Am I wasting wood?

[Bugzapper]

With the early winter falling upon Northern Minnesota, I have fired up the new boiler (CB Classic) in earnest. The 3800' house is pasive solar so I don't need a lot of heat right now, but the boiler keeps the chill off and heats the water.
My question is: How full should I fill the firebox? A 3/4 load lasts at least 24 hours, but even that is quite a bit of oak. The unit idles quite a bit and I was wondering if I am wasting wood by filling it too much with this weather (low 30's daytime, low 20's nite) or if this is how it is done. I have it at factory settings and the draft opens around 165 and closes around 185. I can keep the fire going with less wood, but just haven't had enough experience with a boiler to know what's best.
My old ad on furnace would use roughly a dozen split pieces per day in the dead of the winter and kept the house toasty down to about 25 below when it needed a little help from the gas furnace. This beast seems like it has a bigger appetite. Not what I was hoping for...

Thanks in advance for the advice.

JB

 

[sdrobertson]

I would try to load my CB to the weather. In the shoulder season I would try to only load enough wood to last 12 hours or so. I found that the boiler would burn as much wood as you put in it. A smaller fire will still produce enought heat to satisify your heat load and any excess wood will just smolder away.

 

[jebatty]

What you are experiencing is a problem common to outdoor wood boilers, including the E-Classic, as well as other wood and gasification boilers which depend upon their integral water capacity to provide/store heat when the full boiler heat output is not needed. The boilers need to cycle through burn/idle periods based on heat demand. Some boilers are quite wasteful of wood in this process; others seem to be far more efficient in their use of wood through the idle periods.

The solution is added water storage, typically 500 gal minimum to 1000 gal which is quite practical to even more, depending upon the situation. I don't know what the integral water storage is for the E-Classic, but if it is much more than 50-100 gal, your ability to achieve efficiencies with added storage will be somewhat impaired, as you still need to heat the boiler water, and this water is subject to continual heat loss, depending on how well the boiler is insulated, when heat is not needed by your system.

My Tarm, for example, has 54 gal integral water in the boiler. The Tarm is installed in a space which otherwise is heated. I have 1000 gal of added storage, also in a heated space, and well insulated. When I fire the Tarm, even during the "shoulder" season, I fire a full load of wood and burn full bore until the fire goes out. No idle periods at all. The heat produced, of course, is far more than I may need. The extra heat is soaked up the 1000 gal storage tank, and then, after the boiler has burned out, heat that I need is drawn from the 1000 gal of hot water stored heat. This may last 1-5 days without another boiler firing, depending on demand and how hot I have brought the storage water up to. Very easy, very efficient in use of wood, and trouble free. And because the boiler and storage are in a heated space, all heat lost through the insulation provides heat I need anyway. Another boost in overall efficiency.

So far this season I have just been burning pine and aspen scraps. These are short, hot fires (about 2 hour burns), one burn every other day on average. The 1000 gal of storage is at an average temperature of about 130 degrees.

This might not help you, but it might explain why you're burning more wood that you thought you would.

 

[stee6043]

Even with night time lows in the 30's and highs only in the 50's where I am right now I'm still not running my wood boiler yet. I'm not burning for the exact reason your suggest - wasting wood. With just a little bit of sunshine these days my house needs very little in the way of extra heat. I'd rather pay for the little bit of gas I need to burn to keep warm. I'm saving my wood for when 24/7 heating is required. I suspect I'll be 100% on wood in a couple more weeks. November 1st if I had to guess....but for now I'll pay $20-30 in gas to bridge the gap during the shoulder season.

 

[logjammed]

I am running my e-classic similar to a wood stove. firing after dinner , turning up the thermostat heating the house and charging my superstore for the next day. wheelbarrow full of dry pine and hemlock does the trick. not even half a firebox full. nice hot clean burn also.