# Gas Venting Methods...



## Peter B. (Oct 25, 2010)

This may be off-topic here, but I would sure appreciate some help.

After 25 years burning wood as my primary heat source, I'm planning to add a 'supplemental' propane heater this winter.

I'm leaning toward a basic wall mount furnace... no frills, no fire view.  But I've been looking at a variety of different types.

I'm a little confused about venting methods.  I know direct vent allows you to go straight horizontally through an exterior wall... and that 'B' vent is - more often than not - vertical through the roof.

Is there any way to vent a 'B' appliance horizontally... without a chimney?

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And as long as I'm here...

I estimate that I burn (about) 2.5 cords of oak per season (heating the three rooms I bother to heat, in a poorly insulated house in SW Wisconsin)... which I estimate to be 65 million BTU input per season... burning in an antique wood stove that likely doesn't reach 65% efficiency.

Any easy way I can derive the needed BTU/hour based on the above?

The heater I'm leaning toward is a 30K input (21+K output) propane fired unit... about 73% thermal efficiency.

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Again, likely off topic, but I'd be grateful for the advice.

Thanks.

Peter B.

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## vvvv (Oct 25, 2010)

stove venting is defined by manual & UL testing.......partime burn i'd go ventless @ 99.999999999999%


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## spirilis (Oct 25, 2010)

I wouldn't touch ventless with a 10 foot pole as I value my health, and no amount of marketing BS from the manufacturers is going to convince me that ventless/ventfree is safe.


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## Peter B. (Oct 25, 2010)

To clarify:

I've already ruled out vent free...

The second half of my question was geared toward determining a plausible continuous output rating for the heater I might buy (e.g. 15/25/35 K BTU per hour) to replace the wood stove.

Thanks, and sorry if my phrasing of the question was confusing.

Peter B.

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## vvvv (Oct 25, 2010)

spirilis said:
			
		

> I wouldn't touch ventless with a 10 foot pole as I value my health, and no amount of marketing BS from the manufacturers is going to convince me that ventless/ventfree is safe.


whats a gas cookstove made of?


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## Peter B. (Oct 25, 2010)

~*~vvv~*~ said:
			
		

> spirilis said:
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Pook:

Please... no range wars for now... I'd just like an answer to my question(s)... if someone is good enough to help.

It's getting cool here in Witzconsin, and I've got a bum knee and a bad back.  This year, I won't be able to handle firewood... and need to get some other heater in here ASAP.

Thanks.

Peter B.

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## DAKSY (Oct 25, 2010)

~*~vvv~*~ said:
			
		

> spirilis said:
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Hey, Pook. 
Question: How many people DIE every year whan they try to heat their homes with a "vent-free" cookstove?
Answer: Almost ALL of them...
Case closed.


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## vvvv (Oct 25, 2010)

DAKSY said:
			
		

> ~*~vvv~*~ said:
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depends on the air infiltration of the house mostly & a working CO detector. PARTIAL use was mentioned , eh?  hey. give  me an analysis of unvented gas burn emissions?= CO, CO2,H2O, NO3 or whatever?


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## PastTense (Oct 26, 2010)

Probably you can find something on the internet. What I am thinking is that you probably have 7500 or so heating degree days, which you use 65 million BTU to heat or about 8667 BTU for each degree day. What is the coldest day you have there? Say 20 degrees below zero--so to heat it to 70 degrees is 90 degree days or 780,030 BTU. Since there are 24 hours in a day that is 32,501 BTU/hour. But you are going to use a more efficient stove than the wood stove you have the BTU requirement will be somewhat less. So I think your 30,000 BTU unit is a reasonable choice.

But you should be thinking about what if you want to sell the house (people will want to heat the whole house). If so probably a 60,000 BTU or more unit. You should also be thinking about efficiency. Over the years you will be spending a lot more money on propane with a 73% unit than a 93% unit. (Since propane is 91,600 BTU/gallon to produce 65 million BTU this is about 710 gallons a year--this number  again somewhat lower because of the more efficient stove--maybe 500 to 600 gallons a year).

Although thinking it over your 65% efficiency number for an antique wood stove efficiency is probably much too high.

Can someone run the math and give a better answer?


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## jtp10181 (Oct 26, 2010)

Peter, Anything marked as B-Vent will need to terminate vertically above the roof.  Direct vent can vent direct out the back, or other various configurations depending on mfg specs.

Are you determined to get a wall mount heater? If you would consider a freestanding gas stove and are anywhere near Madison, WI (or surrounding areas) our showroom staff can help you find something that would fit the bill. Also if you have any sort of old wood fireplace (prefab or masonry) in the area you want to heat you could possibly put a gas insert into it.


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## heating8 (Oct 26, 2010)

B-vent can be used to terminate horizontally.  It depends on the type of gas unit you're buying.  If you know you want to vent horizontally, you just need to look for a unit that allows this configuration.

+1 on the vent free discussion.  Gas stoves (the top burners) aren't left on all day to provide heat.  The oven only fires up intermittently when the temperature lowers and more heat is required, but it's insulated and not providing full on while in use.

Get a GOOD carbon monoxide detector, and you'll be amazed at how much carbon monoxide you're exposed to every day.


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## vvvv (Oct 26, 2010)

takes ~1cubic foot of air to burn 100btu of propane which has 90k btu/gal. & produces ~1gal water from combustion....  drafty house i'd locate whichever heater on Northerly side or wherever prevailing wind comes from


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## Peter B. (Oct 26, 2010)

Thanks to all for your replies...

Past Tense: I made an effort to 'run the numbers' myself but ended up getting dizzy... and the answers were variable.  Just thought I'd enlist someone else's brain.  I'm still considering a higher efficiency unit, but frankly, the house is a disaster and may be abandoned in a couple of years time.  I see this as a stopgap solution.

jtp10181: I considered a gas stove, but decided (again, largely due to the condition of the house) that I should go for the least expensive option.

heating8: I'm not having much luck finding furnaces approved for a horizontal vent termination, so I guess I better stick with direct vent options.

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Pook & DAKSY: You may resume your range war now...

Peter B.

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## vvvv (Oct 26, 2010)

i forgot the power venting option for a b-vent furnace which would allow for no chimni......ithinx


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## The Kirbster (Nov 18, 2010)

I work part time in the same office as the local Weatherization Assistance Program.  They install a lot of Rinnai direct vent stoves that run around 83% effeciency (if memory serves me correctly).  If they can afford to install them, they must not bee TOO expensive.


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