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chilltocam
LIF Adult
Member since 11/11 9141 total posts
Name:
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Central Air installation
We have hot air heat in our house and are looking to get central air. We've had a few companies come in for estimates, but the one that came last night is the first to say he would have to put all separate ducts in - that we can't use the same ones for heat and A/C. Does anyone know if this is correct, or the "best" way to do it? Does anyone have hot air heat and use the same ducts for A/C? Are there any issues with using the same ducts for heat and A/C?
Thanks!
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Posted 6/28/12 11:28 AM  |
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alli3131
Peanut is here!!!!!!
Member since 5/09 18388 total posts
Name:
Allison
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Central Air installation
I do not see why you cannot use the same ducts unless they were not sized correctly. I would question it.
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| Posted 6/28/12 12:07 PM |
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TiggerBounce
The Prince & Princess
Member since 7/05 4939 total posts
Name:
J
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Re: Central Air installation
I know nothing, but we had inspection done on a house yesterday (I wasn't there). The house does not have CAC - but we would put it in (eventually) so DH asked inpsector about putting it in, all I know is inspector said all the duct work is on one side of the attic - not sure if that matters.
That may be the case in your house. Not sure though.
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| Posted 6/28/12 1:01 PM |
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GoldenRod
10 years on LIF!
Member since 11/06 26792 total posts
Name:
Shawn
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Re: Central Air installation
We have one set of ducts for heat and A/C. It's just air being moved through the house. I can't see why you would need different ducts for warm 85 degree air vs cool 60 degree air... 
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| Posted 6/28/12 1:33 PM |
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chilltocam
LIF Adult
Member since 11/11 9141 total posts
Name:
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Re: Central Air installation
Posted by GoldenRod
We have one set of ducts for heat and A/C. It's just air being moved through the house. I can't see why you would need different ducts for warm 85 degree air vs cool 60 degree air...
That's what I thought too, but he said something about the AC air having moisture in it and causing rust in the ducts - sounded like a lot of BS to me
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| Posted 6/28/12 2:09 PM |
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GoldenRod
10 years on LIF!
Member since 11/06 26792 total posts
Name:
Shawn
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Re: Central Air installation
Posted by chilltocam
Posted by GoldenRod
We have one set of ducts for heat and A/C. It's just air being moved through the house. I can't see why you would need different ducts for warm 85 degree air vs cool 60 degree air...
That's what I thought too, but he said something about the AC air having moisture in it and causing rust in the ducts - sounded like a lot of BS to me
If your aluminum or galvanized steel ducts start rusting, you've got bigger problems! 
Air conditioning dehumidifies the air, so there really shouldn't be that much moisture anyway.
Many forced air systems have humidifier attachments that ADD water to the air as it circulates.
Message edited 6/28/2012 2:31:41 PM.
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| Posted 6/28/12 2:30 PM |
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chilltocam
LIF Adult
Member since 11/11 9141 total posts
Name:
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Re: Central Air installation
Posted by GoldenRod
Posted by chilltocam
Posted by GoldenRod
We have one set of ducts for heat and A/C. It's just air being moved through the house. I can't see why you would need different ducts for warm 85 degree air vs cool 60 degree air...
That's what I thought too, but he said something about the AC air having moisture in it and causing rust in the ducts - sounded like a lot of BS to me
If your aluminum or galvanized steel ducts start rusting, you've got bigger problems!
Air conditioning dehumidifies the air, so there really shouldn't be that much moisture anyway.
Many forced air systems have humidifier attachments that ADD water to the air as it circulates.
Actually, I think we have that - the humidifier attached to the heating system. I think that AC guy was full of cr@p. (I guess I'm just confused because this was the most well known of all the companies we got estimates from, so I "assumed" he would know what he was talking about  ) I think we'll be fine using our existing ducts. Thanks for your help 
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| Posted 6/28/12 3:14 PM |
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Re: Central Air installation
I've seen it pointed out by inspectors many times during home inspections that using the same ductwork for hot air heat and CAC is not the best/most efficient way to it.
