Today I tried to drink as much liquid as I did on my 100% Huel day earlier. I ended up drinking plenty more not necessarily for feeling thirsty but because it felt right to drink more tea and water. Plus I made a big-ish soup, which consisted of around 700ml of liquid.
Even still I have not urinated as much as when on 100% Huel. I find this interesting along with the fact that only on Huel I peed more than I have been drinking. I will still do a day on Huel aiming to drink about 2-3 litres additionally just to see how that will affect the amounts, but at this point it certainly looks like there is some form of irritation or chemical effect behind this. With today’s measurement I can safely rule out the amount of liquid consumed as being the cause of excess urine.
I might also do a day 100% on Huel when I am not expected to sit around all day, this is to control for the conditions of the measurement on the first day.
I decided to exclude the first wee of the morning from the amount of the day’s sum as it can’t possibly be the result of anything I am yet to drink on the day. It usually precedes anything I do that day 
Instead I will add this amount to the sum of the previous day.
I also missed to register a wee yesterday, so here are the fully revised amounts so far:
100% Huel day, mostly sedentary, felt dehydrated and thirsty
Average frequency 01:00
Count 11
In 3060ml
Out 4113ml
Average out 337.7ml Max 460ml Min 215ml
Regular food day, not caring about hydration, moderate exercise, felt OK
Average frequency 02:38
Count 6
In 2680ml
Out 2388ml
Average out 327.33ml Max 435ml Min 112ml
Regular food day, aiming to drink as much as on 100% Huel day - max hydration, moderate exercise, felt good
Average frequency 01:33
Count 10
In 3830ml
Out 3382ml
Average out 338.20ml Max 711ml Min 128ml