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Help me before I kill a housefull of nuns!


Resident Redneck
May 20, 2020
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I'm looking to install a 100kbtu natural gas furnace in my basement.

100% new install, most likely a Goodman unit off Amazon. 90% or better.

How difficult is it to get the system actually performing well?

We had an ac/heat pump installed from new in AZ, and from a mechanical/ductwork install it seemed to be a piece of cake.

I understand there are some formulas needed to determine flow rates and such, which.is new to me.

So, if I bought a new furnace, and the manifolds, how hard is it to setup a decent system regarding flow?

I would probably be looking at floor registers for the first floor. 2 in the kitchen, 3 in the front room, one in the bathroom (small) one in the first floor bedroom.

A few in the basement and the house has pass throughs in the ceiling of the 1st floor to second floor for a few of the upstairs rooms, so I would likely only run one ductwork upstairs to one bedroom, so say one more register upstairs.

I'm assuming there is a, per register cfm flow schematic that I should follow, but I haven't gotten quite that far in my research yet.
It's not that difficult if you know how to calculate flow rates or possess the software to do it. Bonus would be to have an anemometer to measure air velocity in the duct. Ideally baffles to adjust the system would be in place. If you know the velocity then that is multiplied by the area of the duct in sqft to determine airflow. This stuff is not hard but most of us don't have the knowledge, experience, software and equipment to do it properly.
you will need to get the system balanced after it is installed.
an hvac company would come in check the flow rates in the ducts and adust to the proper flow as determined by the engineering calcultion....which you will not have.
to have the system properly working, you need to hire a company.
I've heard horror stories about Goodman equipment for years from consumers and techs alike. Buyer beware.
Ahhhhhh crap. I figured it would be a calculation thing, but not quite that in depth...shoot.
Ahhhhhh crap. I figured it would be a calculation thing, but not quite that in depth...shoot.
the house i bought last year. the home ower installed the system him self.
i had to.rip out most of the duck work and install dampers into the system, so i could balance it.
the rooms closest to the furnace were 100 degrees, and the ones at the end of the run, had no air at all.
my friend who does hvac systems told me what i had to do. he came over after i completed the work and balanced it.
now all rooms are the same.
i got luck, cuse i own a ranch it at the time had unfinished basement under. everything was accessible.
A good HVAC company is worth way more than the price of admission, not to mention you usually need a licensed installer for the factory warranty to be in effect.
They won't install a crap brand someone picked up on Amazon. They want to sell you their own crap . It's like taking your own parts for a dealership to install.
I'm dealing with this right now. I have a very old ducting system. It gets around the house, but I doubt at all that it's balanced. It's all rectangular ducting. I'm sure that it needs dampers. It isn't completely self-evident how to incorporate them. I have some research to do. The good news is that it only serves my main living level. The upstairs I'll probably run on a mini split with the unit in the eaves and ducts running to the three rooms that it will serve.
I’ve done it without issue, do the calculations for flow needed and ducting size. I used round flexible ducting. I bought a return and filter holder on the internet, along with a Goodman furnace. I had a HVAC company come out and check and certify the furnace. It’s not that hard, just time consuming.
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