BIAB with PID but no pump - thoughts?

[buckerooni]

So I've got my hands on a braudino that's already wired up (sweet!) and am in the early design stages of a 80-100L 1V BIAB pot. But I want to keep things simple and the pump was something that I thought may be optional, at least in the first version and was interested if there was anything from a design point of view I should consider.

My most simplest setup would be pot, false bottom + thermowell with the PID connected to the element/temp probe with no pump.

The issue I suppose is potential hotspots during the mash, is anything else to consider with such a simple design and has anyone given this a go?

As there's a bag involved, and a false bottom, any suggestions for where the thermowell should go? Ideally the position would work for both no pump / pump versions. I have seen a mention of a floating probe as an alternative and am interested in people's opinions for an alternative.

 

[Bribie G]

 

[buckerooni]

yeah yeah, but...ramping temps without me peeling my ass off the couch and having to lift the pot lid and dip my thermapen in?

 

[Benn]

Exposed element? + No recirculation? +!Unwillingness to manually recirculate = potential charring of the element.

 

[buckerooni]

Exposed element? + No recirculation? +!Unwillingness to manually recirculate = potential charring of the element.

was planning on getting a 4200w romar element ( http://www.romarelements.com.au/ ) - would that make any difference to the charring - better/worse - they do homebrew specific stuff now...

 

[user 44743]

If you have no pump or don't stir then you are relying mainly on convection and conduction to carry the heat away from the element and into the wort and mash. Unfortunately, they don't do that very fast, especially through the grain bed. So, with an element of any reasonable power you will get local hot spots which (depending on the watt-density) could denature the enzymes and scorch the wort, whilst most of the mash will see relatively little change.

If you removed the grain temporarily and heated the wort gently enough you may get away with it (assuming the wet grain didn't cool fast enough to negate the heating, anyway). But that still takes some effort and even then it would be best to stir after returning the grain in order to get the mash temperature even.

Another small challenge would be the PID control; with no flow you would also be relying on convection to carry the heat to the probe. So the probe would have to be quite close to the element in order to know what was happening and control it with reasonable responsiveness. Its less likely to give a good representation of grain-bed temperature there, due to the increase in temperature close to the element.

Cheers
Kev

 

[MHB]

Kev pretty much covered it.
For the investment a pump and a bit of plumbing would be a good value. Personally I'm not really a fan of the Little Brown Pumps but they are cheap enough if you cant bring your self to spend the extra.
You would want a fairly coarse grind, the grain bed needs to be very permeable. At 4200W you have the potential to do a lot of harm to your wort, unless that is it's very long (low watt density) element. Might be worth installing a SSR Voltage Controller they aren't all that expensive these days.
Mark

 

[klangers]

Already covered, but I'll add my 2c.

A mash needs to be of uniform temperature. You will need to either stir it or circulate with a pump. No ifs or buts.

There's a reason why brewery mash tuns have enormous rakes spinning around and around the whole time the mash occurs.

Relying on convection currents won't work, as by the time convection currents begin you will have fried the enzymes near the element.

 

[buckerooni]

Thanks fellas, this is very useful to plan my build and associated brew process.

As a BIABer, the recirc/stir must only be necessary when ramping the temp so I won't bother with the PID and step mashes until I get my recirc sorted.

Looking forward to trialling Bribie G's method with the no mash out/slow lift, although to get back to my 'school night brewing' 30min mash/30min boil I expect the recirc would be required to get the efficiency in that shortened timeframe.

 

[CoxR]

Get a keg king pump + stainless steel head. Once I had a small leak from the fitting on my pump and as I was mashing tried to tighten it and snapped the thread.
I tried to carry on with my normal brewing without the pump and ended up with far too high gravity (didn't have a refractory) and heaps of unfermentable wort

 

[CoxR]

Also its in the post.

 

[spog]

Thanks fellas, this is very useful to plan my build and associated brew process.

As a BIABer, the recirc/stir must only be necessary when ramping the temp so I won't bother with the PID and step mashes until I get my recirc sorted.

Looking forward to trialling Bribie G's method with the no mash out/slow lift, although to get back to my 'school night brewing' 30min mash/30min boil I expect the recirc would be required to get the efficiency in that shortened timeframe.[/quote

I Biab and I had a little brown pump for recirc but I took it out and added another tap were the pump was mounted.
Why !
1. I had a filter on the pickup from the kettle to protect the guts of the pump and it didn't take long for it to block....got rid of it.
2. It's just another place for snot to hide and needed cleaning...got rid of it.
3. I now recirc while raising the temp by running into a pot and slowly pouring back into/ over the grain to maintain temp,in between I agitate the bed with an $ 8.00 Coles potatoe masher...not getting rid of it.
4. I don't have a false bottom in my rig, my keggle originally and still has a bottom drain but the second tap ( original pump mount hole ) is 50 mm above the bottom and using Whirlfloc I find if I drain from the bottom first until it discolours this has sucked the trub into the middle,I then drain slowly from the second higher tap , and by keeping an eye on he trub I get get good clear run off by tilting the keggle to get the most out.
5. Get as much " clear" runoff into cleaned bottles after filling the fermentor and use this later for yeast starters.