Insulating over a Brew-belt?

[Kev888]

If using a brew belt (heat belt) on the fermenter, does anyone know if they are safe to cover in insulation? e.g. if I were to bundle the FV up in a duvet or similar.

Thanks,
Kev

[roscoe]

good question and I don't know !

the UK brewshop ones seem to be 20-25w/m and 1m long
the ebay chinese ones seem to be 80w/m & 1m long

I have heard the chinese ones falling off and burning floor rings, rather dangerous, so I presume they are the type constant wattage, i.e. they get hotter and hotter

This stuff is fresh in my head, cos' I have a drum of industrial heat trace cable that is gentler only 10w/m and of the 'self-regulating' type which means as the cable heats up the wattage auto reduces, until at 85oC there 0w/m, so it seems to be a very gentle heat that isn't gonna melt my plastic FV and happily can be covered up with fleeces/coats/duvets

... its always a problem these days getting detailed tech specs from the super-cheap asian/global vendors

I have 3m coiled round some plastic FVs and the gentle boost works great
(due to the warm winter my ferm fridge is queued up for lagering and other chilling stuff seasonal/winter brewing would have taken care of !)

[basswulf]

I use a blanket for insulation over my fermenting vessel ... but I also use a temperature controller to feed the brew belt (one of these, set to the minimum temperature of 20°C with a temperature probe inside the FV). The result is that the brewbelt has to do very little work to maintain my target temperature and the controller cuts the power before it gets anywhere near danger levels.

Wulf

[Fil]

I dont think brewbelts have changed much since they came out, and they were on the shelves in boots in the mid 70's iirc so i would doubt it would be safe..

With a more modern heat source perhaps?? you could use a controller like an stc1000 AND measure the temp either internally or externally CLOSE to the heat source. (2-3cm externally, 1-2cm internally perhaps?)

That way the beer close to the heat should be affected rapidly and monitored, shutting off the power regularly and in effect heat up in incremental steps towards the target.
( a pseudo pid perhaps ) And shutting off the heat source before it can over heat.

Im basing this on the tests and prep i have carried out for heating/cooling a SS conical under a velcro/insulated jacket with a copper coil for cold effect and a heat trace cable for heat.

Test with STILL water revealed that heat applied externally can overshoot target close to the wall long before the heat has penetrated the centre of the mass. Convection alone isnt strong enough to mix the liquor if its still.

Actively fermenting beer will be much more turbulent due to the co2 rising but the initial growth period (depending on how you pitch) and the trailing off towards final gravity may not be as turbulent...

[Kev888]

Thanks for the thoughts, everyone - all very useful. Perhaps I'll look at the heat trace cable instead, or change plans a bit. It may help to have larger but more gently heated areas to reduce local heat build-up, or I could side-step some of the issue with an immersion approach. I was intending to use a thermostat but (just as fil says) I fear that what the wort is doing may not be a very accurate reflection of what the heat belt is doing on the outside of the FV.

Fil, the convection issue is a good one. I guess the currents could be improved by having the heat source low down and any cooling coil high up - in fact now I come to think of it someone (Aleman?) had a horizontal coil a little below the surface for that reason. I'd considered heat pads instead, as of course they do work - but I wonder if heating through the sediment may actually hamper convection currents and possibly also increase side effects of autolysis in the settled yeast cells?

I agree that active yeast will help stir things up. But as the vigorous stage is left behind and also later when trying to crash cool there won't be that help, so your tests are interesting. If its a weak link in accurate control, then perhaps a large but slow/gentle stir plate (so as not to aerate) or some other form of automatic gentle stirring could be useful to keep the temperature even and flowing over the heating/cooling devices. I'm not sure how much variation there would be in practice though, that may be overkill even for an enthusiast!

Cheers
Kev

[roscoe]

my 'mothballed' 130L FV has insulation and a product coil for heat/cool with fancypants internet remote control and works great, however, now I've downsided from garage brewing to proper home brewing in 21L batches, its more a case of manual timers, shuffle to different room or throw on a duvet

With experience of your gear/house/yeast you probably don't need any controller, but as we like to tick off concoctions from anywhere a safe gentle heat can be very useful if you dont have a temp controlled fridge/cupboard. Again, using less temp sensitive yeast like S04/US05 your beer will usually be fine, but its a hobby and when offered saison yeast or some untried liquid slurries the yeasts become rather temperature-fussy, hence the heat source to pander to these creatures. On saying that I find temp stripes hard to read and really want to whack a thermowell in the FV with some logging via arduino/photon, happy to switch the heater/belt whatever manually as long as the its a gentle low power source

I dont agree about the overshoot is a given, the gain/power is likely too high, as for cooling I have no requirement for my situation.

[Fil]

a possible source of cheap 12v dc heat pads suitable for enclosing is motorcycle hand grip heaters (laminated film heat elements thinner than the semi rigid reptile heat mats, and designed to wrap around something ). I toyed with the idea of heating a thermopot fermentor with these braced against the bottom inner skin before realising the insulation of the pot contains the product of the yeasts exothermic activity even over winter And thankfully before i cut out the bottom skin and dug out the foam too phew!!

a gentle stir plate could be powered by a microwave turntable motor 7 revs per minute. though they are generally 240v ac and not earthed, well the 1 i salvaged is?? I intended to use it to stir a paddle in my hlt when heated by a pid in advance of brewing i got the idea from Deller12 in here iirc, but wasnt happy with the level of water vapour or misty steam involved left unattended, i envisaged returning to a cold hlt with the mcb or master breaker tripped in the consumer unit. And perhaps a lively Krausen could pose a similar risk in a FV??

All in all tho I am probably overthinking this (again..) and a simple approach where you lag the fermentor upto the brewbelt but not over it a top coat and bottom coat? is probably the best solution, that way the fv is lagged, the belt itself will provide some insulation, but it can expel excess heat on its outside if necessary
to avoid overheating issues..

[Kev888]

I'd never come across those grip heaters before, could be useful in some situations.

Yeah, perhaps getting carried away with the thinking, but IMO its better to consciously choose not do something than to not do it through lack of inspiration.

In my case I only really need the insulation when crash cooling, so I could make it removable. However it would be of benefit when heating too, for efficiency and consistency, so thats why I'm thinking through the permutations.

Cheers
Kev

[techtone]

I'm on my 2nd ferment since getting a brew-belt. (standard uk one) Previously I tried to avoid brewing in winter to avoid putting the heating up just for the beer! I put 2 or 3 jumpers around the fermenter (23l). I have the brew belt on a timer, on 15 mins in every two hours. After the first 24 hours (depending on pitch temp) I turn it off as it generates enough heat and then on again when it drops. Then off again a few days before kegging. I check the stick on thermometer a couple of times a day to see if I need to modify the timer. Working well so far and the timer schedule can be adjusted as I see fit. Tested it on as couple of kit brews but comfortable enough to use it on all grain all ready.

If I remember correctly I think the instruction sheet does say do not cover but 15 minutes with a timer seems ok as nothing gets too warm.

[Kev888]

If I remember correctly I think the instruction sheet does say do not cover but 15 minutes with a timer seems ok as nothing gets too warm.

Great, thanks, thats good to know.

Cheers
Kev