I'm having some boil problems with our new direct fire kettle. We just bought a used, 1994, 15 bbl Specific Mechanical kettle. We had the firebox rebuilt and reinsulated.
My problem is that my first boils were way overhot. I came to a boil instantly, and carmelized the beer badly; even with the gas regulator cranked as far down as it will go.
So I called Adams, the burner is a Speedflame HP800. They sent me the next sized down orifice. I put that in, and now I am underboiling. Now I'm not getting a great hop break and I think I'm underutilizing the hop oils. I have the regulator cranked as far up as it will allow...
We don't want to buy a new burner. We have already sunk more $$$ into this system than we ever anticipated. Any suggestions??
Last edited by Triose; 07-10-2005 at 10:01 AM.
Are you sure it had the right oriface to start with? could have been built wrong.
Last edited by NickHorne; 07-09-2005 at 08:56 PM.
Reason: spelling error
We have a conversion burner (forgot the brand name) in our forst 7 Bbl Brewery. I've worked on this MoFo a few times and wonder if you have the same type of burner. We can adjust the air inlet shutter to reduce the incoming air to the flame, which will carbonize a snick (not as bad as it sounds, trust me), but reduces the overall burner temperature by quite a bit. Our burner is an Enco, if my memory serves right (maybe not, I'm killing the slower buffalo this evening).
Like a gasoline engine, flame temps increase as you lean the mix out (within certain perameters). Reducing air mix with the shutter setting will create a cooler flame, and may be the answer you're looking for with the burner/orifice you have.
I've dealt with our burner (and replaced burners) quite a bit on our rig (smaller than yours by a half) and firmly believe this to be an avenue of research for yourself. If you have the manual, read the section regarding the set-up or air-gas mix. Ours adjusts with a screwdriver, and is easy cheesey to adjust.
Not to insult your intelligence, but a conversion burner has a squirrel cage air fan on it and directly dams in a high volume of air to the burner assembly, thereby giving a greater amount of heat. Since you did not specify, I'm making assumptions here.
We're not talking about a huge amount of fuel -air richness, here. Maybe up to 10 turns back of optimal on the shutter screw, if you have the same 100+ screw turns I do on my Enco just to set it from absolute close of the shutters.
BTW - We use a 300 KBTU burner for our 7 Bbl kettle. Our firebox is directly below the kettle tub, so we heat from only the bottom of the wort. We have never, ever scorched a beer.
I hope this helps!
Thanks for the replys...
The orifice was a standard size for that model. It seems the previous owners had no such scortching problems. I think we may have upped the heat value in the firebox when we rebuilt and reinsulated it with refractory blanket. My first two beers were insanley scortched. They were dingy and tasted like burnt marshmallows. yuck!
I work with the air intake on the burner quite a bit actually. It does help make the flame more or less powerful. I think my problem right now is hotspots in the kettle. It seems that one side of the surface wort boils nicely while my hot break and hops just drift over to the other side of the kettle.
I've read every word in that manual; what I'm thinking is that I should start stacking up some fire bricks in the chamber to try and spread the flame around more evenly. And/or build an orifice that is between the two sizes.
Anyone have experience getting fire to move around in the box?
Last edited by Triose; 07-10-2005 at 10:00 AM.
Yeah, Tom, I did that too but for a different reason. We found it was taking too long to heat the wort, and reckoned the flame was shorting directly over to the combustion chamber exhaust vent.
I built a baffle wall from refractory brick that separated the burner tube from the exhaust duct exit. It forced the flame and heat to pass around the wall and give the heat more exposure time all around the bottom of the kettle tub skin surface common to the combustion chamber. I just stacked them into a wall and used cermic refractory wool to fill in the gap at the top between the brick and the kettle tub skin. They stay in place OK.
Your observation regarding the increase in effiency due to re-building the combustion chamber makes total sense to me.
Do you have a ball valve in the gas line that's near the kettle and readily accessable to the Brewer? Rather than change the shutter setting, you could restrict the flow a bit to let less gas go into the burner assembly without compromising the line pressure.
To test the thoughts here you could boil water and see where the hot spots are with a flashlight (looking down into the kettle just before boil). The hot spots should be flashing to steam faster, I should think. It's a cheap and easy test.
Just some thoughts...........Good luck, Tom. Let me know how you make out.