You could always look into an Immersion circulator... You can pick them up for less than $150. All you need then is a normal 20L pot. It will keep that amount of sparge water at temps around 80c easy.
Kogan have this one, 1300watts. $99.
https://www.kogan.com/au/buy/kogan-smarterhome-sous-vide-precision-cooker/
they can take a while to bring cold water up to these temps so I start with hot tap and some boiling water from a jug and that cuts the time down.
Plus then, you have the added benefit of being able to cook sous vide which if you haven't will rock your world.
Thanks i did see that when looking but i have just found that my local HB shop sells a 20L Grainfather vessel for $150. Hopefully i will be buying one next week.