General Question

[kwken]

Hi All, I have a 20 year old Lennox 5 ton system That was installed new for me. The compressor has given up the fight according to a repair man I had look at it. I am pretty up on this stuff and I believe it is true. It has been a good unit and we are happy with Lennox. My question is what are the developments in the newer units to make them have a high seer rating? I know on my pool equipment they have made dramatic improvements in the efficiency and assume this is the same. Do they have variable speeds or larger cooling fans on the compressor? Just interested in the reason for greater efficiency. Thank you for your thoughts. I hope I am asking the right area of this forum. Ken

[hapomodi]

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[jpsmith1cm]

hapomodi

This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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[pacnw]

basically, the efficiency comes from larger surface area to dissipate the heat, this means larger outdoor unit and usually indoor coil.

some do have more efficient motors, DC. fan blades are no larger, usually.

some are multi-stage, usually 2 stage unless you get into inverter technology/units.

[carmon]

xc-14 my personal favorite.... quiet and wont break the bank.....

[timjimbob]

Not what you asked. But spend money on a tighter and adequate duct system before paying more for equipment.

20 years ago, duct system was given very little thought. Studies, I've heard, suggests 30% of AC is lost through leaky ducts.

[motoguy128]

Don't forget ot get a load calculation done. IF you've made any energy efficeincy improvements to your home in 20 years, you might not need a 5 ton unit. Maybe jsut a 4 ton. Smaller is better. It pulls the humidity down better (humidity removal on the new system generally is not as good as the older system because of coil size) and longer run time make ht unit more efficient. Sort of like driving short trips in your car and letting the engine cool off each time. It's also possible the systme was even oversized 20 years ago. Finally a smaller unit will use less energy on the same size ductwork, and be much, much quieter. But you need a load caluclation done to determine what ht right size is. Honestly is a 20 year old unit was keeping up even on the hottest days, a 4 ton is likely plenty. Unit lose up to 20% capacity in hot weather from dirty, bent fins on the coils and the age of the compressor.

[udarrell]

Hi All, I have a 20 year old Lennox 5 ton system That was installed new for me. The compressor has given up the fight according to a repair man I had look at it. I am pretty up on this stuff and I believe it is true. It has been a good unit and we are happy with Lennox.

My question is what are the developments in the newer units to make them have a high seer rating? I know on my pool equipment they have made dramatic improvements in the efficiency and assume this is the same. Do they have variable speeds or larger cooling fans on the compressor? Just interested in the reason for greater efficiency. Thank you for your thoughts. I hope I am asking the right area of this forum. Ken

One of the purposes of doing a load calc is to determine if there are areas where you can cost effectively reduce the heat-gain to go to a smaller tonnage system.

Very few homes need a 5-Ton system, because the usually undersized duct system & filter areas plus wrong type filter, reduce the delivered Btuh at least a ton lower than the equipment's Rating.

Power companies ought to provide free, or very low cost, Home Energy Efficiency Audits that also indicate the amount of air infiltration & duct system leakage to be addressed.

What state do U live in - near what large city?
What's the sf of your home & approximate sf amount of E,W, & Southern window areas...we need to get an indication of your situation...

We need to begin to do more things right and, in the right order of sequence...