Regularly our most consistent seller, but not entireley sure why this is over other power ratings, a 6kW immersion heater obviously suits many industrial applications.
The popularity could be down to the fact that, with the correct wiring, fuses, etc, you can get away with 6kW on a Single Phase feed, or as it houses three elements, it is also fine for a Three Phase feed. If the heater is wired 4 WIRE STAR, it can even be reconfigured to single phase by shifting ther busbars around, but that is clever stuff, for cleverer folks than me. If you are sufficiently intrigued, the images on this page will hopefully show this theory in practice.
It could also be down to the immersed length at 20″/500mm or below being a good fit for many liquid vessels. Some customers fit multiple 6kW heaters into a vessel as a bank of heaters, rather than fit an 18kW immersion heater, at about twice that length.
This may also effect the control side of things, with an 18kW immersion heater consisting of 3 x 6000w elements, whereas our friend the 6kW heater has 3 x 2000w elements. Some customers switch entire heaters in a bank on /off for temperature control purposes, some cleverer folks switch phases of just one heater on/off. Others use thyristor control, which basicaly varies the voltage, dialing up & down the power to fine tune temperature.
Insider Knowledge, you can put any voltage thru an element & get proportionally more or less power.
Thank you for visiting, & kudos to you for reading this far. If you have any feedback, suggestions, etc, please feel free to contact me.
Anyone limited to a 240v Single Phase supply, as most domestic situations are, must buy a Single Phase Immersion Heater. These will by necessity be limited to 3kW under normal household circumstances, or 6kW if you have 32 amp wiring, fuses, etc.* If you are reading this & are clever and wish to educate me so I am able to elaborate further, feel free on 07897 246 779 or immhtr at gmail dot com)
If you buy something on a budget, you are likely to get one element on a screwplug, thus you attatch live to one terminal, neutral to the other, and away you go (unless you have a control/cutout stat, but lets keep things simple here & now. If you want complicated, there is a wiring diagram HERE). The downside to the financially economical (cheap) option is that it is likely to have a really high watt density (explanation for normal people HERE , but if you are one of that rare & special breed, THE BREWER, click HERE).
Put simply the more heating power coming out of every square inch or cm of your hot element, the higher the sheath temperature, the more sh1t sticks (calcium & magnesium in our gloriously hard water) and the more any chemicals, acids/alkalis, etc, in your solution will attack the glowing element, and cause it to go pop, sooner rather than later. I sometimes advise customers to follow this disposable route, which is fine if you are proving an application, limited on budget, etc.
But if you want to (hopefully) fit & forget, you will have to spend a little more money on a 3 element Single Phase Immersion Heater, like our Industrial Immersion Heaters Range at 3kW or 6kW or our Brewery Immersion Heaters Range at 3kW or 6kW , or indeed any of the Oil Immersion Heaters Range. 3 element terminals will be linked with busbar to provide a common connection for the LIVE line, and similarly the other 3 terminals will be “commoned” up with busbar to provide connection for neutral. As below, in images I immediately feel the need to apologise for. Sorry.
3 elements will allow the watt density to be chopped into thirds. For example a 3kW heater with 1 x 3kW element, or a 3kW heater with 3 x 1kW elements (If the immersed length & element shape are the same. (It’ll last longer. How much longer? 3 times longer? Who knows? Certainly not me. But surely logic dictates? Only if you are a Vulcan). Which leads me on to U bent or looped elements. On a 1.5″BSP screwplug (Domestic Standard in UK) it is only possible to fit 3 U bent elements (8mm ⌀ , and a coupla stat pockets if you know an ElementJedi) whereas on a 2.25″BSP screwplug (Industrial Standard in the UK) you can fit looped elements, as below.
This enables even more element to be fitted into the space available. Which is why I often annoy customers by insisting on the “MAXIMUM immersed length”. An extra inch (Matron!) on 3 looped element is an extra 6″ of element, which is only gonna extend the working life of your heater a little bit more. So size is important, after all.