It's because heating vents are usually low to the ground (on lower parts of the walls, just above floors) because hot air rises. Conversely, cold air is dense and falls to the ground, so the registers for central air are ideally put in the ceiling (mine are in my house, and we have hot water/radiator heat, so there's no issue).
If you use the heating ducts for the CAC, the cold air will come out near the floor and won't rise, so while it's better than nothing, the room won't get as cool as it would if you had separate ductwork for central air.
Despite the inefficiencies, most people with forced air heat choose to use the same ducts for CAC, because there's obviously a cost savings. But if you are thinking of selling down the road, keep in mind that buyers might have a problem with it.
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| Posted 6/28/12 5:32 PM |
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Serendipity
Summer!
Member since 4/07 7631 total posts
Name:
PrayingWishingHopingALOT
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Re: Central Air installation
Posted by Century 21 Dallow - Christine Braun
I've seen it pointed out by inspectors many times during home inspections that using the same ductwork for hot air heat and CAC is not the best/most efficient way to it.
It's because heating vents are usually low to the ground (on lower parts of the walls, just above floors) because hot air rises. Conversely, cold air is dense and falls to the ground, so the registers for central air are ideally put in the ceiling (mine are in my house, and we have hot water/radiator heat, so there's no issue).
If you use the heating ducts for the CAC, the cold air will come out near the floor and won't rise, so while it's better than nothing, the room won't get as cool as it would if you had separate ductwork for central air.
Despite the inefficiencies, most people with forced air heat choose to use the same ducts for CAC, because there's obviously a cost savings. But if you are thinking of selling down the road, keep in mind that buyers might have a problem with it.
Yup this. Christine is right. My dad is a HVAC contractor and if there is one thing I know it is not the most "efficient" to have the AC vents low.
In my parents house the AC vents are in the ceiling. It was done the right way. My dad did it.
In my house the vents are in the floor, my dad didnt do it as it was here when we moved in but he always saidit wasnt the best way to do it.
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| Posted 6/28/12 8:29 PM |
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TiggerBounce
The Prince & Princess
Member since 7/05 4939 total posts
Name:
J
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Re: Central Air installation
Posted by Serendipity
Posted by Century 21 Dallow - Christine Braun
I've seen it pointed out by inspectors many times during home inspections that using the same ductwork for hot air heat and CAC is not the best/most efficient way to it.
It's because heating vents are usually low to the ground (on lower parts of the walls, just above floors) because hot air rises. Conversely, cold air is dense and falls to the ground, so the registers for central air are ideally put in the ceiling (mine are in my house, and we have hot water/radiator heat, so there's no issue).
If you use the heating ducts for the CAC, the cold air will come out near the floor and won't rise, so while it's better than nothing, the room won't get as cool as it would if you had separate ductwork for central air.
Despite the inefficiencies, most people with forced air heat choose to use the same ducts for CAC, because there's obviously a cost savings. But if you are thinking of selling down the road, keep in mind that buyers might have a problem with it.
Yup this. Christine is right. My dad is a HVAC contractor and if there is one thing I know it is not the most "efficient" to have the AC vents low.
In my parents house the AC vents are in the ceiling. It was done the right way. My dad did it.
In my house the vents are in the floor, my dad didnt do it as it was here when we moved in but he always saidit wasnt the best way to do it.
Reading these two posts make me go "Yeah!" In both my mo and my MIL's houses, the heat vents are floor level and the AC vents are on the ceiling or up on the upper part of the walls.
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| Posted 6/29/12 2:09 PM |
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CunningOne
***
Member since 5/05 26975 total posts
Name:
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Re: Central Air installation
While it's not the most "efficient" way, it can be done. We did it!
