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[mcarter]

Does this contraption translate into using less wood?

I just cut a cord of white oak yesterday, I'm good and sore!  If adding this doesn't use less wood, I'll gladly pay another $2/month for my regular ole draft control.

I'm interested in an actual comparison of wood consumption based on similar outdoor temps with the oem draft control system vs your method.

For me, it all comes down to the wood!

Michael

[ELEproducts.com]

Fuel conservation is the goal. (Less Wood.)  Smoothing volatile water temperatures from the crude installed controller alone is an interest worth noting.

[ELEproducts.com]

My Scenario:
Temperature dropped to approximately 39F last night.  8:30 PM. There were about 2, 1 gallon paint buckets of embers on the grate.  I scattered them out nicely. For an experiment,  I inserted a 8 inch diameter piece of white pine.  This pine had been dead for years and was dry.  The house thermostat was set on 74 (Girlfriend Is Cold) at the time of loading.  When returning inside the house, I reduced the thermostat to 70F.  Done!  I woke at 6AM and the house is warm still at 70F degrees, I visit the Heat Master MF3000@ 6:30AM.  Water temperature is down to 90F and the fire is out!  The pine log is only 1/3 of the way burnt.

Here is what happened: 
1.Outdoor temperature is seasonal, only 39F.
2.Reduction of indoor temperature, from 74F to 70F. (saving energy while sleeping)
3.One 8 inch diameter log of seasoned / dry pine.
4.One factory installed control that is not intelligent.  It’s either ON or OFF.

With the demand on the MF3000 being minimal already, compounded by additional reduction in demand from setting the indoor thermostat from 74F to 70F.  The furnace draft blower shuts down and the solenoid is relaxed, closing the draft valve.   The furnace is now idle for a interval longer than the fire and embers can remain alive.  Fire is now out, without any chance of ignition.
 
I believe the microprocessor controlled, variable draft fan speed controller product, operating in a closed loop mode will solve this issue completely.  Huge benefit for folks heating domestic water in seasonal temperatures.

1st design on paper is complete, firmware is working well.  Laying out circuit board.  Physical product enclosure size is ~ 5” x 5”.  Polycarbonate composition NEMA enclosure with a latching transparent water tight cover on a hinge. 4 SS ears to mount enclosure.  4 terminal strips. 1-POWER IN, 2-BLOWER OUT, 3-TEMPERATURE SENSOR IN, 4-SOLENOID VALVE OUT. Cables enter thru bottom, into sealed cord glands.  LCD display on circuit board provides various information, visible through the enclosures cover.  Mini- USB connector on circuit board to program the controller via PC computer and interface software.

Will this work??   
 
Thanks,
Shawn

[mcarter]

What temperature did you have the boiler set to?

[ELEproducts.com]

Hi,

The boiler temperature was set on 150F from the installed controller. 

I am using a 4 channel type-K cold-junction data logger.  Measuring in-temp, out-temp ambient-temp and immersion-temp.  Sample every 750mS.  There is substantial over and under-shoot from what the display reads.  The installed controllers reading is very smoothed.  Response time is quite slow.

On a consumer level, this is good as the end user does not see the erratic temperatures.

Shawn     

[ELEproducts.com]

I have included some temperature data take today from my MF3000 boiler.  The PDF graft represents 250 samples.  Sample interval is every 60 seconds.  The point of measure is on the output pipe.  Temperature control is set at 150F.

Shawn

[Scott7m]

Ok??  What's the point?  I really dont see what your trying to gain.  Just seems like your trying tommake something simple complicated? 

It takes x number of btu's to heat that water.  Holding it one set temperature to me has no advantages at all, and many many disadvantages.

