Print

[dirtdigger]

Anyone want to venture a guess as to how much less wood a gassifcation  boiler will use compared to a conventional boiler?     Like for example an econoburn unit compared to an aquatherm boiler of comparable size?

[slimjim]

depending on the unit I will say 20-40%

[dirtdigger]

Next question, how do you justify the added cost of the gassifier boilers if your only saving say on average 30 percent on wood?

[randy_1]

It was easy for me to justify the added cost, however I live in the great state of Maine ,, where their is no other choice thanks to our wonderful and environmentally cautious leaders... It defiantly was cheaper than to continue paying the oilman $3500 per year...

[slimjim]

Well for starters, up here in the socialist state of Maine, in fact all of the northeast other than Connecticut, it is mandated by our state overlords. Next some folks have to purchase their wood already processed and want to reduce their consumption as much as possible. The gassers at least those of good quality are far more expensive to build and test, on average it costs between 30,000 to 45,000 for the testing, pass or fail. Who would you think ultimately pays for that test. My suggestion to you would be that if you can still legally purchase a quality conventional unit then grab it while you can, if you can't then get as much as you can out of your old Wood Doctor, the conventional's were not a bad unit and are not that bad to patch, I have done several of them myself.

[martyinmi]

I'd go out on a limb and say that the AVERAGE gasser will use 40% less fuel than the AVERAGE conventional unit.
I'd venture a little farther out on said limb and say that the AVERAGE gasser will consume upwards of 70% less than wood than a few of the more inefficient brands out there.

There are a few manufacturers that employ multiple pass heat exchange to scavenge more heat.
There are a few manufacturers that use a huge amount of firebrick to help burn off most of the smoke (Unburned smoke is wasted fuel. It can burn at temperatures in excess of 2000*F).
At least one manufacturer incorporates both.

It was easy for me to justify the added cost.
During the average winter, my conventional unit would consume nearly 12 cords.
My gasser will be around the 7 cord mark.
I am a wood scavenger. I trim fence rows, edges of woods, take care of my relatives unwanted trees, etc.
I NEED the exercise, but I also need to spend time with my family.
I should be able to use an average of 5 fewer cords/year over the lifespan of my boiler (15 years?).
75 FULL (not face cords or ricks) cords is a LOT of work for this 'ol man.
In this area, a cord (once again, a full cord- 4'x4'x8') sells for $160 - $180 cut, split, delivered,stacked.
Thats $12750 in savings @ $170/cord over the life of my boiler, as well as much less wear and tear on this old body.

[mlappin]

I'd go out on a limb and say that the AVERAGE gasser will use 40% less fuel than the AVERAGE conventional unit.
I'd venture a little farther out on said limb and say that the AVERAGE gasser will consume upwards of 70% less than wood than a few of the more inefficient brands out there.

There are a few manufacturers that employ multiple pass heat exchange to scavenge more heat.
There are a few manufacturers that use a huge amount of firebrick to help burn off most of the smoke (Unburned smoke is wasted fuel. It can burn at temperatures in excess of 2000*F).
At least one manufacturer incorporates both.

It was easy for me to justify the added cost.
During the average winter, my conventional unit would consume nearly 12 cords.
My gasser will be around the 7 cord mark.
I am a wood scavenger. I trim fence rows, edges of woods, take care of my relatives unwanted trees, etc.
I NEED the exercise, but I also need to spend time with my family.
I should be able to use an average of 5 fewer cords/year over the lifespan of my boiler (15 years?).
75 FULL (not face cords or ricks) cords is a LOT of work for this 'ol man.
In this area, a cord (once again, a full cord- 4'x4'x8') sells for $160 - $180 cut, split, delivered,stacked.
Thats $12750 in savings @ $170/cord over the life of my boiler, as well as much less wear and tear on this old body.

 

[dirtdigger]

Thanks for the replies guys, now for the million dollar question, seeing how this a forum about wood furnaces, anyone want to rate each brand for efficiency, starting from the most efficient to the least???   Now after everyone gulps a few times and hems and hey haws around how about actually doing just that, not taking the companies claims for efficiency, but from a stand point of construction and users??

As for the formula mlappin used, I'm not sure I can agree totally, are you paying that price for each cord you burn, or do you sell wood for that price?   I'd think the price would be more in line of your actual costs out of pocket if your processing and doing your own scavenging and the price would be much lower and the cost much less, payback much longer.   Now from the work standpoint, can't argue that one at all, nor the price you put on time spent with family, but that can't be figured into the savings to justify the higher costs, or at least that is what uncle sam tells me when it comes to figuring expenses on my tax's, or my bankers tells me when it comes to applying for a loan.   

[mlappin]

Wasn't my formula, martyinmi posted it and I quoted it.

Year before I installed my OWB i was paying over $300/month for natural gas and the house was kept livable but not near as warm as the wife would like. After building an OWB my monthly gas bill in the winter was $38 which is the minimum and the house is kept at 72.

Being as I'm in Indiana I'd have to go with a gasser, however I could build another standard OWB as homemade is exempt but instead I'll be building a gasser. Less wood burnt is less time spent cutting wood which means more time to take care of other things. If I actually have time to cut wood and sell it, then I'm obviously forgetting about something more important that needs done. A lot more people around here are going back to heating with wood as well so less free wood around for the taking.

I know what my stack temp is with the old OWB, if the on the new gasser the stack temp is a third of what the old is, then I'm obviously saving wood, time, and labor.

From a non engineering stand point and mainly by common sense and hands on experience, with the multiple passes I'd have to go with the scotch marine design like P&M uses as being the most efficient.

[slimjim]

 I think if you are patient there will be some of our P+M customers come on here with actual stack temps on the 250, I know what they are, I use stack temp to set my air on installs, the 250 runs at 260 degrees when the tubes are clean and should be brushed out before stack temp reaches 320 degrees with a water temp of 190 degrees and the boiler firing under a hard load.

[coolidge]

I have a few neighbors with different brands of OWF.
1) Burnt 20 cord last year for an 1800 sq ft house.Central Boiler   Non Gasser
2)Another was at 40 cord (all softwood) CB  Non Gasser  1800 sq ft
3) Another was at 7 cord Aquatherm  1600 sq ft
 4)  myself at 8 cord   PM gasser heating 3200 sq ft

[Jwood]

Coolidge what part of the country was this in? Just so we all have an idea on how cold it was there.

[dirtdigger]

slimjim, if a person would install a separate heat exchanger on top of an existing boiler like the wood doctor that has the tubes in it, how much efficiency would be gained?   I've seen a few guys who have done just that, bring the cold water into their home made heat exchanger and then down into the furnace, was wondering if it was worth the effort, I never got much of an answer from those that did it, seems they did it before using their furnace and didn't really know what efficiency was gained, they just figured it would help out.     

As for the rest of the discussion, great stuff keep it coming

[slimjim]

I put a separate heat exchanger on my WD years ago and gained 10 degrees before my return water from the house went back into the boiler, it worked well but the creosote was dangerous to say the least.

[dirtdigger]

Why was the creasote so much worse on you separate heat exchanger compared to to those built in?   Was it too large and cooled the air too much and thus the creasote buildup became an issue, or didn't you make it cleanable?