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OWB Build

Started by SPD748, January 10, 2017, 07:13:35 PM

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trapper

Try to find a way to keep the wood from touching the water walls I find if I put a small piece of wood vertical against the firebox walls of my classic I get a much better burn but I have a natural draft not a blower.
stihl ms241cm ms261cm  echo 310 400 suzuki  log arch made by stepson several logrite tools woodmizer LT30

DDW_OR

Quote from: trapper on January 20, 2017, 11:20:57 PM
Try to find a way to keep the wood from touching the water walls..........

my CB-750 has steel rods hung on the sides

in photo below, Left and Right steel bars, removable plates over heat exchanger in back. small bypass door at top for smoke when re-fueling.


  

in photo below, door latch and blower switch
how it works, opening the door releases the electric switch that turns on a fan.


 
"let the machines do the work"

r.man

Two things that I can add from experience, creosote control can be largely achieved by burning very dry wood and any tubes used for heat exchange need to be easily accessed for cleaning. I have an Empyre with 18 tubes running the length of the firebox. The cleanout access door has two large nuts that seal it and has to be lifted off each time. Not a good idea, should be hinged with a latch. I think that the ideal for a single pass heat exchanger is to have the smoke go out the back of the firebox and travel to the front to exit into the chimney area.  This would allow a second door above the firedoor to access the tubes which could be cleaned from the front. This arrangement also allows for easy piling of wood at the front of the firebox to maximize smoke and flame travel. I home built my first stove 20 years ago with basically no budget and have been itching to try it again with what I have learned since. Another interesting thing that I have only seen on one make of stove is a large duct like smoke diverter above the firedoor. If you look at many furnaces you will see that most have a heavily blackened area there, if you are in a building you might want to consider that. Unfortunately the front cleanout door and the duct are not compatible together.
Life is too short or my list is too long, not sure which. Dec 2014

SPD748

After hours of reading and thinking and more reading I think I have settled on this design:



 

It definitely won't be super efficient (or even as efficient as most if not all the commercially manufactured units) however I think it will work. As mentioned, there is a clean out door on the front of the unit to handle creosote duties. R.man is on to something with the hinge and latch arrangement. I really like tool-less maintenance features. I've found that I tend to keep up with maintenance duties better if I don't have to hunt a tool first  :)

I think I'll extend the firebox opening so that I might avoid the blackened area just above the door. That should give the smoke room to rise without staining the front of the unit.

-lee
Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

Gearbox

You still need a way to get air in to the second burn chamber and then close it off .
A bunch of chainsaws a BT6870 processer , TC 5 International track skidder and not near enough time

gspren

   It should work as drawn but I wouldn't bring the chimney pipe halfway into the fire box, you may get so close to the hot coals that your getting hotter air, 1/5 to 1/4 is as far down as I'd put it. Is the area just inside the cleanout door big enough for a pan with a roast?
Stihl 041, 044 & 261, Kubota 400 RTV, Kubota BX 2670, Ferris Zero turn

Mt406

Hi

I have been thinking of building my own OWB. My design is similar to yours.
I would think it mite set up a creosote problem buy running the flue pipe though the water jacket horizontal.
You would gain heat in water jacket but would you cool exhaust gas to the point of creosote.
Would running it horizontal in the fire box work better.

Just my two cents
Scott

really good info in this topic thanks for the good input everyone I am not ready to start my build yet you are giving me ideas   
 

gspren

Quote from: Mt406 on January 25, 2017, 01:05:38 PM
Hi

I have been thinking of building my own OWB. My design is similar to yours.
I would think it mite set up a creosote problem buy running the flue pipe though the water jacket horizontal.
You would gain heat in water jacket but would you cool exhaust gas to the point of creosote.
Would running it horizontal in the fire box work better.

Just my two cents
Scott

really good info in this topic thanks for the good input everyone I am not ready to start my build yet you are giving me ideas   


   My Portage & Main OWB runs horizontal through the water jacket and creosote has not been a problem, just need to scrape it a few times a season. A plus to that is that the embers burn out before going up the stack.
Stihl 041, 044 & 261, Kubota 400 RTV, Kubota BX 2670, Ferris Zero turn

NWP

Quote from: Gearbox on January 18, 2017, 07:52:35 PM
Kellyj I will disagree When you start a system you will need to push the water up to the heat exchanger fill it expel the air back inside the boiler then after that you have a closed loop . Now if you are in - 20 below zero and you have a 007 that will not expel the air back to the boiler and you are bleeding it out and trying to beat the frozen pipes . now do you see why I recommend a pump big enough to expel the air . Yes it is not needed till it is .

