50 ft on a 3 ton. That dont even count the 90o L's you will have in it. So I for sure would go with your #1. Dont know if they do it there but we bend up a small sheet metal U duct and put that over the line comeing down the outside of the home and paint it.You dont say where you are .If south Id go for a seer of 15
The way fuel cost are going
ED
 
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Old 07-15-06, 08:32 AM
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Thanks for the advice. The current 3/4 does not have any sharp elbows. When they originally did the lines, the did a gradual bend to go up the wall, so it is 90 degree bend, but not like a sharp 90 elbow that I've used in plumbing.

I have an HVAC contractor friend that will braze the lines, charge the system and check everything prior to startup.
 
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