9kw element wired as 3kw?

[MooseMan]

Thought I'd put this out there for input before I do too much research on it.

Ok, so as a result of a failed install at work, I have several of these elements available to me for free.
They are for commercial hot water boilers and cost between £150-200 each so decent quality.

They can be wired single or 3 phase and have 3 heater loops of 3kw on each element for a total of 9kw.

They are threaded fit, with the thread being brass, but the inward face of the brass is silver, so I'm assuming it's been tinned when the loops were brazed in.
Opinions on this?

Incoloy elements, 400mm long.

I should've taken a pic under the cap while I had it in my hand at work, but basically there's a separate connection for each loop, so 3 one side 3 the other.
So what I'm thinking is, obviously I can't run them as a 9kw element at home unless I install some chunky breakers in the garage, so if I was just to wire one loop, that would be a 3kw element right?

Am I being dumb here or is it that simple?

[Yummyrum]

No moose , you ain’t dumb .
You have it correct

They look like nice units .

[MooseMan]

Why thank you sir!

They do look real nice, very solidly made.
I think there are 5 in total.

I'm slowly forming a picture of a new, upgraded keg boiler, so these should fit the bill nicely and I'll have spares for a very long time!

I do want to put 2 in though, as my current setup, so at 400mm long that's gonna need a little creative thinking unless I have one higher than the other, or mangle the keg wall out of round.

[Wildcats]

Nice score MooseMan. Can't wait to see what you do with em.

[Squint]

Nice score, will the length, 400mm fit across a 50ltr ss keg ?

[elbono]

If you want two why not just connect two out of three on one unit?

[zach]

If the heater power was rated at higher voltage, the power is not the same at a lower voltage, which is likely the case at home.

For instance with a 9 KW three phase heater wired in a delta configuration ,the resistance is 57.4 ohms per leg (assuming 415 V for UK 3 phase power rating).

If you wire the three heater legs in parallel the resistance is 19.1 ohms. With 230 volts, the three heaters in single phase will produce 2,740 watts.

[NormandieStill]

If the heater power was rated at higher voltage, the power is not the same at a lower voltage, which is likely the case at home.

For instance with a 9 KW three phase heater wired in a delta configuration ,the resistance is 57.4 ohms per leg (assuming 415 V for UK 3 phase power rating).

These look like a better manufactured version of the element that I use. Mine is a stainless triclamp one. Each element has an L and an N terminal and the 3 phase configuration is star not delta.

I originally wired mine with one element controlled by an scr and the other 2 switched. I now have all three wired in parallel on an SSR which lets me use it as a very low watt density element when using less than 1500W.

[MooseMan]

These responses are exactly why I did this!

So, rather than wire just one loop, join them all together (They actually are supplied with brass couplers to join all 3 loops) and take a live and neutral from there, and this will act as a LWD element with much lower power, because of the resistivity of all 3 combined?
Is this the case?

Zach you really seem to know what you're talking about on this, so please feel free to school me!

I'll take a pic of the element internals on Monday for a clearer picture of what we are discussing.

[NZChris]

There are seven ways you can wire three equal elements to give you a variety of Wattages to choose from.
Add a power controller and you have infinite control from 0-9000W with some handy low Watt density options.

3*3000W elements
All in parallel = 9000W
Two in parallel = 6000W
One plus two in series = 4500W
Single = 3000W
Two in parallel in series with one = 2000W
Two in series = 1500W and is low Watt density
Three in series = 1333W and is low Watt density

[Yummyrum]

They can be wired single or 3 phase and have 3 heater loops of 3kw on each element for a total of 9kw.

Moose , while Zach is correct that depending on whether they are wired in star or delta will change the available power , but you have already said that they can be either single phase or three phase connected .

This implies that they are intended to be only wired in star configuration on three phase (240v per element ) . It also implies that that they will be 3kw per element on single phase (240v per element)…… which is what you require .

If they were wired in Delta three phase , they would receive more voltage ( 415v )than they are rated for and be over powered and burn out .

So the fact that they are rated at 9kw single or three phase means that you will get 3kw per element per phase.
If they were rated for 9kw three phase with no mention of Single phase , that would imply that they are rated at 3kw per element @415v per element .