I have a hose bib on the outlet side of the circulator.  When I start the unit up in the fall, I hook a garden hose up from the house and turn the valve off between the circulator and hose bib. This forces the pressurized water throughout the system and back through the return line.  It only takes about 30 seconds and all the air is expelled and is ready to go for the season.
1999 Blockbuster 2222, 1997 Duratech HD10, 2021 Kubota SVL97-2, 2011 Case SV250, 2000 Case 1845C, 2004 Case 621D, John Deere 540A, 2011 Freightliner with Prentice 120C, 2012 Chevrolet, 1997 GMC bucket truck, several trailers, and Stihl saws.

thecfarm

My heatmor is like gsprens. Never had a problem with cresote. And I have burned green wood as an experment. Cut it down,cut it to lenght,split it and burn it. Both softwood and hardwood. Never had a cresote problem. As he stated,just scrape it a couple times a season.
There is no pipe that hangs down on my heatmor. Just a round opening that the smoke goes into. Not trying to say anything,but maybe there is a reason the smoke enters the 4x8 inch tubing by the feed door on a heatmor.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

hedgerow


[/quote]

I have a hose bib on the outlet side of the circulator.  When I start the unit up in the fall, I hook a garden hose up from the house and turn the valve off between the circulator and hose bib. This forces the pressurized water throughout the system and back through the return line.  It only takes about 30 seconds and all the air is expelled and is ready to go for the season.

[/quote]  When I set my system up I bought the circulator mounting fitting that had the valves and the hose bibs on them. That was the best thing I did it is a great place to add liquid or remove air from the system.

SPD748

Quote from: Gearbox on January 25, 2017, 08:40:02 AM
You still need a way to get air in to the second burn chamber and then close it off .

As I understand the secondary burn theory, there needs to be a tube to allow (atmospheric pressure) air to enter the horizontal pipe which, in my design, runs through the water jacket. What I found looked as simple as 3/4 black iron pipe with a series of small (1/8" ish) holes drilled along it's length and a cap on the end. What I can't find is... does this air tube need to have some kind of automatic shutoff (when the unit is in the idle mode) or is it open to the atmosphere full time?



Quote from: gspren on January 25, 2017, 08:45:17 AM
   It should work as drawn but I wouldn't bring the chimney pipe halfway into the fire box, you may get so close to the hot coals that your getting hotter air, 1/5 to 1/4 is as far down as I'd put it. Is the area just inside the cleanout door big enough for a pan with a roast?

I'll move the chimney pipe up in the firebox. The idea was to create a space above the coals that would trap heat before the gasses have a chance to enter the chimney. The pipe (as drawn) is 6" square x 1/4" wall tubing. I would need to fabricate a 6" square to 6" round collar to which the insulated pipe that will comprise the exterior chimney would attach.



Quote from: NWP on January 25, 2017, 05:00:24 PM
I have a hose bib on the outlet side of the circulator.  When I start the unit up in the fall, I hook a garden hose up from the house and turn the valve off between the circulator and hose bib. This forces the pressurized water throughout the system and back through the return line.  It only takes about 30 seconds and all the air is expelled and is ready to go for the season.

That's an excellent idea! Thanks. I'll definitely install a similar fitting arrangement.

-lee
Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

Bill Saf

Quote from: SPD748 on January 15, 2017, 10:22:45 AM



Wrap the sides and back of the tank with several layers of fiberglass insulation.



I do have a question about the heat exchanger. My air handler is a condenser on top/down draft style arrangement. The fan draws air down through the condenser then through the floor and into the duct. Could I place the heat exchanger between the condenser and the air handler thus the fan would draw air down through the condenser then through the heat exchanger then into the duct? All the pictures I can find have the heat exchanger on the pressure side of the fan. I can't seem to find an arrangement where the heat exchanger is on the suction side of the fan, exactly like mine.

Thanks guys!

-lee

Lee,

I would use foam insulation it has a higher R value then fiberglass.

When I put my OWB in I built a double plentum for the heat exchanger I have a down forced air furnace and had a concern about a water leak with electric coils and put the heat exchanger under the furnace. The plentum is just a double box with a shelf to hold the heat exchanger the furnace sits on top of the box. Are you going to heat your water with a side arm water to water or just heat? if your going to heat your water to you can put a air bleed a the top to vent trapped air. my side arm is the high point on my system. 
Just my .02 worth

Bill

SPD748

I'm back, sorry. My day job got a little busy.

I'm working on my door design. I won't have an ash grate so I'll have to mount the blower on the firebox door. Looking at other designs, it looks like the blower is simply mounted directly to the door. My concern is that the blower will over heat when it's not running as the interior of the door would be exposed to the heat of the fire box and, with the blower shut off, there wouldn't be any air passing blower motor, blade and housing. Any ideas as to how this arrangement works?

