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A question on efficiency

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by erik, Jan 22, 2006.

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  1. erik

    erik New Member

    Joined:
    Jan 10, 2006
    Messages:
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    Hi all,

    ONce again, i just had my waterford trinity installed, and this is totally different than the old steel plate stove we had when i was a kid.

    One thing that i have mentioned being surprised about is the restricted burn that this stove offers. To get a fresh fire going, or to really get the place warmed up, it is my instinct to crack a door open (the side door works great for this). gets lots of flames and the fire rumbling well. But i wonder, does this result in a hotter fire in the context of heating? I have done this a few times, and thought that the stove itself almost cooled down... could this be due to the rushing air shooting up the chimey? then when i close the door up that is when the room temp soars up (or so it seems)!

    Does this make sense? perhaps its a common mistake!?

    Thanks
    Erik

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  2. Shane

    Shane Minister of Fire

    Joined:
    Nov 21, 2005
    Messages:
    1,830
    Loc:
    Casper Wyoming
    Makes perfect sense. With the door open you're allowing alot more air than normal in so the air/fuel/heat ratio is thrown off and causes the firebox temp to drop alot. Also if your stove has a bypass damper then you probably have this wide open at this point reducing your the residence time of the flue gasses in the firebox to next to nothing. A big majority of the heating value wood contains is in these gasses so you have to have adequate residence time in the firebox to ensure that they all combust.
  3. erik

    erik New Member

    Joined:
    Jan 10, 2006
    Messages:
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    Hooray - i wasnt immagining things!

    Ok, so then how do we build a fire hot enough to clean the viewing window (i find this thing almost too big - it gets dirty easilly and takes a really hot fire to wash!)?

    Erik
  4. Rhone

    Rhone Minister of Fire

    Joined:
    Nov 21, 2005
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    Well, maybe I can help explain why the viewing window gets dirty and this is just what I've come up with. When you start a fire, or reload, the moisture in the wood evaporates and turns to steam. At the same time, the wood releases smoke. Some of the smoke & steam will go out your flue, some will be blown down your viewing window by your air wash system (I'm sure you've seen your smoke whip down in front of your window). That's your air wash system trying to create a barrier to prevent this moisture rich air from hitting the glass. It's not perfect, any of that moisture rich air that hits it, the water condenses on it. Your air wash system has another trick up its sleeve, constantly blowing non-moisture rich, heated air over it so any that does condense, does not stay too long before it evaporates. So, why the dirty window. When water condenses on your window, while it's there it's collecting any smoke particles that blow across it until it evaporates. After it evaporates, the particles it's collected in the meantime stay on your window and I don't know if they burn later or not, regardless it turns it black.

    So, understanding the cause and reasons there are three things to focus on. Moisture, smoke, and air flow. Let's start with moisture, the drier the wood, the less moisture can condense on your window, the faster it warms up, the cleaner it stays. Simple Enough. Also, you want to try to hold off turning down your air until you're sure your unit is in full swing. I normally wait until all the skins of the wood has turned into a flame ball, afterward I then turn down the air. Being to hasty to turn it down the unit is cooler, the air wash blowing less and cooler air, moisture stays on the window longer, and I create more smoke & particles for it to collect.

    Next, is to minimize your smoke. The less smoke, the less particulates the water can collect. If you can learn/do the top down method of lighting a fire, instead of bottom up, it has a double benefit. First, it minimizes unburned smoke & particulates. Second, it gets the air pre-heat channels warmed up faster than the bottom up method so moisture on your glass doesn't stick around as long, nor has as much smoke and particulates to grab. Also, when you reload it helps to empty the ashes just in the front, and then move all your glowing embers and coal to the front and load on top of it. That focuses the heat, and you only have 1 log that's smoking (or just the ends of logs if you load front/back) and in no time almost instantly ignites reducing smoke. If loading side/side, it helps to make it two piles of coals & embers in the front with a space between so the air wash system will blow air through that hole and spread the flames into the middle of your pile.

    Lastly, watch your air flow. Moisture predominately comes out the ends of the logs. If you load your logs front/back I've noticed on my unit (some are designed better than others for front/back) the moisture comes out the ends and there's not much distance for it to travel to condense on my viewing window. Having rather wet wood and loading front/back covers my viewing window in moisture which dirties it right up. Loading side/side has really helped, as the moisture coming out the ends of the logs hit the sides of my insert first and condenses there instead of having a direct path to my glass. The problem with loading side/side is, it's for the experienced user as it is not as easy as front/back and takes getting used to. It also extends your burn since the air flow isn't freely blowing across all your logs.

    Anyway, that's what I've noticed and the things I've done to reduce it. It's not perfect, I used to have to clean it once a week now I'm about once a month, sometimes even two. But, if a log rolls into the glass (one of the problems loading side/side) and it doesn't happen often anymore, that dirties it right up. Wish my unit had andirons.
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