Not Sure What To Do About My Stock Pot Boiler ?

[Greg2013]

Merry Christmas to one and all, i know it's Christmas and all but i have a question. I am currently sitting here looking at my SS stock pot (98 litres) and i was marking it out earlier where i would install my two kettle elements from a normal tea kettle.

Plan was to have it marked out ready for drilling by the weekend. It occurred to me that this thing is really massive (50cm x 50cm) and i am not sure now that two kettle elements will be enough to boil any more than 30-40 litres.

My question is how much wort are two kettle elements capable of bringing to a rolling boil and holding it there for 90 minutes without blowing every fuse in the house ? I don't want to install any more than two elements as i feel it would be too clumsy and cluttered. If it comes to it down the road and i decide to brew a double batch or bigger( think 50 litres and upwards) which granted is not likely to happen, could i use gas on this even though i have kettle elements installed ? 

[Greg2013]

Ok i realise that i am imagining boogeymen where there are none (probably) BUT if i was to loan this out to anyone else for a big brew day or for a club event hypothetically, can it be put on a propane burner with the two kettle elements installed but not plugged in ? I don't want to bollix up potential future usage by installing two kettle elements now if it can't be used on gas for a big boil with them still inserted down the road.

[Greg2013]

You mean 60 degrees as in that is what it comes out of the mash tun at ? Damn had not thought of that actually, that way i only have 40 degrees at most to lift it to a boil  Following on some advice i am putting the elements at 10 to 2 on one side of the pot at equidistance from each handle leaving the other side blank for taps or whatever. The bottom of the pot is 50cm diameter, my concern was that IF i needed to could i use a gas burner on the bottom with the kettle elements installed?

My stock pot is stainless steel so not induction suitable.

[Hop Bomb]

Not sure if two kettle elements will be enough but I guess it depends how vigorous you like your boils.  Ive the same pot and my 8.8kw gas boiler ring hardly makes a dent in it boil wise at full tilt. Ive had pre boil volume of 77 litres & 50 litres & both had shitty rolling boils & low evaporation (new propane tank too so no excuse)  You need some serious electric or gas power to get that size pot rolling. Ive a blichmann burner on the way from USA which is 21kw so that should do the trick.

[Greg2013]

FWIW, my stock pots are also SS (apparently) but work with my induction hob. I'd not rule it out without trying.

Not sure what FWIW means but i will see if i can get a loan of an induction hob to try it on.

[Greg2013]

Not sure if two kettle elements will be enough but I guess it depends how vigorous you like your boils.  Ive the same pot and my 8.8kw gas boiler ring hardly makes a dent in it boil wise at full tilt. Ive had pre boil volume of 77 litres & 50 litres & both had shitty rolling boils & low evaporation (new propane tank too so no excuse)  You need some serious electric or gas power to get that size pot rolling. Ive a blichmann burner on the way from USA which is 21kw so that should do the trick.

For 30-40 litres pre boil i reckon two kettle elements is about on the limits of capability, this is the reason that i was wondering if i ever went for a bigger boil say around the 50-70 litres that you are talking about would i be able to use a burner on the pot with the kettle elements already inserted. A long way off granted if ever but i would also like to be able to loan the pot out for big brew days if any of the lads were stuck and this is another reason i wanted to be able to use both gas and electric on it.

[imark]

If I was to offer any advice it would be decide how you will use it and optimise your design for that purpose. It'll be simpler to finish and more efficient in the long run. So say you need 2x2.2kw elements to boil 40L you should put your efforts into insulating the vessel so you achieve an acceptable performance. I find I can maintain a good rolling boil on 30L with 2000W of power on my induction hob. So I think 2 elements should be more than adequate.

[Stitch]

2 x 2kw elements gives us a nice round figure according to laws of thermodynamics:

~4kw is enough to heat 1 litre by 1 degree in 1 second.

So.... that's 30 seconds for 30 litres. Or say you're trying to bring to the boil wort starting at 60 degrees. That's 40 degrees you want to raise the temperature by. So again 40 x 30 = 1200 seconds, or about 20 minutes to bring it to the boil.

Heat loss through lack of insulation will work against you though, by how much depends on your insulation.

This is to boil water and not wort. The specific heat capacity is different for wort depending on the specific gravity. Therefore this time is always less. Plus you must also take into account that as the wort will get scorched onto the elements their efficiency will be reduced thus taking longer to boil.

I have a 2kw element on my 33litre boiler and it can take up to 45 minutes to get good roiling boiling depending on gravity and how well I have cleaned the element. I usually boil 28 litres if that is Anny help.

Sent from my Nexus 7 using Tapatalk

[Hop Bomb]

Ive two keggles here as well as that same pot as you Greg. One keggle I used on gas & one with two of the HBC elements in there & they both get a great vigorous boil even when full to the brim (boil overs are a problem - thats why I went with the bigger 100 litre pots). Once the keggles are there at full boil It needs very little gas to keep it there & with the electric elements I can drop to just one.

