Heating Element Control

[Hawke]

Klaassen,
There are several that use(d) the two element process. I do think you would be much happier if you had the ability to fine tune it though.

[Klaassen]

Hawke,
Thanks, I think you've got a point. Might as well build things as versatile as I can from the start, instead of trying to revise and piece everything together down the line.

[HookLine]

Is this foolish, is a hard wired power control like this too coarsely grained?

Not at all. If you have dual voltages, like in the USA, and you have two different size elements, then by switching between different combinations of voltage and elements you can in principle get 8 different power levels. So if you pick the element sizes carefully you could do without a dedicated controller, for both reflux and pot stilling.

However the fine degree of control an electronic controller gives is good to have, and is not particularly expensive.

[Gunslinger]

Question for you technosavy guys. I do have a 15 amp variac and intend to use it for my self on 1500w and 2000w elements. But I seen this on ebay and was wondering if it would work to control heating element on 120v AC. I have read through most of the posts on here and like the diagrams and talk in the pages. This may be similar to the posts about router speed controllers, but I am just not knowledgeable enough to know if it is the same or not. Any input is appreciated as I plan to build a couple of units.

http://cgi.ebay.com/AC-or-DC-ELECTRICAL ... %26ps%3D54

[rad14701]

Gunslinger, some folks have had pretty good luck with router controllers while others haven't... For the price it would be worth a shot but I don't know if I'd try one with a 2000W element... The unit in your link, at the bottom of the page, only has an 18 gauge power cord and the amperage would exceed 15A... A 1500W element would be the maximum for that particular controller... A 2000W element would require a 20A circuit, minimum...

[Gunslinger]

Thanks for the reply. For the price, I may try it since if it burns up, would not be a big expense. I always have the variac to use in any case for myself.

[DBDub]

Alot of good info here, I've read over all 16 pages 3 or 4 times I've seen little explanation for sizing of the elements. I'm building a 25g pot and been trying to figure out which way to go with the element(s). acording to a few ignorant calculations it will take 25000Btu to bring 200lb wash from 75 to 200f. I also found a few btu ratings for elements stating 2000w @235 vac = 6824 Btu/H and 4500w = 1863 Btu/H????????? that seems like I'd need 2 large elements to heat my pot at a reasonable time. Is there any info out there on sizing of elements?

[LWTCS]

I'm building a 25g pot and been trying to figure out which way to go with the element(s). acording to a few ignorant calculations it will take 25000Btu to bring 200lb wash from 75 to 200f.

.

I think you may need a bigger boiler to bring a 200 pound charge up to temp. 200 lbs is like 23(and change).
I'm not a math/formula guy so I tried to gauge my element choice by everyone else's OJT so to speak.

I run a 240 volt, 4500 watt element that will produce vapor (from the boiler) from a 40 liter water charge in 45 minutes.
I use a DPDT 30 amp switch to control power input. Its a limited amount of control.

Next year I'll save for the variac switch.

[leob2]

macmaster.com has several heating element sizes and dimmer switches you can use for a boiler control. I have a keg w/a 2000 watt preheater on the upper part,of the keg its plugged directly into the wall until your up to temp. Then on lower element I have a 1500watt running through a 1000 watt dimmer switch, never had any trouble.Not expensive either.they have all sizes check em out.

[E_C_Flanderson]

Thanks to everybody for the information, this is my first post on the board but have been reading for about a year - there is so much information here, I have never had to ask a question. I have just built a voltage controller based around one of these:

http://cgi.ebay.co.uk/POWER-VOLTAGE-SPE ... 19b73a0607

Its seems to be similar to the circuit in the schematic and only costs £20. I simply put a CPU heatsink on it and installed it into a recycled PC PSU case. It works really well and can easily handle my 3000w heating element at 240v.

[leob2]

check mcmaster.com look at their dimmer switches. My 600w from still drinkin burnt up in 2 runs (may they burn in hell). But it gave me the idea to build a good one with stainess fittings etc. mcmaster.com will replace what you need and I havent had a single problem since I have a 1000 watt dimmer but they have much larger including 220 volt ones at a resonable prices.

[DBDub]

OK I found a compilation of usefull info that helped me and may help others.

