crackling noise from rubbermaid mash tun

[vlesperance]

Hi, I just made a mash tun from a 10-gallon rubbermaid cooler (the "standard" build that I see all over). I did notice that the inside liner is slightly warped inwards, if that matters.

I just tested it with hot water (180-ish *F). It kept making a "crackling" noise. After about 20 seconds of that, I poured the water out, just to be safe.

Everything looks fine, though. I did a quick search, and I see that this has happened to a couple people, who posted with concerns, but I've never seen a reply.

I just got the cooler, so I can still do a return, if it sounds like that warping or crackling noise is indicative of a defect.

Or does nobody mention it, because its completely normal? Thanks for the help.

 

[Yooper]

Oh, that's normal. But it's probably not good.

What I mean is that I learned the hard way and poured boiling water into my MLT to prehead. After cracking and warping, I realized that about 180 is the absolute upper limit for those coolers!

It could simply be making that noise as the plastic expands and heats, but I'd definitely use cooler water next time!

 

[ctrlpabrewer]

A friend of mine had his cooler MLT crack after about a year of use. He was going to throw it out but I suggested cutting an expansion joint in the sidewall and filling it with 100% silicone - I don't know if he did it or not though...

That is what I plan on doing if/when my MLT cracks.

 

[H-ost]

It happened to me the first two times I used mine, I thought it was completely normal. It sounds like glue breaking apart the first few times it expands/contracts but it is much quieter now that it is broken in. I have also not been putting boiling water in there anymore but that is because I warped it at one point doing so.

 

[KitB]

Happens to me, nearly every time.
It's normal.

 

[krazydave]

Ditto.
Mine has cracked like that nearly every time I've used it since I got it. Which was probably about 15 brews ago. I usually pre-heat it with water in the 175-180 range, and that's when it does it.

 

[vlesperance]

Thanks all. Based on the answers here, I tried it again... and its already much quieter.

Since I could now leave water in it, I filled it with 10 gallons just to test for leaks and heat retention. It is leak free.

I'm losing about 4*F per hour, a bit more than I was hoping. Do you think that would drop if it actually had grain in it?

The lid is hot. I could stick insulation to it. And the copper fixtures are pretty hot. Everything else is cool to the touch.

 

[bitmask]

That'll drop to next to nothing if you had grain in . I don't have a cooler mash, but even an uninsulated tun won't drop nearly as much when the grain bed is there and retaining heat.

 

[krazydave]

I think at the most I get 1-2 degrees drop per hour. Most times though, it's unmeasurable.
When you tested did you let it sit for a few minutes with the lid on to heat up before you measured your initial temp?

 

[Ceedubya]

mine does it everytime, I haven't had any issues..... yet.

However, this past weekend I took my mashtun outside to clean out the spent grains into a bucket then sprayed it out with the hose. I closed the lid, set it aside while I finished boiling and forgot about it til morning. The closed lid and tem differential must have created a vacuum, because it sucked my threaded nipple with a conduit washer on the outside right through the outer wall. The inside seal is now about 1/2 inch..... inside.

So, they are definitly temp sensitive, and this is not what they are built for so play it safe and you should be fine. I think Yooper has the right idea at 180 for preheat.

 

[LuiInIdaho]

The crackling sound and the warping of the liner are normal. It is due to the plastic expanding because of the higher temps. Since it can't expand in a normal fashion (the circumference getting larger because of the rest of the cooler) you will get the warped liner. The cooler will continue to work fine, but eventually it will crack and start leaking (after a few years). However, that presents another opportunity to create a stainless insulated mash tun using the cooler and a 44 quart Bayou Classic kettle. Check out this thread https://www.homebrewtalk.com/f11/my-new-mash-tun-268370/ It is a thread to convert the rubbermaid cooler into a stainless insulated mash tun. Great project

Mark:rockin:

 

[forstmeister]

One of my igloo coolers had the interior liner warp to the point where the lid wont fit anymore. It is an older one that was given to me by my dad, so maybe the age had something to do with it...

 

[DeafSmith]

I like to heat my RubberMaid cooler MLT slowly and gently to allow time for the outside to expand along with the inside to prevent warping and cracking. I heat my strike water in a kettle which is lower than my MLT. As the water begins heating, I pump most of it into the MLT, then turn off the pump and let the water drain backward through the pump into the kettle. When the kettle fills (takes a few minutes) the water is now about 20º F hotter than it was the last time, so I pump it to the MLT again, let it drain back, etc., until I reach about 165º F, then I let that sit for a while before doughing in. So far, this has been working very well.