Controlling heater elements

[AiredAle]

Hello folks,

First post on this forum, so a short intro. I'm an extract-for-the-most-part brewer, have been beermakin' since 1983, and have the notebooks to prove it... I make top fermented ales, mostly bitters and some porters. I have converted part (well, most) of our utility room to a brewery with about 12 feet of counter to brew on, and undercounter kitchen cabinets to house my brewery stuff. I have been brewing with a propane fired keggle, and have been contemplating converting to electric.

I've read a lot of the posts on this and other boards about this, and have started the process. I saw a thread that I can't find tonight (typical) started by someone who was converting a corny tank to an hlt using a water heater element. I want to make one to boil water since I use boiled water for rinsing, sanitizing some stuff, and want to use it for sterilizing my new Shirron chiller (Thanks, Santa). I have drilled an old corny and installed a 120 V 2000 W heater element in it, no leaks, so far so good.

Now, to get to my question. I want to have some control of the heater more sophiscated than an on-off switch, but not so complicated as temperature sensor-SSR and controller. I was thinking about getting an infinite switch from an electric stove element, but don't know if that will work or not. Does anyone have any experience doing this, or have any advice? Or, an alternative method?

 

[Yuri_Rage]

Use a Ranco ETC-111000 digital controller. It's a sensor/relay controller like you mentioned avoiding, but it's self-contained. The only wiring required is 110/220 VAC in, and 110/220 out.

Here's an eBay link.

 

[passelin]

If you are using 120V you I think you should be able to find a light dimmer switch that is rated for 20A.

 

[Mikey]

I was thinking about getting an infinite switch from an electric stove element, but don't know if that will work or not. Does anyone have any experience doing this, or have any advice? Or, an alternative method?

I can guarantee that this will not work for maintaining a controlled boil. Various members of our brew club have tried it and failed. Although the control is infinitely variable, the on-off cycle for the element is just too long. You get either too much boil or nothing.

 

[Bsquared]

I'm in the process of putting a heating element in to a cooler and picked up a Ranco Like Yuri_Rage said on ebay for $40 (actually I got 2 for 90 including shipping). I think the seller was patriot supply, and they had a bunch at that price. they are not wired but the wiring of the element to the controller then to the power supply is vary simple.

 

[brewman !]

I saw a thread that I can't find tonight (typical) started by someone who was converting a corny tank to an hlt using a water heater element. I want to make one to boil water since I use boiled water for rinsing, sanitizing some stuff, and want to use it for sterilizing my new Shirron chiller (Thanks, Santa). I have drilled an old corny and installed a 120 V 2000 W heater element in it, no leaks, so far so good.

That thread is mine and its here.
https://www.homebrewtalk.com/showthread.php?t=18008

Pictures of the work to day are here:
http://picasaweb.google.com/beermeister1/MashSteamBoiler

Notice that I mounted the element in the lid. These hot water heater elements are designed to be mounted horizontally. My keg will be laying on it side, not standing upright.

Now, to get to my question. I want to have some control of the heater more sophiscated than an on-off switch, but not so complicated as temperature sensor-SSR and controller. I was thinking about getting an infinite switch from an electric stove element, but don't know if that will work or not. Does anyone have any experience doing this, or have any advice? Or, an alternative method?

A stove heat controller should work provided you get one for the right voltage and the element wattages are similar. I believe the small electric stove elements are 1500 to 2000 watts, so it should work. BTW: they are not a switch.

 

[AiredAle]

Brewman, and others:

Thanks for the input. I have talked to two electricians, and one says using a stove infinite switch will work, and one says it won't. I don't have a majority vote yet, so if I can find an appliance junkyard in the MSP area, I may try it. New switches are too pricey to sacrifice one to the gods of science.

I looked into lighting dimmers: 2000 watt ones exist on line, but are north of $100, so forget that. I'll look at the big box stores over the weekend and see what's there.

Brewman, I am impressed with your machine work. I considered mounting my element in the lid, but discarded that idea based on the gyrations needed to put the lid in place. You made it work, way to go.