[martyinmi]

Guess I kinda-sorta agree with Scott7m. I wouldn't want a gasser starting up to only gain one degree. They tend to get more efficient the longer they burn. Even the conventional ones tend to burn more smoke the longer they cycle. I think that what you are trying to achieve might not be possible without giving up some emissions. It takes a high temperature to burn smoke,and most OWB's would probably just start running efficiently when you would like to shut them down. I think that slowing down a blower motor or having some sort of variable dampener setting might really increase emissions. What you are trying to achieve, if I'm understanding it, is very admirable, but I think your starting point should be combustion chamber design(variable displacement somehow?). I think you'd need to be able to constantly monitor your exhaust gasses(enissions)and be able to communicate that data with the fresh air side to ensure a clean burn. If you get a prototype up and running, I'd be happy to use my 250 as a guinea pig for ya.
   

[ELEproducts.com]

I agree with Marty.  I too wouldn’t want to start the furnace to only gain one degree.  The idea here is that the speed of the draft motor is variable, from something like 1 RPM(so slow it’s the same as natural draft)  to whatever the rated RPM is on the blower (maximum draft).  The motor continues to run in a precise mode of varying speeds to maintain a burn that is required for the demand imposed on the furnace.  The system no longer cycles on or off but maintains the water temperature much more “tightly” with this varying draft motor speed.

Like the curse control on your car.  The set speed is maintained (boiler water temperature) and as we travel along various terrain of ascending and descending hills (demand on the boiler from heating house), the computer will apply a variable rate of fuel (varying draft motor speed) to the cars engine to maintain this set speed without overshooting or undershooting.  This precise metering saves energy in a compounding way.

I agree also with Scott, why make something simple complicated?  This is why this product would be simple for users to install and use.

Shawn

[mcarter]

I don't want to discourage your experiment but I have thought about this since you posted here and I'm mostly interested in your end point comparison.

I think your analogy to cruise control may even disprove your theory.  The varying draft motor speed isn't the fuel in the case of an OWB, wood is the fuel.  Yes, the draft provides oxygen required to influence the rate of burn of the fuel just as a car engine burns fuel in the presence of oxygen.  If I understand this right, your draft control 'idles' at low rpm when the water temperature is equal to the set point.  This alone will increase the rate of burn of the fuel (wood) vs. a shutdown of the draft fan and thus using more fuel (wood).  It would seem to me that your stepping on the gas pedal while going down hill.

Additionally, will the variable fan control shut off completely at the set point or continue to idle at 1 rpm or whatever?  If the draft fan continues to idle and the set point has already been reached, I wonder if this would allow enough oxygen to continue to burn the fire and increase your water temperature much higher than desired.  Water boils at 212F, what effect would this have on an OWB system?

I could be thinking along the wrong track with your idea but ultimately, the draft fan has to turn off completely at some point or you may have some undesirable high water temps.

Keep us posted on your work!  Keep it safe though!

Michael

[Scott7m]

If ur idling at 1rpm that's way more than closed!

Something to consider, it takes x # of btu's to keep a firebox of temp at 150.  If ur holding it at 150 or simply averaging 150, its still 150.

If your looking to make something more efficient as far as wood use, I don't think your looking in the right place. 

[yoderheating]

 I can tell you up front what the end result will be. Creosote and smoke, and lots of it.

[Scott7m]

I can tell you up front what the end result will be. Creosote and smoke, and lots of it.

[ELEproducts.com]

Wood Burner control update.  The preliminary circuit board layout is complete.  The circuit board is installed into a NEMA enclosure with a transparent lid / cover, providing visibility of the LCD display which has various information .  Programming via computer using USB interface and software.    Enclosure is ~ 6” x 6”.  There are 4 cord glands/strain reliefs on the bottom of the enclosure where the cables enter and are electrically connected to 4 self contained terminal blocks.  Factory or aftermarket type K thermocouple is used to measure boiler water temperature.  Type J and others can also be used.  The attached PDF will illustrate additional details.

Next:  After more review, I will be sending out to have a small prototype run of the bare circuit boards made.

Hopefully in the near future, someone will be interested in testing the product, gathering user feedback to incorporate 1st production run .

Thanks,
Shawn