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wmmurphy 11-26-2008 05:09 PM

air conditioning ducting
 
Installing central air and duct work in 1986 two story home, air handler in attic. Contractor says that it is not necessary to have ducts into each room on the fist floor but more importantly to have the correct amount of cool air sent to first floor. He wants to duct the air to first floor from stairwell--- the air return will allso be in the stairwell this does not make sense to me--every home I have been in with central ac has ducts into each room. Anybody set me strait??? thanks

jogr 11-26-2008 05:16 PM

Find a new contractor and don't look back.

beenthere 11-26-2008 08:39 PM

Not sure what you mean by duct it through the stairwell.

But, the first floor doesn't require a duct to each room.

Got some, that the kitchen and dinig room have supplies. But not the living room. And or some other room that is near the stairwell.

Generally done in houses where space is a premiumn.

When possible to get to every room, it is better with a supply to each room.

wmmurphy 11-27-2008 04:58 AM

I should have been clearer, the first floor room the contractor would not duct to is a bedroom as it has a closet and a door-- at present I use the room as a home office. As to the stairwell issue he would supply at one end and return from the other end of the well both at the ceiling. My concern is that in putting central ac into an existing home I do not create any future home inspection problems , and of course that the system function properly.

beenthere 11-27-2008 06:15 AM

Using that room as an office, it muct have its own supply.
Even then, it will not be the same temp as the rest of the house.
Since the equipment(computer, printer, etc) will gernerate heat outside that of the other rooms normal heat gain.

A pump and dump stairwell, is not a good idea.
It will most likely leave you with a very cold and uncomfortable landing, with the rest of the first floor air stractifying.

Call other contractors.

wmmurphy 11-28-2008 06:54 AM

ac ducting
 
I am curious about two other aspects of central air. If the return for the system (approx 14X30 for a 1400 sf home) is located on the ceiling of the second floor in stairwell what happens to bedrooms when the doors are closed- the bedrooms get supply but what about return. 2. Location of supply registers in ceilings how to determine? simply as far from retun as possible? Thanks

beenthere 11-28-2008 07:00 AM

Depends.
How much undercut do the doors have.
If not much, then they will warm up when their doors are closed.
So may need to either increase teh undercut, or install transfer grilles/ducts.

As far as supply location in the ceiling.
A popsition that allows the air to either bath the outside walls, or to allow enough time for the room air and supply air to mix, before the supply air hits an object.
And not throw air directly at the return.

wmmurphy 11-30-2008 11:26 AM

ac ducting
 
Thanks for the info--Comments on either Lennox or American standard equipment- Does 3 ton sound about right for 1400sf two story home built 1986 w/ full insulation attic, basement joists, walls and tripple pane glass Boston, mass area. curious as to the summer design temperature for Boston, Mass area thanks

beenthere 11-30-2008 11:32 AM

My place was built right around 1956.
1650 sq ft. 2.5 tons. And I can maintain 72 when its 98 outside.
I have good shading, and crappy insulation. Good double pane windows.

So 3 tons sounds over sized to me.
You need a load cacl done.

You can do your own if you want.
Here is one that is easy to use.

http://hvaccomputer.com/talkref.asp

hvaclover 11-30-2008 11:38 AM

Yo, Murphy!


Three ton sounds heavy to me. Mass in more Northeast and I don't think your summer is a whole bunch longer and hotter than Mi.

I would have a manual J calculation done by a contractor to see how much cooling you need for sure. All that insulation in my area would call for a two tone ac.

wmmurphy 12-05-2008 07:35 PM

ac ducting
 
Thanks for the input .. I have a couple of other questions.1. What size rectangular supply duct is needed for my 12 X 14 residential kitchen-- the duct would be round coming from the air handler in the attic to a round to rectangular 45 degree and rectangular 10W X ???D (can not go wider) stack inside a 2 X 4 wall thru a joist bay and out the kitchen ceiling. 2. the 2X4 wall is an interior partition- does the duct need insulation inside that wall? 3. other than the 45 degree at the top of the rectangular stack it is a straight drop to the kitchen ceiling - 91/2 feet--any problems with this set up like air flow noise, etc.....? 4. Any input on either Lennox or American Standard ac equipment quality would be appreciated. 5. . Same supply ducting set up as above-- but in joist bay would transition 90 degrees back to round then 6 feet horizontally to ceiling register- the room is a 11 X 11 home office. Home has full insulation and double pane windows with new storm windows. THANKS

hvaclover 12-05-2008 07:40 PM

Are you using flex or hard pipe?

Are you ding it yourself?

wmmurphy 12-05-2008 07:55 PM

ac ducting
 
round would be flex--- in wall would be ridgid. I will have contractor do the installation

hvaclover 12-05-2008 08:06 PM

I don't want to second guess your guy. Our methodology might be different.

There are all kinds of approaches that can be taken. Some of them may cause you to compromise due to limitations caused by home construction.

As far as brands keep in mind that the install quality is more important then the brand

wmmurphy 12-05-2008 08:10 PM

ac ductin --
 
then would a 10WX31/4D duct provide enough supply for the 12 X 14 kitchen???THANKS


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