Long time to boil

[MikeCo]

I tested my new eBIAB system in about 6.5 gallons of water.

The setup is as follows:

15 Gallon Blichmann Boilermaker kettle; no insulation
4500 Watt 240v CoilCoil heating element
Auber Cube with EzBoil DSPR320
For now I just clipped the temp probe to the side of the kettle so the tip hangs in the water.

With the lid on the kettle, it took only 15 minutes to get from 66 degrees to 152. Ambient temperature was 66.

When I took off the lid and went to boil from 152 using 100% power, the temperature quickly rose to the upper 190s in about 10 minutes but then stalled around 203/204, and it took another 15 minutes to get from the low 200s to a boil. Calculators tell me I should get to boil from 152 in 12 minutes for 6.5 gallons. Could something be wrong with my set up? I verified that the EzBoil was delivering 100% power during the ramp and that the next step was set for 100% also.

 

[d3track]

Is there potentially a temp setting in the boil mode that is slowing the ramp towards boil? I don’t have any experience with these controllers, but it sounds like that could be a reason causing your slow down.

 

[MikeCo]

Thanks for the reply.

There are the bAST and bOUT parameters.
bAST is set to 204F, which is the temperature where the controller stops using bOUT which is the boil acceleration output percentage and goes to the power setting in the first boil step. bOUT is set to 100%, so it should apply full power to 204.

After reaching bAST of 204, the controller applies the percentage programmed for the first boil step. I had the power output set at 99% at first boil step so it should not have slowed it down much. I've tried it with the step percentage at 100% with similar results. The green power output indicator remained solidly on while I was observing this.

I noticed the Auber probe reads a little low at boil temperatures. It reads about 205, while my trusted thermometer reads 210 which is about the boiling point at my elevation. It seem really stuck around 203/204 according to the probe for a long time, which correlates to a real temperature around 208/209.

The boil parameters are described in section 7.4 here:
https://www.auberins.com/images/Manual/DSPR320_manual.pdf

Maybe I just need to keep the cover on when I'm ramping to a boil.

 

[MikeCo]

I sent an email to Blichmann tech support asking if it should take this long to boil this amount of water and this is what they said:

"All your ramp times look spot on other than the last segment from 205 to 212. That was over twice what I would have expected to see. The BoilCoil is working fine or we would have seen issues in the other ranges. I suspect that the lid off allowed too much heat to escape was part of the issue. You may place a towel or some type of insulated pad under the kettle so the heat is not lost out of the bottom of the kettle. Just wrapping a towel around the outside of the kettle when heating will help also."

Is it standard to ramp to a boil with the lid on when using electric elements to heat? This thing seems to really slow down once it got just below the boiling point.

 

[MX1]

I have the same Boil Coil in my High Gravity set up and do not see those issues, there may be some surface temp swings if you do not have the temp probe mounted toward the center of the tank. this is only a guess mind you, but heat transfr from the water surface may be impacting temp readings,as well as water agitation as you near boil temps.

These are only guesses

T

 

[mongoose33]

I always keep the lid on as I move up to a boil simply because, well, it's faster. You lose a lot of energy without a lid--it's what boiling does.

You have to monitor things when it gets close to the boil unless you want to contend with a boilover.

Something else you can do to help speed things up is wrap the outside of the BK with a layer of reflectix insulation. You could also, as the Blichmann people note, put some sort of insulated pad under the kettle as well.

A couple of things are different on yours than mine (I have an Auber panel, not the Blichmann): mine is a 5500-watt element, and I have the temp probe in a port near the bottom of the kettle. My temp probe never reads higher than 208 degrees, but it's at about as cool a place in the kettle as one could get. Try moving the temp probe around next time and see if you get different readings. I'll bet you do.

Below is a pic of my 10-gallon-batch setup. I use foamboard insulation beneath the mash tun on the left. Just wood under the BK, on the right.