BTU= energy req to raise temp of 1lb of water 1deg 1 hr
1 gal water = 8.333lbs
1 cubic ft of water = 7.48 gal
1 gal = 231 cubic inches
capacity of a cylinder in gallons is equal to (in inches) Length x Diamiter sqared x .0034
water expands 4.34% from 40* to 212*
1ft water column = .4333 psi or 1 psi = 27.6in

Amps (1phase) = KW x 1000 / Volts

BTUs
1 KW = 3412
1cu ft Natural Gas = 1075
1cu ft Propane = 2570

in my case 25g is max (w/6" head space) and probably wont be filled. These #'s are at 100% efficiency and I understand that a mash is going to be heavier than water, so its just a jumping off point.

25g = 208.325 x temp raise 125* (75* to 200*) = 26040.6 BTU
26040.6 / 3412 = 7.63 KW
7.63KW = 33.17 Amps @ 230v

I dont want to go above 30A so I think I'll stay a bit lower at 6500 or 6000W split between 2 elements. 4500w on a thermostat and 2000w on a controller. I don't mind a bit longer heat up time since I will be making 1 run vs 2. It will still save alot of time in changing over and heating the 2nd batch.

Thanks again for all these great posts
D.

[Igor_From_Jdessa]

OK I found a compilation of usefull info that helped me and may help others.
BTU= energy req to raise temp of 1lb of water 1deg 1 hr
D.

"1 hr" is error. BTU don't include time. BTU mesures energy, not power.

If heater element a 1 kilowatt works 1 hour, he gives 3412 BTU in a cube.
if you need 26040.6 BTU, heater element 1 kW must works 7.6 hours - wery long time.
Heater element 7.62 kW will works 1 hour, but 33 amps is large load.
You must choose the middle.

My case. Cube 13g (50 litters). 10g of wash. 2 heater element a 2.2 kilowatt = 4.4. Time of effervescence about 40-45 min.
Time of distillation after diminishing of power to 3 kW - 2-2.5 hr. Result - 11 liters -50%vol (2.9 gallons).

For regulation of power i use simple home-made dimmer with triack BTA41-800 or BTA41-600. Maximum load 40 amps - 9 kW.

[Tater]

OK I found a compilation of usefull info that helped me and may help others.
BTU= energy req to raise temp of 1lb of water 1deg 1 hr
D.

"1 hr" is error. BTU don't include time. BTU mesures energy, not power.

If heater element a 1 kilowatt works 1 hour, he gives 3412 BTU in a cube.
if you need 26040.6 BTU, heater element 1 kW must works 7.6 hours - wery long time.
Heater element 7.62 kW will works 1 hour, but 33 amps is large load.
It is needed to choose in the middle.

My case. Cube 13g (50 litters). 10g of wash. 2 heater element a 2.2 kilowatt = 4.4. Time of effervescence about 40-45 min.
Time of distillation after diminishing of power to 3 kW - 2-2.5 hr. Result - 11 liters -50%vol (2.9 gallons).

For regulation of power i use simple home-made dimmer with triack BTA41-800 or BTA41-600. Maximum load 40 amps - 9 kW.

The British thermal unit (BTU or Btu) is a traditional unit of energy. It is approximately the amount of energy needed to heat one pound of water one degree Fahrenheit. One Btu is equal to about 1.06 kilojoules. It is used in the power, steam generation, heating and air conditioning industries. In scientific contexts the BTU has largely been replaced by the SI unit of energy, the joule (J), though it may be used as a measure of agricultural energy production (BTU/kg). It is still used 'unofficially' in metric English-speaking countries (such as Canada, the United Kingdom), and remains the standard unit of classification for air conditioning units manufactured and sold in many non-English-speaking metric countries.

In North America, the term "BTU" is used to describe the heat value (energy content) of fuels, and also to describe the power of heating and cooling systems, such as furnaces, stoves, barbecue grills, and air conditioners. When used as a unit of power, BTU 'per hour' (BTU/h) is understood, though this is often abbreviated to just "BTU".

The unit MBTU was defined as one thousand BTU presumably from the Roman numeral system where "M" stands for one thousand (1,000). This is easily confused with the SI mega (M) prefix, which multiplies by a factor of one million (1,000,000). To avoid confusion many companies and engineers use MMBTU to represent one million BTU. Alternatively a therm is used representing 100,000 or 105 BTU, and a quad as 1015 BTU.

[Igor_From_Jdessa]

tater, thank You for quotation from vikipediа. I studied this page before writing of my report and changed my numbers from SI in BTU. But unit of measuring of energy does not change time of heating and distilling or rectification.

When used as a unit of power, BTU 'per hour' (BTU/h) is understood, though this is often abbreviated to just "BTU".

Unfortunately this abbreviated gives many misunderstanding in the calculations of power.