We have forced air heat and the vents are low on the wall, about 6 inches off the floor. When we had estimates for CAC, most said it wasn't the most efficient and gave us two estimates - one for using same ducts and one for installing new ducts up higher for the CAC. Only 1 company (Slomins) wouldn't give us a quote for using the same ducts. their estimates were off the charts high, so we didn't go with them anyway.
We did need a new, more efficient furnace when we installed the CAC using the same duct work. Nothing with the ductwork had to be touched, except a new return vent was added for the CAC (they just put it up higher where the return for the heat was).
We've had it for 7 summers now and not one issue keeping the house cool (we have a high ranch). I am so glad we did it, I would never buy another house without it!
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| Posted 6/29/12 4:28 PM |
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GoldenRod
10 years on LIF!
Member since 11/06 26792 total posts
Name:
Shawn
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Re: Central Air installation
Posted by Serendipity
Posted by Century 21 Dallow - Christine Braun
I've seen it pointed out by inspectors many times during home inspections that using the same ductwork for hot air heat and CAC is not the best/most efficient way to it.
It's because heating vents are usually low to the ground (on lower parts of the walls, just above floors) because hot air rises. Conversely, cold air is dense and falls to the ground, so the registers for central air are ideally put in the ceiling (mine are in my house, and we have hot water/radiator heat, so there's no issue).
If you use the heating ducts for the CAC, the cold air will come out near the floor and won't rise, so while it's better than nothing, the room won't get as cool as it would if you had separate ductwork for central air.
Despite the inefficiencies, most people with forced air heat choose to use the same ducts for CAC, because there's obviously a cost savings. But if you are thinking of selling down the road, keep in mind that buyers might have a problem with it.
Yup this. Christine is right. My dad is a HVAC contractor and if there is one thing I know it is not the most "efficient" to have the AC vents low.
In my parents house the AC vents are in the ceiling. It was done the right way. My dad did it.
In my house the vents are in the floor, my dad didnt do it as it was here when we moved in but he always saidit wasnt the best way to do it.
It's also not "efficient" to tear up the entire house to run new ductwork. My upstairs vents for heating and AC are in the ceiling, and the downstairs vents for heating and AC are in the floor. I feel no difference in cooling capacity, or ambient temperature. I would much rather save tons of money on not running new ducts, than theoretically saving on more efficient air flow. Plus, if you turn on a ceiling fan, the air is moving all around the room anyway, so it's basically a moot point.
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| Posted 6/29/12 7:12 PM |
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LoveMyFamily
LIF Toddler
Member since 1/11 418 total posts
Name:
Alyson
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Re: Central Air installation
We had Apple A/C (Merrick Rd in Seaford) do our CAC install. They were OUTSTANDING! I'd give them a call & have them give you an estimate & answer questions. I had a lot of questions, & they were very willing to help and answer every one.
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| Posted 7/5/12 5:42 PM |
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chilltocam
LIF Adult
Member since 11/11 9141 total posts
Name:
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Re: Central Air installation
Posted by GoldenRod
It's also not "efficient" to tear up the entire house to run new ductwork. My upstairs vents for heating and AC are in the ceiling, and the downstairs vents for heating and AC are in the floor. I feel no difference in cooling capacity, or ambient temperature. I would much rather save tons of money on not running new ducts, than theoretically saving on more efficient air flow. Plus, if you turn on a ceiling fan, the air is moving all around the room anyway, so it's basically a moot point.
This is what I was thinking. I get that vents higher up would be more efficient, but we just moved into the house in March and have had every wall patched, spackled and painted, and the thought of tearing that up makes me 
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| Posted 7/6/12 10:00 AM |
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chilltocam
LIF Adult
Member since 11/11 9141 total posts
Name:
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Re: Central Air installation
Posted by AlyJD
We had Apple A/C (Merrick Rd in Seaford) do our CAC install. They were OUTSTANDING! I'd give them a call & have them give you an estimate & answer questions. I had a lot of questions, & they were very willing to help and answer every one.
I will give them a call. Thanks!
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| Posted 7/6/12 10:00 AM |
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