A question for Out door wood stove users

[Old F]

A question  for  Out door wood stove users

I been using a Wood Master for a few years now .

 The way its set the water is pumped 24/7

From the stove to the heat exchanger in the duct work  When the thermostat calls for  heat  the blower comes on .

Now my question is  this a common set up  for most stoves ?

With  the heat exchanger  acting as a constant load  It seems to me  that this could be one of the reasons  why these  type  of stoves  use a lot more wood than they should  

Any info on your  stove set up will be helpful  

Thanks

Old F

[jonas302]

I think that is the most common set up is your pump outside or in the house it would be great to try an experiment with cycling it if its easy

What do you use for pipe I switched pipe this year and save at least a load of wood every day we used to have 1 1/4 plastic in a 2 inch foam box wrapped in plastic now  a 1 inch pex tripple wrapped in foil in a solid drain tile pipe

Where do you live and how much wood do you use?  

[Old F]

Jonas302

Mild or hard winter I go thru all most 12 cord here in Ohio I all so heat  my domestic  hot water.

I am using one inch PEX  run in a 6x6 inch block of foam plastic wrapped

My pump is out in the stove I have given some thought to using cycle timers but I don't want to lose the  domestic  hot water.

 I am thinking of using a zone controller an  a three way valve  to by pass the heat exchanger when the house is not calling for heat.

This will be a big help in mild weather when natural heat convection  in the duct work will run you out of the house.

 Check out my web site and you will see my wood stove saga : )

Old F

[12AX7]

Hello

I do not have a wood burner, nor have I ever heated my house with wood.

However, I have been "looking" at a number of heating systems including outdoor wood burners.

I wasn't overly impressed with most of their control systems, along with their burn boxes.  

The few I've looked at all had their fire box blowers controlled by a thermostat monitoring the boiler water temp, which makes sense.  However I question whether this "loose" control of "forced" draft (often ice cold air) can maintain a nice "even" burn.

None of the unites I looked at had a properly fire brick lined fire  box, can't help maintaining an even burn.

You mention that the heat exchanger would be a "constant load" is there a blower on the exchanger?  and if so it's running 24/7 as well?

I wonder how well the outdoor burners are insulated.  Ever check the walls/roof temps?

The only cords I know have phono plugs on either end, or you yank on them to start the mower.   So with that said, 12 cords sounds like a lot!  is it?

[elvin1949]

1 cord is 128 cubic feet.

later

elvin

[finnsawyer]

His 12 cords may be "face cords" or "tiers", which would be 1/3 of your 128 cubic feet.  That is, 4 full cords.

[Old F]

No sorry to say I am going thru 12 full cords a year. That why I am going  to try  a  zone control valve system

To get rid of the phantom heat load when the house isn't calling for heat.

The blower doesn't run 24/7  but heat exchanger radiator  is a constant load.

I think I can cut the wood use close to haft .  

Old F

[12AX7]

So, it sounds like 12 cords is way past "a lot".

I'm not sure I'd be quick to agree that your heat exchanger is a "constant" load.  It's transferring heat from it to the air that flows over/though it and that air temp isn't a "constant".

But I do agree it sounds like things can/need/should be improved.  

Is the fire box lined with brick?  My opinion (worth more to some than others) is that many of the stoves out there have issues with the heat being removed from the burn to soon.   Everyone knows that fire is   heat fuel and 02.  and when too much heat is taken away "during" the burn, controlling the burn becomes difficult.

I'm guessing that there is a lot of wasted fuel trying to compensate for this issue.

How clean is the smoke?   12 cords is a lot of wood, the heat must be going somewhere.. out the stack?

IS the Wood Master the same as Wood Doctor?

Have you talked to the dealer?   your web page mentions that he and his sons use them as well, how does your usage compare to theirs?

I'm still considering an outdoor system, so I'm looking for pointers.

Getting on in the years, I'm thinking "less effort" dealing with that much wood sounds a lot like "work".  I'm not much of a lumberjack..   When I was much younger and helping my dad pounding nails....  he nick named me "lighting"...   never hit the same place twice.  It's a good thing he never saw me wail a sledgehammer.  I've a small wood stove in the garage, and split wood for it,  not my cup of tea!

