HVAC replacement cost--need feedback (house, calculation, floor)

[alwaysflyin]

We have two air conditioning units in our home and they were installed in 2000 when the house was built. A technician from Morrow Mechnical today told us that the downstairs unit has a leak and that we will need a new unit because it is a 12 seer rating. He quoted us $9100 for one 14 seer, 5 ton Lennox unit and said that he would throw in one new heating system if we agree today. I am curious to see what you all think of this quote.

[hendersj31]

I am not able to comment on the quote. I am curious how it was determined you need a five ton unit? How large is your downstairs in square feet?

[alwaysflyin]

Originally Posted by hendersj31

I am not able to comment on the quote. I am curious how it was determined you need a five ton unit? How large is your downstairs in square feet?

We currently have a five ton unit and our downstairs is 2500 sf. We do have an open floor plan down here. Does that unit sound too big for the house?

[EasilyAmused]

Seems close. I had three 16 series Amana units put in back in October. That included furnaces, new duct work, and the uv light dust/mold air cleaner for each unit... and three years of filters for all three units. The three units ranged from 7-10k each. The 10k being the 5 ton size.

The 9100, should include the furnace. He's not throwing anything in.

I really really liked my AC company. They came highly recommended.

[texsn95]

5ton is more than likely too large. Builders used to oversize units in order to cover up inefficiencies in duct sizing, length of duct runs, leaky collars and registers, etc. So what you have now is not necessarily what size you really need. Without knowing much information about your house, I'd say a 4-ton is closer to what you need. Don't ever go with the first quote you get. I went down from a 4 to 3 downstairs and it's perfect, and am about go down from 3 to 2 upstairs.

How big is the leak? If it's a tiny pinhole leak, then you're probably ok in just having your system recharged as needed while you get more educated as to what your house requires compared to what your budget is. These days you definitely want a variable speed air handler as well. If you want I can give you the # of my AC guy who installed our unit a few years back.

[hendersj31]

As texsn95 already replied that 5 ton may be a bit oversized, which is why I was curious to how the calculations were done. There is a very precise procedure used which I admit I cannot perform.

Originally Posted by alwaysflyin

We currently have a five ton unit and our downstairs is 2500 sf. We do have an open floor plan down here. Does that unit sound too big for the house?

[alwaysflyin]

Originally Posted by EasilyAmused

Seems close. I had three 16 series Amana units put in back in October. That included furnaces, new duct work, and the uv light dust/mold air cleaner for each unit... and three years of filters for all three units. The three units ranged from 7-10k each. The 10k being the 5 ton size.

The 9100, should include the furnace. He's not throwing anything in.

I really really liked my AC company. They came highly recommended.

Thanks! Yeah, after doing a little research on the internet, I figured that out. I guess he figures that this is a way to get rid of his overstock of furnaces now that winter is over.

Yes, I'd appreciate a recommendation. I get the sense that many of these folks are sleazy.

[alwaysflyin]

Originally Posted by hendersj31

As texsn95 already replied that 5 ton may be a bit oversized, which is why I was curious to how the calculations were done. There is a very precise procedure used which I admit I cannot perform.

The total house is 4000 sf, with a 5 ton for the bottom (bigger area) and a 3.5 ton for the top. I've been told it's about 1 ton per 500 sf.

[texsn95]

Originally Posted by hendersj31

As texsn95 already replied that 5 ton may be a bit oversized, which is why I was curious to how the calculations were done. There is a very precise procedure used which I admit I cannot perform.

Manual J calc for heat load
https://www.resnet.us/blog/manual-j-...d-calculation/

The total house is 4000 sf, with a 5 ton for the bottom (bigger area) and a 3.5 ton for the top. I've been told it's about 1 ton per 500 sf.

1 ton per 500 sf is an old way to estimate and often leads to oversized systems. There are too many variables to say for sure online and if you really want to know, have someone do a manual J calc on your house. It may cost some up front, but in the end could save your much more money in the long run.

[hendersj31]

Also oversized units can cause humidity and moisture related issues with your home.

Originally Posted by texsn95

Manual J calc for heat load
https://www.resnet.us/blog/manual-j-...d-calculation/



1 ton per 500 sf is an old way to estimate and often leads to oversized systems. There are too many variables to say for sure online and if you really want to know, have someone do a manual J calc on your house. It may cost some up front, but in the end could save your much more money in the long run.