Size of your hot air outlet going to duct work

 
leoman584
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Post by leoman584 » Wed. Dec. 05, 2018 3:00 pm

I was talking to a HVAC guy, and he recommended going larger on the hot air outlet that ties into my duct work. There is currently a 6" round pipe coming out of the top of my stoker that ties to my existing duct work. He said I am restricting air flow and losing BTU. That seems to make sense, but before I install a larger line, I have to ask, is it worth it? Has anyone else done this and noticed any positive results? I'm thinking of building a heat jacket around the stove. If I do, my outlet line could be theoretically any size that I want. I can probably go as large as 12" x 15" or so and still have it fit onto my existing duct line. Any comments are appreciated. Thanks


 
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StokerDon
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Post by StokerDon » Wed. Dec. 05, 2018 3:15 pm

When you are talking about a stove connected to ductwork, bigger is always better. You can't possibly supply enough hot air to your whole house on the coldest day of the year with a 6" duct.

In my opinion, if you are thinking about jacketing your stove to get more heat into your house, it's time to start looking for a furnace.

-Don

 
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Post by leoman584 » Thu. Dec. 06, 2018 7:39 am

A furnace would be nice, but finances are leaning me towards a jacket set up for now. I have been keeping my eyes open for used units with more BTUs, but haven't found anything yet.

 
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Post by titleist1 » Thu. Dec. 06, 2018 10:42 am

Fabricating your own can be a good learning experience and it gives you time to be patient and find a good deal on a used one if that is the direction you go. :yes:

Beware, it will also give the boiler guys a chance to talk you into a boiler / heat exchanger combo also providing unlimited hot water!!! :D

 
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Post by McGiever » Thu. Dec. 06, 2018 11:03 am

Going bigger is good...don't forget the return air needs to be always 15-20% larger than the supply air to realize the full potiential.of any size supply duct/plenum.

 
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Post by SyrKoker » Thu. Dec. 06, 2018 3:47 pm

I might suggest picking up a Ductilator (google it) and using that to size the duct. You'll need to know what CFM you are pushing and then you'll assume a certain amount of friction loss (typically 0.01). You can also find some online calculators that will help with sizing. Another parameters you'll want to pay attention to is duct velocity. The Trane Ductilator will give you some good guidance on what to design around.

Nate

 
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Post by leoman584 » Mon. Dec. 10, 2018 2:16 pm

Anyone know a supplier of duct work? I need a 12x6 rectangular trunk line. Most online suppliers have 12x8 and sell in bulk. I only need a couple pieces and a 45. I'm having trouble sourcing it. I don't have a break to make my own.

Thanks


 
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Post by CoaLen » Mon. Dec. 10, 2018 5:02 pm

I worked out of the catalog on "www.graymetal.com" and bought from a distributor in my area.
-Len

 
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Post by CoalisCoolxWarm » Mon. Dec. 10, 2018 10:07 pm

RE Michaels can make just about whatever you want in our area. Not sure if they are dealer-only or not...

 
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Post by leoman584 » Tue. Dec. 11, 2018 1:09 pm

So, I've decided to upgrade to 10 inch round duct line. That's the biggest that I can go.

I'm curious to see if it will make any difference. Does anyone have any first hand experience upgrading the size of their line?
My cousin upgraded from a 6 inch to an 8 inch round line coming out of his wood stove, but he also put an addition on his house in the meantime. So, it wasn't an apples to apples comparison. Hoping someone on here has some experience and feedback.

Thanks

 
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Post by McGiever » Tue. Dec. 11, 2018 4:37 pm

Depends, Is the 10" round bigger than the earlier proposed 12"x6"?
All things being equal, with fan speed, a bigger duct will have less velocity and less noise inside than a smaller duct.

Would you choose bigger or smaller arteries for your heart? ;)

 
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Post by leoman584 » Wed. Dec. 12, 2018 8:38 am

According to some geometry there are slightly more square inches or surface area in a 10" circle than in a 12x6 rectangle, so yes.

 
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Post by leoman584 » Wed. Dec. 12, 2018 8:41 am

StokerDon wrote:
Wed. Dec. 05, 2018 3:15 pm
When you are talking about a stove connected to ductwork, bigger is always better. You can't possibly supply enough hot air to your whole house on the coldest day of the year with a 6" duct.

In my opinion, if you are thinking about jacketing your stove to get more heat into your house, it's time to start looking for a furnace.

-Don
The reason for the jacket is due to the single wall design of the stoker. It throws a ton of radiant heat off the sides and warms up the basement great. The problem is, my living space is upstairs. I'd rather have the heat upstairs and have a cooler basement.

 
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StokerDon
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Hand Fed Coal Furnace: Harman SF3500 reduced down to 3 grates connected to its own plenum
Coal Size/Type: Rice, Chestnut and whatever will fit through the door on the Harman
Other Heating: Noth'in but COAL! Well, Maybe a little tiny bit of wood

Post by StokerDon » Wed. Dec. 12, 2018 6:08 pm

leoman584 wrote:
Wed. Dec. 12, 2018 8:41 am
The reason for the jacket is due to the single wall design of the stoker. It throws a ton of radiant heat off the sides and warms up the basement great. The problem is, my living space is upstairs. I'd rather have the heat upstairs and have a cooler basement.
You are correct. That is why it is time to kook for a furnace. A stove is for heating a space. A furnace is for central heating. In my opinion, it is cheaper, easier and faster to find a used furnace than to try fabricating a stove into a furnace.

-Don

 
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Post by leoman584 » Thu. Dec. 13, 2018 2:12 pm

StokerDon wrote:
Wed. Dec. 12, 2018 6:08 pm
You are correct. That is why it is time to kook for a furnace. A stove is for heating a space. A furnace is for central heating. In my opinion, it is cheaper, easier and faster to find a used furnace than to try fabricating a stove into a furnace.

-Don
Wish I could find a used furnace local. Nothing on the market currently. Realistically, probably not going to find anything this winter. Maybe over the summer if something pops up. I certainly don't want to shell out for a brand new one right now.


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