With the costs of gas/oil/elect.   I see wood in many of ours future.

[jonas302]

8-15 cord is pretty common for these stoves depending on temps I cord is a stack 4x4x8feet long if you definatly need to  have a ready source of wood and like to cut it

You are right they are not the best possible designs for efficincy I'm not sure firebrick would be the answer

[Goose]

If you dont' want it going through your air exchanger,  tap off your loop with another pump, and when your house calls for heat....the other pump and heat exchanger kick on.  You can get a relay that is a delay on the fan, so your pump has time to get the hot water circulated before your heat exchanger fan turns on.

[Old F]

Think of  it like a base board  radiator   they don't have fans but the air is heated  and moved   by natural  convection  .  I have  check out every thing else   In  mild weather the duct work blower never come on and the house get way to warm

Old F  

[kenputer]

I just finished installing a wood doctor boiler to heat a 10,000 sq. foot garage which we installed infloor heating.

 it has a primary loop with injection system for the infloor,also heated walkway using plate heater so we only had to fill that zone with glycol to prevent frozen pipes.

[Drives]

Old F

I burn 15 face cord a year...12 full cord is a large amount!

It sounds like you hit the nail on the head..."In  mild weather the duct work blower never come on and the house get way to warm"

Don't you have some damper, or draft control to reduce the fire size?

My indoor wood stove has thermostat damper allows me to adjust my fire/temperature.

How does the wood master control this.  If it adjusts the damper blower control to maintain water temperature, then I would agree, cycling your circulating pump will be a good start.  I just worry about making steam??

I'll be interested to see what you come up with, good luck.

[Old F]

Drives

All  Out doors stoves use pretty  much the same setup

When the water temp reaches  A preset low temp  a damper opens an  the force draft  blower comes on .

When the 150 GAL of water in the tank surrounding  the fire box hits a preset high temp it shuts down.

All of threes stove are vented open systems no worries about steam.

What I am planning  is to keep the pump going but rout the  supply  to  the heat exchanger only when the house calls for heat  when not it is routed back to the return by a 3 way zone valve. I have found some 3 way zone valves for around 30 bucks US

Old F

[finnsawyer]

Wow!  I used to heat a 2,000 square foot house with 5 full cords a year, and I thought that was bad.  Only 4 inches of insulation in the walls and 6 in the ceiling.  My current house has 6 in the walls and 13 in the ceiling (1200 square feet).  I'm at 47 degrees north latitude by Lake Superior.  While I don't know the particulars of your situation something doesn't add up.  It may be your house needs more insulation or the furnace itself is inefficient.  I'd like to know as I may need to go to an outside furnace myself.  One thing you could do is measure the difference in water temperature leaving the furnace and returning during no heat demand part of the cycle.  By determining the rate of flow of the water you can then determine the heat loss per hour in BTUs.  One BTU is the amount of heat needed to raise the temperature of one pound of water one degree F.  Compare this with the heat used when providing heat to the house.  Good luck.  

[Drawbar]

I'm not a big fan of outdoor wood burning stoves. My dad had one and went from burning 8 cords a year to burning 14, and yes that is full cords. My word, he was a slave to that thing, either him having to find wood to feed it, putting wood in it, or getting wood for it. The the darn thing burned his house down.

Don't laugh, its happened to 3 other outdoor woodstove homeowners this year in my county alone.I see two more that are just bound to catch on fire. As is, some insurance agencies are denying homeowners insurance on houses that heat with this type of stove, and the State of Maine is actively seeking to ban them.

No matter what you do, do be careful. Its not worth having your home burn down.

[marv]

Old F,   I Installed a Wood Doctor, outdoor boiler this year. I also was using way

to much wood. The 16" split hardwood was burning up like kindling.

So I started cutting 2-3 foot logs 6-8 inches diameter. These logs wood just smoulder for hours until the damper would open. then they would fire up nicely.

Just use bigger wood.

Marv.

[Drives]

Old F

Sounds like a good solution.  Post an update when you get it running for awhile.  Thanks!

