heating element

What is a heating element?

October 4, 2022 by Jamie Bristoll

For the full shilling version, see the web authority on everything, Wikipedia, or an informative, if uninspiring, site referenced on the wiki page.

The extremely abridged version – its an electrically powered tube which applies direct heat to liquids and gases.

And finally, the Process Heating Services version. Here is one I chopped up earlier –

<[youtube https://www.youtube.com/watch?v=ZV1yuBxdA4Q&w=560&h=315]

Video for those that are allergic to reading.

The top end is the terminal, sometimes a spade connection, but more usually a thread, washer and bolt combination, geared at holding the electrical connection, ie, incoming wire, in place.

Below the nuts is a white plastic plug which serves as a seal against ingress of moisture and also to hold all of the important bits inside in the middle of the tube, away from the sheathing.

The sheathing material is the outer housing, the solid casing, usually made of a metal, in this case Incoloy 800, a stainless steel variant. This serves to encase and protect the important bits, protecting them from whatever is being heated, ie, oils, chemicals, etc.

The white compacted powder inside the tube is magnesium oxide powder, which serves as an insulator against electrical leakage, but as a conductor of the heat generated by that electrical current. It serves to hold the filament wire centrally within the tube so that contact with the sheathing material is all but impossible.

Finally, the tiny wire seen protruding at the bottom of the picture is the filament wire which creates the heat in the core of the element. Usually Nickel Chromium, this converts electricirty very efficiently into heat, with only a little wastage as light, as with the filament of an old light bulb. Whilst it is straight in the picture above (due to being hacksawed), under normal circumstances it would be coiled centrally in the magnesium oxide, as shown below, in this very cool x-ray.

The picture above also helps to explain the terms cold end, cold section, dead length, etc. The bit before the wiggly filament, that looks a bit like a hose pipe, is the other end of the terminal pin, the nuts & washers electrical connection as described above. Usually mild steel, this section is not going to create a great deal, if any heat, and so this is termed the cold section. All elements have two terminals, one at either end, to complete an electrical circuit, and both ends will have a cold section of 2 – 6″ dependent on the application.

This length would have to be subtracted from the element length when calculating watts density, ie, a 48″ 1000W element with 6″ colds has only 36″ active length (48″ – 6″ – 6″ = 36″), so the watts density of this element is 1000 / 36 = 28w/in².

So that is a plain heating element, but what about finned heating elements?

Mainly for use in air duct heaters, finned heating elements are merely plain elements as detailed above, but with finning added by a very clever machine.

This allows for better dispersion of the heat, basically by creating more surface area of heated element in the same available space.

Thanks for your interest. Any comments, feedback, additional information, please feel free to use our contacts page.

Our updated website is up, running and ready for viewing.

August 9, 2022 by Jamie Bristoll

Following a great deal of hard work and patience on the part of our Website Team at Counsell.com, our new WordPress website is ready to view at processheatingservices.com

There is a lot more content on the site, much more product detail, and hopefully, all laid out in a way that a first time visitor in search of a UK based supplier of immersion heaters or heating elements, can drill down through the content to find information about exactly the product that they are after.

For example, someone in search of a 1kW finned heating element, may land on our website from natural listings or from adverts, on the ‘heating elements‘ page, they would then select ‘Finned Heating Elements – PEF Range (250W – 7kW)’ where they would then find a list of the various lengths and kW ratings available as finned elements, from which they would select 1kW, taking them to the PEF Range – Finned Heating Elements 1000w / 1kW page, which lists the various lengths of element that are available with a 1kW rating (20″, 24″, 26″, 30″, 32″, 34″, 36″, 40″, 42″, 48″, 54″, 60″, 66″, 72″, 78″, 84″, 90″, 96″, 104″, 114″, 120″, 132″, 144″, 170″, 180″). They can then choose the length which best suits their application, then ring us on the phone numbers ever present in the right hand bar, to place their order.

Also new additions are many of the photographs, showing much greater detail of terminal boxes, element looping, element diameter, etc.

PIH - HEAVY DUTY INDUSTRIAL IMMERSION HEATER TERMINAL BOX

Again, these are for the benefit of new customers, to get a feeling for the dimensions, quality, etc, of the heaters they are considering purchasing. These pictures are complemented on the specific Range pages, by tables showing all available kW ratings, plus sub pages for each individual heater in that range. We hope that the intuitive nature of the information allows ‘viewers’ to navigate to exactly what they want, then ring us and tell us what they want, rather than ringing ‘blind’ and asking if we supply something suitable to their needs.