-lee
Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

DDW_OR

here is how mine does the air flow
the furnace door is above this

 
"let the machines do the work"

SPD748

That set up looks like two natural draft inlets with one forced air inlet. Haven't seen one like that until now. Interesting...

The door's I've found that have a fan mounted on them (Taylor has this arrangement) seem to all be insulated with what is most likely Kaowool. Building a similar one won't be much of an issue however I still can't figure out how the heat from the fire doesn't affect the fan, which has to be mounted with a tube or opening of some sort running through the door thus exposing the fan to the heat of the fire when the fan isn't running. I can't seem to find any close up pictures of a door with a fan mounted on it. Ideas?

-lee


Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

SPD748

Sorry for the extended absence. I took a little time off to sort some things out. Have no fear, all is well. I'm reviving this thread first because it's the most "needed" item on my project list. I settled on a boiler design and have most of the materials on hand to move forward. It's the btu requirement and head calculations that are the bottleneck at this point. I tried the online calculator route and quickly observed a wild range of "answers." Here's what I have so far:

My home is heated with an electric furnace which has a single 10kW heating strip. With the thermostat set on 66 degrees the furnace used 2000 kWH in the last 30 days. This useage is usually the highest I'll see per month in a given year. We had a bit of a "cold" snap here (cold for NC that is). I did a little research on the previous 12 power bills and noticed that during the spring/fall months (heat/air conditioner not running all month) the power usage fell by approximately 2000 kWH which leads me to believe the furnace used that amount last month. That being said, I did a little math and concluded that my furnace element produces approximately 35,000 btu and had a run time of approximately 28% last month. IF these calculations are correct, does this mean I could heat my home with ~ 35k btu input from an OWB? Turn the thermostat up a few degrees and have a longer run time perhaps? It seems this way, in my mind at least however I've been very wrong many times in the past so...

My OWB will be placed ~130 feet from the house for a 260 foot total loop. I plan on installing a 30 plate heat exchanger for domestic hot water first in the loop then an 18" x 18" water to air heat exchanger in the air handler to heat the home. I plan on running 1 1/4" insulated lines (1.07" i.d.) from the OWB to the house.

My problem is that I have several numbers/specs and don't know if they're enough to make the calculations or what to do with them for that matter.

Any advise will be carefully considered and much appreciated!  :)

-lee
Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

DDW_OR

Quote from: SPD748 on February 24, 2017, 05:58:26 PM
That set up looks like two natural draft inlets with one forced air inlet. Haven't seen one like that until now...........
there is no natural draft

the area in the photo is covered by an 1/8 inch thick steel door
the fan on the right blows air into the center area
then each of the air channels are opened by solenoid. this allows the air that is blown in by the fan to reach the fire.
"let the machines do the work"

Gearbox

I think the domestic water heater needs to go after the heating coil . You don't need that hot [180] to heat your D W . Some where I think I read you only want to pull 2 or 3 degrees out of your water . Mine is doing about 4 degrees at 30 below zero and with the house and shop both calling the boiler runs steady for 2 hours until the shop warms up .
A bunch of chainsaws a BT6870 processer , TC 5 International track skidder and not near enough time

Holmes

The 35000btu may heat the house but your real demand is hot water. how many gallons per minute of hot water do you want/ need? lets say you need 3 gpm  3x8.2pounds per gallon is 24.6 pounds of water per minute heated 80 degrees [50 degrees to 130 degrees] is 1968 Btu's per minute x 60 minutes is 118080 BTU's per hour to heat your hot water. I may be wrong with these calaculations but this gives you a general idea . heating is the easy part.
  This will require a 12 gallon per minute flow rate for the circulator
Think like a farmer.

DDW_OR

Quote from: Holmes on January 20, 2018, 09:50:05 PM
......real demand is hot water......
  This will require a 12 gallon per minute flow rate for the circulator

Here is a photo of my double wall hot water heat exchanger
the OWB water enters at the bottom, then exits the top. then goes to the air heater exchanger, then back to the OWB.

all of this is done with the Taco 007 Pump   1/25 hp

Yes I did insulate all of the tubing after I took the photos


 
"let the machines do the work"

DDW_OR

did some research on the Taco
Maximum Flow Rate    1  cubic_feet_per_minute

using my converter "Conversion Tool for Measurements.exe"
feet3/minute = 448.8312 Gallons/Hour
not to bad for a $100 pump that runs 24/7
UPC    687752187311 , 076335100609
"let the machines do the work"

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