Carrier AC systems using Puron

It has been almost a year to the day since we replaced our 2.5 ton unit that services the down stairs living space in our home, and now the upstairs unit has taken its last breath so it is time to replace it.  Both units were the original TRANE systems that were ‘state-of-the-art’ back in the 1970s, so we definitely got more than the average lifespan out of them.  We attribute that not just to the quality of the units, but just as much to the regular maintenance of the overall systems.

The new unit installed is a Carrier Model 24ABC6 which is a 2 ton units with a 14.5 SEER rating that matches the 2.5 ton Carrier Carrier 24ABB servicing the ground floor.  We live in a 1,5 story home so the three bedrooms, game room, and full bathroom upstairs is about half the square footage of the main floor.  It makes good sense especially when living below the Mason-Dixon line to zone the house as much as possible to provide cooling where it is needed without throwing away money by cooling areas that are mostly unused.  When the house is mostly empty from 7am to 5pm during the weekdays, we use the ‘schedule’ feature on our Honeywell FocusPro TH6000 Series programmable thermostat to set the temperature to about 85 degrees during those hours.  The only time it will kick in is if we are having some extreme heat.  However, the same setting for the upstairs unit will have it running more often because of the nature of heat rising.  That’s when you really appreciate having a smaller unit to service the areas that are needed because the power consumption of a 2 ton units is almost 1/2 that of the 2.5 ton system.

Electric powered Heater/Blower

The house was custom built back in the mid 70′s and the original owners were very quality conscious which is evident by most of the building materials used, yet it is obvious that the upstairs air conditioner was an afterthought from the original design. The gas line for the furnace that is used  for the 2.5 ton units was not extended to the attic to service the 2 ton unit and to try and retro fit a gas line to that area would be costly and somewhat dangerous.  As a result, the heating portion of the original Trane system as well as the new Carrier system we installed is powered by electricity.  Not the optimal solution by a long shot, but given our set of circumstances it is the best solution for us.

Lastly, since we had to tear apart the old unit and everything that was connected to it, we felt that this would be the ideal time to replace the ducts.  We decided to go with the Thermaflex product with fiberglass insulation with an R-6.0 rating which is a step up from the standard R-4.2 that is used in most new construction.  The higher energy rating means moe insulation and less energy loss through the ducts in that steamy attic.

Flex Duct Installation

Here is what a properly installed duct job looks like when it is completed.  Here we see liberal use of support straps to prevent the ducts from making contact with any surfaces to minimize energy loss.

Poorly installed flex duct

Here is another picture found on the web of a poorly installed duct job.  There is a serious kink in the line which obstructs air flow and the duct is actually touching the roof at one point which will transfer heat into the duct by contact and further degree the cooling capability.  I shudder whenever I look at it!

All in all we are very pleased with the job we did and the overall system performance.  The one thing that you can’t control when buying a new air conditioner is the noise level.  Some will run loud and some will run quiet…it’s a crap shoot.  We got lucky with this one.  I can’t even hear when it kicks in!

About a month ago as the temperatures were sustaining in the 100+ range here in Texas, we noticed that our 20-year old Trane system was running for about 5 minutes, cutting off for about 2 minutes, thn kicking in again.  The temperature was getting down to the 81 degree setting on the thermostat (…you see Mr. Obama, not everyone sets their air conditioning to 78), but the humidity was never getting below 50% because the unit didn’t run long enough to effectively bring down the humidity.  Basically it was short-cycling.  Now, we’ve never had this problem in the past so we ran a full perventative maintenance on the system and found that the freon level was down about 20%, but mostly that the clutch on the blower motor was starting to fail.  It was drawing some serious amps in order to kick in.  I could only imagine what the electricty bill was going to look like for this month!

Even though the Trane unit was still working, we decided it was time to get serious about replacing this old unit before we experienced an outage and at the same time, reduce our electricty bill.  Another thing that factored into our decision was that the adjoining central heating system was one of the old pilot light jobs that have been phased out some years ago due to safety concerns.  We contacted a couple of home air conditioners installers who quoted us on a new central air conditioning and heating systems and we finally settle on a Carrier 24ABB4 (14 SEER Rating) split system with Puron refrigerant, and a Carrier 58STA/STX heater.  There were more energy efficient systems available with a better SEER rating that would quality for the new tax rebate, but we could not justify the increased cost vs savings.  The system we chose will give us the best bang for the buck.

Now that we’ve signed on the bottom line and scheduled the installation date, all that is left is the perparation.  In the next post, we’ll tell you all about the installation process and the decisions we needed to make along the way.