An alternative approach you could have tried is to drill and tap the ball lock fitting for 1/4" NPT. The corny I am frankensteining came from a lab I worked in, and that's what they did to the liquid out fitting, and it still sealed pressure when the dip tube and o-ring was in place. I may use that to get hot water out of mine when I finish it.

I used a bimetallic hole saw for mine and was amazed at how fast it cut through the side of the corny - literally in a few seconds. Maybe you have a carbon steel hole saw, they don't do so well on stainless.

I'll keep you posted as I work through this.

 

[brewman !]

Thanks for the input. I have talked to two electricians, and one says using a stove infinite switch will work, and one says it won't. I don't have a majority vote yet, so if I can find an appliance junkyard in the MSP area, I may try it. New switches are too pricey to sacrifice one to the gods of science.

Do you have the owners manual for the <electric> stove in your house ? It has a wiring diagram in it. As does the back panel if you want to pull it away from the wall. A 2KW heating element is a 2 KW resistor, whether its a hot water heater element or a stove element. If the control works with the stove element, it will work with the hot water heater element.

Ask the electrician that said "no" why it won't work. (Then tell us.) Better yet, go to a place that fixes stoves and ask him. Pay him for his knowledge by buying a control from a junked stove.

I looked into lighting dimmers: 2000 watt ones exist on line, but are north of $100, so forget that. I'll look at the big box stores over the weekend and see what's there.

I think you are on the right track with the stove element control.

Brewman, I am impressed with your machine work. I considered mounting my element in the lid, but discarded that idea based on the gyrations needed to put the lid in place. You made it work, way to go.

Gosh darn, gee thanks.

An alternative approach you could have tried is to drill and tap the ball lock fitting for 1/4" NPT.

I thought of that. The pilot hole for 1/4"NPT is 7/16". Once you dill them out to that size, there isn't much wall left and SS is a hard steel to tap. The pilot hole for 1/8" NPT is 11/32" and that might be viable. But it wasn't hard to drill out the posts and I think the bulk head fittings are kind of nice.

The corny I am frankensteining came from a lab I worked in, and that's what they did to the liquid out fitting, and it still sealed pressure when the dip tube and o-ring was in place. I may use that to get hot water out of mine when I finish it.

I guess it works. Are you sure they used 1/4NPT and not 1/8NPT ?

I used a bimetallic hole saw for mine and was amazed at how fast it cut through the side of the corny - literally in a few seconds. Maybe you have a carbon steel hole saw, they don't do so well on stainless.

Mine was bimetallic too. Maybe I shouldn't have used coolant on the mill ? I dunno, but it went about 20 thou down and that was it for the holesaw. It mustn't have been high quality. The sides of the corny are much thinner than the lids are.

I'll keep you posted as I work through this.

Me too. I hope to generate some steam with it this weekend.

 

[Yuri_Rage]

Mine was bimetallic too. Maybe I shouldn't have used coolant on the mill ? I dunno, but it went about 20 thou down and that was it for the holesaw. It mustn't have been high quality. The sides of the corny are much thinner than the lids are.

Coolant is not a bad idea when drilling most metals. You probably inadvertently work-hardened the metal by using too high an RPM with too slow a feed rate. Stainless is touchy that way, and once it's work-hardened, it's VERY difficult to drill or machine. If there's a next time, try reducing the RPMs a bit.


AiredAle:
As for the stove burner control - I'm interested to see how it turns out. I'm not convinced that it's going to work, but I have no logical reason for that other than skepticism. In theory, it should work just fine. Please let us know the results!

 

[brewman !]

You probably inadvertently work-hardened the metal by using too high an RPM with too slow a feed rate.

Absolutely not. The mill has a 5 speed pulley setup and a variable frequency drive. I was running the spindle at 150 RPM, way slower than you would do with a hand drill. The mill has a manual feedwheel and I was feeding plenty of force. Probably too much feed and not enough RPM. And the coolant should have kept it from work hardening. I've machined SS before.

I think I had a low quality hole saw. It was a no name brand bi metallic. And the lid is way thicker than a keg wall.

The regular 1.25" bit I used when through the lid like butter, as did the guide bit on the holesaw.

 

[Mikey]

Ask the electrician that said "no" why it won't work. (Then tell us.) Better yet, go to a place that fixes stoves and ask him. Pay him for his knowledge by buying a control from a junked stove.

