If your Goodman condenser is 12 years old, we didn’t have the 13 seer until 2006, your Goodman condenser would’ve been new in 2001; 1992 to 2005 we had 10 to 12 seer units; 1986 to 1991 we had eight seer; 1982 to 1985 we had seven seer air conditioning condensers, and before 1980 we had six or less seer rated condensers. Some 12 seer condensers when using a thermostatic expansion valve metering device and time delay on the blower could get a 13 seer rating.

What tonnage is the 12/13 seer Goodman condenser? How well did it perform and was it sized correctly? Before you do anything else you need to do a load Calc on your home; I put a link to the free load Calc below.

I would print the instructions and practice doing the load Calc for a number of time until you think you have ballpark numbers. You could do the two floors on separate load Calc’s; the basement won’t affect the air-conditioning load to speak of, unless you use it as a living space I would leave it off of the Calc.

On the coldest days you should be keeping a record of the burner on-time the number of minutes it runs to the next on-time; then divide the total complete cycle time into the run-time to get the percentage factor and then multiply that by the furnace BTU output. BTU output should be on the furnace tag or you may have to the owners manual or somewhere else. That tells you the actual BTUH load at those weather conditions; which must also be logged.

It’s also a very good idea to check the furnace temperature rise; turn the room-stat way up, after the burner runs for around 10 minutes or more check the temperature of the nearest supply diffuser, then check the return air temperature; subtract the return-air temperature from the supply-air temperature and multiply that number by 1.08, then divide that number into the BTU output of the furnace which will give you the cubic feet per minute of airflow that will come in handy later for checking the air-conditioning BTU delivered performance. I'd buy a digital thermometer that reads in tens of a degree.

There are a lot of ways you can check the delivered performance of your air-conditioning system, if it is performing well and it appears to be in good condition I doubt that I would replace the 12/13 seer Goodman condenser, unless the evaporator coil is rusted out.

Before you check any performances, check to see if the evaporator coil is dirty you have to look underneath the coil, also check the squirrel cage blower wheel blades for lint buildup, everything has to be clean before you do any testing of the performance of the equipment.

When you have new equipment installed do all the checks that I have listed and make sure that they do a 'delivered air-conditioning performance test' of the new system. Your major problem will be over-sizing of the air-conditioning and heating systems and not having adequately sized return-air filter areas to keep the velocity through the filters, when clean, below 300 FPM (feet per minute).

You will need at least two large filter areas to begin to have enough filter area for even a three or 3.5 ton air conditioning system. If you want efficiency you have to design for it in every detail and do everything in a proper sequential order.

Here is a link that might be useful: Free Online Whole House Loadcalc

You are right, I meant to type Goodman 3.5 ton instead of Goodman 13 seer, not sure of the seer rating. The new Goodman, Rheem and Lennox suggestions are all 3.5 ton.

You are right, I meant to type Goodman 3.5 ton instead of Goodman 13 seer, not sure of the seer rating. The new Goodman, Rheem and Lennox suggestions are all 3.5 ton.

The Rheem system is the better HVAC of the three you listed. You will need a two stage thermostat that controls the heat staging for best operation. If not you will be running in high stage whether needed or not.

I would recommend a better condenser than the AJM model quoted. You want to qualify for the Fed Tax Credit.

While you don't give the model numbers of the Goodman, you can bet it's low end and long on price over quality. I wouldn't have it.

IMO

udarrell,
nice breakdown of efficiency by year.