recirc mashing questions and observations

[andycook]

I added a pump to let me recirculate from my hot water tank (with burner) to my 10 gallon round cooler with false bottom mash tun and back. Even with the head loss from several 90* elbows and several linear feet of tubing the Mark 2 wort pump can pump faster than the mash tun can drain. The limiting factor seems to be the diameter of the 90* elbow from the false bottom screen to the mash tun drain.

Question: In this design does one slowly bring the temp up to the mashing temp and then hold at that temp for the appropriate amount of time OR heat the hot water and then recirc when the temp is right? I may have to try this on a recipe I've done before.

Observation: use a gate valve instead of a ball valve on the output side of the recirc pump for better/finer control. I needed to relearn this from my aquarium days.

Observation: if I were trying to increase recirc volume I would consider a wide drain on the mash tun bottom instead of on the side.

 

[itsme6582]

Do whatever allows you to pour on the heat until you get close to your mash in temp. Once you're close recirc to heat up your vessels evenly. Once you think you're ready to mash in just go for it. Take notes so you can do better the next time.

Ball valves work fine for choking back my pump. I just close it down and don't think about it again.

You don't need to recirc fast or even the whole time, especially with a cooler. If you've got that pump moving a lot of volume your flow restriction might be a compacted grain bed rather than your outlet size. Recirculation helps with 2 things, you can apply heat evenly and the grain acts as a filter. Your cooler will help a lot to maintain temp so you shouldn't need a lot of heat to evenly distribute and if you weren't running that pump you'd vorlauf only a quart or 2 at the end.

 

[MagicMatt]

I don't understand your comment about the 90° elbow being the 'limiting factor'. What does that have to do with how fast your MLT can drain?

 

[acidrain]

I added a pump to let me recirculate from my hot water tank (with burner) to my 10 gallon round cooler with false bottom mash tun and back. Even with the head loss from several 90* elbows and several linear feet of tubing the Mark 2 wort pump can pump faster than the mash tun can drain. The limiting factor seems to be the diameter of the 90* elbow from the false bottom screen to the mash tun drain.

Question: In this design does one slowly bring the temp up to the mashing temp and then hold at that temp for the appropriate amount of time OR heat the hot water and then recirc when the temp is right? I may have to try this on a recipe I've done before.

A larger diameter with few restrictions on the inlet side of the pump is desirable so that the pump doesn't starve and cavitate. 90 deg elbows also restrict flow.

Observation: use a gate valve instead of a ball valve on the output side of the recirc pump for better/finer control. I needed to relearn this from my aquarium days.

Meh, I don't know about that... a valve is a valve as far as I'm concerned.

Observation: if I were trying to increase recirc volume I would consider a wide drain on the mash tun bottom instead of on the side.

Yes. I went to 3/4 inlet hose with a sweep 90 for a 1/2" system and it has eliminated hot liquid cavitation.

I don't understand your comment about the 90° elbow being the 'limiting factor'.

I'm sorry, you don't understand laminar flow & fluid drag. See section 1.5: http://www.efm.leeds.ac.uk/CIVE/CIVE2400/pipe_flow2.pdf
It explains head losses from sudden pipe diameter changes.

 

[MagicMatt]

I'm sorry, you don't understand laminar flow & fluid drag. See section 1.5: http://www.efm.leeds.ac.uk/CIVE/CIVE2400/pipe_flow2.pdf
It explains head losses from sudden pipe diameter changes.

No need to be sorry (or patronizing). Also I didn't mention anything about fluctuation in ID. I'm well aware of how pressure changes with line diameter. AFAIK there are no diameter changes inside of a 90° elbow.

 

[andycook]

Thanks for the replies.

The diameter of the 90* elbow on the false bottom is small, smaller than .5" and more likely 3/8". Ultimately that restricts the flow out of the mash tun. Everything else is plumbed .5" except the elbow that came with the false bottom.

Ultimately this is more of an observation than a need to do anything. I just restrict or open the flow on the output side of the pump to where I need it to be.

As far as gate valve vs ball valve, from my aquarium protein skimmer days I always found a gate valve better (affords more fine control) at adjusting water flow.

 

[MagicMatt]

Ah that makes sense if the elbow is a smaller ID than the rest of the system.