Gonna build an Electric Boiler...how to control?

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Looks like a dimmer switch will turn on and off 120 times a second. Make sure you have a serious heatsink on your SSR and that you have a fan on it. I'm switching at once a second (as is The Pol I think) and the heat sink gets warm. 120 times faster.... Hey it might work, give it a shot and report back, don't burn down your house. :)

http://home.howstuffworks.com/dimmer-switch2.htm
 
Also, what I would be more concerned with is the current draw through the dimmer switch. Lights don't draw much current, but a heater element running at full tilt or half would draw quite a lot of current I would think.
 
Also, what I would be more concerned with is the current draw through the dimmer switch. Lights don't draw much current, but a heater element running at full tilt or half would draw quite a lot of current I would think.

Right a 30 amp dimmer switch is expensive! I think that's why they want to use it in conjunction with an SSR which doesn't require much current at all to control.
 
Thanks Pol,

While I admire your work and am a bit jealous, not all of us are cut out for such high tech rigs.

i just read this so i thought i would post this:)

you know what i found is the simplest way to get a project done is:
1) tell us what you want to do.
2) Give us a Budget ( Ex. you want it done right and the Cheapest way)
3) I can garrentee you that many of us will put all the suppliers together and im sure you will get complete directions step by step if you need them..

Just ask bc many people on this fourm have got my through some interesting and complicated stuff, and want to spend my money.. so if you want the most complex rig we can help:)
 
Very little current will run through the dimmer switch, since this is only used to trigger the SSR.

The current throught the SSR is what generates the heat. Not the switching on and off. It should not get any hotter if you're switching once per second or 120 times per second.

Switching the heating element at 120 Hz may actually lead to a slight decrease in effective wattage due to the inductive impedance of the heating element. The SSR may actually be cooler, but the heat output may be a little less...
 
That type of variac would make for a slick setup. That specific unit would burn up with a 5500W load, but if you find one at around 9600VA (40 amps) or even better 12000VA (50 amps) you'd be golden.
 
CRYDOM RPC2440 40 AMPS, 240v, $ 154.00

Cheers,
ClaudiusB

See, to me an $80 PID/SSR combo at half the price makes more sense. It works, it is easy and it is 1/2 the price?

But, again, I have room for 2 cars to ACTUALLY fit in my garage. :drunk:
 
Hey ChemE, I am a mech. engineer, and convection will be much higher. Also b/c it is wort and not water that is boiling I would bet that at boiling temp 1g/mL would probably be more accureate due to the increased sugar conten of the mixture, and then once you add hopps even higher. But I will look through my old thermo books to see if I can get a better h value for you. But verry cool to see boltzmans (sp.) equation in action.
 
...Also b/c it is wort and not water that is boiling I would bet that at boiling temp 1g/mL would probably be more accureate due to the increased sugar conten of the mixture, and then once you add hopps even higher...

While it is true that the specific gravity of a mL of wort is higher than that of pure water the water boils and the sugar doesn't so it doesn't make any difference. We still need to boil 1 gram of pure water to dissipate 2,270J. 1 gram of water (with or without sugar) is going to occupy less than 1 mL of volume at 212F. And thanks, this is definitely the first time I've used the Boltzman constant since P-Chem II.
 
Pol,

Would it be possible to not use a controller and just let the element run at 100% if it was sized properly...just guessing here, say 3500w for a 6 - 6.5 gallon boil?

I realize this will be kind of crude and take a bit longer to reach boil.

Mike

For my 7 gallon turkey fryer I have a single 1500w element that works fine. It take about 30-40 minutes to reach boiling and then I just leave it on at full power to maintain the boil.

The element was $8, the switch box ~$5 with the mount, box, gasket, faceplate and switch. The insulation was $12. I used a cord I already had, and the jb weld I already had. The bulkhead fitting and ball valve were about $10-13.

When I use it as an hlt it holds enough strike water for the mash, and will heat enough for the sparge by the time the mash is done.

It runs fine on a 15 amp circut. No upgrade required.
 
Great thread, hate to dig it up...but something occured to me about the radiative heat loss.....I'm no mathematician, but you need to take into account the evaporative and conductive heat losses....convection and radiation ARE occuring but all these processes are happening at the same time. My bet is that the majority of heat is being lost through the steam (wort/water changing phase and leaving the kettle...taking heat with it into the atmosphere) and by putting a cowl over the top you're actually slowing this process down. Sure, the cowl reflects heat back, but I think the steam leaving has a greater effect. Conductive heat loss is easy....just put something under the electric kettle to stop the stand from acting like a heat sink.
 
Didn't want to read through all these pages, but has anyone suggested using an electric stove burner controller.
That's what I use. I have a 4500 watt element to heat my water. The connections to the element and stove controller are housed in a Radio Shack project box attached to the side of my keggle.
Of course I maintain my heat manually but I have a thermometer installed.
So I just watch my temp when it gets close to target I start to turn in down.
 
Didn't want to read through all these pages, but has anyone suggested using an electric stove burner controller.
That's what I use. I have a 4500 watt element to heat my water. The connections to the element and stove controller are housed in a Radio Shack project box attached to the side of my keggle.
Of course I maintain my heat manually but I have a thermometer installed.
So I just watch my temp when it gets close to target I start to turn in down.

Iv been searching the forums for days to find someone that has tried an electric stove burner controller on their element. This is what I thought about doing. How is it working out. Do you use it for a boil or just to heat your mash water. I even thought about using an oven temp controller to heat and keep my mash and sparg water at desired temp.
 
Right now I'm using my keggle as a boil kettle as well as a mlt.
I heat my water for the mash. Then I transfer to my cooler and mix with grain.
When the mash is done I transfer the wort back into the keggle for the boil.
I use a couple of buckets with spigots to for the collection and transfer.
It works pretty good for me.

I have a link somewhere on my computer with info on how to build a infinite switch controlled hot water element.

I'll try to find it.
 
First off, you generally want to boil liquid off during the boil. So it isn't a matter of keeping the pot at 212F, it is matter of boiling off some liquid, which means you generally need a lot of power.

Most simple PID controllers can be tuned to keep a boil going but prevent a boil over. A PID plus a SSR solves that problem.

If you really need a "rheostat", there are these devices that control AC devices up to 10 Kw. They cost about $12 with a built in heatsink.

Most people have been over specing the heat sink for an on/off SCR. Generally a steel/aluminum enclosure will suffice. scrape off the paint and use heat sink grease.

https://www.ebay.com/p/Ac110-220v-1...-Speed-Controller-Dimmer-Thermostat/692538027
 
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