Outdoor Wood Boiler Lifespan

[Rustyiron]

Wsp617 (op) When building new, you have an oportunity to build with some of the "newer" thinking on insulation. You don't need to live in some weirdo caazy "greenie guy" *house. Conventional construction can be built to give you an excelent insulation and more importantly air infiltration results. Every penny spent on insulation will benefit you regardless of how you heat it. The savings can be a big difference both in heating and cooling. Those savings will continue month after month, for the life of the house. I did this on my place, being in the building business all my life, I was amazed at the return on investment over a "normal" or "to code" insulating job. If you have the opportunity, a few small "free" choices can also be made to reduse your heating needs like "orientation" of your home for some solar gains, minimise windows on the north side, etc.
I think one problem with any non traditional heating systems is that they are sold by the s/f of the bldg. A proper heat load needs to be done for your particular home and your window count and "u" rating, wall const. & insulation, etc, will all be considered and make your heating & cooling work efficiently and comfortably. I know that it is easy to just go with the "normal" insul. job, esp if your making dicisions in the spring or summer, but if you double your budget, it will pay you back soon.
First start by thinking about how you're going to keep your heat in! Then about how you're going to make it.
* not a derogatory comment on anything! It's just a hard sell for the general public.

 

[aczlan]

Air quality is measured by sampling a given amount of space in a certain time period. A small living room wood burner emits approximately 7 GPH where an OWB will emit 70-200 GPH. The latter will saturate the air and exceed what is considered safe air many times over. The indoor wood burner will not. I agree its like comparing apple to oranges.

And if the living room wood boiler throws out 7k BTUs while the OWB throws out 70k-200k BTUs, their emissions/btu are the same...

Aaron Z

 

[etcallhome]

Skybox GIVE IT A REST !!


As for life of a OWB ,mine a Taylor made from NC or SC only lasted about 3yrs. My brothers lasted 8-10 yrs. haven't heard anything bad about Central Boiler but ,,a few things I liked and disliked .
Liked the warmer heat noticed you're talking of floor still a very nice heat..If you haven't though of this while doing the plumbing the lines going outside, put them ,if you can , close to location of where you would be able to put a indoor stove , just in case. , liked the savings of fuel cost, and yes it helped me get exercise ,back aches , learned how to sharpen a chain saw , in the field with a hand file.
Haven't read all the replies because of some peoples posting,
but my dislikes,
Cutting wood for 2-4 weeks every year ,talking 18 or more loads of wood using a S-10 4x4 long bed or Dakota long bed 4x4 ,loaded to the top of the cab ,stacked and not split at this point.
Then splitting, the wood, stacking the wood, and then cleaning the building out getting ready for next season.
One thing if you can get for this stove is a extra fuel system , incase you need to be away from your house (dead of winter -10-30 temp.) so fire doesn't go out.
Always had to haul wood in pickup so dents, bangs, lost bumpers, back window glass, Buying the 2 chain saws, using 2 or more weeks of my vacation every year for cutting the wood. Always trying to find where I could get next yrs firewood. Buying a wood splitter , I admit with OWB do not need to split all the wood but still will need to split some. Oh the 1st and 2nd deg burns from tip of fingers to above my right elbow from the 200 deg water coming all over my hand day the line between stove and house had a air lock. Just a few things I can think of, quit the OWB 11 or 12 yrs ago. Now been taking vac's setting around enjoying the relaxing time and didn't replace one bumper after I quit using the OWB or my in door stove or my fireplace.

OWB nicer than inside stove because all your dirt is outside and not in.
Enjoy .

 

[dave1949]

Wsp617 (op) When building new, you have an oportunity to build with some of the "newer" thinking on insulation. You don't need to live in some weirdo caazy "greenie guy" *house. Conventional construction can be built to give you an excelent insulation and more importantly air infiltration results. Every penny spent on insulation will benefit you regardless of how you heat it. The savings can be a big difference both in heating and cooling. Those savings will continue month after month, for the life of the house. I did this on my place, being in the building business all my life, I was amazed at the return on investment over a "normal" or "to code" insulating job. If you have the opportunity, a few small "free" choices can also be made to reduse your heating needs like "orientation" of your home for some solar gains, minimise windows on the north side, etc.
I think one problem with any non traditional heating systems is that they are sold by the s/f of the bldg. A proper heat load needs to be done for your particular home and your window count and "u" rating, wall const. & insulation, etc, will all be considered and make your heating & cooling work efficiently and comfortably. I know that it is easy to just go with the "normal" insul. job, esp if your making dicisions in the spring or summer, but if you double your budget, it will pay you back soon.
First start by thinking about how you're going to keep your heat in! Then about how you're going to make it.
* not a derogatory comment on anything! It's just a hard sell for the general public.

Greenie Guy! Hey, I resemble that remark :laughing:

The pic on the left is my house at the point where all the concrete work was done and we were ready to start framing. You can see it is very similar to a walk-out basement that is facing south. The only difference really is I have several interior concrete wall sections to add thermal mass (absorb and store heat). The building behind the house is a 28 x 48 garage which is also earth-bermed on the north and west ends.

The second pic is from this summer when we had our solar pv installed, you can get an idea of how the house looks finished. It could be sided with anything, I prefer the low maintenance of vinyl, even if it isn't the prettiest thing around. For more money, more attractive windows could be have been used. The large windows were running about $115 each in 2006. They are a commodity-type commercial store front unit.

RustyIron is correct that some people just aren't going to see this as a traditional home no matter how cheap it is to heat, and banks may turn up their noses too.

If you prefer a traditional look, then I recommend looking into Passive House designs: What is a Passive House?

Whatever you do, think carefully about building an energy dinosaur and the money and comfort you will be throwing away for years to come if you build one.

Sorry for derailing the OWB question, but I am not sure you are asking the right questions, so to speak.

 

[Paul N]

Back to the original question. Several people in my neighborhood have OWB's. The most common answer I get about life expectancy is 15 years. Mine lasted 17 before it sprung some leaks. Being the do it yourselfer I am, I rebuilt it and am still using it.
etcallhome is right about the work involved, but many people really enjoy that kind of work. As for myself, I operate a farm. There are downed trees every year on fence lines, fields, and field roads. As long as I have to cut them up anyway, I might as well use them for heat.

 

[Skybox]

Aaron Z,

I apologize for the comment made last night. Some of the posts were deleted but I did get an email from you asking to explain why your math is incorrect so please let me explain.

In your message you ended by saying that if I wanted to compare cubic feet of pollutants per BTU of output (or BTU of effective output to account for the inefficiencies of having your boiler outside) that would be a fair comparison.

OK let's build on your last statement.

I think we both can agree that an EPA certified indoor wood boiler will emit approximately 7 grams of PM 2.5 per hour. Phase II OWBs if sized correctly and using dry hardwood emit approximately 20 GPH maybe more maybe less but for the sake of this explanation let's just use these numbers. You are right during the time span of one hour the OWB is heating 2000 Square Feet and the Indoor Wood Burner 300 Square Feet. I'm sure we can also agree that the reason the OWB is putting out more GPH of PM 2.5 is for the simple fact that it is consuming more wood to heat the entire house. No argument here.

Now before we move forward let me explain how air quality is measured. If we use EPA's National Ambient Air Quality Standard for PM 2.5 it states that during a 24 hour period air quality cannot exceed 35 micrograms per meter cubed. Just a side note here, NAAQS function is to measure air quality effected by cross state pollution and/or large industrial complexes near population centers. It uses three year averages of the 98 percentile reading etc., to arrive at its conclusions. Then it gives the suspect industry or state five years or so to fix the problem. So as you can see this is not the appropriate tool for measuring air quality from one OWB effecting a neighbor. That being said, there are portable monitors that can be used or computer modeling to ascertain the results. Modeling can be tricky because based on the input variables outputs can vary. I won't go into that now. However, the math used in modeling is fairly straight forward absent chimney heights, air inversions, setbacks, terrain, adjacent buildings, trees etc.

To show the math let's use a simple scenario. Again, this is a simple scenario to show how the math works nothing more - bare with me.

On one end we have an OWB with an eight foot chimney. 100 meters away (300 feet) on a flat piece of terrain with no trees or other obstacles we have a 50 foot wide ranch style house. There is a clear line of sight between the OWB and the house. Today's weather presents a temperature inversion with a 2.2 MPH wind. One MPH is considered calm in weather circles. For those of you that don't know temp inversions are a frequent weather condition that traps air close to the surface.

Now when we examine the EPA criteria for safe air it states there can no more than 35 micrograms per meter squared per 24 hour average. What is a meter squared? Basically, picture an imaginary box floating in the air with each side 1 meter long. If the pollutant PM 2.5 passes through that box or occupies the box at a level greater than an average of 35 micrograms per 24 hour period then the EPA considers the air unsafe.

So the OWB is operating and as the smoke exits the chimney it turns horizontal because of the temp inversion and a 2.2 MPH wind. The plume is 10 meters wide and 20 meters high. So essentially we have 20,000 cubic meter box (10 meters wide x 20 meters high x 100 meters long) the smoke is traveling in. The ranch home is downwind so the smoke travels toward it. Again, the temp inversion is holding the smoke close to the ground and it looks like a smoke fog. Now the math:

- There are 1,000,000 micrograms in a gram. (Microgram shorthand is ug)
- If the OWB is emitting 20 GPH that is 333333 ug / minute (20,000,000 divided by 60 )
- If the air moves past the stack at 2.2 MPH (1m/second) it takes 100 sec to go 100 meters. That equates to about 1.666 minutes.
- The amount of PM 2.5 released during 1.666 minutes is 1.6666 x 333333 = 555332.77 ug
- Since our measurement box is 20,000 cubic meters (10X20x1000) we get 555332.27 divided by 20000 = 27.8 ug meter cubed (within air quality standards assuming a constant 20 GPH over 24 hour period)

Now use a 1MPH wind speed instead and see the difference wind or lack of will make.

The conversion from MPH to meters/second is: MPH * 0.44704 so a 1 MPH wind now takes 3.72822 minutes to travel to the home. ( Think about it this way the longer the time period the more PM that is added to the air box being measured -meaning more saturation before moving past the home..

Also note there is a normal 10ug PM 2.5 background amount that is almost always present so this needs to be added to your results. PM 2.5 is accumulative. What would the 10 ug background level do the result above? Don't forget to add it to the result of your 1 MPH equation.

You can find your current PM 2.5 at this site: http://airnow.gov/index.cfm?action=aqibasics.aqi

Type in your zip and you'll see your AQI number on the right. Under "quick Links" click on AQI to concentration. In the drop down box click on pollutant. (PM 2.5) Now enter your AQI number from the previous page and hit calculate. This is your current background number. As stated 10 is a safe average number to use.

Now do the same equations for an indoor wood burner emitting 7 GPH with a 1 MPH wind.

Next use 70 GPH with a 1 MPH wind. This will give you an idea what neighbors are facing when in proximity to an early model OWB. This is why my frequent mentioning of lawsuits that are becoming more common. Some product liability attorneys are now using these modeling programs along with NESCAUM and the EPA's findings. Many people don't know this.

Hopefully this explains the difference between an indoor wood burner and an OWB with respect to air quality. Let me know if I can answer any questions. This will get you in the ballpark mathematically.

skybox

 

[thewickedgoogly]

21 years for us. We live in NC and installed a Hardy woodstove in 1992 and just replaced it this year just because it became high maintenance over the last year or two. Generally just small issues like having to replace a pump or valve, but we had a small leak that was giving us trouble so we just decided it was time to purchase a new one.

After much due diligence, we opted for a Woodsman 400 Woodsman 400 Series because 1) has a good warranty 2) the dealer will service our area 3) has an ash cleanout and 4) is simpler, less to go wrong (circulation pump runs all the time instead of controlled by thermostat).

Too early to tell, but i'm happy with the quality construction so far. The biggest difference we are trying to get used to is the fact that, since the Woodsman is more efficient, when we look out the window we dont see any smoke.

Pretty sure almost all of them will last longer than 5 years...don't think too much can go wrong with a steel box over that amount of time. It's pretty easy to change out the components in the back should they fail. Just make sure you "have a good feeling" about the dealer, ask the right questions about service, warranty, etc and you should be good.

We will be building a new house this year and I want to go with an outdoor wood boiler as the primary heat source. My wife is concerned as a co-worker told her "don't get one of those, they only last 5 years".

I'm looking at one of the Central Boiler E-Classic units that is a high efficiiency boiler.

What have you seen for life span on wood boilers?

 

[mikehaugen]

skybox, not to add to everyone else piling onto you, but you keep speaking of over-sized boilers and their inefficiencies. Some research will show that a lot of people build heat "storage." Gasification boilers like to burn hot and fast so the extra heat created by them in turn heats large water tanks (usually in peoples' basements), then is extracted from there after the "burn time" of the boiler. These of course add a lot of work and cost to the installation, but allow the boiler to burn at 100% until it is out of fuel. A lot of info on the site mentioned earlier (thehearth.com). While researching this for myself, I have not found one account of someone buying one and being disappointed or feeling "duped by the claims." I understand your frustrations and assume that you have been a victim of this at some point, but don't classify all wood boilers (gassifiers come in outdoor and indoor) as these large, primitive, polluting monsters.

wsp617, possibly also check out econoburn. That is the company I am planning on going with when I am ready, unless something changes between now and then. A lot of that, however, is because it is one of the few local dealers I can find around here- but there products seem on par with others.

 

[Skybox]

skybox, not to add to everyone else piling onto you, but you keep speaking of over-sized boilers and their inefficiencies. Some research will show that a lot of people build heat "storage." Gasification boilers like to burn hot and fast so the extra heat created by them in turn heats large water tanks (usually in peoples' basements), then is extracted from there after the "burn time" of the boiler. These of course add a lot of work and cost to the installation, but allow the boiler to burn at 100% until it is out of fuel. A lot of info on the site mentioned earlier (thehearth.com). While researching this for myself, I have not found one account of someone buying one and being disappointed or feeling "duped by the claims." I understand your frustrations and assume that you have been a victim of this at some point, but don't classify all wood boilers (gassifiers come in outdoor and indoor) as these large, primitive, polluting monsters.

wsp617, possibly also check out econoburn. That is the company I am planning on going with when I am ready, unless something changes between now and then. A lot of that, however, is because it is one of the few local dealers I can find around here- but there products seem on par with others.

Hello Mike,

If you read my earlier posts I suggested that if someone's mind was made up on purchasing an OWB, Garn appears to be a more efficient model because of the reason you pointed out. Typical OWB's cycle on an off based on heat demand starving the fire of oxygen lowering the temp causing smoke and pollution. From my research and conversations with state agencies responsible for air quality, the Garn uses a insulated water storage system. The unit burns its fuel at a constant high temp eliminating the cycling. The heat is stored in the water storage unit and cycles water based on demand. I have never seen it in action but keeping the fire hot is a critical function in eliminating pollution.

Now having said all that I have no personal knowledge of the tested efficiencies or knowledge of what owners think of them. Everything I know is word of mouth and what I're read. I still stand by my geothermal heating system but that's not what this thread is about

 

[Rustyiron]

Geo thermal is cool, but not in most peoples budget. What is considered an acceptable return on the additional investment? Of course this depends on energy costs, but I'd be inclined to spend that money on super insulating, or other "passive" efforts. I have the equipment and the land to do the horizontal type myself and my radiant design Co. that I used for my house, (a great bunch of greenies) said that the COP or some other tech, term that is was not really worth it in Maine. This was about 4 years ago, have the water to water heat pumps come along that much since then?

Dave 1949- Cool house, is your (unseen in pics) roof burried also?