[nanotech]

I own a 12 year old Woodmaster 434 modified to run on a newer 4400 control system.  I used to work at Woodmaster building them and got this one second hand and rebuilt it.  http://www.boomspeed.com/bofh1968/stove/index.html

It's odd that you say the outdoor stoves burned a house down as quite the opposite was one of the points that I liked about them.  All high heat producing items are kept well away from the house.  Also all the home owner's insurance companies around here give a DISCOUNT if you use them due to the safety factors.  :confused:

All the fuel, the flames, everything that can get hot enough to ignite a house is kept out and away.  If a Woodmaster caused a house fire, it's because it was installed wrong and put too close to the house, that's the only way it could happen.

If a Woodmaster has a runaway fire, the water will flash to steam at 212 degrees F.  The water pump will not pump steam, so the hottest anything from the stove going to the house will get is 210 degrees (and that's with VERY good insulation on the piping), which is FAR below the 451 degrees F required to ignite wood or paper.  I don't think even gasoline or alcohol will spontaneously combust at 210.

So being an open system (the fill pipe is right behind the chimney at the top of the stove), the steam will just vent to the atmosphere and the stove itself will go into meltdown, but the required distance from the house takes this into effect.  So again, the only way one could have burned a house down is due to improper (and illegal) installation.  Mine is improperly installed (by me) only because it's too close to my wood shed.  But since the shed's not insured and is only used to house my firewood, it's no big deal.

I am with Old F.  I have a poorly insulated 520 square foot modified A frame house and I go through a LOT of wood with this thing.  In the neighborhood of a full pickup truck load of split oak a week at times.  But the piece of mind knowing that my autistic son or any of my cats can't burn the house down by knocking something flammable (curtain, homework, etc) items onto an indoor wood fire heating system is beyond measure.  Also knowing that any and all critters living in the wood pile are not getting inside my house is a little reassuring as well.  Plus there's no chance of smoke, soot, carbon monoxide.  Also a chimney fire is irrelevant as it's only 3 feet long and is out on the boiler.

So yes, they go through one hell of a lot of wood.  They are TERRIBLY inefficient.  But the safety factors and the reliability far outweigh the troubles of acquiring the wood and loading it twice a day.

[Old F]

SO that's  what mine would look like naked :  )

Nano The more look in to it I think I am going to give the bypass a try.

Even if I only get a 25 or 30% cut in wood use it would more than pay for it self.

Old F    

[jonas302]

let us know how it works out hopefully you get some savings

[pr]

    Does your stove have a fixed aquastat or an adjustable one? With the adjustable

aquastat you can experiment with lowering the on-off temp and that will help.

    The heat loss of the pipe from stove to heat exchanger can be significant. Mine

 was good until ground water saturated the insulation, the typical extruded foam box. Need to correct this next summer.

Insulating the hot in pipe in your basement or crawl space to the heat exchanger also helps.

    I don't split any wood and the door will take up to 22 inch dia. Using large wood helps and green wood burns nice and slow. I use 10-12 full cords and that includes the house-1900 sq ft, domestic water and a 24x32 shop on weekends and some evenings.

    The shop has a unit heater mounted on the ceiling and the water circulates by convection and maintains 45 deg F. It doesn't take much for the pump to bring it up to comfortable working temp.

    I use a separate blower and filter from my gas furnace in the house. I searched Surplus center for 1/6 hp motor that would still drive the blower without overheating. I experimented with an adjustable split sheave on the motor for a speed that gives a steady heat with out blasting the air.

    A snap disc switch is mounted on the pipe at the heat exchanger which if the water temp is too low the blower won't turn on even if the thermostat is calling for heat.

    My system is about ten years in service and for the life of me I can't remember the name of the stove manufacturer. I am in the UP of MI.

[nanotech]

Heh, the worst thing about these things is when you don't load it right, like I did last night.

When the fire goes out, the water temp drops too low to heat the house.  I woke up this morning to the house sitting at 59 degrees F.  Not fun.  Especially when I have to go outside and load and light the furnace from scratch when it's 20 below out and there's a 20mph wind!!  Oh, and it let it get so cold in the crawl space that my water main froze.  To say it SUCKED would be a major understatement.  Luckily it didn't burst.

