duct work and SEER

[chrisanddeb]

When deciding what type of duct to use in new construction of a home, what are the advantages of using metal over commercial flex?

Also, is it worth the cost to go from a 10 to 12 SEER??

[hvacfella]

'what are the advantages of using metal over commercial flex?
'

ME: 1. 8" high metal trunkline ducts give you more headroom. 2. Metal rectangular looks neater and more professional-same with branch ducts. 3. Using metal ducts, you dont have to be concerned with the ducts blowing off or sagging. 4. Flex might not meet local code., except for the final 3' of branch duct run to the register.

'Also, is it worth the cost to go from a 10 to 12 SEER??
'
ME: Depends on how extended your cooling season is, if you use your cooling alot, and if youre planning on staying in the house for awhile. Generally speaking , it is better to go with a 12 over a 10 seer because a 12 seer unit will run lower discharge pressures and 'should' make the compressor last longer. Plus, when you go to a 12 eer, most (if not all) manufacturers put a Scroll compressor in the unit which are dependable, quieter, and come with a 10 year warranty versus a 5 year warranty on a 10 seer compressor. Pretty soon, the minimum seer standard is going to be 13 just so you know.

[tinner73]

flex is put in because it is cheaper to install and a chimp can do it. metal costs more, is better for airflow, and never needs to be replaced. if you're cheap or you like monkeys, go with the flex.

[duct dr]

If it were my house I would use series 800 ductboard main trunk with ROUND hard pipe (snap lock). Flex creates too much turbulance and restriction. As far as SEER rating, in 2006 10 SEER will no longer be available. I would go ahead and invest in a good 13 SEER system. It will save you money in the long run.

[dallasbill]

...there are also lots of very happy homeowners out there with properly designed and installed flex duct, esp. those that do not know any monkeys that do such work.

And us happy homeowners would recommend that you never take the advice to install 13 SEER just because 10 SEER will not be available next year. That's like saying buy a new 2005 Prius with all these extras NOW because only 2006 models costing even more be available next year.

And to say, on the Internet, that it will save you money in the long run, w/o running any numbers whatsoever on your home is like saying: "I'm standing across the street and raising 4 fingers -- it covers your house from here, so you need 4 Tons of A/C."

May I suggest that you read this thread:
http://www.hvac-talk.com/vbb/showthr...threadid=70361

...and then go from there. Now, please forgive me while I stand back and put on my educated homeowner flameproof suit.

Good luck to you... this is a great site to wade thru and learn! ;-)

[duct dr]

So you're saying that on 2 identical houses that both have the same sq ft, same insulation, same windows and doors, a 10 SEER will be the same as a 13 SEER??? Maybe I need to enclose a copy of my neighbors power bills, before and after they upgraded.

[tinner73]

chimps aren't monkeys, they are apes. and i'm sure you have a quality system. they just don't come any cheaper. if you're ok with that so am i.

[duct dr]

BTW tonage has nothing to do with SEER. you can have a 4 ton 10 SEER, 12 SEER, ect. And when I stated that in 2006 10 SEER units wont be available, I meant they will no longer be made. If a dealer still has them they can be sold, but after they're gone, thats it. Besides, who would want a costly low SEER unit in a new home anyway. To me that would be like buying a Lexus and going to WalMart for tires.

[Edited by duct dr on 02-17-2005 at 10:44 PM]

[41gasman]

Soooo, Dallis. First you find a
really cool and informitive web
site.Ask lots of things so you
can be a informed buyer(aka ho).
Get alot of really solid info
from about a thousand years
of collected knowhow.Have people
defend you against others who
thought you were just another
do it yourselfer! You were
able to end up with a very
nice install because you are
now"Informed"enough (for free
no less) to correct
"ALL" the mistakes that your
hvac sub contractor made.
Even though they had a big
old post card of BS on the
sides of their truck!!!
I guess my little old
thirty eight thousand
doller,turbo diesel,
sixteen foot cube van.
With another easy twelve
to fifteen grand of tools
and a driver with enough
smarts to at least keep
you out of trouble.
Well I guess I'll
have to go somewhere else
then.
So you must not have
a sign on the side of your
house that says honest
and informed homeowner.
Because if you did than
you certainly would have
had at least enough
professional savey to
say.......post some
PICTURES!!!!

Ya thats it no sign ya
no sign that it
no sign.......... :-}

41Gasman over and out.

[dash]

Flex ,ductboard,or metal all deliver the same exact same comfort and air flow,IF designed and installed properly,peroid.

Tinner,your monkey,chimp or whatever comment is way out of line.



In general it's likely that ductboard or flex have a batter installed R-value than metal,as they are "factory" insulated instead of "field" insulated.They are also likely to be quieter in operation,though many staunch advocates of metal,run the last 6 feet of branch duct with flex,to reduce their noisey design.

[tinner73]

i'm sorry dash. i apologize. i would also like to apologize to any and all the monkeys and chimps.

[pstu]

I would like to introduce another FUD element about 10 SEER vs. 13 SEER. It is my understanding that SEER ratings are test results at a specific temperature and dewpoint. If your climate is always at that temperature and dewpoint, then yes you should get the results that SEER promises. If your climate is different, then you never will get quite the benefit the SEER number promises. If anybody more expert than me can clear up some of the facts, I would be highly grateful.

Some AC people in my S. Texas Hot-Humid climate argue that once you get past 12 SEER, it really doesn't even deliver real benefits, much less pay off. Are these guys right? I cannot tell, they aren't the kind of guys that can calculate numbers to the Nth degree required for this answer (very few are!!!). Yet the AC companies (e.g. Trane) tout SEER as if 18 SEER will always cost 2/3 as much as 12 SEER -- in my judgement this is misleading and they ought to know it.

Approaching the problem from a different perspective, in many cooler regions AC is used only a few hours each year compared to Texas. For a sufficiently short season, a purely money analysis would say go with the lower SEER because you never will see enough savings to pay the initial cost.

I would *love* to see some guys at say, FSEC (Florida Solar Energy Center) with masters degrees in math, have a go at this problem. They seem to be miles ahead of anybody studying and publishing elsewhere in the south.

Best wishes -- P.Student

[dash]

Originally posted by tinner73
i would also like to apologize to any and all the monkeys and chimps.

Come on down South and do it in person!LOL