If this is the case then what Zach was referring too would apply .
If when you take off the cover and find a strapping bar that Connects one leg of each element together , this will confirm that it was wired in Star configuration .
This would be the arrangement in an element such as yours where the three elements are physically in parallel

[shadylane]

I didn't have any luck searching for a Thermco 32040-XTYSC immersion heater.
What voltage is it rated for? Does it have a built in thermo shut off?

A pic with the cover off and an ohm measurement across 1 element would help.

[NZChris]

Searching for the part # finds a 6KW element.

[zach]

I tried to find a submittal or OEM data sheet and was unable to locate on the website.

An Ohm meter could end all debate .

[shadylane]

3 phase in your area is 415 volts?
Single phase house wiring is 230 volts.

A 3kw 415v element will draw 7.2 amps and have a resistance of around 57 ohms.
The same heater connected to 230v will draw 4 amps and 920 watts.
Just guessing, the three elements need to be connected in parallel.
But first a resistance measurement is needed to be sure.

[MooseMan]

Yes I couldn't find that exact part on the web either, strange.

The website gives several iterations with differing letters at the end, but none that match this exact one.

I'll bring one home and do what you guys are suggesting, then report back.
Problem is that won't be until the end of the week as I'm working away from Monday to possibly Friday.
Watch this space!

[kennstminet]

The ratio of a real 3-phase voltage to its single line voltage ist determined by the physics of the construction and is the same in any country. It is the squareroot of 3 which is 1,732.

In Europe, the single line voltage is 230V. 230 times 1,732 gives 400 Volts 3-phase voltage.
For a single line voltage of 120V, this gives 208 V for 3-phase.
As far as I understood (correct me if i'm wrong), in USA the households are normally not supplied with real 3-phase current. They are supplied with triple single phase voltage, each line with 120V. For higher loads, triple single phase voltage of 240 V per line is available.
I do not know about the UK system. It seems to be 240V and real 3-phase of 415V.

In order to decide how to handle the OP Heating Element, it must be understood if it is designed for a real 3-phase voltage system or for a triple single phase voltage system. The elements resistance will be different.
Measuring the resistance of the element will make it easy to calculate the heating power for a certain voltage.
If the resistance is R and the voltage is U, the resulting power P is calculated as P = U^2 / R.
U^2 means the square of U or U x U.

For a UK manufactured Produkt, I would assume that the 9kW are achieved in a 415 V 3-phase system.
Each single element would bring 3000W at 415 Volts and have a resistance of 57,41 Ohms.
If connected to a single line of 240 V, the power would be only 240 x 240 / 57,41 = 1003 W per individual element.
To achieve a heating power of 3009W with a single 240 V mains, all three individual elements need to be connected in parallel.

[NZChris]

Maybe Google gives us Kiwis better results?

https://www.google.com/search?client=fi ... 2040-XTYSC

https://www.advancedwater.co.uk/product ... 2040-WTYSC

[MooseMan]

Maybe Google gives us Kiwis better results?

https://www.google.com/search?client=fi ... 2040-XTYSC

https://www.advancedwater.co.uk/product ... 2040-WTYSC

Yeah that's all I can find too Chris, not the same part numbers, very frustrating.

The engineer that fitted the boiler told us they were 9kw.

Soon find out when I get one home to test and share the numbers I suppose!

[NZChris]

Ohms means more to me than part numbers or the say so of the engineer.

[Yummyrum]

Agree , the resistance will reveal all .

Here are the two possible three phase connections for the European or Australasian system …… ( Just for anyone that is remotely curious )
Note: I have left USA out because Neutral means different things to most there.

In the star configuration , the Neutral does not need to be connected but doesn’t matter if it is . As can be seen , in the Star configuration , the voltage across each element is 240v even though the Phase to phase voltage is 415v

The resistance of the elements required for either connection type is significantly different . So a multimeter check will quickly confirm whether or not the element will give the same power on single phase .

But its quite obvious that the Star connection element lends it’s self perfectly to either Single or three phase operation .

Also of interest is that the in the European and Australasian system , each Phase is 120° to the next .
That is why although each single phase relative to Neutral is 240v , the phase to phase voltage is 415v .

