How Much Coal Is Wasted Per Day Through a Barometric Damper?

If the neutral pressure point is the pressure balance point between the homes upper increased pressure zone and the homes lower depressed pressure zone, and you further depress the lower zones already low pressure by sucking on it with a chimney, just how does that raise the neutral pressure point? I'm confused. My training that energy must travel from high to low (hot to cold, or high pressure to low pressure) leads me to believe that the high pressure from above will press downward to try to fill the pressure void that the chimney is creating at the lower level, taking the neutral pressure plane that resides between the two extremes downward with it. Otherwise negative energy (reduced pressure) is acting like positive energy and pushing the plane upwards.

Yes I understand the confusion and I think this will clear the haze. The neutral pressure plane is the point in the house where pressure outside equals pressure inside. Below the plane is negative pressure relative to pressure outside and above the plane is higher pressure relative to pressure outside. This it how it moves because it's relative to pressure outside! I'm all wound up now hahaha

Where's Fred? Please pardon my enthusiasm.

Lightning wrote:Yes I understand the confusion and I think this will clear the haze. The neutral pressure plane is the point in the house where pressure outside equals pressure inside. Below the plane is negative pressure relative to pressure outside and above the plane is higher pressure relative to pressure outside. This it how it moves because it's relative to pressure outside! I'm all wound up now hahaha

Where's Fred? Please pardon my enthusiasm.

I can see where (and have previously mentioned that) the reduction in pressure in a basement due to the chimney causes more inward infiltration due to the higher pressure outside rushing inward to fill the void. But once again its increased pressure rushing toward the direction of reduced pressure, and things like books that claim it to be so can never reverse this fundamental law of entropy. If outside pressure is rushing in, then inside pressure from above must simultaneously be rushing downward. Pressure must move from high to low. it matters little if the pressure is from inside or from outside.

Unless things are different when the entire house (high pressure to low, upper regions to lower regions) is at a pressure level that is below that of the outside air. Hmmm???

But for that case would the chimney draft, or would it backdraft? Double-Hmmmm???

The bottom line though is still: What relevance does this have to answering the question of which causes more coal to be consumed. The baro damper, or the MPD, or neither of them?

NOOOOOOOOOO!!!
http://web.mit.edu/parmstr/Public/NRCan/rp207.pdf

Double NOOOOOO!

lsayre wrote:The bottom line though is still: What relevance does this have to answering the question of which causes more coal to be consumed. The baro damper, or the MPD, or neither of them?

Whats your topic say?
Yer right and I'm sorry if I hijacked your thread... I assumed that the added coal consumption would be due to added cold air infiltration caused by the baro where it wouldn't be by the MPD.. What other reason would there be??

Looks like from what Carbon12 has found, its more than suspected I guess..

lsayre wrote:Unless things are different when the entire house (high pressure to low, upper regions to lower regions) is at a pressure level that is below that of the outside air. Hmmm???

No the entire house wouldn't be.. The NPP would be raised when an exhaust fan is turned on OR by running a heating appliance that doesn't have dedicated outside air piped to it..

lsayre wrote:But for that case would the chimney draft, or would it backdraft? Double-Hmmmm???

No again, unless the NPP in the house exceeded the NPP in the chimney like by opening a window upstairs...

It still doesn't answer the question, however. I will just happily assume the Baro allows better efficiency by regulating the draft allowing better combustion and heat transfer Now my brain REALLY hurts,.....Mr. Gumby!

Lightning wrote:Whats your topic say?
Yer right and I'm sorry if I hijacked your thread... I assumed that the added coal consumption would be due to added cold air infiltration caused by the baro where it wouldn't be by the MPD.. What other reason would there be??

There was no hijacking. You are on topic, and you are honestly groping for the answer with good intentions just as I am. I admit that I'm lost and not close to a solution to the question.

OTOH: The info that Carbon12 has uncovered seems to bode very badly for barometric dampers, at least for oil fired furnaces. But in an oil fired furnace when the fire is out the damper is still free to open and let heat out, wherein it is not accomplishing anything positive with regard to fire control at the same time. A coal stove uses the damper to control, regulate, and mitigate (suppress) the degree of fire, for a continuous fire that does not turn on and off. What does an oil furnace use or need a damper for? Do they still put them on todays 85% to 87% efficient oil furnaces and/or boilers?

