I have a two story home with 2000 square feet of living space. 1100
down stairs, and 900 up stairs. The house has forced air/natural gas
heat. I'm going to replace some of the old heating duct. Should I
replace them with the galvinized tin ones, or the plastic
coiled/insulated ones? Does it help to insulate the tin type? I have a
basement, but the house has two additions with crawl spaces.
Also has anyone used a secondary inline fan to help push heat though
the house? Home Depot has them, ans says it helps save money on
I just wanted to add, that it appears you may have some problems with
the design of what you have now. If that is the case, you should be well
served to have a qualified professional come in and determine what you
really need, not just guess. A good distribution is critical to a good
system. I would rate it as the most important part.
I'm not sure what you mean by the "plastic coiled/insulated ones". Do you
mean the round dryer vent type? Regardless, what you need to look at is a
material that allows the air to move with minimum friction. I learned this
from the installation of a dryer vent. Steel venting allows the air to
travel more freely allowing for longer runs. Given such, it would seem that
anything "coiled" would work against proper air flow. Also, the coiled ones
would present you with a real problem when you went to clean them. And yes
it does pay to insulate the ducts, especially if they are in an unheated
area. You also get the added advantage of cutting down some of the noise
from your heating system when you do this.
I don't have any personal experience with the inline fans but I have heard
that they are not as good practically as the theory behind them. It is
better to make sure your system venting is balanced properly to ensure
proper air flow to where it is needed.
The "theory" is flawed. The system fan only puts out so much air.
An inline fan is just a way to send more flow to one room vs.
Yes... dampers can probably do the same job with no electricity.
To the OP: You need to do a lot of reading on duct installation
if you plan to DIY. Use metal wherever possible. Flex duct will
reduce flow. You will need some tools like a duct end crimper
(or whatever they call those tools). You will need lots of
It would help to find a local HVAC supply that sells retail with
a nice friendly counter man who is willing to spend a few minutes
with you to make sure you get all the stuff you need.
If your system needs balancing and adjustment, call a pro instead.
Only replace ducts with the same size and only if you like the
way it all works now.
Metal ducts are the most efficient. There are various grades and sizes
of the fiberglass ducts. Some are lined with plastic liner, and are
moderately efficient, some are unlined and absolutely horrible. If you
use fiberglass ductwork, increase the size 2" over metal ducting, and use
suspension saddles if you hang them.
You need to balance your system. That can include installing a new
return air duct as well as adjusting the air flow to individual rooms.
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