It also takes a little while for the fire to heat up 150+ gallons of water, so it's not a fast fix for a cold house.

Another down side to them is if you go on vacation.  There certainly isn't the possibility of leaving one of these things unattended in the middle of winter for more than about 24 hours at a time.

It's now 10AM and we're STILL waiting on retrieving any heat out of it.  But the upside is that our heating bill went from $500-$700 a month on electric baseboards to whatever extra gas I use bringing home a load of firewood on my way home from work.  I stop by the local ODC and grab their scraps.  They make pallets for Arctic Cat Industries, so they make the hefty pallets.  I generally get a pickup truck load every couple days of 8X8X12 inch chunks of Aspen or Alder from them.  It burns hot and long, so I can stuff the firebox in the morning and all I have to do is stir it up in the evening.  Then rinse and repeat the next morning.

So I figure the extra $30-$45 in gas and a little hardship on my part being out in the cold twice a day is worth the (up to) $650 savings.  But that's me.  I'm a cheapskate when it comes to money, but I'm pretty generous when it comes to what I have to do to save a buck or two.

[DamonHD]

Would it be worth leaving the electric heating in place and active on a frost-stat so that if you do accidentally let the fire go out again or you're away at least nothing will freeze (and your power usage would remain tiny)?

Rgds

Damon

[Drawbar]

You are partially right, in that being too close to the house is the only way it would catch on fire, but only partially. In my fathers case it was a matter of having his firewood pile too close to the house. We think some ashes fell out of his stove, caught the slab wood pile on fire (we have a sawmill and thus used to use the slabs to heat the house) which was close enough to the house to catch his vinyl siding on fire via radiant heat...well you can see where it went from there.

Since the stupid things were invented here in Maine, its only natural I guess to have plenty of them around, and sadly its all to common to see these things have firewood piles strewn out all across the lawn. I know of two of these wood stoves that I cannot imagine why they have NOT burned down the owners home. They are way too close and these homes are old Maine farmhouse just ripe for fire.

In your case, just be careful huh? Its not a matter of getting by a bureaucratic insurance company, but a matter of keeping your home intact. From my parents experience I can tell you what you are left with (rich person or poor)after a fire...NOTHING. As I said that is the most important part. The fact that you admit your outdoor woodstove is hooked up wrong is scary. It sounds like the same thing my dad had,and it cost him his home. I am not busting your chops here, just hoping you can think of ways maybe to mitigate the chance of a fire at your house.

No matter what you heat your home with, a prudent homeowner tries to defend his place against a house fire. There is just way to much at stake.

[Drawbar]

As a side note, the State of Maine is not trying to ban these stoves because of the fire danger, but because of the smoke pollution. This is ironic as I said in my last post,an engineer at the University of Maine invented this thing.

I tam not sure how the law reads exactly, but I think if smoke blows over 2 adjoining landowners for more than 2 consecutive days, the stove must be shut down.

In my dad's case, despite having several hundred acres of land, he could not have abided by this new law. In fact I don't think many people could. Between the smoke traveling so far and the winds coming off the ocean, it would be a tough law to live by.

From what I heard its scaring some people away from buying these types of stoves. Rest assured, if Maine has this law, it won't be long before it spreads to other parts of the snow-belt.

[nanotech]

Hence why I no longer work at Woodmaster, they had to lay us all off due to the reduction in orders just the PROSPECT of this law brought about.

And to help put your mind at ease, I went all out on safety when I installed it.  Even to the point that the power mains coming into it are on a GFCI plug.  In other words, I took the old power cord off my (broken) electric pressure washer and used it as the main power lead going to the stove.  The plug itself has a built in GFCI and over-current protection in it.  And it's plugged into an outlet that's run from my garage (which is on a separate breaker panel than my house is), so even electrically it's isolated.

My wood shed and the boiler are 60 feet from the closest portion of my house.  The boiler water level sensor triggers a light and beeper inside the house if it runs low on water, and I programmed the controller to trigger an alarm inside the house if the water temp goes over 200*F.  So other than hooking up some sort of thermal detection on the stack, I've pretty much covered all the bases.

