a few years ago I was given a square alluminium heater that can be used for 4 x demjlohns or 1X 5 gal bucket. Iv’e not used it yet but have had to dig it out as my 12 " tubular heater has failed. The only thing I have noticed it does not have any wattage rating stamped on it or a label. Anyone know what they are rated at ? I also spotted an advert for them on line and it was stated that they were suited for 4 demijohns but not reccomended for plastic 5 gall beer buckets as they caused the bottom to split !! Not heard that before !
If it has the voltage and amperage listed on the device, multiply the voltage times the amps and you will gets the watts of power it draws. For example, 120 volts X 5 amps is 600 watts.
Also make sure that you don’t put the device close to a plastic bucket as a matter of safety o it doesn’t possible melt the bucket.