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Old 11-11-2009, 04:39 AM   #16
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Originally Posted by dizzy46 View Post
the 40000 btus is just for the addition i have a 60000 btus for the old part of the house and it is only only4 years old so i didnt want to replace the 4 year old furance and the 40000 btu is in the basmemet under the addition. and the 60000 btu is far from the addition
Did you do a heat gain and loss calculatio?
You need only 19.5k heat for that space. 1.5 tons ac is tooooo tooo much.

You better resize that equipment

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Old 11-11-2009, 04:53 AM   #17
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He has a 2 stage 40,000 BTU 80%, so he isn't going to get a smaller furnace per say.

York, should still have some 1 ton A/Cs available, they're R22.

But, he then needs to have a VS blower, which he didn't indicate if his furnace has or not.


He already has one supply, that has a total equivalent length of 165'.
And no indication of how his return duct is ran.

So at his .1" FR, he's gonna have a higher then planned static, and probably a noise issue.
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Old 11-11-2009, 08:35 AM   #18
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Originally Posted by hvaclover View Post
Did you do a heat gain and loss calculatio?
You need only 19.5k heat for that space. 1.5 tons ac is tooooo tooo much.

You better resize that equipment
that is why we went with the 2 stage and planing on finshing the basmnet with in the next year
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Old 11-11-2009, 08:54 AM   #19
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Originally Posted by beenthere View Post
He has a 2 stage 40,000 BTU 80%, so he isn't going to get a smaller furnace per say.

York, should still have some 1 ton A/Cs available, they're R22.

But, he then needs to have a VS blower, which he didn't indicate if his furnace has or not.


He already has one supply, that has a total equivalent length of 165'.
And no indication of how his return duct is ran.

So at his .1" FR, he's gonna have a higher then planned static, and probably a noise issue.
what can i do to cut down the noise and i do have vs blower. what do you need to know about the return air ?
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Old 11-11-2009, 10:58 AM   #20
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How its run. Its duct layout. Or if its a free return. What size grille etc.

A load calc to determine how many CFM each room needs. And then since the furnace, and possibly the A/C will deliver more CFM then needed. You would proportionally increase CFM to all rooms.

EG:
If one room needs 90 CFM, and another room needs 60 CFM.
And your system had to move 20% more air then your combined rooms need.
You would increase air flow by 20% to both rooms. Meaning the 90CFM room would get 108, and the 60CFM room would get 72.

Since your trunk is not a reducing trunk. Better off with an 18X8
Your long 6" run that is marked 110CFM, and runs 20' plus has that 90 in it, would be better off as a 7" for 110 CFM.

But, you may have to increase that CFM. depending how much air your SYSTEM NEEDS to move.
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Old 11-16-2009, 02:25 PM   #21
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my duct work runs Through web floor joist the joist are 16 in by 16 in. they are paneled off to make the run. the run makes a L shape. 5 ft one way 12 ft the other leg there is 16in by 31/2in hole cut in the floor that runs up the wall to a 14in by 5in vent. there is two of these vents one in bedroom and one in living room space i was thinking that i should put one in the finished basement area too.
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Old 11-16-2009, 04:10 PM   #22
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Only if you put a return in it also.

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