Trust me, I used to be a volunteer fireman back home, I've seen my fair share of house fires.  And I live in a house that resembles a box of kitchen matches.  One of the main reasons I went with the Woodmaster.  No high heat sources inside the house.  It was one of my biggest fears the year we heated with baseboard electric heaters.  I was always worried the cats were going to knock something flammable into one of them and we'd wake up on fire!!  I was SO happy to throw those things in the storage shed!!

[nanotech]

You can see in this picture what I mean.

That little shed next to the boiler is the wood shed.  The roof is tin, so even if a spark or ember landed on it, it's going to have to be a hefty lump to start the wood underneath on fire.  And since the shed's only a 10X10, there's not a whole lot of thermal mass there to burn for long.

After this spring though, I might be moving it.  I'm gong to expand the shed to hold the entire winter's wood instead of less than a week's worth.

[adobejoe]

WoodCHIPS.  Do these stove/boilers work with woodchips?  References ?

AdobeJoe

[nanotech]

Not really.  There's no way for the draft air to get underneath anything that small, so you get a little burn from the top layer, then the fire goes out from the ashes smothering the remaining fuel.

Wood chips would work in one of the corn burners if you were able to modify the augers to handle the chips.

[walsdos]

Old F, I have manually (ball valve) shut off flow to heat exchanger in basement furnace plenum and seen about a 30% reduction in wood burnt overnight. I have another circuit in the opposite end of our old brick 3800 sq. foot house with a rad and fan on stat in laundry room and 2 8' baseboard rads on zone valve in kids apartment. These circulate 24/7 .If I was brave I may also fit a demand control on pump circuit but at minus 30C would be concerned about short length of minimally insulated pipe going into ground from body of furnace.

   Previous house had gas heat via water filled rads and if there was no demand everything shut down. Was a very efficient and reliable system. Still is over thirty years later.

  Take a Google at Greenwood Technologies. Personally I think there are better but they are still good. Also Google AHS and Combustion Engineering , look for discussion board or its equivalent and pull up queries by Sproutman and ProE Designer for some more ideas.

 I burn about a truck load a week. My immediate neighbour, with a bigger model, was burning TWO loads a week. Try hooking an immersion heater for your dumpload into the hot line to give it a boost when available.

 Have tried big logs (longer burn) and small logs (faster fire)

For anyone contemplating this option only look at gassification types and preferably downdraft. Ask about OVERALL efficiency as well as emission levels at various loadings, they vary significantly.

Good Luck with the mods.

[walsdos]

Hello Old F You are correct in your initial assumption. I have a manual valve which saves about 30% overnight. My Furnace is a Pacific Western but too small for our 3800 sq. ft house. I also improve performance by insalling a baffle to take the firebox exit down to about a third of the height.Pretty much level with the top of the fire. Got rid of a lot of creosote accumulation and smoke. Also lined firebox door with firebrick since original door was being scorched on outside. We use about a truck load of mixed wood weekly. That's a bit like saying how long is a piece of string!! If I were to start again I would go for a gassification type furnace.

Good luck

[williamG]

my set up...home made  stove  250 feet  from house...circulating pump in the basement.. 3 outlet  manifold..1st goes  to  heat  plenum in furnace (plenum full of  rads) original furnace  has  a  24/7 blower in low  speed..thermostat and zone valve control water flow to rads (1st off manifold) ..next is heat  exchanger for  domestic hot  water (home  made) runs  24/7 to this (2 foot long  by 12 inch pipe for  furnace water..and  a  50 foot  1/2 coil inside for  domestic water)..

and  finally  another  zone  valve and thermostat and mixing  valve  to control and maintain  floor heat in  basement...1- 1/2  story  century old  farm house...quite a bit of  insulation  added over the  years and then  i aslo heat  (mildly) a  30 by  40 shed to around  40 or 45 all winter long  for  my  dogs  to sleep in..all this on about 25  face  cords (8 or  9  real cords)

these  stoves  are  not  the most  efficient but  you trade that  off for  some other  things....no  fire in the house...no  bugs in the house..no flying  ashes  when you clean the  stove in the  house....no  sweeping  an mopping  when you have to  pile  wood in the  basement every  month....i built  my  own  stove and  i think i can build  a  more  efficient model and  will begin maybe this fall