Based on your location and without knowing specific system details that were quoted, I would recommend quote #1 . I do not like quote #3 .

IMO

Your contractor is probably very honest, but it seems he does not know how to calculate the operating costs or the additional cost of investment of the three systems he is proposing.

I second Tigerdunes recommendation. You have not posted model numbers, but from the description quote #1 is the best value. Quote #2 may be a very nice system but it is unlikely you will ever make up the extra $3300 in initial costs. Quote #3 would only make sense if you had very high gas and very low electricity rates. Even if the rates were close you are better off with a gas furnace then a mini split as the source of heat. I am surprised he even quoted this option.

Your old system was probably rated for 10 SEER, and possibly even less.

The key thing here is how long you plan to live in this house. Also what price utilities are now, doesn't mean they won't go up.

The chart above is for the Houston area, but your area should be similar.

Everyone,

Thank you very much for taking the time to respond to my post. This is extremely valuable information in more ways than one.

I really want to stay with this HVAC contractor as he excels in customer service. One of my units went out on the night of the 3rd of July when I had a lot of relatives visiting from out of town. I called the company the morning of the 4th and the owner personally came over and fixed my unit that morning! That response really earned my loyality. He was selling primarily Trane at the time, and while he still will sell Trane he is primarily an American Standard and Mitsubishi dealer. As an aside, I asked the HVAC instructor at the local community college what he thought were the best brands and he told me “whoever gives the best service”, so I’m taking that advice to heart.

Thanks again for your time and advice. I really appreciate it.

Regards,

Frank

American Standard and Trane are the same equipment. Only difference is the label. American Standard tends to be a little less in cost.

Frank, that is more true than you know.

With that being the case reach back out to them and have them rework a quote to include 80% efficient gas furnace variable speed blower and the highest SEER rated AC equipment they have available. Then it just comes down to where the numbers fall, using the operation costs I provided above as a comparison.

In my opinion an 80% variable speed furnace is more than adequate for our southern climates, put your money toward a higher efficient AC, as long as the furnace is variable speed blower it will hit your higher efficiency goals on the AC side of the equation.

Also don't forget manufacturers will quote blanket SEER ratings in many cases so equipment that is rate like 20 SEER or whatever, the SEER rating can change due to configuration as well as size of the equipment (in Tons of cooling per output, not physical size). This is why there are what is called AHRI number to give exact SEER rating that equipment is capable of.

The problem with Am. Standard and Trane is that they don't publish this information, you have to trust your dealer. So very easy for dealer to cheat the system. Not that they would, but just saying....

I don't want to leave that last statement by Austin hanging out there. I certainly think one can rely on matching system AHRI efficiency and performance data on outside condensers, both AC and HPs. You just need to know your model numbers for furnace/air handler, evaporate coil, and outside condenser. Compare to what dealer tells you.

IMO

Thanks Austin and Tiger,

i did reach out to my contractor to spec higher SEER and 2 stage 80% furnace. So, prices for new 3 ton and 4 ton installed - this is American Standard brand.

1. 17 SEER, 2 stage cooling, 80% 2 stage variable furnace $15,526.00

2. 18 SEER, variable speed cooling, 80% 2 stage variable furnace $17,928.00

3. 20 SEER, variable speed cooling, 80% 2 stage variable furnace $20,762.00

What do you think?

Regards,

Frank

Hi Mike,

My house is single story, 4000 sq ft.

Regards,

Frank

94 would be low for the summers I spent in Memphis.

#1 with a correct thermostat (Trane 824), best matching Trane coil, and I like the Trane Perfect Fit media cabinet...you need to be sized correctly both heating and cooling...I know the South well both cooling and humidity...ask for load calc in writing especially for cooling...7 tons of cooling for 2 systems 4 K size house worries me...do not judge sizing based on existing...

IMO

The design temperature for Memphis is also 94. Design temperatures are supposed to represent the typical high temperature you can expect in the summer. It is not the record high ever recorded.

The south east has long and humid summers. The goal is get the humidity below 50%, and ideally down to 40%. Properly sized equipment is part of the solution. I would want to see a load calculation before installing 7 tons of cooling in a 4,000 sq. foot house. Rules of thumb don't work with situations like this.

The 17 SEER 2 speed is the value leader in this instance.

The 20 SEER variable would provide the best comfort at the most economical operational cost view point, if your utilities are above 15 cent per KWH then this would be a no brainer.

At a 15 cent operational cost it would take you 21 years to recoup the cost difference. At a 10 cent operational cost it would take you 31 years. This is in comparison to the units offered and doesn't reflect the additional savings you will get from the equipment you currently have.

So comparing this to your current utility usage could put the pay back much faster than the 17 SEER system would provide.

Sizing: yes sizing is important, but in terms of variable inverter systems they run via load matching so sizing is only important in terms of duct sizing / air flow distribution and so on. The variable speed / inverter AC will only supply the cooling need to match the load. So over sizing of these systems is really impossible, they don't start up in high stage. They start slow - ramp up and then match the load of the structure.

While it's more costly to over size an inverter system, there are certain manufactures that sell only 5 ton condensers and 3 ton condensers. There are settings that can limit these machines to either 4 ton capacity or 2 ton capacity. I suspect this trend will only continue as HVAC industry looks to cut costs in the number of SKU's required.

With that said sizing varies all day. Even a properly sized AC system can be oversized during specific time periods. A 2 speed AC is probably over sized somewhere around 50% of the time. A single speed AC is over sized 80-90% of the time.

A variable inverter (full inverter) never over sized.

A 5 step variable inverter rarely over sized maybe 5% during seasonal changes.

If you look at electricity local for Tupelo Miss,, the average electric rate for this area is 9.68 cents per kWh. The pay back is going to be longer than the life of the equipment. Take the extra $3300 and invest it in an S&P 500 index fund. In 20 years you will have enough money to buy new equipment.

Thanks guys! My current electric rate is 10 cents/kWh.

BTW, as the 18 seer unit is variable speed, would it provide more comfort vs. the 17 seer 2 speed? I’m not saying $2400.00 difference is not significant, but if I get 20 years out of this system? Would you doubt that I would be able to get that lifespan on this new system compared to my old system of 24 years?

Yeah the 18 SEER variable would provide better in terms of humidity reduction. If you drop humidity in the home a mere 5% you feel much better at almost any temp in a humid climate like we live in.

Not that the 17 (2 speed is bad) but there will be times of the year that you will notice it's short comings which usually leads to fidgeting with thermostat. ( I speak of experience as I have a two speed system at my home.)

The 18 SEER variable is less likely to have those kinds of issues. So it's a matter of preference really.

The other thing is that while the utility rate is 10 cent now, if it jumps to 15 cent in a few years from now??? You just don't know.

Thanks Austin Air,

And thanks to everyone to take the time out of their day to help a stranger on the internet. I really appreciate it and hope it may be possible for me to return the favor someday.

Austin, if I lived near you you would be my HVAC company. I wish you much success in your business.

i believe I’m going to go with the 18SEER units with two stage variable speed furnace. Thanks to everyone’s input, I feel comfortable with my decision.

God Bless!

Regards,

Frank

for above poster...this is an open forum...your link includes advertising and is not allowed...I have reported this to the moderator...if you want to advertise, buy an ad!...

TD