That 100 litre pot is a different beast altogether. It wont get a good rolling boil even at full blast on an 8.8kw burner.  Im sure its the diameter of it that effects the thermo dynamics but maybe an expert can fill in the blanks on that. If you want to go electric Id recommend one of those camco low density elements http://www.amazon.com/Camco-02963-Screw-In-Ripple-Element/dp/B000BPG4LI/ref=sr_1_15?ie=UTF8&qid=1385766701&sr=8-15&keywords=camco   They seem to be the standard for pots & brewery builds of this size. The downside is you need a dedicated line for it electric/fuse board wise as its 23 amps.

If you want to go gas then you'll need a gas burner that packs a lot more punch than the standard ones most gas brewers use. Im not trying to poke holes in your plans here. Im just telling you what Ive been through with this pot & the same with the keggles I used before hand.  Imo for 30-45 litre batches you wont get better than a converted keggle.  Anything larger & that bigger pot is well suited once you've the power under it to get it to a rolling boil.

[Greg2013]

Thanks Hopbomb. Yes i seem to remember "somebody" offer to swop a keggle setup with me a while back for my stock pot, kinda sorry now i bollixed that one up 

[Hop Bomb]

I got another insulated stock pot instead for the HLT.  My word isnt gospel on this btw. Its just my experience.

[Greg2013]

It has occured to me that it might just be easier to buy a fecking boil kettle be damned and stick the stock pot up in the attic for down the road, all the bloody boilers seem to be 28-30 litres though, would rather 35 litres if i could get it. If i saw a nice boiler in the 35 litre range ready to go and not too much i would consider it seriously, the stock pot will not go to waste anyway.

[Shanna]

Ive two keggles here as well as that same pot as you Greg. One keggle I used on gas & one with two of the HBC elements in there & they both get a great vigorous boil even when full to the brim (boil overs are a problem - thats why I went with the bigger 100 litre pots). Once the keggles are there at full boil It needs very little gas to keep it there & with the electric elements I can drop to just one.

That 100 litre pot is a different beast altogether. It wont get a good rolling boil even at full blast on an 8.8kw burner.  Im sure its the diameter of it that effects the thermo dynamics but maybe an expert can fill in the blanks on that. If you want to go electric Id recommend one of those camco low density elements http://www.amazon.com/Camco-02963-Screw-In-Ripple-Element/dp/B000BPG4LI/ref=sr_1_15?ie=UTF8&qid=1385766701&sr=8-15&keywords=camco   They seem to be the standard for pots & brewery builds of this size. The downside is you need a dedicated line for it electric/fuse board wise as its 23 amps.

If you want to go gas then you'll need a gas burner that packs a lot more punch than the standard ones most gas brewers use. Im not trying to poke holes in your plans here. Im just telling you what Ive been through with this pot & the same with the keggles I used before hand.  Imo for 30-45 litre batches you wont get better than a converted keggle.  Anything larger & that bigger pot is well suited once you've the power under it to get it to a rolling boil.

Hi Greg and Hopbomb,

I can talk with a little authority on the 5.5kw heating element that Hop Bomb linked to as I have a HLT with one of these in it. It brings about 45 litres of water to a boil in about 45-50 minutes. I would add though that I got an electrician to fit it for me. I have an insulated external junction box that houses the electrics and there are two individual earths on it. There is a round three pin plug (think heavy duty) that fits in to a dedicated round socket. All of this is wired up to a dedicated 30 amp fuse on the fuse board in my shed. The cabling for the HLT is heavy duty braided cable that will take a fair bit of abuse. The HLT itself is a bit unwieldy to use but for what it does it does it really well. The only down side is that I can't use it anywhere else (well at least not easily).

It was by a pure fluke that the wiring in the shed was sufficient high enough rating to support the electrical requirements. I had originally intended to use it for also a wort boiler but discounted it soon after buying it due to the higher than normal electrical requirements and also the inability to be able to easily reduce the power. Instead I got two variable resistors and got them wired up in conjunction with the two sockets that I plug two 2.4kw heating elements in to. The system works well with the caveat that I can't use the any of the dish washer, washing machine or electric shower while the HLT is being used.

Shanna

[Will_D]

One of the reasons keggles are good on gas is the "skirt effect" of the keg. This tends to constrain the hot gases (aka Flames) to the base of the pot.

Put a big pot on a gas burner, turn it up high and just see how much flames are going up the outsides!

That is why handles and the ball valves can get dangerously hot.

The answer to a stock pot is somehow fab a skirt from SS or just use a smaller flame. It will put the same amount of heat into the pot but as there is less wastage you will use less gas.

We can then get into flame dynamics:

Certain parts of the flame are hotter that others but as its Steven's day lets's not! 

[Hop Bomb]

No flames up the sides on these 100 litre pots. They are that big! I think the standard gas boiling ring just isnt enough for a pot this size.