Off-grid FV temperature control possibilities?

[Kev888]

As far as I can tell, any direct use of a generator to power a fridge or small heater would be very inefficient, because I'd hardly be using the potential of even the smaller generators, so most of the fuel would be wasted just keeping the engine running - I estimate around £5/day which seems quite a lot. Unfortunately it appears that the same applies to charging lead-acid batteries, as even they are slow to charge to capacity, which has rather scuppered my plans. So I'm looking for a different solution to keeping my FV at the correct temperature.

Unless I want to spend hundreds on a super-efficient 12v compressor fridge + solar panels/windmills + batteries, it looks like a propane powered absorption fridge may be a good way to provide cooling for the FV - perhaps cooling a reservoir to automatically circulate around the FV when needed, or else just making ice, to manually put in an insulated box from time to time. Alternatively, a shelf cooler and generator running only for a few hours per day could work, by storing energy in the cooler's ice bank. (I got quite excited about evaporative cooling until I did a test some weeks back - it was pretty pants in times of high humidity).

For heating, the best I've come up with so far is a small LPG/propane burner turned low and heating a pot of water to recirculate to the FV. Though there are safety issues leaving a burner running unattended (maybe even with flame failure devices fitted?), so perhaps I could possibly heat water manually from time to time and put that in a very well insulated reservoir to recirculate if/when needed. I did also consider a small air/greenhouse heater, but I can't find any of those that would be safe indoors, let alone in a camper-van/caravan (or fermentation cupboard!) and its hard to think how I would control the heat without dicking about with gas valves and so in, which I'd rather not do.

I know some people on here are into boats and camping and so on - is there anything I'm missing?

Cheers
kev

[roscoe]

depending on the time of year stick with yeasts with a wide temperature tolerance eg US-05 or Nottingham
and find a way of moving the beer to a nearby damp place for 'cave-chilling'

[themadhippy]

pitch up next to a river and your sorted

[barneey]

What Kev needs is a Rachael

[Kev888]

Hmmmm, yes a Rachael would certainly be a very tempting addition to the brewing setup... Though in reality I 'strongly' suspect the apparent level of obedience to be staged

Roscoe, yeah I've been looking at yeast strains or beer styles that can be fermented warm, like Saiasons & Belgians, but they're a bit specialist; I don't remember any 'normal' British ale type yeast working well in summer temperatures (though notts was good cool), but maybe I've been too long with my fridges to remember - do you have any experience of them at say 25c-30c? (EDIT, just found a useful article here suggesting us-05 is good to 26c and listing some others, mostly Belgian).

So, in terms of cooling and heating then, and aside from not bothering or parking next to a river or cave or something, I'm probably not overlooking anything
The only other idea I had - inspired by themadhippy's video - was to somehow use the hot side of the fridge (and/or maybe the gas flu) to provide the heating as a gas-powered air-source heat pump that I'd be willing to leave unattended. But I've never had my hands on an absorption fridge before so I don't know how practical that would be to do.

Cheers
kev

[Jocky]

I started looking at the same thing, as I was potentially wanting to ferment in the shed at the bottom of the garden, but not sure I wanted to add electricity to the shed.

The best conclusion I have come to was to hide it near the house - make a really well insulated FV with a built in brew belt and put some wood panels around it so it looks like a garden bin or something.

Alternatively, insulate well and brew with the seasons so you don't have to chill - lager in winter, ale in spring/autumn, saison/sour in summer.

[Kev888]

Interesting stuff, thank you. Space would be at a premium, but I could use something like sleeping bags for insulation that could be packed up small and kept in the FV. I guess in theory with 'lots' of insulation I shouldn't need to heat the FV very much at all, especially during the vigorous stage of fermentation, so possibly even in winter I could just top up the heat manually in some way once or twice a day - my main objection to most gas-based possibilities is not wanting to leave DIY propane creations running unattended and/or in small spaces.

Cooling is probably more serious; I measured the big water butts that were in the permanent shade of my house and they weren't really much below ambient.. so with self heating as well... But it may be nice to 'go seasonal' and get more variety to my brewing, and gas powered fridges look to be a very workable solution if necessary. Looking around, people seem to manage by adding between say 4L-8L of ice per day to recirculated cold reservoirs, which gives an indication of the amount of cooling needed.

Hmm, perhaps a decent solution would be a very well insulated FV with a tny battery powered aquarium pump in a very good cool box would work - to which I could manually add either iced or hot water as the season required.

