Where did the water volume go?

[Gavo]

Well I finally went and added a HEX coil to my brewery after many years of running a simple 3v rig and have come up with a curious result. Other than airlocks boilovers (due to having my back turned while efficiently cleaning while starting the boil) this one has me a little beat.

In my usual process with a double batch of 42lt using 8.5kg grainbill I mash in with 20lt of water let it rest for 90min then drain to kettle, using good old gravity (no mashout). I then follow up with a double batch sparge with a volume of an equal 20lt each. So all up 60lt of liquor volume. Once all liquor is drained into the kettle I end up with a pre-boil volume of approx 51 lt and a post boil of 42 lt into the fermenters. Usually getting close to 82% efficiency.

So yesterday I did my standard APA recipe using my new HERM's system and it gets a little interesting. I mashed in with 30lt at 60deg and ramped to 65deg. The ramp took some time due to airlocks and such, probably 20 or so minutes (I wasn't timing while undoing hose clamps etc) let it rest at 65deg for 60 min then ramped to 75deg for mashout then pumped to the kettle. Next I pumped 30lt of sparge water up fo batch sparge and re-circulated for 10 min and again pumped to the kettle. So 60lt or liquor in total, same as always, however I was left with approx 45lt in the kettle, so 6lt less than usual. I then pumped another 6lt across to the kettle to achieve my target pre-boil of 51lt. Efficiency was dead on 80% pre and post boil.
Pumping from the MLT is faster than straight draining but surely there can’t be 6lt still hung up in the grain, there would be no more than half a litre in the lines.
So the question is where did the 6 lt of water go?

 

[The Judge]

I wouldn't be surprised if your grain was holding a lot more than you think! Also seems a little obvious, but are you sure you hit your volumes from your HLT transfer correctly? Either that or check the floor for a watery mess ;-)

 

[Ducatiboy stu]

Grain does soak up a fair bit of water....

But then again, as you have previously used the system you should have already accounted for grain soak.

 

[bradsbrew]

Try turning the pump back on about 10 minutes after sending to the kettle. You should get a few more litres.

 

[MastersBrewery]

if you have added your herms coil to the HLT, you should have re calibrated for volume, this together with losses from what has remained in the herms loop may explain your missing 6 litres.

MB

 

[Adr_0]

Try turning the pump back on about 10 minutes after sending to the kettle. You should get a few more litres.

If you have gone from gravity fed to pump this might do it. Might struggle to get that last couple of litres out if your pump doesn't have enough head on the suction side, and this may be helped if you allow the liquor to settle out of the grain as Bradsbrew has suggested.

What sort of pump is it, and how much height do you have between the pump and the mash tun on the suction side? Tube size? Did the pump cavitate?

 

[Gavo]

Hmmm, fluid in the lines would account for half liter to a liter at most, spill was minimal. I havn't changed the rig configuration and only put the HEX in the system. I am using a little brown pump and recirculation is painful due to a lot of head for the pump to work against. However, flow from MLT through pump to kettle was good in fact better than gravity as used in the past as the pump is assisted here by gravity and siphoning action as the MLT is higher than the kettle.

I plan on trying Brads suggestion as I suspect there was sweet wort absobed by the grain and not draining through as fast as the pump will transfer. I tend to think this would be the case as after topping up the kettle I flushed the lines from HLT to MLT and then pumped from the MLT to a bucket in order to make the MLT lighter to lift for cleaning. The resulting liquid had quite an amount of colour in it although still the same amount I used to flush the system.

My HLT is calabarated with a sight tube, so no guessing there, I used a calabirated dip stick in the kettle to check for volume there. I did not check what was left in MLT at the time of cleaning (It was dark and I had to get a mate to empty it out as I am unable to do any heavy lifting ATM) so some wort may have been left in the grain and slowly drained out.

Still accounting for wort in lines, some wasted wort clearing airlocks etc, I would think the differnce is still significant. Just need to work the new sytem out and create a consistant result.

Cheers,
Gavo.

 

[Gavo]

If you have gone from gravity fed to pump this might do it. Might struggle to get that last couple of litres out if your pump doesn't have enough head on the suction side, and this may be helped if you allow the liquor to settle out of the grain as Bradsbrew has suggested.

What sort of pump is it, and how much height do you have between the pump and the mash tun on the suction side? Tube size? Did the pump cavitate?

Oh, about half a meter of head on the suction side and at the time only had cavitation once the wort was drained from the MLT.

 

[Adr_0]

If you can throttle the pump with a valve on the discharge you will reduce your flowrate while still letting the pump produce enough head. That way you can slow it down while draining the MLT and just open it up fully when you are using your HEX.

How do you control your pump flow - with a valve on the discharge or variable speed?

 

[Adr_0]

If you can throttle the pump with a valve on the discharge you will reduce your flowrate while still letting the pump produce enough head. That way you can slow it down while draining the MLT and just open it up fully when you are using your HEX.

How do you control your pump flow - with a valve on the discharge or variable speed?

 

[Gavo]

I didn't throlle the flow back this time as I didn't think it will be an issue. The faster flow rate by pumping out to the kettle was most probably the cause of the issue. Will need to give it a try on the next batch as I can throttle the flow either by the ball valve or voltage control to the pump. Planning on another brew next week and will try this along with Brads suggestion.

Cheers
Gavo.

 

[Adr_0]

When the liquid level on supply to the pump is dropping, throttling with a valve on the discharge is best as described above. If you use variable voltage/PW you run the risk of the transfer stalling and/or cavitating the pump.

When the liquid level is constant ie during recirculation in the MLT, variable voltage/PM is best as you get smooth control and slightly increase pump life.

So you sorta need both.

Enjoy...