You are correct that a heating element is nothing more than a big resistor. The problem is that a stove control is not a variable rheostat- it's an adjustable on off switch. The element is either full on or full off, the only variation from 'low to 'high' being the the length of the time interval between 'on' cycles. It appears to us that the heating action is constant when using a kitchen stove because the bottom of the pot acts as a thermal mass and heat sink to modulate the amount of heat transmitted to the food.

To control the boiling action of wort when directly immersing a resistance element in the liquid requires a different type of control that will modulate the temperature of the element and not just turn it on and off for extended periods.

You could use a giant 220V rheostat if you can find one, or a more modern solution like a silicon controlled rectifier:

http://instrumentation-central.com/pages/scr_power_controls.htm

Most home brewers make up something equivalent from Radio Shack parts. Mine is in the 'hardware gathering' phase as part of my upgrade to all electric indoor brewing.

 

[brewman !]

I believe the poster said he didn't want to get into SCRs, etc.

"To control the boiling action of wort when directly immersing a resistance element in the liquid requires a different type of control that will modulate the temperature of the element and not just turn it on and off for extended periods."

Why ? If the on/off durations are short enough, as they appear to be for soup and such on a stove, and the thermal mass of the brewpot and contents is high, which it is, what is wrong with turning the element on and off ? What do you think the PID controllers that everyone is using do ? They control a SS Relay !

And btw, an SCR circuit is also on-off ! It just so happens that the on/off frequency is 60 HZ !

 

[Yuri_Rage]

You are correct that a heating element is nothing more than a big resistor. The problem is that a stove control is not a variable rheostat- it's an adjustable on off switch. The element is either full on or full off, the only variation from 'low to 'high' being the the length of the time interval between 'on' cycles. It appears to us that the heating action is constant when using a kitchen stove because the bottom of the pot acts as a thermal mass and heat sink to modulate the amount of heat transmitted to the food.

Finally, someone justified my skepticism! I'm usually not a big fan of direct rheostat controls for anything other than light dimmers to begin with. Given this new info, I'll go back to advocating the Ranco controller.

 

[AiredAle]

A quick update & some responses:

1. I'm not looking to control boiling as in a brew kettle, but to heat and boil 4 gallons of water in the corny tank, and then reheat it when I want to use it for sanitation or rinsing. So, I think if I can find a stove element switch it will be fine, I can keep the water near boiling if I want or turn it off, whatever.

2. I called a couple appliance recyclers here in St Paul today, and one said, no way we don't sell parts and you can't come scavenge some. The other said, sure we sell used parts, a switch like you want is $30. That's about what I'd pay for a new one, so I thanked him and moved on.

3. The new Lowe's opened here today, and I found a 1000 watt lighting dimmer, which apparently is also an on-off type control, by the way. A 2000 watt one is special order only, and too pricey.

4. I did find a couple nice bits of hardware in the plumbing section. One is a brass Pex tubing fitting, a 1" pipe thread cap with a removable insert so one could convert it to a tubing barb fitting in the future. I drilled out the rim that held the insert so the hole was big enough to pass my heater element through, and now for $6 I have a lock nut for the inside of the corny to hold the heater element.

5. The other find was a swivel barb fitting, also brass, with a glass filled nylon 1/2" nut that I can use for my new Shirron chiller for the wort in and out hoses. These were also Pex fittings. All were made by a company called Zurn, if anyone is interested.

So, next step is to clean it all up, assemble and try it out. I will try to figure out how to get my wife's digital camera to talk to my computer and post some pics of the final assembly if anyone is interested.

 

[Mikey]

Why ? If the on/off durations are short enough,

That's the problem, they're not short enough. 30 seconds on, 30 seconds off (let's say) for a mechanical switch, vs 60 hertz for an SCR.

During the 30 seconds the element is on, it will 'overboil' the wort. When it switches off, everything goes dead. No happy medium when you're trying to achieve a consistant rolling boil. An SCR on a 60 hertz circuit will avoid the extremes.

It's one of those things that (in theory) should work just fine. That's why several of my fellow club members tried it. In practice, each experiment failed for the above reasons.