Cheers
kev

[aamcle]

Heating shouldn't be a problem insulate very well and use a 12v heater running from your battery. If the insulation is good the drain on the battery should be quite low.

Cooling, insulate as above and either an immersed cooling coil and the cool box you mentioned or a heat pipe and the cool box.

There is quite a lot of discussion about this on
http://www.homebrewtalk.com/f10/ cause they have trouble with heat.

ATb...... Aamcle

[Kev888]

Thanks Aamcle. Yeah, perhaps I'm getting over-concerned with the heating; I calculated I'd probably lose about 10 watts in winter, which a leisure battery would supply for around 3 days before needing recharging, and that would be after the main exothermic stage stopped heating itself. Though those estimates are a bit theoretical until I can try it in winter.

Thanks for the link, I'd been poking around there before but perhaps not in enough detail. They seem to like evaporative cooling, which I'm not keen on in the humid UK, but some of them did use ice in air or water baths so I'll go back and look in more detail.

I think I have a sort of plan forming: I'll use a leisure battery to run a 12v temperature controller and tiny aquarium pump to recirculate to a heavily insulated FV; should run for an entire fermentation on a single charge. With that method in place, I could then recirculate from a variety of sources; say a saucepan in a gas-powered fridge/freezer or on a camping hob, or alternatively from a passive insulated reservoir to which cold-water/ice or hot water could be manually put as necessary, and I could include a small 12v heating element as an additional option to heat with. If/when a mains supply is available the whole thing would still be applicable, just needing a small transformer. Though I guess in times when the climate is being indecisive it may be ideal to have two pumps and reservoirs to let it cool or heat as and when.

I'm also going to do some research into brewing more seasonally, so the yeast strains I use need as little cooling/heating as possible.

Cheers
Kev

[Charles1968]

The best way to keep FV below ambient temp without a brew fridge is to use ice bottles inside an insulated bag, like this:
http://www.cool-brewing.com/

Works fine with an all weather sleeping bag or any kind of insulation. The problem with swamp coolers or water butts, besides mess and huge bulk, is that you're trying to lower the temp of a much larger mass of liquid, which takes a lot more effort, and the basic wet t-shirt/towel system isn't insulated so you can't get more than 3-4 degrees below ambient. Water on its own has no cooling power without evaporation or ice being added.

I gave up on swamp coolers last year and now use the cool-brewing technique. I brewed a lager over the last 2-3 weeks and kept the temp inside the FV at a stable 12 celsius while ambient temp was in high 20s during the day. A brew fridge is obviously better but certainly not necessary, even for making lager in warm weather.

[Kev888]

That looks encouraging, Charles, thank you, and welcome to the forum!

I haven't seen those before and wouldn't have guessed they'd be so effective. I suppose it loses the option for tight thermostatic control, but its even simpler than recirculating water or air and is much more compact and energy efficient, which could be of great benefit to me. I quite like the simplicity of it, too.

I suppose (with suitably heat resistant insulation) heated rocks could be used instead of ice during winter, though I think its the solid/liquid state change that really stores the energy in ice so maybe the rocks wouldn't be slow/long enough release without continually replenishing them.

Cheers
Kev

[Charles1968]

It's obviously better to have a thermostat, particularly if you want to raise temp in steps for a diacetyl rest or similar. However, 23 litres of water has a lot of thermal mass and temperature consequently fluctuates very little, so it's surprisingly easy to maintain a cool temperature in the FV once you've got there. I've found it a very effective, simple and space-saving technique and am surprised more people don't do this instead of messing about with swamp coolers and fans, which are very inefficient.

The average domestic freezer has a temp of -18 celsius, so a couple of frozen 2 litre water bottles will extract a lot of heat from the FV. It takes a long time to bring the temp down but once down it's easy to hold it - just a matter of switching a frozen bottle for a thawed one once a day or so.

I tend to keep a stock of frozen water bottles in the freezer as they're also handy for quick wort chilling after the boil, since I don't have a wort chiller. I let my volume drop a little and then top up with ice to crash the temperature.

[Kev888]

Useful, thanks. Some of the gas-powered/absorption fridges have freezer compartments, I'll have to check if they freeze properly.

Cheers
Kev

[barneey]

Solution

http://www.ebay.co.uk/itm/mobile-drinks ... 4ad9db281a

[Kev888]

Heh heh, I'm sure that would attract no unfavourable attention at all from the neighbours...

Cheers
Kev