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-   -   PID with two heating elements and how to wire it? (http://www.homebrewtalk.com/f170/pid-two-heating-elements-how-wire-287935/)

diS 12-18-2011 08:47 AM

PID with two heating elements and how to wire it?
 
Hello to all of you!

I have dilemma on how to connect and wire two heating elements and one PID, I hope someone will help me out with this.

This is my setup:
Auberins SYL-2352
2 SSRs 25A
2 Heat sinks
2 2000w 220V heating elements (both in HLT)

I will use two heating elements (2 x 2000w) in my HLT, and I would like to be able to turn on both of them or only one to heat and maintain water temperature.

They will both work at the start, when water temperature is reached PID will turn off both of them and I will turn off one of them (with switch) and let the other one to maintain temperature.

I searched through forum and I found that they have to be wired in parallel, can I use one of these wiring diagrams (and which one) to wire it:

http://www.homebrewtalk.com/f51/elec...2/#post1931368

http://www.homebrewtalk.com/f170/my-...5/#post3485613

What dou you think about this idea, can it be done or maybe it is wiser to connect both heating elements so they run as single one (if I run them as single one do I need two SSRs)?

Lucky_Chicken 12-18-2011 01:04 PM

doing what you are looking for is very doable! You will need a contractor for each element then you can switch one or both elements off. You would want to auto tune your PID to the single element so it functions correctly when up to temp.

The the diagrams you show will power one or the other not both. you would need something that has at least one ssr fired off the pid and two contractors (or strong enough switches) on switches, one of the elements can just be wired up with the contractor so when the switch is on its on the other one gets fired per the pid

Bobby_M 12-18-2011 01:23 PM

I'm curious why you feel having one turn off completely is of any advantage? Is it so that you have some capacity to run the boil kettle?

onthekeg 12-18-2011 01:44 PM

OP, I would think you could just run the SSR's with a jumper line between the two + posts from the PID, and put a toggle switch between the two SSR's so the other one is "dead" to the PID.
PID + to SSR 1, Jumper to toggle switch, toggle switch to SSR 2 +.

JRems 12-18-2011 03:11 PM

Quote:

Originally Posted by Bobby_M (Post 3581382)
I'm curious why you feel having one turn off completely is of any advantage? Is it so that you have some capacity to run the boil kettle?

I'm wondering the same as well. Won't the pid take care of everything? Why not just run one 4000w element and use the pid to scale back the temp, I don't see the advantage to having 2 heating elements.

diS 12-18-2011 03:54 PM

I already have 2000kw elements from previous setup, so I would like to employ these two.

@jtsims21I & onthekeg

I am trying to figure what you said (and have hard time with it since my electrician knowledge is for shame..).
Is this jumper:
Western Electric Wax wires Bi-Wire Speaker Jumper Cable | eBay
toggle switch:
3-Pin SPDT ON-OFF-ON Toggle Switch 6A 125VAC | eBay
and contractor:
LC1-0910 M7 Safety Electric Circuit AC Contactor Switch 25A | eBay??

@Bobby_M
Main reason is associate with AC power available to my whole house which is 4.4kw on each of 3 phases (13.2kw overall), so when PID runs 2 heaters there is reduced power on 2 phases which can cause in break on that phase (if someone else in house load that phase), not big deal but pretty PITA..

Another purpose is to disable frequently firing SSRs which should decrease heating of them.
It is not big deal if I have to run both heaters at the time, but it would be nice to prevent phase break and SSRs overheat.

Bobby_M 12-18-2011 04:03 PM

That makes sense now.

onthekeg 12-18-2011 04:57 PM

Any wire of the proper gauge can be a jumper wire. Essentially you have a + wire from your PID to SSR 1, and a wire from this post to the same post on SSR 2. Cut the wire in the middle and run it to your toggle switch. Its low voltage, so pretty much any light wire you have will work.

You will only need a OFF ON toggle switch for this. When its off, only one element fires, when its on, both will fire.

diS 12-18-2011 06:28 PM

Thanks!
So you are saying to put toggle switch between +wire on SSRs input from PID.
Would this diagram work (made by P-J on other thread), I"ll be using two pumps also:
http://img194.imageshack.us/img194/6...simple1.th.jpg

or remove upper switches and put jumper w/switch:
http://img847.imageshack.us/img847/9494/80634951.th.jpg

onthekeg 12-19-2011 12:25 PM

I would do it like the bottom picture. You can use a cheaper switch, but its up to you.


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