Hello,
I'm glad to have found this forum. Although it seems I found it a tad bit late as my new HVAC installation is scheduled for this weekend (my first!) :)
Following is the necessary background:
1) Single story primary residence located in Phoenix area, AZ. 1998 built, 2050 sq ft, high ceilings, glass windows, french doors. Most windows have sun shade.
2) Currently installed HVAC equip - 1997 5 ton R-22 Carrier AC + Gas furnace (80%??). Split system (furnace and evaporative coil in the attic)
3) New upcoming installation -
Trane16 SEER 5-ton XR16 split gas system.
Model#
4TTR6061C1000
S8X1C100M5PSA
4TXCC009DS3
4) Decision between 14 seer and 16 seer was just based on the fact with Fed and utility credits, they were coming out to be almost similarly priced.
5) All the contractors I spoke with insisted on 5ton for my area/built size. I was told Manual J will be required anyway to qualify for utility rebates. But I'm not sure when it will be performed.
Current issues:
One of the main problems with the current setup is that there’s uneven distribution of cold air throughout the house. The fact that Sun hits every room differently doesn’t help either.
The main reason for the uneven distribution, I am being told, is the way “output” (supply?) ducts are sized. The biggest one dumps most of the air in bedroom (air taking the path of least resistance) leaving smaller proportion for other rooms.
I discussed this with my installer and he suggested:
A) Adding balancing dampers with the new plenums.
B) Installing an additional air return (currently there's just one in the ceiling. I use two 20x20x1 filters ).
I wanted to discuss the last part in more detail. I skimmed through the forum last night and at least got the importance of right duct sizing. From what I got a 5 ton AC means 400*5=2000CFM.
Q1) Does this mean that both the supply and return path should be able to sustain this flow rate separately (2000 CFM on both the paths)?
Q2) How can ensure that my existing ducts are capable of handling this ? ( As mentioned above, the current system is also 5 ton, but that doesn’t necessarily mean much). I don't think, I can get a Manual D calc done in two days. Are there any "rough" estimations I can do ?
Q2) I started looking at this http_//_library_coburns_com/hvactechtips/Charts/Coburns%20Duct%20Size%20Chart.pdf
(Replace _ with a . I have also attached the chart here) This is a handy chart that shows the “expected” return and supply air CFM and Grille size (see pic below). I understand the latter - Grille sizing..but for supply and return column, should their summation be at least equal to the HVAC's CFM?
Q3) Anything else that you would suggest me, I can do in the next 2 days before the installation beings ?
Thanks a lot for reading this.
Appreciate any guidance on this.
I'm glad to have found this forum. Although it seems I found it a tad bit late as my new HVAC installation is scheduled for this weekend (my first!) :)
Following is the necessary background:
1) Single story primary residence located in Phoenix area, AZ. 1998 built, 2050 sq ft, high ceilings, glass windows, french doors. Most windows have sun shade.
2) Currently installed HVAC equip - 1997 5 ton R-22 Carrier AC + Gas furnace (80%??). Split system (furnace and evaporative coil in the attic)
3) New upcoming installation -
Trane16 SEER 5-ton XR16 split gas system.
Model#
4TTR6061C1000
S8X1C100M5PSA
4TXCC009DS3
4) Decision between 14 seer and 16 seer was just based on the fact with Fed and utility credits, they were coming out to be almost similarly priced.
5) All the contractors I spoke with insisted on 5ton for my area/built size. I was told Manual J will be required anyway to qualify for utility rebates. But I'm not sure when it will be performed.
Current issues:
One of the main problems with the current setup is that there’s uneven distribution of cold air throughout the house. The fact that Sun hits every room differently doesn’t help either.
The main reason for the uneven distribution, I am being told, is the way “output” (supply?) ducts are sized. The biggest one dumps most of the air in bedroom (air taking the path of least resistance) leaving smaller proportion for other rooms.
I discussed this with my installer and he suggested:
A) Adding balancing dampers with the new plenums.
B) Installing an additional air return (currently there's just one in the ceiling. I use two 20x20x1 filters ).
I wanted to discuss the last part in more detail. I skimmed through the forum last night and at least got the importance of right duct sizing. From what I got a 5 ton AC means 400*5=2000CFM.
Q1) Does this mean that both the supply and return path should be able to sustain this flow rate separately (2000 CFM on both the paths)?
Q2) How can ensure that my existing ducts are capable of handling this ? ( As mentioned above, the current system is also 5 ton, but that doesn’t necessarily mean much). I don't think, I can get a Manual D calc done in two days. Are there any "rough" estimations I can do ?
Q2) I started looking at this http_//_library_coburns_com/hvactechtips/Charts/Coburns%20Duct%20Size%20Chart.pdf
(Replace _ with a . I have also attached the chart here) This is a handy chart that shows the “expected” return and supply air CFM and Grille size (see pic below). I understand the latter - Grille sizing..but for supply and return column, should their summation be at least equal to the HVAC's CFM?
Q3) Anything else that you would suggest me, I can do in the next 2 days before the installation beings ?
Thanks a lot for reading this.
Appreciate any guidance on this.
source https://hvac-talk.com/vbb/threads/2228739-Unsure-of-new-HVAC-installation-in-a-few-days-Help!?goto=newpost
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