We stock the Industrial Immersion Heaters listed below for rapid delivery, but can make bespoke items to suit your specific needs if required. In BRASS that can include BSP screwplug sizes including 1″BSP, 1.25″BSP, 1.5″BSP, 1.75″BSP, 2″BSP as well as the British Industrial Standard size of 2.25″, which can be fitted with an adaptor to take it up to 2.5″BSP. In STAINLESS STEEL we can offer 2″ & 2.25″BSP screwplugs.
Bespoke items usually take a coupla weeks, but can be shuffled to the top of the pile if you are willing to pay a premium surcharge of approximately 50%. Customers only tend to do this when they are desperate, due to a production line being down & costing £££’s due to not carrying a spare. The moral of this story being, CARRY A SPARE, especially if your heaters are not standard (ie, 2.25″BSP and a multiple of 3 in terms of kW power output) and stock as listed below.
1.25″, 1.5″, 1.75″, 2″, 2.25″ and 2.5″ screwplug sizes are available in brass.
2″ and 2.25″ BSP also available in stainless steel.
Available with 1 or 2 thermowells at 7, 11 or 18″ for thermostats / cutouts.
1 additional M25 cable entry glands as an option.
Available with no thermowell if specified by the client. If you don’t need it, omit it from the build, as it is an unecessary weak point.
Call Jamie on 07897 246 779 to discus your Single Phase Immersion Heater needs.
*Fair play to you for checking out the footnote, hope it’s worth it? Having said all of the above, I have spoken to many a mad brewer, telling me they are running 12 & 15kW on a single phase, but that is mere rumour & hearsay, and my calls are not recorded for training & quality purposes). Again, if you are clever and can explain htf that is doable, please contact me, explain in small words, and if I can grasp it, we will share it with the world. I love a bit of Collaboration.
…one of these, drilled through, for the elements to be braised or welded into…
…and one of these to attatch to the screwplug, to house the terminals and wiring.
And, in the best Blue Peter traditions, here’s one we made earlier…
II Industrial Immersion Heater
The heater is then screwed throught the side of the tank using a weld boss…
Mild steel weld boss
Mild steel tanks require mild steel weld bosses, and likewise, stainless steel tanks require horribly priced stainless steel weld bosses. I’ll tell you what brass bosses are used for when I find out.
Informational content provided by Jamie at ImmersionHeaters.UK or 07897 246779.
I was going to provide a link to the best definition of watts density available on the web, but they are in very short supply, so here goes.
Watts density is the amount of heating energy emanating from any given amount of surface area of the hot part of an element.
In Imperial Britain and the States, this is usually described in terms of watts per square inch, but could be expressed (to keep the Eurocrats happy) as watts per square cm, mm, or indeed, meter. But why bother?
For 8mm diameter elements, simply divide the heating power output (in watts) of the given element by the length of hot section, ie. subtracting the cold ends at either end of the element, which can be 2″, 4″, 6″ or any custom length.
So, for the benefit of a simple example, if we have a 1kW, 54″ element with 2″ cold sections, we first take 4″ (2 ends of 2″) of cold off the total length of the element to give our hot section, 50″. Then we divide the power output of 1000w by 50″ to give us a watts density of 20w/in².
Now imagine we have a 1kW, 104″ element with 2″ cold ends (c/e), giving a hot length of 100″, do the maths as above, and you should get a watts density of 10w/in². Now, picture an inch square in your mind, or draw it if you prefer. Now, fill the box with 10 or 20 little boxes, happy faces, “watt monsters”, whatever crumbles your cookie. The size of the square doesn’t change between the 2 examples, but the size of the contents do, more watts per square inch means more squashed, little watts trying to get out of the same space. Now draw a box, mentally or on paper, and squeeze 40 of your little watt icons in that box. While your at it, have think about how long a 1kW element with 2″ c/e, would need to be to give a watts density of 40w/in²?
For the less imaginative among you, somebody kind drew this –
Different watts densities are requires for different applications. Some are set in stone, for obvious reasons, such as oil heaters needing to be no more than 12w/in², others are a little more flexible and open to “interpretation”. ElementYoda always told me 5w/in² for elements in still air, but as can be seen below, grill elements can work at up to 42w/in². Fortunately, we don’t supply many of them, cos there wouldn’t be much of a guarantee at that top end. We are mainly suppliers of immersion heaters for water, with soft water being fine between 50-75w/in², but hard water being better suited to 40w/in² or below.
