AC Line Set Diameter question

Hi All,
I'm not sure our HVAC subcontractor (chosen by our contractor) is installing the proper diameter line set and I was hoping someone would know what the correct diameter is. We are adding an all new system (2nd zone) in the attic and I lost confidence in the contractor when I heard the price (and his justification for it) for replacing the older condenser and coil in the basement system.
Anyway, the condenser is a TCA230AK - Tempstar 2200 2.5 ton 12 SEER (13 SEER with matching coil) and the run up to the attic is about 70 feet with a 20 foot rise and 5 90 degree bends. (Have I learned enough searching through old posts in this group in the last 24 hours to at least ask the question properly?) I believe the two lines he's using are 3/4" and 3/8" but, I could certainly be off by 1/8". I've seen references to 1 1/8" lines for longer runs on some equipment and this definitely isn't that large.
Is he using the right size? Are there any other important installation issues I should be aware of?
Thanks in advance for any help.
-Incabloc
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You would have to reference the installation guidelines for that unit and I don't have them handy. A comparable unit in the brand I sell recommends 3/4" up to 50' and 7/8" maximum for long line applications. You would likely never see 1 1/8" on a 30,000 BTUH unit. The 3/8" line is correct regardless.
- Robert

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First, you are not going to get 13 SEER unless you use a 'Variable Speed' air handler!
Second, the oil charge is only good for 50', and the 3/8 - 3/4 line set is good for up to 75'.
What's the numbers off the coil and furnace/air handler? (get me those and I'll get you the actual SEER rating)
~kjpro~

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The coil EPM36B15CZ/Internation Comfort Products (Tempstar's parent company right?) and the furnace/air handler is Tempstar/T8MPN075B1ZA1 (hard to read the furnace number since it was underneath and only a few inches off the floor). I noticed the furnace has an AFUE of 80 is this reasonable for a suburban NYC area home (reasonably cold for 4 to 5 months a year). This unit is heating/cooling about 1400 sq. ft. - 4 bedrooms & 2 baths and laundry room.

Excuse my ignorance but, if the charge is only good for 50' does that mean the installer has "add charge"?
If the 3/8 - 3/4 is good for 75' does that mean a 75 foot run of actual tubing with or without bends or do 90 degree bends add extra "length" to the actual length?
Thank you very much for the info you've already provided.
-incabloc

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Comments inserted:

First, UT (United Technologies) owns ICP (International Comfort Products) which then markets several brands... (Tempstar/Heil/Arcoaire/Comfortmaker/Air Quest/Keeprite/Etc......SAME EQUIPMENT!)
The figures you have been told are WRONG!!
The TCA230AKA condenser, EPM36B15C piston coil, and regular blower with blower delay timer is rated for 11.0 SEER! (BTW, In my opinion.....this is a stupid combination!) The only way to get more is to use a TXV coil and a Variable Speed blower.
It'd be cheaper and perform better if you used a 10 SEER condenser with a TXV coil. (living in NYC, you are not going to see a great deal of savings by using/going to a 12 SEER unit) Pay off would probably be in the 12-15 year range to start saving money in operational costs.
Then the 80% furnace is another BAD choice! If I'm right you use heating the majority of the time, and this is where you want the most efficiency you can afford. And the 92% is not a major upgrade. And you could very well see a savings in little as 2-5 yrs easy. I live in a warmer climate than you and haven't installed a 80% in like 1 1/2 - 2 years now. (home furnaces that is)
But, one thing I think is being missed totally is a load calc, this is a calculation that is performed to size the units according to your homes particular needs. (as I feel the 2 1/2 ton ac is larger than you need, this is a guess as I haven't done a load calc on your home either) E-mail me a copy of the prints and I could give you a quick calc to see if it's even close. (need the layout, measurements, windows, which way the house sits, low/high temps, home winter/summer temps, insulation R values....)

If the line set is over 50', they have to add oil per the install instructions. (which gives the amounts to add)

90's add to the overall length of run. So, this means in order to achieve the rated SEER the suction line size has to be increased.

Where did this contractor come from? (Lowest Bidder??)
~kjpro~

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kjpro,

The contractor hasn't actually given any figures - I've been spending the last day or so trying to figure out if he knows what he is doing and I saw the Tempstar 12SEER condenser (13 with the correct coil according to Tempstar's web site). The general contractor picked the hvac contractor and my wife and I don't feel he's doing things right. We got suspicious when we got a price of about $4500 to replace the downstairs condenser and coil in an existing system. We're still not sure if the hvac contractor gave a high price or if the general contractor marked it way up.

We live in the burbs outside of NYC. Summers are warm and humid more often than not and A/C is used about 4 months a year. If we install a 13 SEER unit (not sure if that's a simple rating off of the condenser or the whole system's actual rating) we get a $300 rebate from the electric co. so, payback may be sooner if the extra cost isn't too much more for 13 vs. 11 SEER.

