Need help to decide which Central AC to get

[dcl2008]

Hi, I need help with deciding which Central AC unit is a good match with my existing furnace. The existing equipments are all Ruud. The old condenser and coil are UAKA-042JAZ and RCBA-4882GG21. The AC is 7 yr old and the compressor has failed. The refridgerant lines are 5/16 liquid and 3/4 vapor. The indoor unit is up in the attic and the outside unit is ground level. The vertical seperation is about 26 ft and the total travel length is about 56 ft. The existing furnace is UGPH-10EBRJR which I like to keep to reduce cost of the replacement.

A couple of contractors did manual J calcaulation and recommended a bigger unit (4 Ton). This unit is for upstair. There is a 2nd HVAC unit for downstair and that unit is still working fine. The upstair area is about 2100 sf. However, the foyer and family room are two-story high; so the heat from downstair goes up to upstair. The family is open to the kitchen. The family room is 323 sf and the foyer is about 170 sf. The upstair hallway overlooks the foyer and the family room. The main return of the HVAC unit is in the hallway. There are smaller returns in 3 of the 4 bedrooms. The bedroom that does not have a return opens to the part of the hallway that has the main return (this is the biggest return). The unit is in the attic. The following are the proposed replacements that I got from various estimates. It will be great if you can tell me which is the one that is good for me.

Ruud UAND042JAZ and RCFAHM4821, use existing lines

Carrier 24APA5-48-3 and CNPVP4824, use existing lines

Carrier 24APA5-48-3 and CNPVP6024, new lines

Carrier 24ACA4-48-3 and CNPVP4821, new lines

Carrier 24ACA3-48-3 and CNPVP4821, new lines

Carrier 24ACR3-48-3 and CNPVP4821, new lines

Trane 4TTX4042 and 4TXCB048BC3, new lines

Lennox XC14-042 and CX34-49C, new lines

[beenthere]

When the unit worked, did it cool ok.
None of the units are actually better then the other.
I don't think any of those units ae approved for 5/16" liquid line.
I would use one of hte ones planning on replacing the line set.

[dcl2008]

The air conditioning was a little weak when it was working. The two rooms facing south-west are the worst. There was no return in those two rooms. I added the returns in those two rooms and it got a little better. Any one of the proposed configuration works best with the existing furnace? Thx.

[beenthere]

They should all work fine with your existing furnace.
Post your furnace mod number and someone should be able to verify the blower size.

[BaldLoonie]

The RAND does allow 5/16" on the 3.5 ton but your vertical separating is about 10' more than allowed. Probably not enough to prematurely kill the compressor but it is outside of what Rheem approves of. I wouldn't do it with Carrier.

Looking at your other choices, remember the "15 SEER" Carrier won't get 15 without a variable speed blower, actually gets 13.50 as does the "14 SEER" unit quoted. The 14XLi Trane is only 13 SEER with standard blower. The Lennox XC14 really does give you 14.00 SEER.

The RAND is a nice unit. Copeland scroll plus high & low pressure protection, well built, fairly quiet. If you want to save some bucks, you can keep your existing indoor coil and have the dealer install a factory expansion valve kit on it. That would be a Rheem approved match getting 12.80 SEER instead of 13.00 with the new coil. The current coil is much less restrictive than the new ones for better airflow.

[dcl2008]

The existing furnance is UGPH-10EBRJR.

[dcl2008]

The RAND does allow 5/16" on the 3.5 ton but your vertical separating is about 10' more than allowed. Probably not enough to prematurely kill the compressor but it is outside of what Rheem approves of. I wouldn't do it with Carrier.

Looking at your other choices, remember the "15 SEER" Carrier won't get 15 without a variable speed blower, actually gets 13.50 as does the "14 SEER" unit quoted. The 14XLi Trane is only 13 SEER with standard blower. The Lennox XC14 really does give you 14.00 SEER.

The RAND is a nice unit. Copeland scroll plus high & low pressure protection, well built, fairly quiet. If you want to save some bucks, you can keep your existing indoor coil and have the dealer install a factory expansion valve kit on it. That would be a Rheem approved match getting 12.80 SEER instead of 13.00 with the new coil. The current coil is much less restrictive than the new ones for better airflow.

Baldloonie, thx for your help. How about the Ruud RANL? I think it is the same as the RAND, except this one uses the R410a. I has asked the contractor to give me a quote on this one. At the moment, I am incline to have the lines replaced, and therefore consider going to R410a.

[BaldLoonie]

Yea, I see in the other thread Doc thinks the lines should go and he's the one to know.

The RANL is identical except for the refrigerant. It would require the RCFL coil for sure. We've been moving more of them than RANDs lately.

[dcl2008]

Hi, guys. I just want to give you an update on my central AC project. I finally went with the contractor that gave the most detailed estimation and also did the heat load calculation to figure out that I needed a 4T AC. I decided to go with the Carrier 24ACA3-48-A003 and CNPVP4821 for a good compromise between price and efficiency. I would not be able to recoup the extra few hundred dollars that I paid up front for the higher SEER units. The final price that I paid is $xxx (I got 5% off for paying with check instead of credit card). This also includes a nice TP-PAC18 Edge programmable thermostat. The contractor did the installation today. He put in new lines (3/8 for liquid and 7/8 for vapor) on the outside of the house going from ground up to the attic. He also had to install a couple of extra things due to the vertical seperation is more than 20'. The job is pretty nice and clean. This installation also includes Carrier extended warranty for 10yrs, part and labor, on everything. Pretty nice. I guess now I have to wait till the first hot day to see how well this work. Thx for everyone's help.

[RyanHughes]

Did they adjust the airflow to match the new 4-ton A/C?

[dcl2008]

I didn't ask the contractor about adjusting the airflow. But I noticed that there is an extra white box about 4"x4" outside of the furnace and there are wires from the white box going into the furnace. I assumed this is used to control the fan that is in the furnace. I am just guessing.