FSD Element series parallel circuit

[pecker]

I just finished my new still build and along with it I made a simple power controller for the welded FSD element that I bought.
It's a 2400w element and for any of you who have used them you'll notice that they are actually 2 x 1200w element in parallel.

This is not instruction for anyone to try but if you know a sparky he or she should have no problem wiring this up for you.

What it will allow you to do with just 2 simple switches is run the 2400w element at full load - 2400w, half load - 1200w, or quarter load - 600w

Here's the wiring diagram:

Element wiring.jpg

Back of the element:

Element 1.jpg

Back of the switches:

Switch wiring.jpg

Now here is the current/amp draw on each configuration, ignore the SSR in there as it has nothing to do with this post.
Full load:

10amp.jpg

Half load:

5amp.jpg

I have a pic for quarter load which reads 2.59amps but I can only upload 5 images.

Let me make it clear that I have used standard household light switches which are rated at 10amp, 2400watt is essentially going to pull around 10amp, could be more or less depending on voltage but what I will recommend is you use 15amp switches if you plan on running mostly in full load mode. If you constantly pull the rated current things may start to get hot and possibly melt and short out, or worse, hurt you. I use this just to heat my boiler up for about an hour then switch to half load mode - 1200watts.

So what's going on here is when the 2 switches are in the on position the two 1200watt elements are connected in parallel which allows 2400watts of power to be consumed. This is your maximum output you can get from this element.
When one switch is turned off, doesn't matter which one, the power only flows through one of the 1200watt elements which halves your power output/consumption.
When both switches are switched off the configuration of the 2 elements are now in series (which means power is flowing through 1 of the 1200watt elements first then on through the next one), this increases total resistance which in turn drops the power consumption by half again, now you are consuming 600watts which is a quarter of the maximum.

To achieve this you need a 4 core + earth circular cable of 1.5mm2 per core. I found this will just fit into the provided gland on the element guard which is also from FSD.
There isn't much room inside the guard and if you get something wrong you could short out your power and make some nasty burn makes on your equipment so I really recommend using a sparky, with this information they would be able to connect it for you.

Just a cheap and easily acquired way of regulating you power input to your beloved boiler.

[pecker]

Here is quarter load current - 2.59amps:

2.5amp.jpg

Here is the front view of the switches:

Switches.jpg

[punchy21]

Top work packer, nice detailed explanation... :clap:

[WTDist]

Very interesting, Ill look into this when i start running 2*2.4kW elements

[scythe]

Why tho?
I have thought the same thing actually, and was going to wire it up in a similar manner but then i cottened on to SSR power controllers and they are more adjustable and simpler to use.

And if you controll both elements then you can adjust them both so they are not running at "red-line" so to speak.

[pecker]

Why tho?
I have thought the same thing actually, and was going to wire it up in a similar manner but then i cottened on to SSR power controllers and they are more adjustable and simpler to use.

And if you controll both elements then you can adjust them both so they are not running at "red-line" so to speak.

The SSR's are good I'll agree but this is a bulletproof way of stepping down power consumption with the flick of a switch which you can buy at your electrical wholesaler or even bunnings if you like. They cost a few bucks each and anyone can get them in their town or city.

Another thing, you can put your SSR inline with this circuit so when your SSR fails you can bypass it and still have some simple control.

For my 2" Boka I run 1200w and can reflux at 600w, I don't really need much more control then that and others may not either.

[WTDist]

Has anyone else tried this? im soon to buy a couple of FSD elements and instead of using a controller this might be worth looking into for me.

[warramungas]

Makes sense. Could even rig a t500 like it the same as it has the two elements as well though I think they have different wattages.
The only thing I could fault is it uses a 4 wire cable (not counting earth) so the element would need to be connected to the box on a permanent basis. You couldn't just unplug it, roll it up nice and neat and store it away. Or maybe use a 3 phase plug?
I've heard of people putting a switch on one side to halve the wattage from one element but not putting it through both to quarter it.
Kudos for thinking outside the box! :handgestures-thumbupleft:

[WTDist]

Certainly seems interesting to me. Would love any input to help me understand it more.