 

[Vale71]

I sent an email to Blichmann tech support asking if it should take this long to boil this amount of water and this is what they said:

"All your ramp times look spot on other than the last segment from 205 to 212. That was over twice what I would have expected to see. The BoilCoil is working fine or we would have seen issues in the other ranges. I suspect that the lid off allowed too much heat to escape was part of the issue. You may place a towel or some type of insulated pad under the kettle so the heat is not lost out of the bottom of the kettle. Just wrapping a towel around the outside of the kettle when heating will help also."

Is it standard to ramp to a boil with the lid on when using electric elements to heat? This thing seems to really slow down once it got just below the boiling point.

As you get close to boiling temperature evaporation really picks up and that carries off a lot of heat. If you keep the lid on as tightly as possible the atmosphere in the kettle headspace will quickly become saturated with water vapor and this will suppress evaporation and heat loss. The lid will also reflect some heat back into the wort which also reduces losses. I always heat up with the lid on and remove it as soon as the wort is visibly boiling.

 

[balrog]

What @Vale71 says. Physics. Water to vapor phase change sucks yuuge energy from the system.

 

[MikeCo]

Thanks for the responses. I think the way I had the probe tip dangling into the water is causing error, since much of the probe was exposed to air. The error was probably higher at the higher water temperature. I'll be drilling another hole in the kettle soon and will test again. As for the boil time, I guess I'll keep the lid on until it's closer to boiling and see if it's much faster.

 

[sicktght311]

Although my system is only 120v 1650watts, so i need the lid partially on to maintain my boil, i still keep it on until im at about 210, then i'll start cracking the lid. Makes for much quicker heat up times between 200 and boil. If i kept it cracked it would undoubtedly increase my heat times substantially

 

[MikeCo]

I got up the nerve Saturday to drill/punch another hole in my Blichmann kettle for the temperature probe. After struggling with the pilot hole and punch a bit, I made a good hole exactly where I wanted it so the probe would fit between the BoilCoil coils.

I repeated my test with about 7.25 gallons of water.

Time from 67F to 152F: 18 minutes (lid on kettle)
Time from 152 to boil: 17 minutes (lid on kettle)

Probe reading at boil - 209 (one degree off from my trusted thermometer that read 210). 210 is roughly the boiling point here.

Overall, I'm pleased as the heating and boil times are close to what others are getting and what the electric heat spreadsheet predicts. With the probe mounted on the kettle and fully immersed in the water instead of just the tip dangling in the water from above, it appears accurate within a degree.

The last few degrees to get to a boil still took a longer time than the rest of the ramping time, but as others have said, that's due to the phase change.

Thanks for all the input. Cheers!

 

[bgmac]

Here is why it takes a long time to reach a visible boil when water is at or near boil temps.

Taking water from a liquid at 212F to a vapor (boiling) at 212F takes more heat then you would think. It takes 1 British Thermal Unit (BTU) to raise one pound of water in a liquid state 1 degree Fahrenheit. So if water weighs 8.34 Lbs per gallon, then it takes 8.34 BTUs to raise one gallon of water one degree F. Not much heat to change liquid water by 1 degree.

Here is the kicker, it takes 162 BTUs to convert one pound of water from a liquid to a vapor (boiling) and its still the same temperature of 212F at sea level. So that's 162 times more heat to change the water from liquid to boiling then to raise the temp 1 degree. That means it takes 1351.08 BTUs to convert one gallon of water in a liquid state to vapor (boiling) all while at the same temp of 212F at sea level. There is always going to be a long lag between reaching boil temp to actually boiling because you have to add so much heat for the liquid to change state to vapor (boiling).

Changing state from a solid to a liquid to a vapor takes a lot of energy.

Similar rule applies to changing water from a liquid to a solid (ice). You have to remove 144 BTUs per pound of water liquid at 32F to change it to a solid (ice) at 32F.

This is a long and geeky explanation, but if you have a basic understanding of water change of state dynamics then you will know why it takes longer then you would think.

Basic air conditioning and refrigeration lesson.