See my comment here - https://news.ycombinator.com/item?id=19012171 - and maybe try the low-tech Indian way next time. Proven for centuries, doesn't need fancy gadgets :) Only thing you may need to tweak is the sitting temperature. Either insulate the dish with cloth if ambient temperature is too cold, or put it in a larger vessel of cold water, if too warm.

> some place in your house which is at the right temperature for fermentation to not only happen but be facilitated

Welcome to Saskatchewan, Canada, where there aren't any places in the house that are at the right temperature in the winter :). That's roughly what the Instant Pot does though. You bring it to a boil first, let it cool off, and then it'll keep the pot at the right temperature while it ferments. Nothing special, other than a nice place that's kept around 43degC in a house that's usually around 17degC overnight.

>Welcome to Saskatchewan, Canada, where there aren't any places in the house that are at the right temperature in the winter :).

Ha ha, good one. I stand corrected, probably, if I didn't mention earlier, that the yogurt-making procedure I gave, was specific to the warmer temps of most regions of India. And even some of those regions get pretty cold in winter (at least by sub-tropical country standards).

>a nice place that's kept around 43degC in a house that's usually around 17degC overnight.

Like where I am now, min temp has been 7 C or even 6 C at night lately, and in some places I've been (which are not even in northern India, which is colder), the min has been known to drop to 2 C at times, though rarely. Goes to zero or below, in some places, sometimes, of course.

(I do know that places in the world further north (or south) can get a lot colder, like -40 C (= 40 F) or more.)

Like with any other venture worth doing, you have to have the patience to tweak the process some, for your local conditions, which will include local microclimate, kind of milk, kind of starter, etc. But after around 10 or so tries, usually, you should be able to get it right. After that you may only need to tweak it if something (like the season of the year or weather) changes, once in a while.