What do you man by it will be always connected to the box on permanent basis? do you mean always connected to the switch box, always being moved with the boiler as one?

Edit; Just googled 3 phase plug, i see what you mean i think. would bump the cost up a bit but would make it easier to use.

If i printed out this page would this be enough for me to describe to an electrician how i want it wired up?

[warramungas]

A lecky probably could. It confused me a bit until I realised the switches must be in the closed position but they look open except for the little line joining the switch to the line. When both switches close they activate the 'bypass' which wires them both in series. I didn't know light switches had two positions. I thought they were on or off.

[WTDist]

oh i see now, in the diagram. i didnt see the little line too. 8-}

Now i understand how it works :handgestures-thumbupleft: .
I really think i will do this on the new boiler. make the other controller not required

[WTDist]

Just looked over on FSD to check elements. Can you do this to the weldless elements? back of the element is different on FSD page for weldess. Looks like the other one in the pic.

Anyone got a pic of the back of the weldless elements?

[rumdidlydum]

It can't be done with the weldless element due to only two wires exiting the sealed end.

[WTDist]

Cheers Thx rummy,
with the welded element. I read it has a 1" BSP thread which i assume it screws into a 1" socket of some kind thats welded to the boiler? with some PTFE tape

What are these sockets called?
want to do a search for them to see what my costs would be if i had to buy 2 and weld them on. I have no idea when it comes to what fittings are called :-D

Ill add a pic just for show


Cheers
WTD

[warramungas]

Cheers Thx rummy,
with the welded element. I read it has a 1" BSP thread which i assume it screws into a 1" socket of some kind thats welded to the boiler? with some PTFE tape

What are these sockets called?
want to do a search for them to see what my costs would be if i had to buy 2 and weld them on. I have no idea when it comes to what fittings are called :-D

Ill add a pic just for show


Cheers
WTD

Its a socket you need. Fsd sell gaurds for welding on. They look the ducks nuts.
Someone on one of these threads said they were 32mm bsp thread but not 100% sure for that. I haven't measured mine.

[scythe]

"1inch BSPT socket" is what they screw into.
No such thing as a 32mm bsp, bsp being an imperial thread form and all.

BSP fittings will work with BSPT as they are the same pitch, but you will need to use more thread tape to get it to seal which is not really a drama, well it is for me because i am me, i only use BSPT with BSPT.

I made my own tho.

[WTDist]

Sorry for revisiting this guys. still got my attention.

So i did an ebay search for those BSPT fittings and found BSP fittings. Is BSP best with BSP? I say that knowing it sounds stupid but i need to ask, and does this one in the link below look acceptable?

http://www.ebay.com.au/itm/1-4-BSP-Fema ... nw4X-d4miw



And as for the switches in this diagram below can i simply use a rocker. The one i have now in my controller i think would work well for this given it has power to what ever side it is switched to. I can have it on, or off and if both are off it should do the series shouldnt it? i have power going in middle prong and out to the side it is switched to.


Thinking a 15A rocker might be better than a light switch

Cheers
WTD

[punchy21]

Hi WTDist, just refer to scythes post above regarding the threads :handgestures-thumbupleft:

As for the switches, 15A is fine, just check that they are rated for 240V and they are double pole with NO and a NC contacts on each switch(normally open and normally closed) :handgestures-thumbupleft:

[Psykamaholik]

My 2c worth would be to use a rotary 5 position switch instead of multiple light switches so that way it's as easy as turning a dial to the output you want.

Something along the lines of this:

rotary switch.jpg

[warramungas]

Reviving an old thread here.
I just unplugged the dryer in the laundry that was on a stand alone switch and found 'well bugger me! That's a 20 amp socket!'.
Any reason I couldn't rig this to a 4800 watt element (if fsd have one) so I can run it in a normal socket or a higher powered socket for more power when available?