Upgraded to 10 gallon.... OG too low

[Howiebrews]

I have been all grain brewing 5 gallon batches for a couple of years now. I use a HERMS system in the MASH. OG and FG were never perfect.....but they were close. I recently increased to 10 gallons.....naively thinking i would just double the recipe. I have done 2 batches ( same Mash tun setup) and both times my OG was hugely low....... .039 instead of .058. FG was similar. I will try to MASH a few minutes longer on the next batch and do an iodine test (which i have not). Any insight or thoughts would be appreciated.

 

[VikeMan]

When you doubled the recipe, did you double the water? You shouldn't, because the amount of water boiled off doesn't increase. Also, things like the wort lost in dead spaces and transfer losses don't increase with batch size. So if you use too much water, you end up with a more diluted wort and a lower OG, which could be a part of your problem.

 

[Howiebrews]

When you doubled the recipe, did you double the water? You shouldn't, because the amount of water boiled off doesn't increase. Also, things like the wort lost in dead spaces and transfer losses don't increase with batch size. So if you use too much water, you end up with a more diluted wort and a lower OG, which could be a part of your problem.

Thank you for your help. I use a water calculator which should account for that....but i will take a closer look at those numbers.

 

[IslandLizard]

In regard to what @VikeMan said, how were your volumes? If you ended up with your intended ~10 gallons in the fermenter and none left in the kettle, your volumes were just fine, and there's definitely an extraction problem.

What does your mash tun look like? Could doubling the amount of grist cause problems with recirculation? Such as much wort channeling along the sides instead of through the grist?

Especially a potential problem when recirculating, since your grist load is twice the height compared to 5 gallon batches, it may become denser toward the bottom (compaction), as more dust and finer particles end up toward the bottom, making it less permeable, and change the drainage pattern. Check the coarseness and evenness of your milled grist.

How was your mash temp? Grist in a full mash tun loses less heat per pound than in a half-filled one.

 

[Howiebrews]

In regard to what @VikeMan said, how were your volumes? If you ended up with your intended ~10 gallons in the fermenter and none left in the kettle, your volumes were just fine, and there's definitely an extraction problem.

What does your mash tun look like? Could doubling the amount of grist cause problems with recirculation? Such as much wort channeling along the sides instead of through the grist?

Especially a potential problem when recirculating, since your grist load is twice the height compared to 5 gallon batches, it may become denser toward the bottom (compaction), as more dust and finer particles end up toward the bottom, making it less permeable, and change the drainage pattern. Check the coarseness and evenness of your milled grist.

How was your mash temp? Grist in a full mash tun loses less heat per pound than in a half-filled one.

Thanks. I think you solved my problem .....extraction. My Mash tun is a converted 50 litre stainless keg..... higher than it is wide. It makes sense that doubling the height of the grain bed is causing me some recirculation problems......which explains everything. Can you suggest a solution? Thanks.

 

[IslandLizard]

Thanks. I think you solved my problem .....extraction. My Mash tun is a converted 50 litre stainless keg..... higher than it is wide. It makes sense that doubling the height of the grain bed is causing me some recirculation problems......which explains everything. Can you suggest a solution? Thanks.

With that kind of tall and narrow geometry, you may indeed run into issues with flow direction and likely suffer from channeling along the sides instead of through the grist.

But many coffee urn type all-in-one brew kettles that are abundant now, have a similar geometry, and they also recirculate, alas, rather slowly for it to work. They use a "mash pipe" with mesh in the bottom. Some have perforated or even (partial) mesh sides too. So it must be possible.

How finely or coarsely milled is your grist?
Why not use a round (prefered for recirc and fly sparging because of the depth and round geometry) plastic beverage cooler? Rectangular coolers can be used with some keen manifold and "spray pipe" design.

 

[Howiebrews]

With that kind of tall and narrow geometry, you may indeed run into issues with flow direction and likely suffer from channeling along the sides instead of through the grist.

But many coffee urn type all-in-one brew kettles that are abundant now, have a similar geometry, and they also recirculate, alas, rather slowly for it to work. They use a "mash pipe" with mesh in the bottom. Some have perforated or even (partial) mesh sides too. So it must be possible.

How finely or coarsely milled is your grist?
Why not use a round (prefered for recirc and fly sparging because of the depth and round geometry) plastic beverage cooler? Rectangular coolers can be used with some keen manifold and "spray pipe" design.

Thanks for the information. My next batch i will attempt to stir a lot more.... and perhaps increase my liquor to grist ratio. I was at 1.5 qt/ gal. I can increase that to 1.8 which will give me more water in the mash. Do you think that will help with the flow problem?