Could it be that bad?

[VeggieFarmer]

I just met a guy the next town over who has a Tarm Solo 40 and 1,200 gallons of storage in his basement. Since this is almost exactly what I was planning to install this summer, I went over to take a look.


His house is 2,500 sf, built 6 years ago, with not too much glass. He heats it to 75 degrees, along with an 800 sf garage heated to 50 degrees, plus dhw.


When I asked him how much wood he burned in a season, I just about slipped a disk: 16 cords.

Could it be that bad? He's a retiree and loves nothing better that thinning out his 90 acres of ratty red maple. But I'm not ready to quit my day job - I was hoping to get away for about 6 to 8 cords per year.


I noticed a few things right away (being a regular reader of this forum.) He's using standard baseboard heat, so he tries to keep his storage at 180 all the time. His tank (the foldable rubber ones that Tarm recommends) was warm to the touch, even in a 75-degree basement. And when I was there, the boiler was idling; he claims to stoke it three to four times per day, never letting it go out. (When he opened the door, I saw the creosote dripping down the inside of the fire box.)


My question: could the aggregate of these various sins (high tank temp, poor tank insulation, and endless idling (I'll leave out the red maple and the house at 75)) add up to that much wood? Like many readers on this forum, I've been mightily impressed by reports of people heating similarly sized houses with 4 to 6 cords or so. But I'm skeptical that poor operating practices could be tripling his wood use, which makes me reconsider my enthusiasm for the going down the same road.

 

[Mainewood]

This is another reason why this forum is so important for those of us who are learning. Any product can me misused because of operator ignorance. Continue your investigation with other tarm users who are getting better results and follow their prochedures.
Thanks for sharing. The resulting questions and answers will help others.

 

[JustWood]

Maybe he meant face cords.

 

[VeggieFarmer]

I can't vouch for the accuracy of his measurements, but I saw the woodshed, and it was big enough to hold 16 true cords (or thereabouts.)

 

[Mainewood]

Sounds like he is over-fueling the boiler. long idling and creosote...

 

[Eric Johnson]

I'd say that if he has storage and his boiler still idles, then he's overfiring it. It's the idling that robs efficiency in a gasifier. As somebody who gets his wood through a woodlot improvement project, I can understand his free-spending woodburning habits. There's always some pressure to do more improvement work, and that results in a lot of wood. And red (soft) maple has pretty low btu value for a hardwood. Etc.

My Ford Ranger gets 22 miles to the gallon when I drive it (full of wood, half the time). On the rare occasions when my wife drives the truck, she gets around 15 mpg.

Every time I've ever put in a new wood burner, it has always taken me a good year or two to learn how to operate it more efficiently. There are subtle tricks and observations that you learn and make over time, and they have an impact on wood consumption.

Finally, to put it all into perspective, you won't find a more efficient wood-fired boiler than a Tarm gasifier. You're not heating your house with oil or gas. It is what it is.

 

[Vtgent49]

16 cords would fill a space 12 feet wide, 6 feet tall, by 32 feet long if stacked tight. or 400 square feet by 6 feet tall. or 600 sq feet if 4 feet tall? Could he really have used that much?

4-5 cords should be plenty, gassifier or not.

Al

 

[Reggie Dunlap]

I also have a Tarm 40 with storage and I will burn under 5 cords this winter. I am heating around 4500 sq. ft. I think your buddy is talking about a face cord.

 

[Jim Post]

Sounds like a lot of wood to heat a newer 2600sf house....

Lot's of creosote on the inside of the firebox on my tarm too. The manual says this is to be expected....should not be any creosote in the refractory or heat exchange tubes...

You should check back when the boiler is firing to see if it is gassifying properly. Look in the lower door when the draft fan has been running for awhile. Also check the smoke out of his chimney...if gassifying properly there shouldn't be any blue/grey smoke.

One possible cause of excess wood consumption on a tarm is not getting the bypass damper closed and locked properly during operation. That handle for the bypass damper needs to be within 3/4" of the loading door or you will be losing heat up the flue. It's a pretty stiff spring to push against to get it locked properly. Also creosote can build up on the bypass damper opening and the metal flap that closes over it. I clean mine regularly when I clean the heat exchange tubes. There should be a metal on metal closing sound (clang) when you close the bypass damper.

I use around 6 cords to heat a 1400 sf 40 year old house without storage so his wood consumption does sound high to me.

jp

 

[Nofossil]

If he's keeping the storage at 180 and running the boiler continuously, then he might as well not have storage. The whole point is to run flat out and then shut the boiler down for a day (or two or three). Maybe he doesn't have enough baseboard to get usable heat out of cooler water. One thing I'd suggest for anyone heading down this path is to plan radiant if possible and extra baseboard if not.

I'm ending the season at almost exactly 4 cords (3500 square feet in Vermont. plus hot tub and DHW). My brother has a smaller and better insulated house. He's ending the season at under 3 cords with a gasifier. He used to burn 5 with a conventional boiler.