How to determine return air duct size for a 50,000 BTU Gas Furnace

Posted by kck3888 on September 19, 2006, 4:52 pm

Hi, Folks,
I am trying to install the 50000 BTU Weather King gas furnace on my
rear house.
Before, there were only space heaters in that house, so I have to
"design" the ductworks and install the whole system.
I can never image that it is really complicated for me to finish this
project.
I have a few questions hope someone can help me.

How can I determine the size of the return air duct?
Where should I put the opening of the return air duct, do I have to
connect the ductwork to the furnace itself? Or can I just let the
return air duct connect to the furnace room (4'x4')?

Thanks

Posted by Bubba on September 19, 2006, 5:57 pm

I doubt it but here we go

>How can I determine the size of the return air duct?

Put up 4 fingers, step back, click your heels and repeat: "Theres no
place like home." It should come to you by fairy messenger.

>Where should I put the opening of the return air duct, do I have to
>connect the ductwork to the furnace itself? Or can I just let the
>return air duct connect to the furnace room (4'x4')?

Normally, you just put it near the floor drain or real close to the
flue opening of your water heater.

>Thanks

You bet. Hope this helped.
Bubba
"Bubba Certified"

Posted by on September 19, 2006, 6:47 pm

kck3888 wrote:

look at some similar sized installations

> Where should I put the opening of the return air duct, do I have to
> connect the ductwork to the furnace itself? Or can I just let the
> return air duct connect to the furnace room (4'x4')?

no, it will suck in the gases from the flue as well as the return air
duct, you have to connect it up to the furnace.

> Thanks

Posted by udarrell on September 19, 2006, 8:36 pm

kck3888 wrote:

>Hi, Folks,
>I am trying to install the 50000 BTU Weather King gas furnace on my
>rear house.
>Before, there were only space heaters in that house, so I have to
>"design" the ductworks and install the whole system.
>I can never image that it is really complicated for me to finish this
>project.
>I have a few questions hope someone can help me.
>How can I determine the size of the return air duct?
>Where should I put the opening of the return air duct, do I have to
>connect the ductwork to the furnace itself? Or can I just let the
>return air duct connect to the furnace room (4'x4')? Thanks
>

Installing ductwork systems is NO simple task! You will need an
experienced sheet metal duct system installer, or you will have a mess!

Here is a rough outline of what you are faced with!
http://www.udarrell.com/proper_cfm_btuh_duct_sizing_air_conditioning_systems.html

- udarrell

--
Air Conditioning's Affordable Path to the "Human Comfort Zone Goal"
http://www.udarrell.com/airconditioning_eer_ratings_over_seer_ratings_central_systems.html
(Solving ESP)
http://www.udarrell.com/udarrell-air-conditioning.html

Posted by zero on September 19, 2006, 11:56 pm

<sniff,,,,,,,sniff,sniff,,,,sniff> hmmm, smells a little trollish.

> I have a few questions hope someone can help me.
> How can I determine the size of the return air duct?

Oh OK, the whole btu vs. filter size thing.......

> Where should I put the opening of the return air duct, do I have to
> connect the ductwork to the furnace itself? Or can I just let the
> return air duct connect to the furnace room (4'x4')?
> Thanks

-zero

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