serious hlt hotspot issues

[Deebee]

Hi all.

I got hold of a 115 l hotwater tank for nothing. This is connected to an stc 1000 so i can use it as hlt for both doughing in and sparging.

I filled 90 l today and fired it up. After a few hours i checked. The stc was showing 55 degrees but it sounded as though the thing was about to boil. I lifted the lid and stirred the water.... the stc showed suddenly 80 and the heating naturally cut out. My thought was to put this on when i am at work so i can brew in the evening... or in the evening so i can brew i the morning but suddenly i have my doubts... there appears to be a cold or hot spot issue.
the only way i can see of recirculating the water is to use a silicone hose to the tap and opening it. The pressure of 90 l should be ok to press the water upward enough.

any thoughts on a better way to ensure the water mixes so the temperature is more realistic?

[themadhippy]

The pressure of 90 l should be ok to press the water upward enough.

the water will only rise as far as the water level in the tank.not above it,if you try and return it at this point the water at the top of the tank will fill the tube,there might be a bit of thermal movment but i doubt it would be enough to stir up the water.Best way is a small pump,a cheap solar pump will do nicley

[Deebee]

The pressure of 90 l should be ok to press the water upward enough.

the water will only rise as far as the water level in the tank.not above it,if you try and return it at this point the water at the top of the tank will fill the tube,there might be a bit of thermal movment but i doubt it would be enough to stir up the water.Best way is a small pump,a cheap solar pump will do nicley

Was trying to avoid pumps. Was thinking of a simple mixer type thing that comes on when the heat side starts. Cant find anything local here though.. as you know nothing is cheap here. Put it this way i buy 500 grams of hops from the maltmiller and pay less for them inclusive postage than for one pack her plus postage....

[Fil]

one other thing you could consider is using something like a microwave turntable motor on the lid to turn a stirring padle..




I cut open a 2l pet bottle and threaded it onto a length of beer line which was just the right size to friction fit onto the knob of the turntable motor, hard to see a transparent paddle in hot water tho and as it warmed up the beerline softened and bent a bit but it did stir the liquor

[Andy]

Where is the stc temp probe in relation to the heating element ?

Sound like it's not very close.

[Fil]

fwiw i found to my detriment any hlt left under temp control be it pid or stc1000 or atc800+ will end up banded with the target temp at the probe level and cooler bands below and higher temp bands above, so i am guessing the temp probe in the OP's big hlt is sat quite low down in the pot. mixing with a spoon or any automatic measure like recirculation with a pump or stirring with a motor should sort this out.

its a pita and no doubt there is some good scientific explaination for it too but all we are concerned about is the solutions.. I have ended up with a solar pump recirculating myself..

[themadhippy]

fil that stirrer is pure genius,only concern would be steam getting into the motor.

Was trying to avoid pumps

Any particular reason why? As for cost the solar pumps are only £26 ,p+p to europe (assuming they class norway as europe) only adds £3.70 to the bill so under £30,power it of a locally source 12V psu and your sorted,plug the psu into the same timer as your HLT and it will burst into lifer the same time as the boiler. If its only being used for the HLT you wont need to worry about it getting clogged up

[boingy]

Put the temp probe directly above the element, about half way between the element and the "full" water level.
There will always be a temperature gradient unless you stir or agitate it but positioning like this will mostly average out the errors. It might need a bit of experimentation for your particular set-up.

You also need to consider that the water is typically used in two batches; one at the start of mash and the other for sparging so you need to make sure that the latter case is catered for with the probe positioning.

[Fil]

fil that stirrer is pure genius,only concern would be steam getting into the motor.

I cant take credit for the original concept, i only copied it from Deller12,
as for steam ingress i think its ok if fitted through a lid (the above pic was testing only ) as the motor came from a dead microwave oven which creates a very steamy environment and the drive is inside the oven to turn the turntable, and is exposed to pooling of condensation. fwiw when in the hlt lid i used the beerline to connect to the motor and then a jg fitting to connect to a SS tube onto which i epoxied 2 x HDD platters which later lived as a mash paddle.

[Andy]

My HLT has an immersion element fitted and I put the temperature probe in the thermowell "prong" of the element (where the element thermostat would normally go).
So I'm measuring probably the hottest liquid in the HLT and so the STC does switch on/off fairly frequently. A quick stir of the water is required when the STC is showing
the desired temp and the stirring reduces the measured temp by 5 degrees or so. Doesn't take long to catch up those 5 degrees.

Works for me.

[Deebee]

Interesti g.
The other night was the maiden voyage. I filled the tank with warm water during the day (i am unemployed) and the temp was stable the stc was set at sparge temp and turned on and off no problem holding the temperature constant. Could this be due to the water temperature being stable and constant hence being little to no temp deviation regardless of where the probe is?

Will experiment today. Give the water a damn good stir first then check regularly. I am interested to know how long it will take to warm upto temp so i know how long in advance i need to set the time.

[Deebee]

Excuse me being dumb.... but what is a 12v psu??

[Andy]

Power supply plugged into mains and giving 12 volts output.

[Deebee]

Power supply plugged into mains and giving 12 volts output.

So this? http://www.biltema.no/no/Kontor---Tekni ... 000030021/

Supplies max 2150 ma? Would this just plug straight into the pump???

[Monkeybrew]

There's a good little water heating calculator here -

http://www.jimsbeerkit.co.uk/calc.html

Cheers

MB