Print

[Sloppy_Snood]

Although I have recently purchased a BL 34-44 Ultimizer, I am wondering why these Portage & Main units have such smaller water jackets than many other P&M and other brands of OWBs.
 
Why is this not a problem with the Ultimizers? 

Does this ever have the potential to be an issue with high heat demand situations due to the reduced volume of water used to transfer the BTUs?

Just trying to edjumikate myself more on heat transfer using water.  Thanks for any and all input.  -Slopster

[slimjim]

  Great question, the ceramics in the B-L series acts as the water jacket thermal mass, it stores the energy that the water jacket used to on the M-L series as well as quicker recovery for the fire itself

[CountryBoyJohn]

It's not how big it is.......it's how you use it!! 

[Pinehouse4]

Hi Slopster,

I used to wonder about that too but came to understand what Slim says about the ceramics storing heat in tandem with the surrounding water.  They talk about a very fast recovery time.

It says on the brochure -

 * Extra water volume is usually a by product of a large firebox because of inefficient design. Think of which pot boils faster— a big one or a smaller one?

Bob

[Sloppy_Snood]

Thanks for the replies gentlemen.   

Anyone know the heat capacity of refractory cement versus water? 

I am quite certain that refractory cement can store a boatload of heat in the form of BTUs but I would also think it loses that heat rather quickly as well. 

How long can the thermal mass of the refractory cement in the Ultimizer hold the heat versus going to a water storage tank system?    This would seem to be an important attribute from my understanding. 

[mlappin]

Well, not exactly scientific here but I bought some refractory brick to play around with. Took one of the 4.5x9x2.5 and placed it in my OWB, left it in all day, took it out late afternoon and sat it on a piece of 4" angle iron clamped in the vice, hour later you could just pick it up with bare hands. Got the underside of the angle iron up to around 300 degrees. Angle iron was quarter inch thick btw.

[karlk]

I build wood fired pizza oven kits that are refractory lined , when you bake bread you take the fire out and the refractory retains heat for baking. 24 hrs later the refractory will be 250 degrees without any fire.

[Pinehouse4]

The same refractory bricks in the grate are the same as the ones that line my maple syrup evaporator. I can let the fire die off and hours later still have light steam coming of the pans. Since I boil with 2 inches in the pans I have to be sure to have enough sap left in the reservoir to hold that level after the fire is out.

Bob

[Sloppy_Snood]

The same refractory bricks in the grate are the same as the ones that line my maple syrup evaporator. I can let the fire die off and hours later still have light steam coming of the pans. Since I boil with 2 inches in the pans I have to be sure to have enough sap left in the reservoir to hold that level after the fire is out.  Bob

Thanks gentlemen.  Unfortunately (fortunately?  ) for my BL 34-44, I had Portage & Main installed the shaker grates in the bottom of the fire box (this deletes the refractory bricks that serve as the "ash holes" in the bottom of the firebox).  I suppose that would mean my true refractory thermal mass is actually going to be the refractory cement "bowl" rather than those 7 or 8 bricks.  1/2" steel shaker grates don't retain heat for a long time like refractory bricks but I guess I can put refractory brick in there later if I choose to.  Dunno. 

Anyways, it probably won't make much difference but it could if I just use regular firewood.  It has been known for someone to throw 3" black ultra-compressed wood nuggets in these type of boilers though....         Blame CountryBoyJohn....LOL! 

[CountryBoyJohn]

Those nuggets cut your regular wood usage in HALF!!  I doubt the fire bricks can do that!!