Vent Free Gas Furnace - Moisture Issues?


This unit seem like the perfect solution for my chilly basement.
http://www.heatershop.com/20k_blue_flame_vent_free_natural_gas_heater.html
While reading up on vent-free heaters, I found that they add a lot of moisture to the house.
See "What about Moisture?" here:
http://www.stpaulmercantile.com/ventfreeFAQ.htm
My 95% furnace is in the same area where this heater would be installed - basically a single room basement. The furnace vents to the outside but uses interior combustion air.
Can I expect that the extra moisture will be handled by the furnace and sent to the drain via the condensation pump?
P.S. I have a heat vent in the basement, but it doesn't do enough to keep it warm.
Thanks.
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DerbyDad03 wrote:

If you have a forced air furnace, extra humidity is likely not a problem. I live near DC which is nasty humid (I have to run a dehumidifier most of the year) and when I actually need heat, I also need a humidifier running, else everything dries out very badly, things get staticky, etc.
nate
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wrote:

Unless your basement is the size of a bowling alley or has a lot of leaky windows, I'd advise against a vent-free down there.
The problem won't be moisture, it will be CO.
There is a chart someplace- maybe the building inspector- maybe an insurance company- maybe your gas company. when I put my vent free in they told me how many btus in an enclosed area- and gave some leeway for windows & doors.
My vent-free was close to too big for the square footage where it sits-- but there are 6 windows and an outside door in the room- and the passageway to the rest of the house is 4 feet wide and can't be closed off.
It has never set off the CO meter or fogged up the windows, even when we've cranked it up to 'old people hot' as my son says.

Probably not- it will just exhaust to the basement. In my case, the rest of the house is heated by a hot air furnace so whatever extra humidity gets thrown off is welcome.

I'd make the vent to the basement bigger. Is your furnace sized to heat the basement, too? Even if you steal some heat from upstairs, a warm basement will make the upstairs more comfortable- and most of the hot air will end up there anyway.
The only advantage of the ventless could be that it would run if the power was off and the rising heat could keep the house habitable.
Jim
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Jim Elbrecht wrote:

.
OK, this is just "I've got nothing better to do tonight" rambling...
The closest I could find to a "table" on Google was this paragraph from the Florida building code. Florida is about 1300 miles south of me, so I don't know if this applies. ;-)
In the section of definitions, I found these:
SPACE
(a) conditioned space
(2) heated space: an enclosed space within a building that is heated by a heating system whose output capacity relative to the floor area is greater than or equal than 5 Btu/h.ft2.
and
(b) semiheated space: an enclosed space within a building that is heated by a heating system whose output capacity is greater than or equal to 3.4 Btu/h·ft2 of floor area but is not a conditioned space.
The total square footage of the area I want to heat is roughly 500 sq ft. The unit described in my OP is 20,000 BTU.
Doesn't that put my basement somewhere between a semiheated space and a heated space by Florida's definition?
I know that doesn't really described the permissible maximum BTU/sq ft, but it seems to imply that those numbers (5 Btu/h.ft2 and 3.4 Btu/h.ft2) are acceptable.
Am I even close here?

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Jim Elbrecht wrote:

.
Forgot to mention this...
We have to keep the basement doors closed or the dogs go downstairs and pee when we're not home. They won't pee in "house proper" but the basement must seem like "not inside" to them.
I'm not too sure how much heat would make its way upstairs, although the floors would probably be warmer.

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Unvented and unattended heater inside the house????????????????????? Wow!
We have an unvented emergency heater, rarely used, in case electricity goes off for an extended period.
If/when used it is taken from storage, placed on metal tray with air space underneath and located near the fire place; the chimney vent is opened and something else is opened slightly to permit slight air ventilation.
That heater is never left burning unattended or when everyone is sleeping! Even if someone has to get up and run it again for an hour or so during the night; although that's not usually necessary unless it's very cold and/or especially severe storm.
Please be careful.
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You will enter alot of Co and burnt gas poisons into your house that you just dont need in winter, we all need more fresh air in winter not more poison, water isnt the real serious issue, but could grow mold if its high enough. A 95% efficent gas furnace designed for exterior combustion air cant run at 95% efficency when you are sucking in interior air, it may be now 90% efficent.Cant you heat the basement off the furnace by adding supplys, I did. Do you still use a chimney for the water heater, maybe you could vent a vented heater into that chimney. Burning gas inside reduces oxygen you need, and adds alot of poisons , Co, Mercaptan and whatever gas contains naturaly
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I suspect you'll find that the furnace doesn't draw enough air out of the cellar to compensate for the humidity. That said, winter humidity is often needed. My residence takes as much as 2 galons of water per day to keep the comfort. I know; I'm the guy with a bucket who fills the humidifier.
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