The ‘OddBins’ page is also new, and is my attempt to sell off some of the accumulated bits and bobs at bargain prices, just to get rid of it and reclaim some space. These are items, sometimes ordered in error, sometimes sent as samples by prospective suppliers, but just oddments that may fit somebodies exact requirements. I’d never even heard of a ‘Hopper Heater’ but now you can buy one from us!

The website will grow, as will this blog, over the coming months and years, and we welcome any feedback, input, guidance, etc, from anyone with the interest and motivation to give it.

Just to repeat our enormous gratitude to all at Counsell.com for teaching a man to fish. Cheers!

How to choose a water immersion heater

July 23, 2022 by Jamie Bristoll

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, (if I can’t taste it in my tea, and remember not to look in the kettle when filling it, I can pretend it’s not there) 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 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.

How to calculate the kW required to heat a volume of water in a particular time.

August 28, 2021 by Jamie Bristoll

Click for our online water heat up time calculations page HERE.

One question which comes up time and again is “How many kW do I need to heat up my tank?”

Or phrased a different way, “How long is it going to take my ? litres of solution to raise ? °C using my ? kW heater?”

If we can calculate the volume of water and the required temperature rise, we can answer these questions using the following formula.

It is used to calculate the power of heating element needed to heat a specific volume of water by a given temperature rise in 1 hour.

volume in litres x 4 x temperature rise in degrees centigrade / 3412

(4 being a factor and 3412 being a given constant)

for example 100 litres of water, to be heated from 20ºC to 50ºC, giving a temperature rise of 30ºC would give –

100 x 4 x 30 / 3412 = 3.52

meaning that the water would be heated in 1 hour by 3.5kW of applied heat.

Also we can use this information to extrapolate both ways. To heat the same water volume in half the time (30 minutes) would need twice the heating power, ie, 7kW.

Converesely, if we only use half the heating power, 1.75kW, it will take twice as long to heat up to desired temperature, ie, 2 hours.

If we only have a 1kW element available, we will expect a heat up time circa 3.5 hours.

Also we can use this formula as the basis of similar calculations for heating oil. Generally speaking, oil heats up in about half the time of water, due to its viscosity & density. However, oil requires a much lower watts density element than water, as described here in the “How to choose an oil heater” article.

Another variant of this formula, given here at the excellent website Sciencing.com gives the following varaint of the formula & subsequent explanation-

Pt = (4.2 × L × T ) ÷ 3600

Calculate Kilowatt-Hours

Calculate the kilowatt-hours (kWh) required to heat the water using the following formula: Pt = (4.2 × L × T ) ÷ 3600. Pt is the power used to heat the water, in kWh. L is the number of liters of water that is being heated and T is the difference in temperature from what you started with, listed in degrees Celsius.

Solve for Thermal Power

Substitute in the appropriate numbers into the equation. So imagine you are heating 20 liters of water from 20 degrees to 100 degrees. Your formula would then look like this: Pt = (4.2 × 20 × (100-20)) ÷ 3600, or Pt = 1.867

Divide by Heater Element Rating

Calculate the amount of time it takes to heat the water by dividing the power used to heat the water, which was determined to be 1.867 with the heater element rating, listed in kW. So if your heater element rating was 3.6 kW, your equation would look like this: heating time = 1.867 ÷ 3.6, or heating time =0.52 hours. Therefore, it would take 0.52 hours to heat 20 liters of water, with an element with a rating of 3.6 kW.

Which made better sense in my little brain when I put a multiplication sign between P and t, allowing 30+ year old math class memories to clarify that if you move the Power (P) or the Hour (t) to the other side of the equals symbol, we gotta divide by that number also. “Change the side, change the sign” Thanks Mr Phipps, some of it actually stuck, hope you are still above ground, happy & healthy.

P x t = (4.2 × L × T ) ÷ 3600

…which doesn’t usually “show” as t = 1 hour, as in kW(1)h.

Hope you found this useful.

Any feedback, suggestions, improvements, etc, PLEASE COMMENT, I promise to read ’em.