Like kennstminer said

The ratio of a real 3-phase voltage to its single line voltage ist determined by the physics of the construction and is the same in any country. It is the squareroot of 3 which is 1,732.

[zach]

Zach you really seem to know what you're talking about on this, so please feel free to school me!

This question could have been on the test for my first semester circuits class in engineering school. (I took 35 years ago.) I am a mechanical guy so it's kind of fun to see if I can still remember the basics of other disciplines.

[MooseMan]

I didn't have any luck searching for a Thermco 32040-XTYSC immersion heater.
What voltage is it rated for? Does it have a built in thermo shut off?

A pic with the cover off and an ohm measurement across 1 element would help.

Ok so I whipped off the cover and snapped a couple of pics this morning when I swung by the office to go on my travels.

Here's what they look like under the cover.
The brass connector bars can be removed, obviously.

I won't have chance to put a meter on it until Friday though.

[Yummyrum]

Boom
And there it is.
All wired up for single phase .

Three 240v elements

Now all you have to do is remove the strapping bars and with a multimeter , work out which elements are still OK .
Presumably one element has failed and gone open curcuit .

The good ones will measure 19.2 ohms .

Now , if NZchris’s detective work is correct and your sparky was wrong , meaning its really only a 6kw ( 2kw per element) , then the good ones will measure 28.8 ohms

[elbono]

When you put an ohmmeter on it you should get about 6 1/2 ohms with all the elements connected in parallel like the pic. Each element should be about 19 1/4 ohms separately.

If not it's not 9 kw.

[Yummyrum]

When you put an ohmmeter on it you should get about 6 1/2 ohms with all the elements connected in parallel like the pic. Each element should be about 19 1/4 ohms separately.

If not it's not 9 kw.

Correct , but Mooseman has acquired them from work as they were replaced because they were faulty . So it’s highly likely that at least one element is O/C , so testing them all strapped together won’t give the same reading as a new unit with three working elements .

[elbono]

When you put an ohmmeter on it you should get about 6 1/2 ohms with all the elements connected in parallel like the pic. Each element should be about 19 1/4 ohms separately.

If not it's not 9 kw.

Correct , but Mooseman has acquired them from work as they were replaced because they were faulty . So it’s highly likely that at least one element is O/C , so testing them all strapped together won’t give the same reading as a new unit with three working elements .

I saw failed install, not failed element. In any case pulling the copper straps and testing each element is the best way to know what you have. Test from power connection to the sheath on the highest megohm scale as well if there were element issues

I have an old hand crank megger I use on any suspect items to be sure it's not got a grounding issue but I doubt anyone else does. They are also great for fishing as long as the game warden isn't around.

[MooseMan]

Sorry my initial post has caused confusion gents.

I have these elements because an intended water heating installation ended up not happening. (That's what I meant when I said failed install)

They're all new and in perfect condition, no issues at all.

I found a wiring diagram in a box, showing single phase wiring one page and 3 phase on another page, with a little explanation about wiring for single.

So I put a meter across both sides with them all joined as I pictured.

And I got 10ohm


Then I removed the bars and measured across just one loop.

And got 31ohm

What does this tell me?

[NZChris]

I use this.

https://www.rapidtables.com/calc/elect ... lator.html

[elbono]

I'm more familiar with US electrons but I believe that tells me in Wales each loop is 2 kw and all three together are 6 kw.

I did some work in Britain and I thought the power was 410V three phase, 240V single phase. What I see on the interwebs now is 400V/230V. If your single phase is 230 you'll only get 1750 w with one loop and 5250 w with all three.

All the combos listed here are still valid, just multiply by 2/3 to account for what you actually have.

There are seven ways you can wire three equal elements to give you a variety of Wattages to choose from.
Add a power controller and you have infinite control from 0-9000W with some handy low Watt density options.

3*3000W elements
All in parallel = 9000W
Two in parallel = 6000W
One plus two in series = 4500W
Single = 3000W
Two in parallel in series with one = 2000W
Two in series = 1500W and is low Watt density
Three in series = 1333W and is low Watt density

I wondered what the two dead end tubes were, I doubt you have use for thermostats but it could be a handy place to put a temp probe if you want one.