HERMS heat exchanger idea

I'm in the process of building a HERMS using a small electric deep fryer and putting a copper coil in that for my heat exchanger. I like the idea of using cooking oil because it heats so much more efficiently than water. The pump will run constantly and a Ranco ETC will measure the wort temperature as it reaches the MLT, turning the fryer on and off. I have a relatively short coil, 10' of 1/2" soft copper tubing.




I've already tested it without the temperature controller. The fryer has no problem keeping the oil warm. It has no problem raising the temperature of 5 gallons of water a few degrees per minute, with the flow fast or slow. I'm confident with the temperature controller it won't have any problems maintaining constant temperatures throughout the mash. I hope to be able to step up the temp for mash out.







You may not find it pretty, but I don't care, as long as it gets the job done.

Seems interesting. Can the Rancho handle the amount of wattage the fryer will draw? I'm guessing it has something like a 1500 or 2000 watt element running on 110V AC?

I'm guessing you can heat the oil to well over 212, which would make for some quick heating. What kind of temperature differential do you think you will have between input & output? Any chance of denaturing enzymes if you overheat the wort above your intended mash temp? If your temp delta is just a few degrees, does it matter if your heat exchange comes from oil or water?

I'm just curious how much you've worked this through. I like the idea of a compact HEX. I've been toying with a similar idea.

Are you going to heat your strike and sparge water with this, or are you going to use it to regulate the mash temperature? If you plan to use this to regulate you mash temperature it may work. If you plan on this unit heating your strike water you may have a problem. If this unit has a 1500 watt heater, all it will supply is 1500 watts of heat whether it is filled with oil or water or anything. With 1500 watts, it will take quite a long time to heat up say 3 gallons of strike water. The oil will not make it any hotter.

+1 for mash temp only.

This looks like it would work well with a solenoid valve and a PID to control the valve position based on temperature.

wort exiting too cool, close valve to restrict flow = more contact time

wort exiting too hot... open valve to increase flow.

Make some fries while mashing!

Best. Idea. Ever.

Like Sawdustguy said, if you are going to use it to regulate the mash it should work fine. Your setup is very similar to mine, only difference is that I have 25' of 1/4 copper submerged in water. The key to the whole thing is to put the temp probe in the return near the MLT, that way you never overshoot your temps. Right now I'm only using a digital thermometer with an alarm I set at a certain temp, if I go over it beeps... when the temp of the wort returning to the MLT is about 2-3 degrees higher than what I want to mash at I turn the knob down on the fryer till the light goes out... it holds there with very little attention. Works quit well to be so low rent.

However, it just doesnt have the guts to bring up strike water or step mash, it takes too long. If I insulated the hoses it might cut that time a bit, but I just go ahead and heat my liquor on the gas burner for now.

Hope the pics help. (If i'm able to get them to show up here in the thread... I've never posted pics before. Anyway they are in my gallery)

By the way, try it with water first and then maybe fool around with the oil... that stuff is awful messy.

Good luck!

sjlammer said:

+1 for mash temp only.

This looks like it would work well with a solenoid valve and a PID to control the valve position based on temperature.

wort exiting too cool, close valve to restrict flow = more contact time

wort exiting too hot... open valve to increase flow.

Click to expand...

Yup - that's the way my HLT exchanger is setup. I keep the mash tun on constant re-circluation and open/close the heat exchanger valve when the temp drops below my setpoint. I've figured out that if I keep my HLT at around 185 degrees, I get a positive increase in mash temp, acheive a good balance between open/close throttle times and don't increase the wort temp in the exchanger line above 185 degrees when the valve closes. I do this manually today but plan to use the BCS to automate it here shortly.

moonbrew said:

Like Sawdustguy said, if you are going to use it to regulate the mash it should work fine. Your setup is very similar to mine, only difference is that I have 25' of 1/4 copper submerged in water. The key to the whole thing is to put the temp probe in the return near the MLT, that way you never overshoot your temps. Right now I'm only using a digital thermometer with an alarm I set at a certain temp, if I go over it beeps... when the temp of the wort returning to the MLT is about 2-3 degrees higher than what I want to mash at I turn the knob down on the fryer till the light goes out... it holds there with very little attention. Works quit well to be so low rent.

However, it just doesnt have the guts to bring up strike water or step mash, it takes too long. If I insulated the hoses it might cut that time a bit, but I just go ahead and heat my liquor on the gas burner for now.

Hope the pics help. (If i'm able to get them to show up here in the thread... I've never posted pics before. Anyway they are in my gallery)

By the way, try it with water first and then maybe fool around with the oil... that stuff is awful messy.

Good luck!

Click to expand...

Yes the probe will be in the return immediately before the MLT. It took over an hour to heat 55F water to 170F. However, this was only for a test. I was never planning on this heating my strike water, maybe just dialing it in if I'm off by a couple degrees.

Also, somebody asked about the temperature differential between the input and output. I've only tested this once so far, but I had it up to as much as 10 degrees warmer coming back in the the MLT than the water leaving the MLT. I don't plan to have that big a differential when I'm mashing, as I will primarily be using this to maintain temps for the mash and possibly to step up for mash out.

I don't think the oil will heat the wort any better than water. It's just more efficient to heat the oil.

I use a 10 Gallon Igloo cooler for my MLT. Because it is insulated I'm not loosing that much heat from the mash itself, so the HERMS isn't working that hard. I've never measured the output of the MLT but I have checked the temp deep in the grain-bed and found that it is usually 1 or 2 degrees lower than what I have the input flow heated to. That is why I set the fryer to heat 2 degrees higher that I want to mash at. As long as I hit my mash-in temp correctly I have very little problem maintaining that temp +/- 1 degree. Now I do add a mash-out infusion, to help ramp up that last step to 170 but then again, once I'm there, its no problem holding it there.

Sooner or later I'm going to break down and get a PID, and automate this whole thing.

I completed my setup last winter and I'm very pleased with it. I heat up my strike water in the HLT which then gravity feeds into the MLT. Once I dough in I leave the pump constantly circulating the wort. I ended up getting a digital Johnson Controls temperature controller. It cycles the deep fryer on and off to regulate the temperature. I just set it and forget it. The oil is effective. I don't worry about the mess because I just leave the oil in it. Water didn't give me a good temperature differential for heating and the unit was on much longer just maintaining temps. It maintains temperature within 1 degree, no difference on hot summer days or cold winter nights. Ramping up for mash out takes about 15 minutes on a typical 5 gallon batch. On 10 gallon batches I add hot water from the HLT to assist. I've brewed over 150 gallons with the system so far and I love it. I love the simplicity. It's not as simple as moonbrew's setup and it may not be pretty but it sure get's the job done.

In the future, I might upgrade to a larger deepfryer and MLT to handle larger batches.