HERMS air problem

Hello,

All of a sudden my HERMS has started getting air in the system. Whatever I do it doesn't go. It used to be airtight and after purging the air with the bleeder valve on my pump I would get 60-90 minutes of no air at all in my system. Now I turn onthe pump at the beginning of the mash, the wort looks like it's air free, but after a minute I see loads of bubbles being pulled from my mash tun.

Whatever I do it doesn't go away. Does anyone know why this might be happening all of a sudden and if there's anyhting I can do to stop it?

Thanks.

pictures of the set up may reveal something? its unlikely to be due to gas agitated out of suspension due to the temperature of the mash, so that leaves leaks in the system, the first place to check imho would be the plumbing before the pump, re-wrap any thread fittings with ptfe tape, and ptfe can also be used as a temporary wrap over tube friction fitted over pipes, paying extra attention to wrapping over the tube end and the pipe its installed over.

any kinks in your hex coil?? when fitting my herms test coil into its vessel i bent and kinked it in a couple of places, and any 'kink corners' are weak spots prone to leaks.. if found you could fix with a dab of lead free solder onto a heated and well fluxed spot??


Then If no Joy If possible can you submerge your herms system in a large trub or similar and pressurise with air (finger on the out pipe and blow in the in pipe if no easy co2 available) that could then indicate any leaks??

Fil said:

pictures of the set up may reveal something? its unlikely to be due to gas agitated out of suspension due to the temperature of the mash, so that leaves leaks in the system, the first place to check imho would be the plumbing before the pump, re-wrap any thread fittings with ptfe tape, and ptfe can also be used as a temporary wrap over tube friction fitted over pipes, paying extra attention to wrapping over the tube end and the pipe its installed over.

any kinks in your hex coil?? when fitting my herms test coil into its vessel i bent and kinked it in a couple of places, and any 'kink corners' are weak spots prone to leaks.. if found you could fix with a dab of lead free solder onto a heated and well fluxed spot??


Then If no Joy If possible can you submerge your herms system in a large trub or similar and pressurise with air (finger on the out pipe and blow in the in pipe if no easy co2 available) that could then indicate any leaks??

Click to expand...

Thanks for your reply, I've attached photos to this post.

What do you mean by "gas agitated out of suspension due to the temperature of the mash"?

Thanks for the advice. I will re-wrap my joints in PTFE and ensure they are all done up as tight as possible. For my HERMS coil, I use my stainless steel wort chiller submerged in my kettle, so there won't be kinks in that. Also any hosing is short so there isn't any chance for a kink.

The air is coming straight from my mash tun tap. When I sparge, I take the hose from my MT tap and fix it to my kettle, but when I run the sparge water through the air is purged very quickly. I don't know if it's because the sparge water is slightly hotter or because it's running through much slower.

Picture = 1000 words..

Nice set up.. and i can clearly see the gap in the hose leaving the tun alright, Im just wondering if this is perhaps a vacuum caused by a combination of the suck of the pump and resistance to flow of the grain bed? If the 'gap' remains pretty constant in size without the mash sticking then that may support the vacuum theory, if it grows during the mash without altering the flow rate then perhaps your right and there is a leak.

It looks as if it may be the tun valve or its fittings, so a pull and re-wrap with more ptfe and reseal may be in order,

forgive me if i am telling u what u know.. but ptfe and SS pipe fittings works great Until you back up on the thread perhaps to line things up, the hard SS shreads the ptfe in its threads as its tightened even a slight loosening can allow a leak, so to fit and line up mate the 2 bits without tape counting the revolutions needed to mate tight, call that count X, Then tape up the fittings and fit by turning X-1 or 2,3 turns before lining up.. Dont back turn at all and if yu over tighten undo retape and start again..

Is there a bag in the mash tun? Is the air flowing between the bag and the wall of the mash tun?

I think it's the pump. It's not keeping up with the feed. I had a few of those black pumps. They work for a bit but as you start steralizing it by running boiling water through it towards the end, it hurts that pump. Somewhere I saw that those pumps are only good up to 80 degrees. The light brown ones are made for boiling water. There a tad more but way cheaper than a chugger pump.

Quick fix is to put a smaller diameter hose on the output side.

No bag in the mash tun.

I took apart the tap and wrapped it in PTFE and did it up tight. This really helped, but was not perfect. Towards the end of the mash I opened the outlet on the pump more and I got loads of air in the system again. I purged it but it would come back. Which makes me think something isn't done up properly or there are a couple of issues and I've only solved one.

I think it's the latter. This is because my MT has an elbow joint on the inside to siphon up the wort, but the space between the opening and the floor of the MT is very small, we're talking millimetres here. I think it was tipping to one side which would provide a good flow through the tap, but it's been moved since the last 3 mashes so it's straight down, and the metal has heated up, expanded and is not allowing a good flow through the tap.

Trouble is I can't try much out now as I can't brew any beer for a while due to moving house. I might put several litres of 70°c water in the MT and see how well it flows out with the elbow joint down and pointing to the side.

@JapanBrew I don't think it's the pump right now as it's only a couple months old. Thanks for the suggestion though and if the above doesn't work out I can look into the pump.

sounds like your tun drain is very similar to my hlt and kettle drains ive fitted

Fwiw I use 1 x SS elbow fitting 1 x SS hex nipple, and 2-3 x M20 SS washers.

the hex nipples have a tapered thread and the elbow a parallel thread so it may require 1 or 2 extra m20 washers to bulk out the space on the inside.. screw together with out any tape to judge how namy will be needed taking into account 0.4mm pot wall.

to fit and seal i have

1) wrap the hex nipple on one thread with a good healthy wrap which comes up and onto the hex providing a tight soft shoulder onto which 1 x m20 ss washer can almost be pushed onto, the tightening will squeeze it in place and form a good seal. (as long as it would slip onto the hilt and not over pre wrap.. there are some varying tolerances with these bits out of 10x ebay sourced M20 ss washers 2x had too small a central hole!!)

2) the wrapped hex nipple and m20 washer are then inserted (taped thread thru) though the pot wall from the outside before wrapping again with more tape to provide some resistance for fitting 1 or more m20 washers depending on the spacing needed, the elbow is then screwed on till tight then held in the down position with a big adjustable wrench while the external nipple is tightened to seal.

the external valve can then be fitted and lined up with more ptfe

if you dont spare the ptfe that should seal well for you, my 100l kettle has its main drain output recirculated via a lil brown solar pump for the full 90 minute boil via the hop spider and i have had no air ingress issues , even with the final drain aspect when pumped thru the cfc into the FV.

I'm sorry but I still think he has a forward pressure problem with his pump. I had the same thing happen after 1 month of using my pump with my chiller. To do that, the last 10 minutes of boil, run the boiling wort through the system to steralize it. Those black pumps start to wear down. Quick fix was to make sure the feed hose was shorter then the output hose. Then to step down one size of hose on the output. That stopped it for me. If you notice, those pumps have the same threads But the input inner diameter and output diameter are different.

an update to this issue:

I've started brewing again and I turned the mash tun's elbow joint so it's at an angle and there's no possibility of it being blocked - no air in the system. I'm on my second brew and no issues.