General > General Technical Chat
Need 13Amp variac device to 'modulate' a water boiler.
Andy Chee:
--- Quote from: paulca on April 18, 2024, 03:11:55 pm ---Interesting. To be clear though, I am not aiming at holding a temperature. I am interested in controlling the amount of latent heat of evaporation of water at boiling point. With the 3kW element alone it will of course hold 100*C fine. Unfortunately with a high enough evapouration rate that it literally rains beer afterwards from the cieling. About 5 litres of beer turns into rain.
So temperature regulation is out. If I needed temp regulation I could use the built in bi-metalic thermostat.
--- End quote ---
The proper way to do this is to install two heating elements, one double the power of the other e.g. 1kW and 2kW
Run the 2kW element from a standard bi-metallic thermostat. Use the PWM controller on the 1kW element.
paulca:
--- Quote from: Andy Chee on April 19, 2024, 06:55:40 am ---
--- Quote from: paulca on April 18, 2024, 03:11:55 pm ---Interesting. To be clear though, I am not aiming at holding a temperature. I am interested in controlling the amount of latent heat of evaporation of water at boiling point. With the 3kW element alone it will of course hold 100*C fine. Unfortunately with a high enough evapouration rate that it literally rains beer afterwards from the cieling. About 5 litres of beer turns into rain.
So temperature regulation is out. If I needed temp regulation I could use the built in bi-metalic thermostat.
--- End quote ---
The proper way to do this is to install two heating elements, one double the power of the other e.g. 1kW and 2kW
Run the 2kW element from a standard bi-metallic thermostat. Use the PWM controller on the 1kW element.
--- End quote ---
Interesting. I had been bouncing a similar idea around. As this is a "rush" job now, ideal can wait.
If I simply take what I have now, the built in 3kw ring element in a "tea urn", but purchase a "Travel Kettle" with a 1kW immersion coil element.... then I can jury rid that 1kW element into the boiler to hold the boil.
I expect 1kW (based on the variac position) would be grand to maintain the boil. At least in a pinch.
By "jury rig" though I mean something your mum wouldn't like and your spark would disown. Like cut the element out of the kettle in it's full doubly insulated form and "dump" it in the wort, cable and all!
At least it's "boil side" so it doesn't need that much sanitation first!
The whole stainless steel boiler is earthed. "What could possibly go wrong?"
The "Proper" and "Best" way I believe to solve this is actually a large 8kW propane burner and a proper stainless steel "kettle" on a stand. That would however force me to do the full 1-1.5 hour boil outdoors... and if I don't fancy carrying around 25 litres of hot wort, also the cooling, transfers etc. Trouble is, a "home brew" kettle is about £300. An industrial sized pot capable of taking first propane heat for hours is probably half that, but it will lack nice features like temp probes, proper ball values, filters etc.
My £40 coffee/tea urn does just fine! Eventually it's bottom will rust out, but it's got a few years left in it yet.
themadhippy:
--- Quote ---If I simply take what I have now, the built in 3kw ring element in a "tea urn"
--- End quote ---
guess youve removed the stat from the urn,pity as they usually have a simmer setting.
--- Quote ---The "Proper" and "Best" way I believe to solve this is
--- End quote ---
add a false bottom,grain basket ,ssr, pid and pump and make it into a grainfather clone.
paulca:
--- Quote from: themadhippy on April 19, 2024, 11:24:12 am ---
--- Quote ---If I simply take what I have now, the built in 3kw ring element in a "tea urn"
--- End quote ---
guess youve removed the stat from the urn,pity as they usually have a simmer setting.
--- Quote ---The "Proper" and "Best" way I believe to solve this is
--- End quote ---
add a false bottom,grain basket ,ssr, pid and pump and make it into a grainfather clone.
--- End quote ---
LOL. I have spent enough already. Home brew specialised kit is offensively expensive.
The original thermostat is still in the urn. It still works. It was not luck that I sourced one which goes to 110*C so it doesn't cut out at full boil.
For example, the very first thing the urn will do at the start of a brew is take 10 litres of tap water up to 75*C and then I dump about 50g of chorline donor powder into it and proceed to pump that water (by gravity) through every pipe/hose, fitting, valve, strainer, etc. Then it gets dumped into the other equipment like the mash tun and fermentor.
Use the thermostat for that and for giving me 70-75C "strike water" for mash. Although I confirm with 2 probe thermometers.
There is no setting for 99.999.. *C. No matter how finely I adjust the thermostat "I canny change the laws of nature". It will be boiling at 3kW constantly set to 100C or not boiling at all at 99C.
I'm going to find a "portable" water boiler element with a 1kW rating. I am however struggling with only finding things that look like candidates for the "Big Clive" "Death Heater" videos. I need a proper fully immersible immersion heater! Not one that has to hang out the side and stay dry. I am NOT taking that risk!
EDIT: It leads me to question the need for the "boil". Is there something about the water actually vapourising and recondensing that is necessary? What if I did just leave it at 99C and not rolling?
NiHaoMike:
A series diode would cut the power in half, use a SCR instead and trigger it just before the peak to get to 30% power.
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