Downsides of a Penrose Kettle?

[Hex]

+1 for the 22 gal. version.

 

[jeffzx9]

I can Attest to their quality and customer service. The kettles are heavy duty contruction and customer service is excellent.

 

[smokinghole]

Well I got the email tonight and have an order placed. This thing should make my boil off less with a 15.75" diameter vs my current 18" diameter pot. I'm looking forward to possibly using it over spring break!

 

[Jaysus]

I wish I got in on this at the old price... but a good buddy of mine called the extra $20 a snoozing penalty - and I guess I agree with him.

 

[StMarcos]

The boil off rate doesn't have anything to do with the diameter of the opening.

 

[motobrewer]

what's the wall thickness?

what's the bottom thickness?

thanks.

 

[Bruin]

Wouldn't the ratio of surface area to volume be a factor in boil off rate? As it is not an enclosed vessel like a boiler, only the surface exposed to air is where the liquid can make a transition to gas (steam), so one would intuitively assume that a gallon of water would boil off faster in a frying pan than it would in a narrow and tall vessel.

 

[smokinghole]

The boil off rate doesn't have anything to do with the diameter of the opening.

I beg to differ. Do me a favor. Fill a 20"x20" pan with a gallon of water. Then fill a 2" cylinder with 1 gallon of water. Then check back here and tell us which one is dry first.

 

[StMarcos]

That's from evaporation, not boiling. Different principle. 2260J/g, and that's coming from the flame/element.

 

[Bruin]

I just read a lengthy thread on the boil topic. So lengthy I didn't get everything done SWMBO wanted done before she got home. Now I"M in hot water!

 

[AnOldUR]

I just read a lengthy thread on the boil topic.

Care to share what you took away from it?

 

[smokinghole]

You're talking strictly vaporization at 2260J/g and when we're boiling in a pot like we do there's both vaporization and evaporation.

If I lived 2000ft below sea level my pot wouldn't boil until it's past 212F. The heat simply allows the molecules of water to liberate themselves from the liquid much easier which is why a pot of hot water (not boiling maybe 200F) has considerably more water vapor than an ambient temp pot of water. So I think it's perfectly safe to say with a certainty that pot diameter is a big part in the boil off/evaporation rate.

 

[jeffmeh]

Boil-off rate is absolutely a function of the surface area of the kettle opening. In fact, at sea level, one can approximate the gallons boil-off per hour = pi * r squared * 0.007289791872. [Note the absurd precision on the constant, lol].

 

[WhiskeySix]

I beg to differ. Do me a favor. Fill a 20"x20" pan with a gallon of water. Then fill a 2" cylinder with 1 gallon of water. Then check back here and tell us which one is dry first.

Boil-off rate is absolutely a function of the surface area of the kettle opening.

This.

Boil that gallon of water in the 20"X20" pan and the 2" cylinder and see which one gets dry first.

 

[StMarcos]

Look at an example. Keep it easy at say we have an immersion element. Find how much power you need to maintain the wort at a little under boiling. This is equal to the heat lost around the perimeter of the vessel. I don't know what it is, say 1000w. Any and all power put into the system, above and beyond this value, goes into vaporizing the water. Add another 1000w (J/s), and you are vaporizing 1000/2260 = 0.44g/s. Add another 1000w and you will vaporize 0.88g/s.

That's roughly 3.5L/hour.

Seems clear as rain to me.

 

[WilliamWS]

Boil-off rate is absolutely a function of the surface area of the kettle opening. In fact, at sea level, one can approximate the gallons boil-off per hour = pi * r squared * 0.007289791872. [Note the absurd precision on the constant, lol].

Thanks for the info. I, too just bought one of these kettles and was just figuring it would take me a batch or two to get my new boil-off rate. This equation really helps my initial estimate. Just to be sure, though: I'm assuming this equation is using inches, correct?

 

[jeffmeh]

Look at an example. Keep it easy at say we have an immersion element. Find how much power you need to maintain the wort at a little under boiling. This is equal to the heat lost around the perimeter of the vessel. I don't know what it is, say 1000w. Any and all power put into the system, above and beyond this value, goes into vaporizing the water. Add another 1000w (J/s), and you are vaporizing 1000/2260 = 0.44g/s. Add another 1000w and you will vaporize 0.88g/s.

That's roughly 3.5L/hour.

Seems clear as rain to me.

The vapor needs to escape the vessel, which is dependent upon the surface area of the exit point. Empirically, we experience different boil off rates in different diameter vessels, regardless of whatever thought experiment one may conjecture.

 

[Bruin]

jeffmeh, I'm with you, but the earlier thread on this is here:
https://www.homebrewtalk.com/f39/boil-off-rate-192966/
Arguments were making my head spin. My Dad's a physicist, I'm gonna cut to the chase and ask him.