So the decision I have to make is to A) leave the door to the furnace/boiler room open to the rest of the basement to allow makeup air to be drawn from the rest of the mostly unused basement while at the same time allowing heat from the boiler to passively heat the basement, or B) close the door to the boiler room and crack the window 6 feet away from the boiler to allow for make up air. Both A and B using the Baro, of course. The ceiling of the furnace/boiler room is insulated, the wall between the furnace/boiler room is of block construction with brick on the other side facing the finished part of the basement. What to do,...what to do??? Did I factor in wind pressurization/depressurization of the side of the house with the window???? Head,.....hurt it does

lsayre wrote: OTOH: The info that Carbon12 has uncovered seems to bode very badly for barometric dampers, at least for oil fired furnaces. But in an oil fired furnace when the fire is out the damper is still free to open and let heat out, wherein it is not accomplishing anything positive with regard to fire control at the same time. A coal stove uses the damper to control, regulate, and mitigate (suppress) the degree of fire, for a continuous fire that does not turn on and off. What does an oil furnace use or need a damper for? Do they still put them on todays 85% to 87% efficient oil furnaces and/or boilers?

The baro on the oil burner is set with the burner running and up to heat. Running at 100,000 BTU or better with probably 400 degree stack draft would be very high without it. When the burner shuts off the baro closes and willl mostly stay closed because it was set with a lot of heat going up the chimney which is no longer present. The need for it is the same as for coal stoves and stokers which is to provide uniform draft which in turn provides uniform air to the fire.

As to being wasteful it would depend on how important a uniform air supply is to a particular installation. Lightning found it stopped the yo yo heat production of his unit. Overfiring and underfiring are both wasteful also. The baro overcomes this and allows a setting to be relied on.

The baro on an oil burner is necessary to control how the flame is produced in the combustion chamber. Let me "splane" this.

The oil burners have their own forced draft fan which is required to get the oil mist created by the nozzle assembly to burn. There are a number of reasons why draft is very closely set on an oil burner. Not enough air and minimal draft and you will get a sooty burn and possible puffbacks...not good. It gets very messy trying to clean up a puff back from an oil burner!!! Those little oily strings go everywhere and get on everything requiring special chemicals to wipe the stuff down. Too much draft or too much forced draft from the combustion air blower and you will get what I call a hyper-burn, overheating the combustion chamber and the heat exchanger. The burners are tuned and the baro's are set and left alone after that. A yearly check to make sure nothing moved is usually all that is required after installation.

The baro's are put on almost every oil burner to keep the stack draft at a specified set point to help ensure complete combustion of the oil being burned. The baro's are adjusted after the burner is tuned and the unit is up to temperature.

There is a good description of the equipment at http://inspectapedia.com/heat/DraftRegulators.htm

Rev. Larry

The original question is how much, but what I got from Carbon12's post was that the best form of heat would be electric radiant as there are no stacks to cause a draw on the house. And electric is 100% efficient. Here, where it is only about 8 cents/Kwh, that is exactly what I am doing. I was going to add an outside air vent to the fireplace, but maybe I will just seal it off. Maybe put a little glowing light in there for effect.
I disagree with the post about baro's reducing draft by lowering stack temps. The reason the baro is wide open is because the wind is howling and sucking air up the stack. Draft created by hot air in the stack is only one part of the draft equation. That may be true on a perfectly calm day. In this respect, the mpd is just as good, or better. It reduces stack temp also, and puts a ridged block in the flue to limit the amount of air that can be sucked through as does the air controls on the stove. Sort of like trying to breath through a straw with your finger across the opening.

Kevin

How much coal is wasted per day through a barometric damper? I say none. It saves coal by maintaining proper draft over the fire. Stove efficiency and house efficiency are two different animals. And yes there is a relationship but some are confusing the two.

Your house is a semi-sealed environment. But it leaks and breathes. Heat moves to cold. This movement of heat to cold plus vents and stacks in the home create vacuum. (negative pressure) Air infiltration is the homes response to this vacuum. You can do things to manage this vacuum but you cannot stop it. Your home will not tolerate a vacuum. The best way to manage it in my opinion is to seal the home and provide targeted make up air.

Also this is a good time to say that only coal burners like us would fret over pennies of coal when most of us are saving hundreds if not thousands of dollars by heating with coal. Don't get too worked up about the impact of a baro vs an MPD on the coal bottom line. Seal all the cracks around sill plates, windows, doors etc and manage your air infilatration. Open a cold beer and smile as you see the oil man filling up your neighbors tank.