"anita" wrote in message
...
That was a detailed reply!

I have some update on my issue. When u say sealed I am assuming that all
the registers being in place too. Is that right ?

Well..its a plus, but not needed.
When I say sealed, imagine this..
You have a central return, and for the sake of arguement, thats the start of
the airflow to the unit, back into the home, (technically, it is)
What I mean by sealed is:
Return filter grill is set into the return box. The return box has had all
seams and connections sealed with mastic, and even the filter grille itself
may be calked around all 4 corners...some higher end homes have this done to
insure that no air is being pulled around the filter.
The duct, metal, or flex, or even that crappy fiberboard, is sealed at the
start collar, or take off on the box, with tape, and mastic. All joints, if
metal where the duct is connected is sealed and mastic on top of that. The
connection to the furnace, or air handler as the case may be is also sealed
and mastic added. All doors and access plates on the furnace or air filter
are in place and all screws holding them in place are there.
In the case of a furnace, with AC added, the AC coil is sealed to the
furnace with tape and mastic, with all mounting screws in place. The supply
duct, be it metal, flex, or ductboard is also taped to the take off and all
joints are sealed.
Every room supply feeding off the main trunk line, is sealed with mastic at
the very least at each take off joint and any and all joints leading to the
supply boot is sealed. Where the boot comes into the home, be it the floor,
or ceiling, the area around the boot is sealed with either caulk, or
silicone. The register is in place...this keeps indoor critters from being
inside the AC critters, unless they are tiny mice and you have large
openings in the grilles, altho its been said that a mouse can get into a
hole smaller than a dime...believe it.


I got a shopvac and tried to remove some of the grains/seeds etc., that
had fallen down there and guess what I got- a coke can and tons of other
junk and all this with cleaning only two registers! rat droppings too. :
(

All kinds of stuff normally fall into the ducts over time. When I went to
clean my return trunk and return lines (I have a return in each room of the
home) I found toys and all kinds of things that had fallen in over time and
since there had been no children in this home since the 50s..you can imagine
how long they had been there with no problems.
When we go out to replace a duct system, normally the majority of the
garbage in the ducts can be found withing arms reach of the register boot.
Worst case we ran into was a kitchen duct that was literally filled with
roaches. Real fun...


I put my hand in one of the registers and after the metal end thingie
(floor box ?) came across plastic sheeting like material inside the
duct. It seemed to be connected to the duct with seams of somesore, and
a little frayed at the point where the floor box connected to the duct.

Cant see it from here, but sounds like the 90 might have come apart and you
are feeling the ductwrap...not sure...have it checked.


Looks like right now I'm looking at having to replace the ducts at some
point of time soon. Can anyone give me a ballpark figure for how much
this endeavour might cost ? I mean an order of magnitude, for a 2400
sqft home.

Depends.
If you go back all metal, you can expect a high price. Remember something
however.....
If you are going to do this, and your current heating and cooling system in
the home is over 15 years old, dont bother doing the ducts, unless you go
ahead and get a new system unless the ducts are just totally crap.
The duct system is part of the cooling and heating system, matched to the
unit. If you have to go later and replace the furnace, you MIGHT find that
you have to replace the ducts too.
any legitimate contractor that you call out to price out a system for you
will perform what is called a manual J, (*T* in the case of a heat pump)
that is a load calculation based on the construction of the home that takes
into account many different things. What was right 20 years ago, with todays
equipment might not be right today, or the unit you have now was never sized
to be correct for the home. In addition to this J, or T calculation, they
must do what is called a manual D duct size calculation. In a nutshell, what
this is for is to insure that each room has enough airflow to supply the
proper heating BTUS and airflow to each room for cooling.
The joke around here with contractors like myself that ACTUALLY do this work
is:
But...EVERY take off is 6 inch..right?
Wrong.
Some rooms might be 6 inch, some might be 4, like a bathroom, or closet area
that needs to be heated and cooled, or they might be 7, or 8 or larger to
insure that the system is working right, and if you get the ducts replaced,
INSIST that the installers place balance take-offs on the system so that you
do not have to rely on the registers to control the airflow...many times,
you may be geting too much flow to one room, and not enough to another, even
after a manual D and the installers can control that, lock the balance in
place and you dont have to worry about it again.
Flex duct....its cheaper, its frowned upon by some, but its legal and works
great provided its a quality made duct and it DOES remove much of the noise
that most metal duct systems tend to have to a degree.
It also MUST be sized correctly, and supported per its instructions. Its
fast, its easy to seal, and the right crew can put in an entire system in
under a day.
Prices?
Metal will vary literally on the time you place the order. Most tin shops
are now only making promises to hold the quoted price for a few days due to
the rising and falling almost daily price of sheetmetal.
I have done some for as little as $900 for a small non complicated home with
what some would call a spider web of duct, to several thousand...most
expensive system was actually installed BEFORE the price of metal went nuts
and it was over $10,000.
Flex duct requires someone that isnt a hack to install it correctly. While
its simple, and quick, it needs to be supported correctly, thought out in
advance if there is a long run, and the proper manual D is not an option,
period. It MUST be done correctly.
Flex duct offers the advantage of no code requirements on a particular run
length, when sized right, and the insulation and duct are all in one nice
neat package. Boot attachments are quick and easy, and require in some areas
nothing but some duct mastic, and two tie straps and the proper tension
tool.
Prices vary. I use a very high quality duct, and have to as flex is the
option more people chose when they see the prices of metal. Again, it will
depend on number of runs, how hard it is to replace the existing, and the
sizes needed to do it right, but expect quotes over $1000 normally for any
sort of quality work and if you have more than 7 runs to be replaced. The
crap sold at Home Depot and Lowes is that....total and complete crap. You
cant use those prices, to get ballparks, since most of the stuff a pro will
use costs more than twice that wholesale.


Do the HVAC guys charge by the square foot/ time and materials or the
whole job -in one go ? How long do these things take ? I know I have to
ask a contractor but I'd like to have SOME idea so as to not get too
ripped off...

Pricing will be by the amount of materials used for sure. Some will flat
rate the job, and others will do it by time and materials.
I flat rate on this type of thing, since I have run into some issues that
are unforeseen and if the customer had paid time on the job, it would have
ran WAY more than I quoted.

My guys as a time example can normally remove and replace a complete system
on what you might call an average home in under a day, if its flex, and I
have been known to personally do a remodel by myself, as in solo, no help,
in one day...including the furnace and AC installation.
This was in a home with NO ducts at all...just a Monitor heater. I have
another coming up in the next couple of weeks and I might take a little
longer, but I plan on taking pics for the website, so it might take a day
and a half.
Its not a pretty home, but one of my remodel contractors that I work with
bought it, and wants central air and to remove the Monitor that is in there
and get away from oil so that whoever buys it has cheap heat.



My inspector told me we have metal ducts so I am hoping we can reuse
some of that...dont know if its a square duct. I see only the ends of it
in the furnace room. Have to look in the crawl space for the rest.

I would dare to guess that you dont have insulation on the inside of the
duct if its wrapped.
If its metal on teh outside, it MIGHT be, but thats rare.


I am going to get someone to try some of what you suggested with the
cutting and the mastic. Dont have the stomach to be making holes in
parts of my house.


only takes a second and when in doubt..
Check

Thanks
anita

Any chance u are in the washington area?!

Washington DC? Washington state?
Neither...closer to DC but we are not licenced up there.
Just in NC and SC.

www.carolinabreezehvac.com
thats us.