Test drove my burner

[Jim Karr]

Yesterday was my maiden voyage on my keggle setup. I installed a 170,000 btu burner to the underside of my kettle, attached some gas, and fired it up.

Being somewhat prudent, I didn't run it full tilt for a while, wanting to see if everything was safe or not. After a bit, I turned it up completely.

Here's my question. It took an hour and eighteen minutes to bring 15 gallons of 54* water to a boil. I realize this is an eternity, so I'm wondering if my distance from the top of the burner to the bottom of the kettle is incorrect.

From the top of the burner to the kettle is about an inch, so when I poured the coal to it, the flames were diverted/mushroomed out to the side instead of rising straight up towards the kettle bottom.

Could this be a factor in what seems an extremely long time to boil?

 

[Lil' Sparky]

Yeah, it sounds like your burner may be too close and most of the heat is blowing out the sides. You want the flames to spread out around the bottom, but not out around the sides. Are you using a turkey fryer, or did you mount the burner on a stand yourself? BTW - I never turn my burner all the way up, even when boiling 13-14 gallons for a 10 gal batch. I would just be a waste of propane.

 

[casebrew]

Yeah, it sounds like your burner may be too close and most of the heat is blowing out the sides. You want the flames to spread out around the bottom, but not out around the sides. Are you using a turkey fryer, or did you mount the burner on a stand yourself? BTW - I never turn my burner all the way up, even when boiling 13-14 gallons for a 10 gal batch. I would just be a waste of propane.

On the other hand, if it is taking too long, he's wasting propane too.

I think he should move his burner away, my turkey fryer is about 4 inchs. And try another boil with it cranked up a bunch. Adjust the air butterfly for the bluest flame too, yellow is unburnt fuel, makes soot.

 

[brewman !]

"It took an hour and eighteen minutes to bring 15 gallons of 54* water to a boil"

Lets say the burner put out an average of 120,000 BTU. I'm just guessing here, how long it ran at less than full and how long it ran at full.

15 gallons x 8.33 lbs/gallon = 125 pounds of water.
212 - 54F = 158F

Work done = 125 lbs x 158F = 19,750 BTU.

Energy used = 120,000 BTU x 1.3 hours = 156,000 BTUs.

Efficiency = 19,750/156,000 = 12.7%. That's terrible !

The heating rate of the water in KW is 19,750/(3412 x 1.3) = 4.45KW.

A high efficiency 6KW electric or possibly radiant propane heater would have heated the water just as fast.

 

[Lil' Sparky]

On the other hand, if it is taking too long, he's wasting propane too.

I think he should move his burner away, my turkey fryer is about 4 inchs. And try another boil with it cranked up a bunch. Adjust the air butterfly for the bluest flame too, yellow is unburnt fuel, makes soot.

I agree. Moving the burner away will probably help. Jim, what color was your flame?

 

[Jim Karr]

Pretty much all blue. I adjusted the air device to obtain the bluest, cleanest looking flame.

 

[WOP31]

While that is a long time to heat 54deg water. Are you going to be starting out with 54 deg water all the time. If you are doing AG then your wort will likley be around 170 when you run off into your kettle, plus you can kick the klettle on before the run off is complete to retain the heat. If you are doing extract I would suggest starting off with water out of the hot water heater, most house hold ones are around 130-150 deg, just make sure that you drain it for a couple of minutes first or use the tap.

Cheers

 

[brewman !]

The efficiency will actually be higher with cold water than it will with water at 170F.

The problem is the burner power is vast compared to the surface area you are heating and the heat isn't contained to the pot in any way. Sure it contacts the bottom, but there is a ton of heat, way over half, going up the sides and away from the pot.

I've pretty sure that one could get faster heating with a smaller burner and better efficiency. I say that because I think everyone is focused on speed.

The other thing is that the boil is an hour long after the water gets up to boiling temp.

 

[WOP31]

The efficiency will actually be higher with cold water than it will with water at 170F.

The problem is the burner power is vast compared to the surface area you are heating and the heat isn't contained to the pot in any way. Sure it contacts the bottom, but there is a ton of heat, way over half, going up the sides and away from the pot.

I've pretty sure that one could get faster heating with a smaller burner and better efficiency. I say that because I think everyone is focused on speed.

The other thing is that the boil is an hour long after the water gets up to boiling temp.

Understanding that I don't know all the fancy math equations that you used to come up with the numbers in the other post, it just doesn't seem, from a logical and common sence aspect, that you would use more propane heating up hot water to boiling then you would heating up cold water to a boil. It's like saying hot water would freeze faster. If youre meaning that you are getting "more for your money" when it comes to how effective the burner is working, then you are probably right. but to use less propane and take a shorter time to heat up then you would want to start using hot water. Just sounds like common sence to me.

I do agree that you need more space between your burner and your kettle.

cheers

 

[Chillbrook]

Understanding that I don't know all the fancy math equations that you used to come up with the numbers in the other post, it just doesn't seem, from a logical and common sence aspect, that you would use more propane heating up hot water to boiling then you would heating up cold water to a boil. It's like saying hot water would freeze faster. If youre meaning that you are getting "more for your money" when it comes to how effective the burner is working, then you are probably right. but to use less propane and take a shorter time to heat up then you would want to start using hot water. Just sounds like common sence to me.

I do agree that you need more space between your burner and your kettle.

cheers

From what I've heard, hot water can sometimes freeze faster than cold water....sound counter-intuitive, but it has been proven.

http://en.wikipedia.org/wiki/Mpemba_effect

 

[brewman !]

The heat transfer is proportional to the temp difference between the flame and the water. Lets say the air moving by the outside of the kettle is 400 degrees for argument sake. It might be higher, like 700-1000, but maybe not, depends on how the burner and pot are set up.

If the pot is 54F, the temp diff is 346F. If the pot is 212F, its only 188F. Plus, it takes a ton of energy to boil off the wort, so the burner is probably running fairly hard during the boil.

 

[olllllo]

If you are doing extract I would suggest starting off with water out of the hot water heater, most house hold ones are around 130-150 deg, just make sure that you drain it for a couple of minutes first or use the tap.

You should not do this:

Try never to cook with or drink water from the hot tap. Hot water can dissolve more lead more quickly than cold water. Also, hot water stands in your water boiler and pipes for longer than cold water, contributing to higher contaminant levels. If you need hot water for cooking or drinking, draw water from the cold tap and heat it on your stove.

Source: http://www.mit.edu/people/rjbarbal/SB0/lead.html
http://www.epa.gov/safewater/lead/leadfactsheet.html#four

among others.

 

[WOP31]

Ok You all are right, As usual. Not going to argue on this one.

 

[Ol' Grog]

Well, I will on the hot water tank. If your house is old, lead MAY be a problem. However, all that is required is to let the water flush for a few minutes and then your good to go. I know, I've taken tons of water samples and had them analyzed for lead on both hot and cold sides. You will get a lead spike the first 30 seconds and then almost nothing for the rest of the run. We are only talking about solder and/or flux. There is absolutely no lead in modern water heaters period.

 

[WOP31]

Grog, I was going to raise the point that my house is only four years old and all the plumbing is pvc, and i really feel that there is minimal, if any, risk of leaching lead from those pipes. But I felt that no matter what someone would disagree and I didn't feel like raising a rukus. Oh, yeah I also hooked up a garden hose to my hot water heater to fill my HLT....gasp...:cross:

cheers