Heating element ? (wireing in series)

[rod734]

How will it effect the amp. wattage, ect. if I wire two 4500 what elements in series. Will I have 9k whats or a extra low density 4500? I could probably drag out the book and figure this out, but I know some of you guys know it by heart.
What I'm shooting for is a more gentle heat to avoid scorching. Im building a 80qt BIAB using a steamer basket. My spa panel has a 60 amp 240v, and a 20 amp 120v breaker in it. I'm not sure how much power I will need to maintain a boil with 15 gal. but I was thinking of running two elements, one on a contactor to run continuisly, and one on an ssr with a pwm to controll. After a few batches I can size my elements accordingly. After reading about some scorching issues I thought about this series thing.

 

[Docgineer]

The resistance of the elements will add in series so just double the power and current. Paralell will drop the power and current by half in each assuming the elements are of equal resistance.

 

[ChuckO]

The resistance of the elements will add in series so just double the power and current. Paralell will drop the power and current by half in each assuming the elements are of equal resistance.

Sorry, just the opposite. In SERIES you add the resistances, therefore dropping the current by half. In PARALLEL you double the current draw and therefore double the power.

 

[pvtschultz]

CHuckO is correct. 4500 Watts at 240V results in a heater resistance of 12.8 Ohms and 18.75 Amps. The resistance of elements in series is additive making two 4500 W elements appear as one having 25.6 Ohms. Using the same 240V will give you 2250 W.

In parallel, the circuit resistance is 1/Rt = 1/R1 + 1/R2. For our example, the resultant resistance will be 6.4 Ohms and at 240 V the current draw will be 37.5 Amps for a power of 9000 Watts. The benefit of a parallel circuit is that each each element operates at the line voltage and the failure of an element in the circuit will not prevent the others from operating.

This is a sloppy solution to a $25 problem though. Instead of guessing what you are going to need to boil a particular batch of wort, why don't you instead use a Pulse Width Modulator ($10) and a Solid State Relay ($15) so you can nearly infinitely vary your boil strength?

PWM DIY - https://www.homebrewtalk.com/f170/pwm-show-us-how-221301/
PWM Purchase USA - FK804 DC Motor Speed Control (you'll need to substitute one capacitor though)
PWM Purchase China - DC 12V-24V 3.2 A Motor Speed Control PWM Controller High Quality Low Price | eBay (you'll need to substitute one capacitor though)
SSR China -http://www.ebay.com/itm/300620508416?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 (quick shipper)
SSR USA - 40 A SSR [RS1A40D40] - $19.00 : auberins.com, Temperature control solutions for home and industry
Heat Sink for Solid State Relay, 40A [HS40] - $18.50 : auberins.com, Temperature control solutions for home and industry

 

[Docgineer]

Oh ya, got em crossed up! Thanks for correcting me before I messed his setup up. The PWM driving both is a nice solution for maximum control

 

[rod734]

Oh ya, got em crossed up! Thanks for correcting me before I messed his setup up. The PWM driving both is a nice solution for maximum control

I have a controll panel with a pid and a pwm that I built. I'v used it to do xtract batches and to can pickles in a smaller pot. I'm building an 80qt pot to do 15 gal biab and I was concerned about scorching. It's my understanding that even with a controll panel when the elements are firing they are at full power and get very hot. I read a thred a while back by firebird 400, and he said he was usinging two sets of two elememts and was getting scorching, so he added two more elements and wired them two sets of three elements to get the same power with more surface area and eleminated the scorching.

thanks for replys