HERMS pump flow rate

Had a somewhat trying brew day today. Hope someone can shed some light on this, as I now starting to run out of ideas.

Treated myself to a early Christmas present and bought a chugger pump, also fitted the new stainless steel coil into my HERMS pot, insulated the hoses, and clamped them to the camlocks with oeticker clamps.

The initial flow out of the HERMS coil to the mash tun, was quite acceptable after first doughing in, allowing grain bed to settle, and vorlauf several litres to try to prevent small particles from getting to the pump. But after draining the mash tun for batch sparging, the flow from the pump had significantly diminished and virtually stopped.

My current set up is a 38L mash tun with a Mr Lard custom false bottom, with a Y strainer fitted before the chugger pump. The pump is approx 1ft below the output of the mash tun, and a Y strainer is fitted to the input of the pump which in turn, is connected via camlocks with approx 1 foot of hose. There is another 1ft of hose that connects the output of the chugger to the input of the HERMS coil, then the output of the HERMS coil is then laid on the top of the grain bed in the mash tun (2m max).

I primed the pump before start up, but noticed small air bubbles in all hoses exiting from the pump and HERMS coil when mashing was underway. When the mash was completed, I checked and further nipped down the clamps and that seemed to have solved that one.

My mash grain to liquor ratio is 3.25Kg/L.
The grain bed does not seem to be compacted, I have throttled back the flow of the output of the chugger with the valve, on initial start up, ensured the pump is correctly primed, checked and cleaned Y strainer.

I have removed the head and checked the impeller, everything is OK. I have tried it with just water and it appears OK. There was a reasonable flow of water when primed, and coming through the pump on gravity alone.

The only conclusion I can think what may be causing poor flow rate, is cavitation.

Would adding another valve on the output be of any benefit? because I dropped off the camlock from the exit of the pump to check flow and to start again, but there was only a dribble from the output.

Any help would be most appreciated.

Best regards,
WM7793

Can't see cavitation being too much of a problem at that temp although I can see the y strainer causing some problems. It only takes a little bit of grain to block it and reduce the flow.

we use a herms and dont use a Y filter anywhere during the mash. Just underlet the required liquor to the grains and let it sit for 10 mins after an initial stir. Then from the tap on the mash tun draw off around 4 to 6 jugs liquor and return to the mash tun. We have a Y filter fitted on the boiler thats all. Our flow rate is around 1 litre per min or slightly more

I think you have a blockage somewhere as Cy says, easy to do if you suck at the grain bed to hard. I believe 1 to 1 .5 litres max is the ideal flow rate. I don't use HERMs anymore as with big volumes to heat I did not get a quick enough temperature rise. Prefer a good mash tun and careful attention to strike temperatures, put the lid on and walk away for one and a half hours, nothing to go wrong.
S

Thank you everyone, for your replies.
I periodically checked the Y strainer during the mash, and there was a thin coating of particles surrounding the mesh filter. I originally fitted the Y strainer as I thought that it would be good practice to do so.

Do you use anything to prevent particles from reaching the pump? I have read of some brewers using either a BIAB method or a fine voile sat at the bottom of the mash tun. Or is this simply not required.

I forgot to mention in my opening post, my brews are small, 23L maximum. Yesterdays brew was only 15L. There was only 11L of water in the mash and just over 3Kg of grain.

The grain bed was definitely not compacted, I have kept the grains from the mash so it would be easy for me to remove the Y filter and see if there is an improvement.

Mark1964, you mention in your reply.
"Just underlet the required liquor to the grains and let it sit for 10 mins after an initial stir. Then from the tap on the mash tun draw off around 4 to 6 jugs liquor and return to the mash tun."

Do you mean, you pump the required the required water for the mash, into the bottom of the mash tun and let it filter up through the grain bed?
I use Beersmith, and I am trying to update the software with accurate numbers to get a handle on mash efficiency, brew house efficiency etc, as I have upgraded my system. If I am reading this correctly, how do you measure the water accurately? Do you have a sight glass on your boiler?

Do you then allow everything to settle before recirculating via the HERMS coil? Does this improve the circulation using this method?

Sorry for asking dumb questions, but I have no experience with underletting, just the procedure outlined in my opening post.

Thanks again for all your replies.
Best regards,
WM7793

no we dont use the pump to underlet just gravity. We then let everything settle in the mash tun then run a few jugs off back into the mash tun to remove the large bits before recirculating with the pump through the herms.

Thanks Mark, it would be difficult for me to underlet, as the mash tun and boiler are on the same level.

First thing to try, will be to use the old grain, and check for flow with the filter removed from the Y strainer, and see how it goes. If that does not improve, then it will be back to the drawing board.

Thanks for all your contributions,
Best regards,
WM7793

I thought it was only right to update you, since you have all taken time out to help me.

I have removed the Y strainer, and lo and behold, the flow rate is phenomenal !!
On reflection, it is does common sense.
However, I thought I was maintaining good working practice to reduce particles to the pump, and when you are in the thick of it with stuck mashes and poor flow etc, sometimes you cannot see the wood for the trees.

So thank you, for all your help in solving this problem.

Before I let you all go.
I noticed that when draining the mash tun tonight after the dummy run with the old grain. I noticed that the grain bed was in a conical shape. This was due to the return hose being laid on the grain bed. Now this is my second brew with the new mash tun and false bottom, and I have noticed that the mash efficiency is lower than what I was getting with my old cool box, where I devised a copper manifold to return the liquor to the top of the grain bed.

Would the lower efficiency be a result of the return hose laid on the grain bed, which in turn is whirl pooling the returning liquor and not filtering through the entire grain bed?

How do you return this liquor? Do you use a sparge head, or something else. I would appreciate your comments regarding your own systems.

Again, many thanks for all your input.

Best regards,
WM7793

Glad that you have it sorted.
I think you will need to have some sort of manifold to distrbute the input flow evenly, otherwise you could get "easy" channels forming leading to partial washing. In its simplest form a piece of foil with holes in it, complicated a rotating sparge arm. Now they are simple and nice to watch.
S

+1 cap the grain with some fork stabbed foil.. it needent cover entirely as long as the return flow is directed over it so it dosent didturn the grain bed..

depending on the levels you could underlet from a source sat next to the tun, the liquor will flow from the source pot till it reaches the same level in the destination pot. it does help saturate the grain bed minimising the need for extensive mixing in and reducing the risk of dough balls too.. you could use the pump to transfer the strike liquor too

I have my out let on the lower front while my herms return is on the far side top area and then have a length of copper pipe with a bend on the end that sits just below the surface and it points towards the side ish causing movement and it looks like it's just being stirred . This insures movement in the mash so it all gets pumped ( no cold spots ) p.s the optimum flow rate is apparently 3.8 litre per minute , enough to pull the bed but not compact it .

I use a H shaped return in the mash tun through a perspex lid. Seems to work well.

+1 for the H-shape return, ensures a good even return of wort to the top of the grain bed.

No its H shaped pipe in from the top to a letter H in copper pipe with an upturned elbow on each end

I've just tried on my phone I'll do it at home

This works well under the perspex lid

Now I get it Mark.....I take it the 4 outputs sit just below the mash liquor to avoid oxyginating the wort. Neat.

yes i can adjust it through the perspex lid the pipe slides up and down through a drilled out tank connector

15mm