 

[brewman !]

That's the problem, they're not short enough. 30 seconds on, 30 seconds off (let's say) for a mechanical switch, vs 60 hertz for an SCR.

During the 30 seconds the element is on, it will 'overboil' the wort. When it switches off, everything goes dead. No happy medium when you're trying to achieve a consistant rolling boil. An SCR on a 60 hertz circuit will avoid the extremes.

Stove controllers are built for ummm.... a stove (!) where one might be boiling a quart of water. I have never had a situation where my quart of water over boiled for 30 secs and then was "dead". And if that scenario doesn't happen with a quart of water, it ain't going to happen with 5 gallons.

And don't tell me its the thermal mass of the pot because I've boiled water with some pretty thin pots. And how quickly the water boils has to do with the thermal mass of the system, ie including the water.

Your criticism of a stove controller being impractical because of its on-off cycle is not justified by real world experience.

It's one of those things that (in theory) should work just fine. That's why several of my fellow club members tried it. In practice, each experiment failed for the above reasons.

You might want to go back and redo the experiment because those results don't make sense.

 

[Mikey]

You might want to go back and redo the experiment because those results don't make sense.

No, been there, done that. Seen others try it too.

Maybe you might want to give it a try yourself and let us know how you make out, instead of debating a point based purely on a theoretical opinion.

 

[brewman !]

Are you sure YOU did it ? In your previous post you say "That's why several of my fellow club members tried it. In practice, each experiment failed for the above reasons."

It doesn't make any sense that a stove controller would be too sensitive for boiling wort and yet work fine for smaller vessels on a stove.

As a matter of fact, this description makes it sound like the stove controller is an SCR circuit.
"When turned, the dial sends electricity to the burner, causing it to heat. The way the controller works is similar to the way a dimmer switch affects a lightbulb: the higher you turn the dial, the more electricity gets sent to the burner, and the less you turn it, the less hot it gets. It's all a matter of current control. Depending on the type of stove you have, the burners may be wired directly to the controller, or they may be the type that have connectors on them, which can be pulled out of the terminal."

http://www.doityourself.com/stry/howovenswork

It might depend on the age of the stove too.

It seems like other HBers have tried this too.
http://hbd.org/hbd/archive/1985.html#1985-8

CD Pritchard (kind of the father of RIMS) seems to say it works OK too.
http://hbd.org/hbd/archive/4337.html#4337-4

 

[Mikey]

Well you're persistent, if nothing else. I assisted my club mates in conducting this experiment not just during the planning stages but in fact actually held the components in my own hands at least once. In addition I contributed to the post mortem to analyse why it wouldn't work. Is that good enough for you?

Try this experiment. Go your stove and set it so that you keep a pot of water at a rolling boil. Time the intervals where the control turns the element on and off. So many seconds 'on', followed by so many seconds 'off'

Now get an typical kitchen electric kettle. Fill it full of water and allow it to boil. Now try to maintain a gentle rolling boil by plugging and unplugging the kettle according to the time schedule above. No overshoot or undershoot allowed.

If you're happy with the on/off timing, now hook up a stove controller and try to find a setting that precisely replicates the cycle you established manually.

 

[brewman !]

Well, lucky for you guys, we have an element on our stove that doesn't work properly and needed attention. SWMBO has been bugging me about it for a while.

So, I removed a good element and connected my voltmeter. I found the total on/off cycle on the switch on our stove is about 10 seconds. So with the control set to medium, the element is on for about 3 seconds and then off for about 7 seconds. On High, the element is on all the time.

I found the problem with the bad burner. The connection where the element plugs into the stove was corroded. Someone must have boiled over a pot and got liquid in it. I cleaned it up with some sandpaper.

 

[AiredAle]

A quick update:

I assembled the corny boiler tonight and boiled up a gallon of water in less than ten minutes. I have worked around the controller issuse by plugging the cord directly into the outlet, and controlling it from the corduit breaker which happens to be right there on the wall in the utility room subpanel.

So far no leaks and no surprises. I will update again when I try it in earnest with a full four gallon load, and when I get a range switch to control it. The description of the switch operation by Brewman sounds just what I want. Thanks for all the comments and entertainment.