Wood Burning (part 2)

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A Scan Andersen 10 woodstove, installed in the MCNZH.

People commenting on a recent national CBC article about Edmonton’s NetZero Energy houses spent a lot of effort criticizing the fact that the Mill Creek NetZero Home (MCNZH) has a wood burning stove. Besides proving beyond a doubt that the only thing worse than an ignoramus is an anonymous ignoramus, the comments taught me a bit about what messages to send in a sound bite culture such as ours.

For the record, the MCNZH will consume net zero annual energy without taking the wood burning stove into account. Even if we never burn a fire, the house will consume about 8000 kWh of electricity per year and its PV modules will produce about 8000 kWh per year.

Our Scan Andersen 10 wood stove has been installed, and we really love the quality of warmth that it radiates. Our source of wood will be construction waste from renovation projects in the neighbourhood. If we heated only with wood, here’s how big a pile the MCNZH would use annually:

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A pile of tightly packed construction waste this size will heat the MCNZH for one year.

The pile is 1500 litres in volume, and it represents two thirds of a cord of wood (the cord would be 30% bigger because of the extra spaces between split firewood). We’ll be able to burn the wood very cleanly, because the stove is surrounded by the thermal mass of the concrete floors and a brick mass wall that will installed behind it. A quick clean hot fire will radiate heat into the mass, which will slowly release it into the house for hours afterwards.

Because the heat from the fire will be displacing electric heat from our baseboard heaters, we will in effect be converting construction waste into electricity. The wood stove should make the MCNZH a net electricity exporter of 2000-2500 kWh per year. Because the construction waste wood would have rotted in a landfill anyway, I consider it to be completely carbon neutral. That’s good for the environment, and wood heat provides a good deal of the resiliency that the times ahead will demand.

(cross posted at raisingspaces.com)

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I'm hoping to start construction of my own home in Bonniedoon. We have the same size lot as you and regulations to follow. Thank you for everything you've posted here so far. This site has been an amazing resource for me. I have a different vision and ideas than you of course, but our basic philosophies could be cousins. A few questions come to mind.

1: Has your wife been onboard from the begining?
2: How difficult/time consuming has documenting your progress been?
3: Did you consider in-floor electric radiant heat?
4: Is there any support for this kind of project outside well-wishers and rainbows?

Hi Devin,

Thanks! Answers:
1. Pretty much. She balked at getting a composting toilet, but she's been really on board for the rest of the stuff.
2. It's been somewhat time-consuming, but I've enjoyed it. Plus, I've met quite a few people and learned some things through the process. If you want to write about your project, I'd be happy to set you up with a blogging account on this website (for free).
3. We didn't consider it, because heating up the concrete floors is counter productive for us. We want them as cold as possible when the sun starts hitting them so that they absorb as much heat as they can.
4. Mostly rainbows. A few leprechauns along the way. Besides that we're on our own. It's the Alberta way.

Hi Conrad and Devin,
Regarding heating a house with electric heat in the floor. In houses of this caliber you want to put the smallest and least expensive heating system in that you can, and it really doesn't matter where you put it. My experience comes from a number of very low energy homes. The latest one a Four-plex in Regina has R50 walls, triple, low E, Argon fill windows. Air to air heat recovery ventilator etc. Each apartment is about 800sqft and is heated with a 22,000 BTU NG fireplace in one corner of the suite. We put a 500watt heater in each bedroom and I don't think anyone has turned them on, they are not needed. My daughter who is living in one of the suites said that she always has had a cuddle blanket on the couch in Yellowknife, but here she doesn't have or need one. When you have walls and windows insulated like this you are not radiating heat to the cold walls and windows, and you feel warm at cooler air temperatures. ("reduce your temperature 1 degree C and save 2% on you fuel bill")

Hi Conrad

I have some questions about your solar system. I hope it is ok to ask them here on the fireplace page. I am asking here as it is the last post you have made.

Anyways, I know a bit about solar. I have a 2.5 kw grid-tie system on my house near Toronto. Are you grid-tied. Do you net meter or does Alberta have a program where they buy power from you at an increased rate. Here in Ontario, the government buys PV generated electricity to promote solar. They pay, get ready for this, 80 cent a Kwhr! That is the new rate they will be offering in a few months. I got lucky with my system as I just installed it in November and I didnt sign the contract with the government to sell at the old rate of 42 cents. Once I heard they were increasing the rate I decieded to wait until it becomes law. So for now, I am hooked up to the grid, but I am just giving my power away for free. At the new rate, my system should produce about $2500 a year, enough to cover my electric, gas and water bill. I guess in a sense that makes my house a Net zero house. Now if I can only get it to cover my mortgage and taxes, life would be good!

Hi Peter,

We will be grid-tied. We have a brand new law in Alberta that enforces net billing. So we get paid the retail rate (7-10 cents/kWh) for the power that we produce. That's pretty good for Alberta. I'm actually surprised that it's not the wholesale rate. If Ralph Klein was still in power, it would have been :)

The rate that you are currently able to get in Ontario (42 cents), and will soon be able to get (80 cents), is amazing. It also makes perfect sense - my electricity is clean, and I get no premium over dirty coal? Too stupid. It's the Alberta way.

Conrad

Hi Conrad
You probably have not had to use the stove much in November...lots of sun and nice and warm. Great looking stove!! One question for you... How are you handling the need for combustion air with your new stove? I have looked for a dedicated pipe through the floor in the pics, but I can' t see one. In a house as tight as yours, I am sure you have a plan for this...

