Slow To See Activity With Conical

[leaky_porch]

If you don't see bubbling, pull a sample and check the gravity. You get much better information that way.

[ajdelange]

There is more to cooling jackets than just the jacket. The first cylindroconical I owned had a simple jacket welded to the outside. The inside of the jacket was the wall of the fermenter and the outside was a sheet of stainless. Fill that with glycol at 35 °F and where is the "cold" going to flow? Through the inside wall to the beer at 38°F or through the ouside wall to the room at 70 °F?. I could get it to work only by wrapping it in glass wool insulation and boy did that get to be a mess after it filled up with condensation, spilled beer etc. But I made some good beer with it.

A real cylindroconical is an arrangement like the one I had inside a larger cylindroconical with the space between filled with insulation. The insulation is as important as the chill band(s). But this should make it clear that the cost of a real cylindoconical is going to approximately double the cost of an arrangement like mine or more than double in the case of the bandless units sold to home brewers.

As to the original question: you don't need to be able to see inside the fermenter. If you note a pH drop of a couple of tenths (or more) in the first few hours fementation is commencing properly and visible gas evolution will follow a couple of hours later. This may be the most underappreciated aspect of pH measurement in brewing. The pH drop occurs well before gravity reduction is detectable.

[Cliff]

I could get it to work only by wrapping it in glass wool insulation and boy did that get to be a mess after it filled up with condensation, spilled beer etc. But I made some good beer with it.

I dunno when in time this was, but these days insulation options have really expanded. you can get insulation with metal foil lining on both sides that is as thin as 1/4" with good R factor. Bubble wrap is a nice insulation too, and it's so cheap you can tape it on and toss it if it gets dirty.

I had a quote on an insulated 15 gallon unit from China for under a grand, but they screwed up all the welds so I never took delivery.