Our (Element Air) EA Range is rated at 27w/in², designed for forced air heating units, where the airflow needs to be 2m³/s. The simple way this is achieved is that every meter of element equates to 1kW, so if you want 3kW you have to bend/coil a 3m element into your available space.
Below is a detailed table of watts density in inches and equivalent cm, plus details of colour change and suitable applications.
W/in2
W/cm2
94
14.5
Immersed only
83
12.9
Immersed only
73
11.3
Immersed only
63
9.7
Immersed / High Arflow / Machined Fit
52
8.1
Immersed / High Arflow / Machined Fit
42
6.5
Equivalent to Grill / Radiant / Orange
31
4.8
Glow Red
21
3.2
Colour Change
10
1.6
Little or no Colour Change Still Air
9
1.5
Little or no Colour Change Still Air
8
13.0
Little or no Colour Change Still Air
7
1.1
Black Heat
6
1.0
Black Heat
5
0.8
Black Heat
4
0.6
Black Heat
3
0.5
Black Heat
2
0.3
Black Heat
And for the visual learners among you, here is that same info in colourful form that I “borrowed” from a friend –
To convert to other element diameters, please divide your solution as above by the following factors. If you think of the 1kW, 54″ element with 2″ cold sections that we started with, only this one is 12mm in diameter, share our 20w/in² initial answer by the factor of 1.484, gives a watts density of 13.48w/in², which makes sense as a wider element will have more surface area for the 1000w to “escape” from.
mm diameter
FACTOR
8
0.99
8.5
1.05
9.5
1.175
10
1.24
11
1.36
11.5
1.42
12
1.484
12.7
1.57
13.4
1.657
16
1.98
20
2.474
50.8
6.28
When you understand all this, and realise that glowing ain’t good, you can see the sense in squeezing as much element into the space available, cos simply put, the lower the watt density, the longer it’ll last, whatever it is heating.
Informational content provided by Jamie at immersionheaters.uk Call on 07897 246779.
BSP really stands for British Standard Pipe, but some days it feels like it should stand for Bloody Sizeable Pain when it causes confusion. Best to be sure before ordering, as bespoke items cannot be returned!
2.25″BSP is stock & standard for our Industrial purposes. 1.5″BSP is Domestic Standard in the UK, and we can do them bespoke, but our heaters are Industrial Quality, Fit & Forget, IP67 terminal box, highest quality elements manufactured in the UK using the highest quality component parts. So we simply don’t compete with the “Eastern” shite online for 3 shillings & sixpence.
This is the simple INCH version…
BSP “
DIAMETER ACROSS THREAD “
1/2
.825
5/8
.902
3/4
1.041
7/8
1.189
1
1.309
1 & 1/4
1.650
1 & 1/2
1.882
1 & 3/4
2.116
2
2.347
2 &1/4
2.537
2 & 1/2
2.95
…so 2.25″BSP measures 2.537″, great!