Garth

Hi Garth,

There is a dedicated air intake pipe tied directly to the stove.

Conrad

Can construction waste, that has some concrete residue (dust) on it, be burnt in a wood stove?

Will the chemicals in the cement adversily affect the condition of the wood stove?

Bert,

I believe that it's fine. I've burned wood with some inert dust on it (concrete dust) without fear of affecting the stove. It's only been one winter though, so I certainly can't provide a definitive answer.

Conrad

I'm curious to know how cold your stove is in the winter when it is NOT burning? My experience with sealed combustion stoves is that they act as heat sinks in living spaces. The stove warms up the air inside it, sends it up the chimney and draws nice cold air in. This happens continuously, ejecting space heat from your home until you light a fire in it. One way to stop this is to close the chimney and the air intake when the stove is not in use. Is this something that you did? Do you also experience cold stove problems?

Cheers

Hi Dave
Good questions....I have often wondered how severe the energy penalty can be from a wood stove that is not in use. Even if the chimney and air intake dampers are tightly closed (is this even legal?), warm air inside the stovepipe above the damper will become buoyant and will continuously rise up the pipe and be replaced by cold outdoor air from above.

The same thing happens in plumbing stacks. Anyone know of any research on this topic?

please help, my neighbors are burning wood in their wood stove which is in their garage. The smoke comes out of their chimney down to the ground and into our fresh air pipe. Everything in our home smells like smoke and our eyes and throat burn. We have no idea what to do about this matter. Yes the smoke crosses the property line, yes its coming out of the chimney thick, no the stack does not extend above the hoof of their house. And we also know that they don't have a permit for the garage. Please can u help us.

yours truly
janet.

Janet, You could try contacting the local public health unit/officer or the building inspector/bylaw officer about a stove which was installed without a permit. There also may be an air quality - environmental officer who could deal with this for you. Hope this helps. Merry Christmas -Jim

For a faster response call the fire department and tell them there's smoke in your house.

Conrad -

When you were burning wood last winter, how often did you make a fire? Every day, 2x a day? Every 2nd day? What % of your heating did this practice represent? This would be useful info to guage the performance of the stove a person were to select.

We intend on bringing our Jotul 500 with us when we move into the new house we hope to build this summer, mainly because this will save us about $2000 even after we install a cheap made in Canada EPA stove when we sell. However, I wonder if the Jotul is too large for the 2800 feet we'll be heating in a house with similar performance #s as yours (at least in HOT2000).

Thanks again,

Mississippi John
Mississippi Mills, Ontario

Has anyone considered Dave and Garth's queries re heat loss from woodstoves not used regularly?

Mississippi John
Mississippi Mills, Ontario

John,

Our house has an ACPH rating of 0.9 using the Energuide For Houses methodology (which leaves all vents like dryer and stove vents open during the air test). Using the R2000 method, it is 0.36. So, our two hood vents and the wood burning stove vents combined add about 0.54 ACPH at 50 Pascals.

There is definitely an air movement penalty, but as far as research goes, I'm at a loss.

Used even a few times during the winter, I'm confident that a wood stove easily makes up for the penalty.

Conrad

Last winter we burned wood on most days. At -30, the fire would burn for about 7 hours (2 in the morning, 4 in the evening.

We got about 90% of our heat from wood last winter (best guess).

Will you have thermal mass in your new house? If so, don't worry about it being oversized. That's what the mass if for!

Ours is small as far as wood stoves go, but it could easily be bigger without any overheating.

Conrad

Hello again Conrad -
We're just about finished our house and are looking for a wood stove. My house has similar attributes to yours with R80 attic, R54 walls and R25 pad, triple windows.

We're considering a SCAN 10 and a SCAN 5-2 which has a baking compartment. I'm leaning toward the 10, since it seems to be a proven unit. How has your stove worked out for you? Can you estimate the floor space you are heating with it?

Many thanks once again.

John near Ottawa

John,

Awesome job on the house! Sounds very efficient :)

We are very happy with the wood stove. It heats the entire 2200 square feet of the house (not including the basement, it is heated by the baseboard heaters and kept at 20 degrees).

In minus thirty we need to keep it burning pretty hot to keep the upstairs heated, but it does manage to keep it about 17 degrees up there.

It is a beautiful stove, and we often boil water on top of it. A baking compartment sounds very intriguing though!

Conrad

Hi Conrad -

Yes the SCAN 5-2 bake compartment sounds intriguing, but we've decided to stay away from it. That stove burns less cleanly (4.3g/h) and has been discontinued for reasons unknown. We cannot find any info about it online, so have decided on the proven Scan A 10. A couple more quick questions -

Did you place it directly on your acid-stained floors without additional ember protection?

And are you still managing to burn construction waste and if so how has that worked out?

Thanks again,

John

John,

It's not directly on the floors, it's on tile, and the tile extends about 1.5 feet beyond the door of the stove. Embers do fall out, and I'm sure that they would melt the finish of the floors if it wasn't for the tile.

We burn less than a cord of wood per year, so the construction waste burning has worked very well. This year I got most of our wood without even trying: I would just notice clean dry 2x4s getting thrown out in the alley. Just yesterday my boys and I picked up a bunch.

Conrad

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