Tuesday, November 14, 2006

wood-fired boiler

i have the opportunity to install, at bobs, a hydronic system with a high efficiency wood fired boiler. his unit has combustion efficiency nearing 90%. the reason that this is significant is most wood stoves are at best around 70% efficient, even most gas (natural or propane) boilers are around 80% efficient. this unit uses standard cord wood that is readily available here in the ozarks.

what all this jargon and percentages really mean is. the owner of this unit loads the firebox with wood and lets the boiler do the rest. the thermostats control the heat in the house like we were using a more refined energy source. but what it really means is, for a little effort each day (loading the fire box) a person can heat a really large house all winter for the price of a couple cord of wood. the additional benefit of hot water for household use is included.

one of the best benefits for a farmstead minded sole like myself is that it complements solar water heating almost perfectly. plus i like to cut wood to heat our house. do i need one of these units? most emphatically YES. can i afford one? sadly NO. but i'll figure something out.

my dream would be to get one of these units and use it to heat the house, the hot water and a hot tub. and during the summer i'd use the solar collectors to heat the hot-water and hot-tub (i don't have a hot tub yet either) but i'm working on that too. i'm excited to get my hands on this technology i aspire to work a business solution where i'd install these units into houses on a semi regular basis. this is ahead if its time but with my experience in the hydronic industry from california it'd be a perfect fit.

enough about that.

here are what my older kids look like on pbs.

toly is really cute when he is sleeping.

tristan and kassi had a crafty day with homemade play clay. tristan made a volcano and kassi was rolling it with her rolling pin


Rebekah said...

That is fascinating about the boiler!! I learn the most innovative things by reading your blog.

The kids, as always, are a treat to see. :0)

pablo said...

Question: what happens to all of that extra heat the firebox is producing when the thermostat decides the house is warm enuf? Is it simply transferred to the room rather than to the water?

Danielle said...

Thanks for the memory! I used to play with homemade playdough too! I guess I need to be doing that with Max. So fun!

So do you have to fill the water in the boiler or is it tapped into the well?

About the house being hot and germs festering...I've always been told a hot house is just an incubator for illness. I'm not sure how much fact is there, but letting some of the outside germies in to combat the inside germies is always good! Hope it helps!

karl said...

the fire box is plumbed to a large buffer tank which it keeps warm via a thermostatically controlled (power vent) the house thermostats use the tank as their heat source.

karl said...


the fire is basically controlled by the thermostat for the buffer tank. the buffer tank is a huge thermal mass that compensates for when the wood in the fire box is low or used up. properly sized this such an elegant solution that i believe it will become prevalent. the energy source is renewable and can be sustained from several wooded acres easily. i'd be happy to talk about this in depth while you are considering your options for your rr house.

Ed Abbey said...

I used to have a wood stove for years and although I liked the direct heat source, I added it up once and found that gas was a cheaper way to go. (70% efficiency and much cheaper gas back then) By the time I added in chainsaw upkeep, slitter upkeep (hydraulic or myself), and handling of the wood several times before it ended up in the stove and all the times when it was 30 below and I would rather have stayed inside, it was easy to justify it.

Of course with 90% efficiencies, a lot farther south so you need less wood and the higher price of gas, I would definitely consider it again. There is something honest about cutting and splitting wood with a chainsaw and a ten pound maul.

Anonymous said...

We recently installed a corn stove in our den. It looks like an old Franklin cast iron stove. It is run on a thermostat, so no need to start it all the time or worry about leaving the house. Corn is plentiful around us and it's easier than chopping, splitting, hauling, & storing wood. We go through about a bushel a day. The trick is storage, however. Unless you have a gravity wagon or bin system near the house, there's a lot of planning that goes into grain/fuel storage.

karl said...


two words, play clay. it is so good for their little imagination.


i couldn't agree more about the honest work of cutting wood. also the gassification technology has only been implemented in the past few years in wood stoves. prior to that wood stoves were at best 40% efficient. the tides are turning.

karl said...

gracious acres,

if i were building a new house, i'd consider one of the combo, pellet/corn, stoves as a backup heat sorce--tabitha doesn't start fires easily. i like cutting wood so i'll have to be very old to give that one up.

uncle matt said...

I snuggle with my dog to keep warm. Not as much techno knowledge is needed.

karl said...

you forgot one little fact.
snuggleing with your dog in

happy and blue 2 said...

The wood fired boiler sounds really interesting..

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