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Old 01-10-2010, 01:08 PM   #31
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I am not much of a duct guy so I may be wrong but I thought it was best to pull through a coil. I thought when you pushed a coil most of the air goes through the center portion of the coil and when you pulled through you pull air through the entire surface. Is that not why air handlers started pulling through the coil as opposed to pushing the air through as they used to many years ago.

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Old 01-10-2010, 01:23 PM   #32
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No.
Air handlers. Were pretty much always pull through.

Electric furnaces were, and still are push through(yeah, thats were it gets dumb, an air handler is often an electric furnace, but still configured as an air handler).
Electric furnaces came out before air handlers. Since A/C wasn't a common thing in houses 40 years go. And had no provisions for a coil to be placed in it.

You can take a modular coil. that can be used with either a modular blower/air handler, or a furnace.
And its capacity will increase with one furnace and decrease with another, and remain the same with yet another furnace.

So its position in the air stream doesn't really change its capacity.
Since in all configurations, it has coil bypass(obviously not all the air going through the coil touches the fins or tubes).

The distance between coil and blower, weather push or pull through. Will have more effect on the air flow pattern through the coil.
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Old 01-10-2010, 06:47 PM   #33
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Whats the PD of the 12X24 coil you found.

Will the 12X24 you found add less?
They didnt list the info online, I'll call them tomorrow and find out what the specs on it are.

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He doesn't have a lot of room between his air handler and the trunk line.
Already has an air flow problem.

The hydro coil will compound his air flow problem.
Correct, I don't have the room and I already upgraded all my trunks from 8x24 to 10x24. If I was to make the trunk any bigger, I'd have to redo my return dropdown box and the box the AH sits on....I am not about to spend the money to do that again.
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Old 01-10-2010, 06:51 PM   #34
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So what is the current static pressure at what CFM???


Oh. And incase I forgot to ask earlier.


What is the current static pressure at what CFM???
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Old 01-10-2010, 06:56 PM   #35
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I stopped at Home Depot to price out the plumbing supplies I needed, $210. *gulp*

I'll check a real supply house tomorrow.

Can I use PEX instead of copper?

---------

PEX tubing can be used up to 200 Fahrenheit for heating applications. For plumbing, PEX is limited to 180 F. Temperature limitations are always noted on the print line of the PEX tubing. Recommended 140 max for safety and conservation.
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Old 01-10-2010, 07:07 PM   #36
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Hpex is fine.
With that boiler, you MUST use Hpex. If you use a pex without an oxygen barrier. You will have a internally rusted up boiler. that clogs your water lines.
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Old 01-10-2010, 07:15 PM   #37
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If the numbers on the 12x24 exchangers are acceptable, could I make an A with them and stick them like this? (The brown in this image)

Then I wouldnt need turning vanes up there anymore, right?

The downside is that I need more airflow to the left than the right....the line to the left has more supply takeoffs than the one to the right.

My plan with the turning vanes was to shift them as I needed to force more airflow one direction or the other.
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Old 01-10-2010, 07:21 PM   #38
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I meant put an increaser on each side of the trunk, then coils, then decrease back to the 10x24. Only would require removing one section of supply duct on each side of the air handler and not change the return or platform at all.
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Old 01-10-2010, 07:24 PM   #39
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Afraid installing them in an A like that. Will decrease air flow.

The air would be directed at a 45 angle toward the top of the trunk line.

Marty has the right idea.
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Old 01-10-2010, 08:31 PM   #40
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Quote:
Originally Posted by beenthere View Post
So what is the current static pressure at what CFM???
I haven't forgotten to check. Its on my todo list tonight.

I did an audit of all the return vents in the house and finished adding one to the "guest" room, which had zero.

2nd floor, approx 1400 sq ft, 9 supply ducts via 6" round pipe.

Returns:
Bedroom #1: 14" x 5.5" - interior 2x4 wall
Bedroom #2: 14" x 5.5" - interior 2x4 wall
Bedroom #3: 14" x 5.5" - interior 2x4 wall


1st floor, approx 1,800 sq ft, 14 supply ducts via 6" round pipe

Returns:
Family: 21" x 6" - interior 2x6 wall
Dinning: 30" x 6" - interior 2x4 wall
Toy: 14" x 5.5" - interior 2x4 wall
Guest: 6" x 6" - interior 2x6 wall (cavity is 6" wide)
Hall: 14" x 5.5" - interior 2x4 wall, across from tstat
Office: None, on slab, no way to add
Kitchen: none, will be adding one to a 2x6 wall cavity.

Basement: 1500 sq ft (unfinished)
4 supplies via 6" pipe each from supply trunk, no return.

I dont think I have adequate return vents which is attributing to my high static pressure on the return side.

The basement really needs to be heated because most of the 1st floor is either tile or wood flooring, and its cold to walk on. The basement is current 55 degrees.
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Old 01-10-2010, 08:32 PM   #41
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Quote:
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I meant put an increaser on each side of the trunk, then coils, then decrease back to the 10x24. Only would require removing one section of supply duct on each side of the air handler and not change the return or platform at all.
My current duct is 10x24. So would I be going to something like 10x36, or 12x24 or even 14" x 24"?
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Old 01-10-2010, 08:42 PM   #42
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Don't add a return to the kitchen. Unless it will be more then 10' from the range hood.

You don't have enough return either.

You might want to install a central return on the first floor somewhere near a hallway.
Plus add a return to the basement.


Just have a transition(2 of them) made to put the coils in.

If you give the coil submitals to a sheet metal shop. They can make them for you.
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Old 01-10-2010, 08:52 PM   #43
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Quote:
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Don't add a return to the kitchen. Unless it will be more then 10' from the range hood.

You don't have enough return either.

You might want to install a central return on the first floor somewhere near a hallway.
Plus add a return to the basement.
It is an open kitchen design. The return would be approximately 18' from the stove/oven and at the entrance to the hallway.

So is it safe to assume the original dutwork in the house was sized incorrectly then? As you may recall, I upsized the trunks from 8x24...and am now trying to find a creative way to add additional returns.
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Old 01-10-2010, 08:59 PM   #44
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Yep get the coils first then have the tinners make the transitions. Might want them to make a pair of flex connectors also to make assembly easy. Beenthere suggested 18x18 coils for each side earlier to keep the PD minimal.
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Old 01-10-2010, 09:23 PM   #45
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Just by count you have plenty of suppies for a 5 ton system but are lacking on returns. Add your one in the kitchen hall and two 6x30's in the basement.

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