Stratification in HLT

I have built a PID controlled HLT that uses a 1500W 120v element. It's sole purpose is to heat my strike water. It takes about an hour and a half, but I don't care much about the time. It will be set up on a timer so that I will have strike water ready as soon as I step into the garage to brew.

The element is short and is as low in the kettle as I could place it. The temp probe is at the same level as the element, offset about 90 degrees.

Given enough time, will the stirring motion of the heated water rising from the element stir the water enough to avoid major stratification or do I need to add a bubbler or small pump to move the water around?

I'm going to do some experiments, but I though someone might have been down this road before.

Thanks

No. You need a way to stir or recirculate the hot water.

I have a little motorized stirrer in mine, but others use a pump and recirculate.

Do a full time recirculating pump to heat quicker and avoid stratification.

Yooper said:

No. You need a way to stir or recirculate the hot water.

I have a little motorized stirrer in mine, but others use a pump and recirculate.

Click to expand...

Is that something you built or bought somewhere?

disney7 said:

Is that something you built or bought somewhere?

Click to expand...

The guy that I bought my original set up from made it. I had an HLT with a 1500 w element as well, and he built a little stirrer with a motor through the lid of the HLT. That was a long time ago, and many new HLT set ups have come and gone- but I still have that little stirrer and motor!

I think I have a picture. I'll see.

Yep, I found some photos. The only changes I've made have been changing it to a board (instead of a lid, since I changed HLTs), and "beefing" it up with another piece on the stirrer since I"m doing bigger batches (more water).

It's a plastic spoon, with an added motor, and I have a switch on my control panel to turn it on.










And holy smokes is it dirty/dusty in the photos (as is the HLT!). I've cleaned it all up of course, so that's not typical!

Thanks Yooper. That gives me some good ideas to start on.

Yep, you must agitate the water.

Another way to do it is to blow air down into the sight gauge. A small aquarium pump would work fine. I've tried this and it worked. I've never seen anyone else do this though.

I have a sight gauge on my new HLT. Once I have the correct water volume I simply put a piece of tubing over the sight gauge and run it to an aquarium air pump. The slight bubble action stirs the water sufficiently. When I go to draw water out and need to know the volume I simply disconnect the air line.

Thanks guys. I fixed mine up. Running the air through the sight glass works great. It actually looks like a rolling boil when the air is going.

I did a little testing beforehand. Set it at 175F and waited an hour and a half. The PID showed 175F. Stirred it and lost about 8 degrees. The same test, but waiting 2.5 hours, and I got a 4 degree drop by stirring it.

So, there is enough water moving from the heat differential that I think it would eventually equalize. However, that would be a pretty big waste of energy.

Also, with no lid I lost a little more than a quarter of a gallon in two hours. So, I'll put the lid on next time.

Neat. I wonder what you're using for a timer?

I'm using a GE 15 Amp 7-Day Plug-In Dual-Outlet Digital Timer, Model # 15079.

Home Depot generally has them. I usually use them for the Christmas lights :cross:

Ahh neat, I wondered how many amps those things did. I have a few laying around and might try one on my 1500 watt heatstick.

I wonder if I put the heat probe near the top of the water if I could avoid stirring...

I think that would make the stratification worse.

By heat probe I meant thermowell, not sure if that makes a difference.

Ah, I thought you were talking about the heat stick.

If you put the temp sensor at the top, it would see the temp changes sooner since heat rises and would stop heating sooner I would guess.

If you put the sensor in the bottom it should continue to heat until the sensor sees the set value. That probably means the water at the top of the kettle would be quite a bit higher than the set value. When you mixed it you'd probably be several degrees higher than your goal.

Try it. I found significant stratification in my vessels. Fermenters too. Let the reading settle then give it a good stir for 15seconds. Check again....

Odd. In my two uses of my (new built) rectagular cooler electric HLT I found NO difference in temp from one side to the other or with the probe at different depths. I still stired it just before dumping to my mash tun but the temperature diference was less than 1 F.

I would think simple convection would take care of this assuming the element is near the bottom of the HLT anyway.