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How to choose an immersion heater

February 23, 2022 by Jamie Bristoll

There are several different considerations that apply generally to all types of immersion heater, regardless of what liquid they are to be immersed in or what type of application they are part of. If we deal with the generic aspects first, then readers can follow the links below, which will tie dowm the specifics of the various types of application you may be purchasing for.

An immersion heater is, simply put, a number of elements, usually 3, elements, a screwplug and a IP rated terminal box to protect the connections.

element
3 of these (preferablynot chopped up)
screwplug sizes
One of these, drilled through, for the elements to be braised or welded into.
Terminal box
…and one of these to attatch to the screwplug, to house the terminals and wiring.

First off, you need to decide on the necessary IP rating required for your terminal box. This will be dictated by your application, its location and position. As the name suggests, Ingress Protection ratings grade the terminal boxes ability to keep stuff out, thus protecting the connections, thermostats, contactors, etc, inside. See our IP entry for details as to the specific meanings of the 2 digits, but you need to match your application & situation, ie, indoor/outdoor, installed near to floor which is jet washed daily, in a chemically hazardous environment due to fumes from heated liquid, etc, to a minimum required IP rating. Our stock heaters range from IP54 (suitable for outdoor use) to IP 67. It is unlikely that you IP need will exceed what we supply, unless you are in the market for explosion and flameproof, flanged heaters, which we can supply, but in a rather different cost bracket and massively increased leadtime, as they are sourced from Italy.

Next on the list of considerations is the screwplug. The standard size in this fine country of ours is 2.25″ or 2 & 1/4″ BSP, which is probably a historical hangover that has, as yet, resisted the metric march of Brussels and the Eurocrats. It is indeed a quirky system, which I found downright confusing to begin with.

“What does a 2.25″ BSP screwplug measure across the thread?”
“2 and a quarter inches, stupid!” would be most folks reply (including me a couple of years ago!).
WRONG, its a little over 2 and a half inches, or 2.537″ or 2 & 5/8, if you prefer.

Have a look at the screwplug blog entry if you need further detail, & good luck.

Next thing to consider is what are you heating? Hopefully the answer is nice, clean, fresh council pop, or water, as it is known in more affluent areas. Our PII Range has Incoloy 800 sheathed elements, which are ideally suited to water heating and, if you believe the manufacturers is a “superior stainless steel” which has the “…ultimate chemical properties for high-temperature strength and resistance to oxidation, carburization and other types of high-temperature corrosion.”

Unfortunately, all waters are not created equal, and problems can occur with bore water and even good old tap water in hard water areas, usually due to calcium and magnesium, forming limescale deposits, attacking the elements, causing corrosion and splitting. Such problems are not insurmountable, but are more costly. Make sure to let your supplier know of any such potential issues ahead of time, so you can look into the costs associated with prevention, and if they can’t provide such solutions, contact me, because we can!

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 choose a brewery heater

Click above for the specifics relating to brewery immersion heaters.
 

Selecting an oil heater

…and above for oil immersion heater specifics.

Water hardness and it’s implications when choosing a water immersion heater

…and above for further information on water hardness and it’s implications when choosing a water immersion heater.

Filed Under: Immersion Heater

How to choose an oil immersion heater

August 17, 2021 by Jamie Bristoll 1 Comment

In addition to all the requirements for water immersion heaters, for oil heaters our target is to get the watts density down, requiring more element or less power, that is the compromise facing the customer, who is always right, even when they are wrong!

For HEAVY INDUSTRIAL OILS we are aiming for <=12w/in².

For LIGHT COOKING OILS we are good with up to 25w/in².

If we stray above this, the sheathe temperature is too high, the oil caremelizes onto the elements, thus preventing dissipation of the heat, so it gets hotter & more stuff sticks, until something goes BANG!

POIL Oil Imersion Heater
Oil Imersion Heater

The FOIL 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.

On 2″BSP & above screwplugs, the elements drop from the screwplug to your maximum available immersed length, before looping back up to within a few inches of the screwplug (taking care not to stray into the cold section), 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. Thus, nearly halving the resultant watt density.

If you are in the privilidged position of having a very large tank with a massive space available for immersed length, you may choose not to double loop, but to have plain U bent elements over a meter in length.

But for most folks, size is important! And this is where compromise is required to achieve the target watt densities shown above.

Filed Under: Immersion Heater Tagged With: brewery immersion heater, considerations, immersed length, immersion heater, immersion heater for brewery, specifications, watts density

TP Fay

Liverpool-based suppliers of bespoke heating elements and immersion heaters

Hassett Industries

international supplier and manufacturer of infrared heating products in Amesbury, near Stonehenge.

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