The unit is in the attic and we were told that the high efficiency units use water lines that can freeze in the winter. This sounded a little strange to me but I believed what I was hearing. Is this a bunch of bull? Winter temps rarely go below 0 degrees F but occasionally they get into the negatives.

I love to but I don't have any prints and I really don't want you to go to that much trouble. I can see what I really need to do is tell them to STOP and have another contractor (of my own choosing) come in and evaluate the situation.

Is there an easy way for me to tell the difference between 3/4" and 7/8"? I saw in another post that a penny is 3/4" diameter and it appeared to be the same size as the tubing but, I don't know how easy it is to see a 1/8" difference.
Thank you VERY much for the quick and informative info. I really appreciate it.
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Post a link to Tempstar's site that says it's a 13 seer rating with a matching coil. (for I'm a ICP dealer and their dealer site says NO, unless TXV & Variable Speed Motor)

Then the 12 SEER unit is probably not a wise choice. (all depends on electricity rates and usage)

92 % in my opinion, some areas require the unit to be in an inclosed room in the attic. (all depends on the area)

Would be a wise move. Make sure the company did a load calc!

Measure the outside with a tape measure, the OD is the size of tubing. (yes a penny is 3/4 while 7/8 is between a nickel and a quarter)
And the outside insulation on the line should also have the line size marked on it.
~kjpro~

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Here's the link:
http://www.tempstar.com/its2200ac.html
Please keep in mind I just assumed things were simpler than they really are - I've learned alot in 48 hours. I guess the 13 SEER is a best case. Is the combo he chose really bad? We did tell the general contractor we wanted a quiet condenser. According to Tempstar's site the 2200 is quieter than the 10 SEER units (2000 series I think). As long as we've got the 12 SEER condensers we should certainly have the most efficient coils to go with it, right? Is a variable speed motor an option on an 80% furnace?
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See previous post, they assume the best equipment used.

Correct.
My opinion, YES.

12 SEER....2 1/2 ton....72 db
10 SEER....2 1/2 ton....74 db
And if you find out that the unit is over sized the smaller units are quieter yet.
10 SEER....2 ton....72 db 10 SEER....1 1/2 ton....70 db
All of these units are pretty quiet, I wouldn't let that lean me one way or the other.

If you want to gain the efficiency you spent the money on the condenser for, YES. (otherwise, you should go with the 10 & TVX, same SEER but less money, and better coil control)

Yes, instead of a T8MPN it's a T8MPV....V or 'Variable Speed' option.
~kjpro~
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Never mind, they have it on their regular site....
'up to 13 SEER with the proper inside coil'
That in real life means.....this is the HIGHEST rating they can achieve out of this unit using the highest quality units available to match up to it!
The real facts are that this unit is usually as follows....
11 SEER with piston coils 12 SEER with TXV coils 13 SEER with TXV & Variable Speed Blowers
The fact is that most people don't have VS Blower, so there goes the 13 out the window. (but they use it for marketing)
~kjpro~
BTW, I still say you are better off with a 10 SEER & TXV.....for 11.0 SEER unit. (saving the upfront cost that are going to probably take 12-15 yrs to payback)
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How about the 80% furnace in the attic - if it turns out a 92% requires an enclosed room I'd like to know if there an option on the 80% furnace for a VS blower? If so would it sounds like that would be worth it.

How much extra is TXV and VS? If the $300 rebate covers a reasonable amount of the extra cost I'd certainly do it.
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Variable is avail in the 80, but if you don't plan to run the blower constantly, I wouldn't opt for it. (the 1 extra SEER just isn't worth it, in my opinion)
One thing for sure, if you go with VS Blower make sure you get a 10 yr parts & labor warranty. (for the VS motors are very salty to replace if it's not under the standard 5 yr warranty)
92% on the other hand is going to save you 12% in fuel cost, this is a major savings.
What's your heating fuel cost per year? ($12-1500?)
If so it's going to save you roughly '$150-200' a year.
~kjpro~

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Always remember those kinda estimates assume no inflation in future energy costs--a worst case chrystal ball sort of proposition, unless energy prices somehow plummet, which is fairly unlikely.....
--

SVL



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Very true, I just don't think if something has a 10 yr payback that it is worth it. But, one never knows what inflation is going to do and how quick it's going to do it.
But one thing is for sure, he needs more efficiency on the heat side than on the cooling. (for the heating is the more used appliance in his area)
~kjpro~
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Agreed.
And it just goes to show how much difference it can make where you are located......there are few rules of thumb that pan out everywhere.
--

SVL



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It was too late and too dark to check the line set last night but I looked this morning and it's definetely 3/4". Thanks for the tip about the diameter being written on the insulation - I kept looking at the tubing itself.
-Incabloc
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There should be a book that comes with the equipment. At this point, it sounds good to me.
--

Christopher A. Young
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