 

[StMarcos]

If you're dumping that extra heat in there, the vapor will exit through a 1'' tube just fine, and at the same rate to boot.

 

[jeffmeh]

Thanks for the info. I, too just bought one of these kettles and was just figuring it would take me a batch or two to get my new boil-off rate. This equation really helps my initial estimate. Just to be sure, though: I'm assuming this equation is using inches, correct?

Yes. In my setup, the kettle diameter is 17.375 in, so my approximate boil-off rate is =PI() x (17.375 in/2)**2 x 0.007289791872 gal/hr/sq in = 1.73 gal/hr. There is some variation based upon ambient humidity, boil vigor, etc., but this should get you pretty close.

 

[StMarcos]

In that thread, crusty and RDWHAHB have it right.

 

[jeffmeh]

In that thread, crusty and RDWHAHB have it right.

That may be. Their position is that the faster boil-off rate is due to the larger surface area of the kettle bottom transferring more energy to the liquid. As a practical matter, we do experience faster boil-off rates with larger diameter kettles, regardless of whether the physics attribute it to the surface area of the bottom or the opening. I will concede that I do not know which.

 

[smokinghole]

I guess it's a combo of both btus and surface area (of the bottom). I can throw up a flag when there is evidence supporting something else. While surface are has a influence it's considerably tiny. Either way my boil off should be less (albeit hardly) unless this pot causes a much more efficient use of my burner. Touche'

 

[a_w_taylor]

Back to the Penrose Kettle...

I have one on order with a buddy and will update with our boil-off rate once we get a couple of batches under our belt.

 

[Jaysus]

Back to the Penrose Kettle...

I have one on order with a buddy and will update with our boil-off rate once we get a couple of batches under our belt.

I have one on order too... what have folks been using as a lid for the PK?

 

[smokinghole]

What do you guys use a lid for? I have one for my current kettle and it sits in my garage and gets in my way.

 

[a_w_taylor]

Agreed - I don't use a lid on my boil kettle.

 

[Jaysus]

well, for one, to keep bugs and debris out after whirlpooling and before transferring to primary...

 

[AnOldUR]

. . . also, why waste time and fuel. Keeping a lid on until the worts reaches 200 degrees speeds up boil time.


For me, pre boil and post boil, a lid is a must have item.

 

[Hex]

I us my lids on all my other pots...

 

[smokinghole]

I could see a lid for whirlpooling but I give my kettle a quick swirl and then I run into my fermentor since I do no chill.

 

[Bruin]

Lids can easily be purchased from any restaurant supply store.

 

[JEBrew]

The Penrose Kettle is 15.75" in diameter (roughly). Restaurant supply, Dragon Trading (IIRC), or Home Depot or Lowes (if you want the trash can lid idea).

That's just a few to get you started! We don't have the ability to make a lid for these...the material just isn't available to us. Unless you want to spend $95 for a lid, then I MAY be able to get one made, but that is still a longshot!

-Josh

 

[RobotWerewolfLabs]

Will this diptube attach to the inside of a Penrose kettle?

 

[JEBrew]

Will this diptube attach to the inside of a Penrose kettle?

It SHOULD be able to...it's 1/2" NPT, so that part is right...I can't see a reason why it wouldn't!

 

[smokinghole]

Looks like I'll be brewing with my penrose on Friday if UPS does in fact drop it at my house as scheduled for thursday. Due to its height I'll have to change my setup a bit. Right now my grill is perfect to use as a brewing stand but that won't be the case when this kettle arrives. I'll take pics of anything more detailed for you guys that isn't already pictured on the brewhemoth site.

 

[Jaysus]

Looks like I'll be brewing with my penrose on Friday if UPS does in fact drop it at my house as scheduled for thursday. Due to its height I'll have to change my setup a bit. Right now my grill is perfect to use as a brewing stand but that won't be the case when this kettle arrives. I'll take pics of anything more detailed for you guys that isn't already pictured on the brewhemoth site.

It looks like Harrisburg will be getting two Penrose kettles tomorrow! My brewday is looking more like Sunday though.

 

[ghoti]

Does anybody know of a good false bottom to utilize with this kettle?

 

[Hex]

I think the Blichmann 15 gal will fit, call Northern Brewer for the exact diameter, but you will have to modify it with some type of stand off, here is how I did mine for a 7.5 gal kettle with the 10 gal FB. I'll walk you through making one if you decide to go this route, I used siphon, but you could make a dip tube, or silicon hose to barbs inside the kettle.

Or you could make a copper or stainless tube manifold...

 

[motobrewer]

what's the wall thickness?

what's the bottom thickness?

thanks.

all your boil-off bickering got in the way of my question