Then my codged version, cos even I have to admit mm are a good deal easier to work with…
BSP”
⌀ ACROSS THREAD”
INTERNAL BOSS mm
EXTERNAL SCREWPLUG mm
Circumference mm
0.25”
0.518
41
1/2
.825
66
5/8
.902
72
3/4
1.041
83
7/8
1.189
95
1
1.309
104
1 & 1/4
1.650
39.5
41.5
131
1 & 1/2
1.882
44.8
47.7
150
1 & 3/4
2.116
51.2
53.5
168
2
2.347
57.5
59.2
187.2
2 &1/4
2.537
62.5
65.4
206.4
2 & 1/2
2.95
72.4
74.9
236.2
…and this is the complicated version, from Wikipedia –
Thread Form Type
Major Diameter mm d=D
Pitch mm p
Threads per inch tpi
Pitch Diameter mm d2=D2
Minor Diameter Male Thd. d3
Thread Height H1
Tap Drill Diameter mm
1/8 “
BSPP/BSPF
9.728
0.907
28
9.147
8.566
0.581
8.7
1/4 “
BSPP/BSPF
13.157
1.337
19
12.301
11.445
0.856
11.6
3/8 “
BSPP/BSPF
16.662
1.337
19
15.806
14.95
0.856
15
1/2 “
BSPP/BSPF
20.955
1.814
14
19.793
18.631
1.162
19
5/8 “
BSPP/BSPF
22.911
1.814
14
21.749
20.587
1.162
20.75
3/4 “
BSPP/BSPF
26.441
1.814
14
25.279
24.117
1.162
24.5
7/8 “
BSPP/BSPF
30.201
1.814
14
29.039
27.877
1.162
28
1 “
BSPP/BSPF
33.249
2.309
11
31.77
30.291
1.479
30.5
1 1/8 “
BSPP/BSPF
37.897
2.309
11
36.418
34.939
1.479
35
1 1/4 “
BSPP/BSPF
41.91
2.309
11
40.431
38.952
1.479
39.5
1 3/8 “
BSPP/BSPF
44.323
2.309
11
42.844
41.365
1.479
41.5
1 1/2 “
BSPP/BSPF
47.803
2.309
11
46.324
44.845
1.479
45
1 3/4 “
BSPP/BSPF
53.746
2.309
11
52.267
50.788
1.479
51
2 “
BSPP/BSPF
59.614
2.309
11
58.135
56.656
1.479
57
2 1/4 “
BSPP/BSPF
65.71
2.309
11
64.231
62.752
1.479
63
2 1/2 “
BSPP/BSPF
75.184
2.309
11
73.705
72.226
1.479
72.5
2 3/4 “
BSPP/BSPF
81.534
2.309
11
80.055
78.576
1.479
79
3 “
BSPP/BSPF
87.884
2.309
11
86.405
84.926
1.479
85.5
3 1/4 “
BSPP/BSPF
93.98
2.309
11
92.501
91.022
1.479
91
3 1/2 “
BSPP/BSPF
100.33
2.309
11
98.351
97.372
1.479
97.75
3 3/4 “
BSPP/BSPF
106.68
2.309
11
105.201
103.722
1.479
104
4 “
BSPP/BSPF
113.03
2.309
11
111.55
110.072
1.479
110.5
4 1/2 “
BSPP/BSPF
125.73
2.309
11
124.251
122.772
1.479
123
5 “
BSPP/BSPF
138.43
2.309
11
136.951
135.472
1.479
136
5 1/2 “
BSPP/BSPF
151.13
2.309
11
149.651
148.172
1.479
148.5
6 “
BSPP/BSPF
163.83
2.309
11
162.351
160.872
1.479
161.5
I hope these are useful for reference purposes.
More importantly for us, on a daily basis, are the following limitations as to what will fit onto the smaller screwplug sizes. We deal with up to 2.25″ only, with 2.5″ being accommodated by fitting a brass adaptor to 2.25″ screwplug.
2.25″
3 loops + 2 STAT
2″
3 loops + 1 STAT
1.75″
2 loops + 1 stat / 3 U + 2 stat
1.5″
3 U 1 STAT
1.25″
3 U NO STAT or 1 element looped + 1 stat
Anything smaller than a 1.25″ screwplug will be limited to 1 element, having immediate implications for the achievable watts density. Likewise, being limited to U bends only, makes reducing the watts density more problematic. Many domestic and commercial plumbing applications use 1.5″BSP, and are thus limited to 3 hairpins and only 1 stat pocket. maximising the immersed length of those U’s is all that can be done to reduce the watts density. To overcome the issue of only 1 stat pocket, we find ourselves increasingly selling dual control and cutout stats.
By U bent element, we mean
…and looped means –
To determine what element is suitable, for U’s you merely double the maximum immersed length available, ie, 24″ immersed length will use U bent 48″ elements. However, if double looping is possible due to the screwplug size and other factors relating to the application (cleaning, etc), that 24″ maximum immersed length could be multiplied by up to 3.5, allowing the use of 84″ elements. See the watts density article to appreciate what a difference that will make. 48″ to 84″ almost double the hot element available, so is almost going to halve the watts density. A big issue on little screwplugs.
