Ferment with spunning Valve?

[alegi]

Hello, I bought a spunning Valve so I could carbonate the beer while fermenting it but also be able to ferment under pressure.

But what I do not get is when to actually activate it.

Im brewing a belgian wit now with No pressure and the temp is 19C (Will rise to 22C later). When do I actually activate the Valve to say 30-32PSI to get the pressure to make co2 so when I chill the beer it will have co2?

Some yeast doesnt like pressure so of lets say fg goal is 1008-1010 when should I start the pressure build Up?

 

[McMullan]

About 1.020 works for me. A bit lower if I didn't catch it in time. 30 psi is quite high.

 

[HighVoltageMan!]

I spund lagers. I wait until the fermentation slows down and then I bring up the pressure, nothing precise, but I rely on the regulator to keep the pressure at a given point so the yeast can finish without creating a keg bomb. I bring it up to 22psi at 13C for a lively beer. 30 psi at 22C isn't too high because it will take more pressure to carbonate a beer as the temperature rises, it's pretty much what happens when you bottle condition. I doubt it would hurt the yeast, again, it's like bottle conditioning.

 

[HM-2]

If you're brewing a Belgian Wit, I'd probably only start carbonating as fermentation is trailing off- maybe last 5-10 points, Otherwise you'll nuke a good chunk of the esters that may Belgian Wit taste like Belgian Wit. I've made the mistake of fermenting expressive yeasts under pressure and always been disappointed by the results. These days I only ever ferment lagers under pressure, and will only usually run pressure in my fermenter for dry hopping post-fermentation.
I never normally let it build more than 10-12 PSI, which is fine for natural carbonation and doesn't require too much bleeding off for kegging.