10cm headspace for electric boiler

[Martin G]

After much delay I'm going to fit my 2.4kW Haden element to my 60l thermopot so I can try a few BIAB no chill and see what results I can get. I measured up today and discovered I actually have a 55l thermopot! I was hoping to do a straight forward 40l brew so I can still fill one of my casks. At a starting volume of about 45l it looks like it will be about 10cm below the rim at the start of boil. I don't have a means of control and am worried about boil over. Anyone got experience with this sort of setup and able to advise on the vigour of the boil?

[Fil]

10cm , you can sit back n relax imho.. with a mango barrel boiler fitted with 2 x (2.2 or 2.4kw) kettle elements and both on the boil would have been easily contained with a 10cm headspace, 2 x the input of your set up, i dont know but im guessing that its a safe bet that the boiler wouldnt radiate 2.2kw or anything close, as if so i wouldnt maintain a boil with just a single element on in the pot.. - hope that makes sense..

fwiw in the said mango barrel running on a single element most of the time 5-7l was about the boil off rate i got, so you may find you boil off a bit more what with the insulation.. if so you may need to liquor back some? a dipstick is a simple tool to monitor the boil off rate during the boil, the volume boiled off in the first 30 mins should be about 30% of the total boil off volume

a simple power controller might be worthwhile investing in so you can dial back the boil if you are boiling of more than initial estimates, the first brew will tell you happy brewing

out of interest how are you fitting the element? hope you can post some pics of the build??

[Martin G]

Thanks Fil, reassuring. The plan is to use cobalt hole saws, 38mm for the element and 76mm for the outer skin as I have one of the metal nuts (something like KV8, cannot remember the code) and will need some space for tightening, possibly need more?
The element is coming out of my HLT because if BIAB no chill gives reasonable results I'll be converting and selling off the bits I don't need. I used a 40mm hole saw on my HLT and it wasn't really as snug as I would like so thought 38mm would be a bit better, I wonder if it should even smaller? I have a lovely sturdy false bottom from Rob and have worked out the element hole centre needs to be 75mm from the base so the false bottom can be slid under. Will photo the change.

[Fil]

The inner pot skin is very thin, iirc cazamodo put elements through the bottom of a thermopot using hole saws and had a very rough inner skin cut which was a problem when making a seal.. perhaps a qmax punch for the inner skin hole could be a safer bet? fwiw ive used a 38.5mm qmax for element holes with no problems..

[Kev888]

(I think the nut is called KM8)

I agree that Q-max cutters are likely to give a superior result and fit for the inner element hole; very neat and accurate things.

I have used cobalt hole-saws on the bergland pots, but the stainless is hardened so a little challenging to cut through (and it has the potential to become worse if you work harden it further during drilling), its also very thin which can let the pilot drill (and so the whole cutter) wander sideways. I know some people (such as Barneey IIRC) have found the Starrett TCT holesaws for stainless very good but I've not yet used them myself.

Cheers
kev

[Martin G]

(KM8! so close!)

Brilliant, many thanks, looks like the QMAX for the inner it is. I did my old HLT with a cobalt a few years ago, and think part of my problem with a larger hole than expected was due to the cutter 'wandering'. Looks like QMAX will cost about £10 more, but it is stressful cutting holes out of perfectly good pots, anything to reduce the chance of messing up has to be worth a little extra cost of the tool.