barometric dampers-Why Not Outside?

Re: barometric dampers-Why Not Outside?

PostBy: BIG BEAM On: Wed Sep 17, 2008 9:30 pm

Yeah but if the temps go down and the wind picks up don't you want the fire to rev up?
You all know how I like passive controls.
DON
BIG BEAM
 
Stove/Furnace Make: USS Hot blast
Stove/Furnace Model: 1557M

Re: barometric dampers-Why Not Outside?

PostBy: coaledsweat On: Wed Sep 17, 2008 9:59 pm

Devil505 wrote:Do they require readjustments after the initial installation? (I thought once balanced you leave hem alone?)


Not as a rule, but if you burn wood even in small amount, the baro's backside will get covered with creosote and lose its delicate balance. It's accumulation period varies depending on a bunch of factors, but rest assured it will. I recommend removing the baro and capping its port if you plan on burning any wood.

The baro works on an incredibly small amount of difference in air pressure and is used to control the total draft through the firebox. It cannot perform this function if it is not in the room at the exact same air pressure as the burning fire. If you want the baro outside, move the appliance with it. ;)
coaledsweat
 
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

Re: barometric dampers-Why Not Outside?

PostBy: gambler On: Wed Sep 17, 2008 10:14 pm

coaledsweat wrote:The baro works on an incredibly small amount of difference in air pressure and is used to control the total draft through the firebox. It cannot perform this function if it is not in the room at the exact same air pressure as the burning fire.


That may be true of a hand fired stove but what about the stoker stoves? I get 100% of my combustion air from outside.
gambler
 
Stove/Furnace Make: Leisure Line
Stove/Furnace Model: Pioneer


Re: barometric dampers-Why Not Outside?

PostBy: coaledsweat On: Fri Sep 19, 2008 7:53 am

Stoker or hand fired doesn't matter, neither does where your air supply comes from. The coal unit is inside, right? That is where the firebox is so the baro needs to be with it. The outside air is feeding the fire INSIDE your home, the fire's draft is balanced by the baro in relationship between the room's air pressure and the pressure in the stovepipe prior to the baro. The baro actually must be in the SAME ROOM as the appliance, if a door were closed to the room the appliance was in, it will affect the proper operation of the baro.

Installing a baro other than recommended by the manufacturer is asking for trouble.
coaledsweat
 
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

Re: barometric dampers-Why Not Outside?

PostBy: Cap On: Sun Sep 21, 2008 10:12 am

LS wrote:
With the same 1/4" opening in your air control, you will get roughly double the amount of air feeding your coal fire, this will increase the burn rate, increase the heat in the stove. The increased heat in the stove is being drawn up the chimney by twice the draft [suction], so the temperature of the flue goes way up.[more draft], More very hot air from the stove is going up the chimney, the fuel is burning faster, and the stove may not even be hotter, the heat may be just going up the chimney


This idea proves a point I have recognized and mentioned for a few years here. (Maybe a little off topic )

Let's assume I have small hand fired stove. I have this puppy really fired to produce the heat I need. My hot stove air is 300F but my TRUE flue temps are even hotter at 350F. My draft is set at .05" (I often read guys stating very hot flue temps. Very hot to me is over 250F )

Now let's assume I have a larger stove capable of creating the necessary btu's to create the heat I need. My stove hot air is a mere 200F and my true flue temp is 175F. and draft is .05" My fire is at a mere simmer and not blazing red as in the first scenario. My coal usage is at the minimum for this unit.

Pound for pound, the 2nd larger stove is using less fuel than the 1st unit to make the same amount of heat in a period of time.

My point, hand fired stoves are designed to fire at a simmer, not at a blazing hot fire. Not at a high rate as I have read from others on this list. They are not as adjustable as folks make them out to be unless of course you have no regard for the amount of fuel use or the amount of times a day you tend to it.
Cap
 
Hand Fed Coal Boiler: Harman SF 250, domestic hot water loop, heat accumulator

Re: barometric dampers-Why Not Outside?

PostBy: LsFarm On: Sun Sep 21, 2008 10:28 am

Cap, your SF250 has built in heat exchanger, this changes the situation and comparision. Pounds of coal for Btu's into the house depends on heated surface, a fan washing that heat off of the surfaces, and many, many variables..
One variable is that a smaller stove, that is fired hot, is going to have a much hotter stove body, this will radiate and tranfer convective [heated air] into the house better than a cooler stove body, even if it is larger..

Yes there is some more heat going up the chimney, but the stove is still giving off a majority of it's heat into the house.. A hot stove box has a much higher temperature differential, therfore gives off more heat..

Think of it like this: if you wanted to warm a 20'x20' room but only wanted to use 90* temperatures, you would have to have a whole 20' wall at 90* to keep the room warm.. [I know, depends on insulation, heat loss etc] .
But if you wanted to heat that room with 350* max temps, you could have a small MarkI , roughly 20"x24"x30" at 350* and the room would be way too warm..

A stoker uses a small but very hot fire to heat the stove body, and fans to transfer that heat convectively.. there is radiant as well.

Just my take on the hot fire vs low fire ideas..

Greg L
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland