Need help with new construction heating alternatives-in favor of wood furnace

[Piston]

Beenthere,
How much maintenance is involved with your IWB?  Also, is it only wood, or is it dual fuel of some sort? 

Holmes,
Your recommendation to spend the extra money on insulation and good windows is a good one.  How do SIPS compare to the spray in foam insulation your speaking of? 

If you do insulate it that well make sure to invest in an air to air exchanger. I just put one in and I'm really impressed with it. Houses now that are really well insulated and have really good windows will have water running down them in the winter without one.

Norm, could you explain a bit more about the air to air exchanger?  How do they work?  I'm aware that they are needed for air quality in very well insulated homes, but what do you mean about the water running down the walls in the winter? 

Boy there sure are a lot of decisions  ???

[Piston]

If I wanted to go with an IWB with the dual fuel option of propane gas (assuming they have this?) I would plan a separate room in the basement just for the IWB, it could be made when the foundation was poured and all walls could be concrete, with some sort of fireproof ceiling as well, and access to outside, making wood handling easier and reducing the risk of fire to almost none.

When IWB are running on the back up fuel, are they still very efficient as heaters?  Or are they only efficient burning wood, and the propane is really only meant to be used in the even that you run out of wood, but in that case do they burn more propane when operating on propane, than a standard 'propane only' furnace? 

[jdonovan]

When IWB are running on the back up fuel, are they still very efficient as heaters?  Or are they only efficient burning wood, and the propane is really only meant to be used in the even that you run out of wood, but in that case do they burn more propane when operating on propane, than a standard 'propane only' furnace?

They are much less efficient than a dedicated propane furnace/boiler. A dedicated burner can get to the 96% range.

Many of the wood gassifiers are 60-70%, I've seen a few near 80%... on wood. I've never seen a rating for them on the back up fuel.

[Piston]

They are much less efficient than a dedicated propane furnace/boiler. A dedicated burner can get to the 96% range.

Many of the wood gassifiers are 60-70%, I've seen a few near 80%... on wood. I've never seen a rating for them on the back up fuel.

Hmm, well that is a little disappointing. 

I am quoting a post from LorenB from the IWB vs. OWB thread, as it was very helpful to me and answered some of my questions.  I am quoting it here so I don't lose it....from this thread-https://forestryforum.com/board/index.php/topic,56230.0/all.html
I'm learning a lot from that topic  8)

I have lived with our H.S. Tarm indoor boiler since 1999 and I really like it.  You can see one here:

http://www.woodboilers.com/product-detail.aspx?id=47

Our boiler is the dual-fuel model, with the backup being LP gas.  You can also order the boiler with an oil-fueled backup.  The boiler can be set to switch automatically to the backup burner if the wood fire goes out.  If desired, you can select wood only operation.  You can also select backup fuel only. 

This has been the mildest winter in our 18 years in southern Indiana.  I have burned about one cord of dry firewood so far this season (12 February).  This is unusual.  It would be more normal for us to burn three to four cords of wood during the winter season.  This includes wood to heat all the hot water. 

The H.S. Tarm boiler uses a secondary combustion chamber where additional air is injected into the hot gasses.  The combustion is excellent.  There is NO creosote downstream of the secondary combustion chamber.  There is lots of creosote in the firebox itself. 

I installed a lot of Tarm indoor wood boilers and they are good. I like the idea of the inside boiler and keeping most of the btu's inside the house, but having had to go to houses in the middle of the night to fix overheated boilers that the owner left the door ajar and gone to bed has cured me from wanting the boiler inside the house. Those people were very lucky they did not burn their houses down.

I have had this happen to me twice, but neither time did it get out of hand.  Those two times did give me a good scare, though.  I didn't have to call someone to come cool my boiler down; it's a simple matter to turn the heat on inside the house and run some hot water (from the heat exchanger water heater) down the drain. 

This problem occurs ONLY if the owner leaves the door open (even a crack) and has inserted enough wood to heat the boiler full of water to a dangerous point.  I used to leave the firebox door open a crack to get a fire started.  I have stopped doing that unless I am standing next to the boiler. 

I don't think that this situation would ever cause a house fire, but it certainly could cause the boiler to open a safety valve and vent steam.  I guess if there were even more wood in the boiler after it had drained itself, you could get a fire, but even then it's enclosed in the boiler's firebox.  My guess is that the worst you could do is ruin the boiler.  That result is no small matter; the boiler is thousands of dollars. 

I have had both and by far the biggest reason I now have an outdoor stove is my wife, she doesn't like the smell in the house and there is no posibility of burning inside without an occasional puff of smoke when loading or cleaning the stove. I also like the mess outside, when handling wood there are always pieces of bark, dirt etc.

We do get smoke inside the house occasionally, although very rarely now.  The trick is to start a small fire first, then add more wood after the fire gets burning well.  If you load the firebox up with a cold boiler, the fan will not supply enough air for the size fire you are trying to start, and it will smoulder for quite a while.  Smoke will escape from the auxiliary burner hole and/or the flue vacuum regulator.  (I don't know the proper terminology for that item.  There is a Tee fitting in the stovepipe that leaves the boiler.  It has a flapper in it that will open to allow ambient air to enter the chimney if the chimney is drawing too much vacuum.  I'm sure this is to prevent the chimney from sucking air through the fire when the boiler's fan is off.)

As far as the mess is concerned, it certainly could be an issue.  Our boiler is installed in the basement, in its own room with the water heater and water softener.  That room has an outside door through which I bring firewood.  The mess is contained entirely in that room, which I sweep up occasionally.  You must keep the area directly in front of the boiler clean, because hot coals and embers sometimes fall from the loading or clean out doors. 

One of the keys to using a wood-fired boiler, including mine, is to load an appropriate amount of wood.  If your heat load is low, don't fill the firebox full.  This will prevent the hazard of an overheated boiler if you don't get the door closed properly.  It will also cut down on the smoke issue.  Last, and perhaps most important, it will prevent long periods where the boiler has a smouldering fire in the firebox.  This situation creates gasses that encourage corrosion and should be avoided if possible. 

The water temperature in the H.S. Tarm boiler is controlled by starting and stopping the combustion air fan.  This fan has a damper that closes automatically when the fan shuts off.  When the fan shuts off, virtually all air is blocked from the firebox.  If you shut the fan off manually (by switching the boiler off) the fire will extinguish.  It will not ALMOST extinguish; it will go completely out.  During normal operation, if heat is being removed from the boiler, the fan will cycle enough to keep the coals hot enough to ignite when air is again provided.  The system works very well. 

Our installation includes an additional safety system.  I think it is required by the H.S. Tarm instructions, and maybe also by the building code, but I don't know.  My boiler and radiant floor system was installed by a professional.  Tarm Biomass (the U.S. distributor) told me that they would not warranty the boiler unless it was professionally installed.  Now that I see it, I realize that I would never have done it right. 

The additional safety system is a large baseboard heater that is used to dissipate boiler heat in the event of a power failure.  If the boiler loses power, valves automatically open to allow the boiler water to thermosiphon to the baseboard heaters. 

All in all, I really like our indoor boiler.  One of the main reasons for choosing it over an outdoor unit is that I was unable to find any outdoor boiler with a secondary combustion chamber. 

I used to travel for my work, and for my wife (who refuses to deal with the boiler) I would leave the boiler set up to switch to LP gas after my last load of wood burned up.  Since I retired in 2007 we have bought only one tankful of LP gas (which we also use for cooking).  This season, our 500 gallon LP tank is still over 50% full. 

-- Loren

[sparky1]

I do love my OWB. I would recommend them to anyone! with that said, if i were to be building a new house, i wouldnt hesitate on putting in geothermal!!!  I know there pricy, but so is an OWB. plus if your busy, which many of us are. your free time is spent cutting wood!  Im gone everyday during the week and am only home on the weekends. so a good chuck of my weekends (spring) are spend cutting wood!

[bandmiller2]

Piston, radiant floor heat,if engineered and installed right is hard to beat.A well insulated house ,radiant floor ether oil or propane,and a good wood stove in the house is probibly your best option.Open timber frame house lends itself well to wood stove heating.When your around  or during a power outage the wood stove will carry the house.When your away let the conventional boiler handle the heat.A wood shed attached to the house would be handy for mommy to keep the wood stove stoked.Good news on the little one,they will change your life. Frank C.

[Piston]

Thanks Frank,
The woodstove in the open floor plan home, with traditional style, efficient furnace does seem like the most practical way to go. 

I'm still looking into the IWB and geothermal ideas.  I do really like the idea of heating with wood as much as possible, sort of my way of 'sticking it to the man'  :D

As of my initial impressions, my ideal setup right now would be a dual fuel model IWB in a separate room in the basement, easily accessible from the outside for firewood storage and handling.  I still don't fully understand the water tank storage and where that comes into play yet. 

However, the unbeatable ease and economy (post installation costs) of geothermal is probably going to sound pretty good to my wife! 

[AsaG]

Norm, could you explain a bit more about the air to air exchanger?  How do they work?  I'm aware that they are needed for air quality in very well insulated homes, but what do you mean about the water running down the walls in the winter? 

Boy there sure are a lot of decisions  ???

I'm not Norm but I'll take a stab at an answer.

The air exchanger he is making reference to passes the "stale" air being exhausted from the building through a heat exchanger where, depending on the season, the heat is transferred to or extracted from the fresh incoming air.  These come in two flavors;  A  heat recovery ventilator transfers only heat between the two air streams.  An energy recovery ventilator transfers heat and humidity between the two air streams.  Many localities are requiring these in new construction.

While on the topic, I must concur with the others about foam insulation and quality windows.  Year after year, both will pay off big time!  We've been doing 2 pound closed cell foam and triple-pane low-E long before "green" was the new buzz word.  Energy costs are only going to go one way and is sure isn't down.

[Holmes]

  Piston  Properly installed sips panels are very good, r5 per inch about r28 for an exterior wall. Stick frame with 2 lb spray foam r6.8 per inch r 24 for a 31/2 " exterior wall r 35 for a 51/2" wall and basically no air infiltration.  A draw back to sips is installing electric wiring in the sips panels.                   
I like your approach to building your new house. You are asking great questions and getting lots of feed back. You can not make an educated decision without learning how all these processes are done.

[Dustin]

I have been contiplating this very same thing. This summer we are hoping to lift the house up, pour a new basement, and add on to the house.  Right now we have a propane furnace that is barely big enough to heat the house now let alone the addition. What we are thinking about was geothermal and a "Fireplace Xtrodinar Elite" on the main level of the house. The main level of the house will be a open layout for the most part. Is a fireplace and geothermal a good combination? I really would like to get away from having to pay to fill a propane tank.

[Hilltop366]

Well Piston, you got a lot of thinking to do.

I'll chip in with my $.02.

Here's what I got. A 10 year old house with some timber frame (1500 sqft main floor +1000 sqft loft with about 1/2 of the loft usable living space), the walls are 6" fibreglass  in between studs + r5 of foam over the outside studs then boards and siding, the roof has 8" of fibreglass + r5 of foam on the inside of rafters so it is fairly well insulated.

The main floor is 4" of concrete with r7.5 foam under it with in floor hot water heat.(no basement) the heat is supplied by a 1970s HS Tarm solo boiler that I picked up unused (had never been installed) when I was building my house, I think I paid around $1100 for it, so there was no question on what to buy when I checked it out.

The pros:

Warm floors feel nice on the feet.

It takes a long time to cool down.

Draws less than one amp at 110v (no zone valves on my set up, I use one 110v thermostat to turn on the circulator pump) so it can be run on a small inexpensive inverter with no ghost draw from transformers. I can also run some lights with this as well.

I cut my own wood and have the time to do it so it is cheap for me to run, saw gas, chain oil and some diesel for the tractor is less than $200 per year cleaning up wind fall and bug kill trees.

The cons:

It takes a long time to heat up when the temperature cools off quick and takes a long time to cool down when the temperature goes back up. this may not be as much of a problem if you outside temps are more steady but around here it can go from 14°f to 50°f and back from one day to the next. In floor with concrete would be better suited for a basement living space for me.

The floors are hard (it makes a tough place for a kid to learn to walk)


So this is where I would be looking if I was building again, wood hot water low mass in floor with a large mass storage with an electric hot water heater for backup, solar hot water collectors would be nice as well. Or a wood stove with a hot air system, if the hot air system was set up right it can be used to circulate the wood stove heat to the rest of the house by adding a cooling thermostat near the wood stove that turns on the furnace circulator fan.

[Piston]

Well Piston, you got a lot of thinking to do.

Hilltop,
You said that right!  I'm actually a bit overwhelmed at this point.   :D
Thanks for your informative post.  I'm gonna sleep on this for tonight, and reread this thread tomorrow and see how much I retained  :D

I'll comment more tomorrow.  Thank you to all who contributed thus far.   ;)

[jdonovan]

I still don't fully understand the water tank storage and where that comes into play yet. 

The real benefit to the storage tank is that you can run the OWB at its ideal burn rate/temp until the fuel supply is exhausted. Once the house heat demand is met the 'extra' heat goes into the water for storage. In spring/fall you might be able to get away only firing up your OWB every few days, perhaps even once a week depending on how much heating you need and how much water you can store.

Lets say you have designed for 120 degree water for the in floor radiant, and you store water at 190 in the  tank. That gives us a delta of 70 degrees, and lets assume 500 gals of storage.

500 gal * 8.3 lbs/gal = 4150 lbs of water
4150 * 70 degrees = 209500 BTU's stored.

Get to 1000, or 2000 gal's of water and you could potentially store the energy of a full load of wood into that water tank. This gives you a very nice buffer so the short term demand from the house could exceed the OWB's capacity assuming the storage was hot. But the OWB will need to be sized properly so as to exceed the homes worst-case needs.

Properly designed/sized water storage can make a big difference in how well a OWB system works.

[Norm]

AsaG did a great job of explaining the air to air exchanger Piston. Our house is really well insulated with tons of windows that are high quality. Comes winter and I'm getting water running down the windows. I blamed it on the windows leaking but last year while having the ac unit replaced I mentioned about what crappy windows I have. The installer said you don't have crappy windows quite to the contrary they are not leaking and what you have is all of the humidity from living there causing this. I was skeptical but thought what do I have to lose, the windows were going to rot out if I didn't do something. Much to my surprise it works better than I ever imagined. No moisture on the windows and the air in our house is so much fresher. The first day of using it Patty and I both went wow it's like having the windows open. Mine ran $2200 installed and is a Lenox, best money I've spent in ages.

http://www.lennox.com/products/indoor-air-quality-systems/HRV/

[blackfoot griz]

Piston,
One more consideration would be a masonry style wood burner. About 5 years ago, we built a new house and went through the same agony you are going through. We finally decided to install a Tulikivi. The entire thing is made out of soapstone and weighs about 9,000 pounds. These dont burn like a traditional wood stove. You build a big hot fire and let it roar. It will burn for 2-3 hours and when its done--shut it down. Because of the mass, it will achieve it's max temperature about 2 hours after the fire is out. They are clean burning and only burn for 2-3 hours a day.

Ours also has a bake oven in it. My wife loves to cook and she loves the bake oven. Last Christmas, we had a housefull of family/friends and we cranked out 12 pizzas. She calls it the"magic oven". From Sept--early May, we rarely use our electric oven.

I hope someday to build a shop and heat it with an OWB. But, living in Montana, if I ever build another house I would definately install another masonry fireplace.

[jdonovan]

These dont burn like a traditional wood stove. You build a big hot fire and let it roar. It will burn for 2-3 hours and when its done--shut it down. Because of the mass, it will achieve it's max temperature about 2 hours after the fire is out. They are clean burning and only burn for 2-3 hours a day.

If you needed more heat, you could add more wood and burn more than the 2-3 hours right?

[blackfoot griz]

These dont burn like a traditional wood stove. You build a big hot fire and let it roar. It will burn for 2-3 hours and when its done--shut it down. Because of the mass, it will achieve it's max temperature about 2 hours after the fire is out. They are clean burning and only burn for 2-3 hours a day.

If you needed more heat, you could add more wood and burn more than the 2-3 hours right?

Yes. Last night here in Western MT we had a high temp of 40 and a low of -4. Last night, around 6:00, I started a fire and it burned until around 8:30. I shut it down and it is still plenty warm.

If we have sustained sub zero temps, we'll burn two fires a day--morning and evening--using a little more total firewood than the usual once daily fire. It is just a big heat mass. Unless we both go away for a few days, this thing never totally cools down from September--May.

[Holmes]

  Piston Let me help muddy the water. If you want a top performer that will last your life time look into the Garn boiler. It  gasifies and will heat your house on a load of wood a day. It should be installed in an unattached garage. 250,000 btu's and 1400 gallons of water storage.  Holmes

[Piston]

I still don't fully understand the water tank storage and where that comes into play yet. 

The real benefit to the storage tank is that you can run the OWB at its ideal burn rate/temp until the fuel supply is exhausted. Once the house heat demand is met the 'extra' heat goes into the water for storage. In spring/fall you might be able to get away only firing up your OWB every few days, perhaps even once a week depending on how much heating you need and how much water you can store.

Lets say you have designed for 120 degree water for the in floor radiant, and you store water at 190 in the  tank. That gives us a delta of 70 degrees, and lets assume 500 gals of storage.

500 gal * 8.3 lbs/gal = 4150 lbs of water
4150 * 70 degrees = 209500 BTU's stored.

Get to 1000, or 2000 gal's of water and you could potentially store the energy of a full load of wood into that water tank. This gives you a very nice buffer so the short term demand from the house could exceed the OWB's capacity assuming the storage was hot. But the OWB will need to be sized properly so as to exceed the homes worst-case needs.

Properly designed/sized water storage can make a big difference in how well a OWB system works.

Thank you for that excellent description.  I understand a lot more clearly now the reason for additional storage.  If I were to have an OWB (or IWB whichever) without storage, I would have to keep it running anytime I needed heat, which in the winter would be most of the day, however in the shoulder seasons when I didn't need much heat, then the boiler would basically shut down, which would leave a smoldering fire, until I called for more heat.  Whereas, with a large amount of storage, I would heat the house when my boiler was firing and calling for heat, then when the house was heated and didn't call for heat any longer, the boiler would continue burning at an efficient rate, and all the heat generated would be used to heat up my storage tank, and eventually I could let the boiler go out.  Once my storage tank was back down to a low enough temperature, to where it needed to be reheated, I would relight my boiler.  I think I understand it pretty well now.  Thanks again  ;D


Blackfoot Griz,
I've looked into masonry fireplaces before and always thought they were very interesting.  I've never seen one run or felt the heat from how they work.  It would be worth looking into. 
My wife really doesn't like lighting the fires.  She doesn't mind at all keeping them going or tending to them, but she doesn't like to light them.  She'll do it, but she would prefer to have it going all the time, and simply add wood to it.  She actually really likes the woodstove a lot more than I ever thought she would.  I'm away from home now, and she is sitting in the living room with the woodstove going, it's 82° in there now, with snow falling outside.  I'm really proud of her to say the least!  I just wish I was there  :D


Holmes,
I really think I'm starting to get pretty interested in the IWB, particularly some sort of dual fuel model with propane backup.  Any recommendations for those? 
I do worry about the fire hazard of an indoor boiler, but if I planned it ahead of time and added on a well thought out, separate room in the basement dedicated for the boiler, I imagine it could be a very safe setup.

[Norm]

I don't want to hijack Piston's thread but is there any chance of you showing us your Tulikivi on a new thread Blackfoot Griz? I'm thinking of getting one but have never seen what they are capable of.

[Holmes]

  Years ago you needed to find a good mason to build a masonry heater. Now you can buy a kit and assemble the heater yourself. These units are mostly soapstone all you have to do is follow the instructions.  Once assembled a fire is started in the fire box with the top damper open. When you have a decent fire going the lower damper is opened and the top damper is shut off. The chimney draft pulls the fire downward thru the bottom of the fire box, the smoke travels down into the flue. This flue travels horizontally for a few feet then wraps  around the heater a couple of times entering the vertical flue before going thru the roof. Most of these units are vented with a metal flue after leaving the Masonry heater.    Between the fire and the flue gasses  the mass of soapstone gets heated and delivers a warm steady heat for many hours .  These are air tight heaters.

[Piston]

I don't want to hijack Piston's thread but is there any chance of you showing us your Tulikivi on a new thread Blackfoot Griz? I'm thinking of getting one but have never seen what they are capable of.

Feel free to post some pics here as well.  I'd be interested to hear about the price of something like this?

[Holmes]

 Piston  Woodstock stove has a masonry heater.

[blackfoot griz]

I don't want to hijack Piston's thread but is there any chance of you showing us your Tulikivi on a new thread Blackfoot Griz? I'm thinking of getting one but have never seen what they are capable of.

Feel free to post some pics here as well.  I'd be interested to hear about the price of something like this?

I sent Norm a PM. I have new fancy Nikon camera and took a couple pictures...they are in a jpeg format :(

[Piston]

Piston  Woodstock stove has a masonry heater.

I'm VERY surprised I let that slip through the cracks!  I usually watch they're developments pretty closely too.  I really like the looks of that unit  ;D

http://woodstocksoapstoneco.blogspot.com/search/label/Masonry%20Heater