If you wanna buy some stuff, take your pick between
IP Explanation and Ratings EN 60529 outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies (i.e. tools, dust, fingers) and moisture. This classification system utilizes the letters “IP” (“Ingress Protection”) followed by two or three digits. (A third digit is sometimes used. An “x” is used for one of the digits if there is only one class of protection; i.e. IPX4 which addresses moisture resistance only.) Degrees of Protection – First Digit The first digit of the IP code indicates the degree that persons are protected against contact with moving parts (other than smooth rotating shafts, etc.) and the degree that equipment is protected against solid foreign bodies intruding into an enclosure.
0 – No special protection.
1 – Protection from a large part of the body such as a hand (but no protection from deliberate access); from solid objects greater than 50mm in diameter.
2 – Protection against fingers or other object not greater than 80mm in length and 12mm in diameter.
3 – Protection from entry by tools, wires, etc., with a diameter of thickness greater than 1.0mm.
4 – Protection from entry by solid objects with a diameter or thickness greater than 1.0mm
5 – Protection from the amount of dust that would interfere with the operation of the equipment.
6 – Dust tight.
Degrees of Protection – Second Digit The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g. dripping, spraying, submersion, etc.)
0 – No special protection.
1 – Protection from dripping water.
2 – Protection from vertically dripping water.
3 – Protection from sprayed water.
4 – Protection from splashed water.
5 – Protection from water projected from a nozzle.
6 – Protection against heavy seas, or powerful jets of water.
7 – Protection against immersion.
8 – Protection against complete, continuous submersion in water.
Remembering all of the aspects and considerations discussed on the “How to choose an immersion heater” page, water hardness must be taken into account when designing a water immersion heater.
A detailed description of water hardness can be found HERE, but for the purposes of this blog, we will say that hard water has a higher concentration of calcium and magnesium which leads to limescale, which we are all familiar with in kettles, etc, within the home. Whilst merely being an inconvenience in the home, (one that can be avoided by using one of these beauties which are awesome and well worth the money if like me you consume litres of water a day, highly recommend, no business interests or bias by bungs!) it can be a real issue in commercial and industrial applications.
The problems are caused by the limescale deposits building up on the hot part of the elements. Once this process starts, it becomes self perpetuating, and indeed self accelerating, if not removed by jet washing, disolving or other means. Basically, the limescale build up prevents the heat getting away from the element, acting like an unwanted insulating jacket, increasing the element surface temperature, which in turn, attracts more deposits. An example of which is shown below, courtesy of gimmecoffee.com, which would perhaps be better used as a christmas tree than for making coffee!
The easy way to maximise the working life of your immersion heaters, whether in a hard water area or not, is to minimize the Watts density. The article explains in detail a simple concept which we are using every day, maximise the element length THUS minimising the watts density THUS maximising the working life of the element, all other things being equal.
Informational content provided by Jamie at immersionheaters.uk Call on 07897 246779.
Remember all of the stuff that applies to all water immersion heaters, plus for oil heaters our target is to get the watts density down to 12w/in² or below for heavy, industrial oils, and 25w/in² or below for lighter cooking oils.
Oil Imersion Heater
The II Range has many benefits, including bespoke screwplug size, immersed length, double stat pockets, etc, all with a 2 week leadtime. The 8mm elements can be double looped to fill your maximum available immersed length with a large overall length of element. As can be seen in the fifth image on our PII web page, the elements drop from the screwplug to your maximum available immersed length, before looping back up to within a few inches of the screwplug, before dropping back to full immersed length, then returning back up to the screwplug. This allows us to fit nearly twice the length of element possible in a plain U bent element. For example, in 24″ of maximum immersed length, we could use an 84″ element double looped.
if you have a very large tank with a massive maximum available immersed length, you may choose not to double loop, but to have plain U bent elements over a meter in length.
Informational content provided by Jamie at ImmersionHeaters.uk …who would love you to leave a comment.
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