What are the different types of immersion heater spanner?
What are the different types of immersion
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There are two main types of immersion heater spanner: ring headed (flat and cranked immersion heater spanners) and box headed (box, heavy duty box and box ring immersion heater spanners).
Advantages and disadvantages, as well as the reasons why each type has been designed, are listed below. |
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Flat immersion heater spanners |
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This is a basic immersion heater spanner. It can be used on any uninsulated hot water cylinder to remove the immersion heater element.
It can also be used on cylinders with removable insulation. |
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What is insulation?In order to prevent heat loss (which would result in an inefficient heating system that costs more money to run), hot water cylinders are usually insulated. Insulation can also be referred to as ‘lagging’. There are two main types of insulation: fibreglass insulation inside a vinyl sheet or jacket, which is easily detachable from your cylinder, and polyurethane foam, which is attached directly to your cylinder. |
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Hot water cylinder insulation – fibreglassThis type of insulation works in a very similar way to putting a coat on a human being. By wrapping a sheet of fibreglass insulation around the hot water cylinder it prevents heat from escaping. The vinyl coating prevents fibreglass fibres from coming loose. If your hot water cylinder is insulated in this way and you need to change the immersion heater element, you will be able to remove the insulation by simply pulling it away. This means you will be able to use a flat spanner for the job. |
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Hot water cylinder insulation – polyurethaneMost cylinders are insulated with polyurethane foam sprayed onto the cylinder by the manufactureres. The thickness of foam around the immersion heater element will prevent the use of a flat spanner, so you’ll need to try a cranked or box spanner instead. |
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Cranked immersion heater spanners |
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The cranked immersion heater spanner has been designed with insulated cylinders in mind.
The cranked (bent) handle will clear the insulation while the head of the spanner still maintains a snug fit over the immersion heater element. |
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Recessed immersion heater elementsSome models of hot water cylinder are built into a separate housing. Insulation lies between the cylinder and the housing or cover to prevent heat from escaping. This works in the same way as an insulated cylinder. The cover may be made from stainless steel, or steel sheeting that has been coated to protect from corrosion. The immersion heater element is usually located underneath a panel, inside a gap in the insulation. This is referred to as a recessed or inset element. |
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As with insulated cylinders, you would not be able to use a flat spanner to change this kind of immersion heater element because the handle would not fit into the recess. Cranked immersion heater spanners can be used instead as the handle will clear the recess, allowing the head to fit snugly around the heating element. | |||||||||
Box immersion heater spanners |
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Also known as an element key, the socket of the box immersion heater spanner fits over the heater element to create a snug fit. The base of the tool is octagonal to create the best possible grip. | |||||||||
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The tommy bar is used to rotate the spanner and can be adjusted to make one long handle or two short ones. It can be used on any type of hot water cylinder. | |||||||||
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It is possible to use a Stillson pattern pipe wrench or a pair of adjustable grips to turn this kind of spanner if it does not have a tommy bar, although gripping it anywhere other than the base (close to the hot water tank) comes with a risk of damaging the tool. | |||||||||
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Some models of box immersion heater spanner come with slots cut into the part of the tool that grips the immersion heater element.
Elements are connected to mains power and most spanners require the power cable to be detached before the heating element can be tightened or slackened. Box spanners with slotted bases allow for the tightening and slackening of the element without detaching the power cable. |
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Heavy duty box immersion heater spanners |
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A heavy duty spanner is made from thicker high quality steel than a standard tool. This increases its resilience and makes it less likely to break. | |||||||||
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Box ring immersion heater spanners |
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A box ring spanner has similarities with both box spanners and cranked spanners. It is cast from one piece of metal, which means that it is more efficient at converting force applied to the handle into torque to loosen a stiff immersion heater element. It can be used on any type of hot water cylinder.
It is expensive compared to other types of immersion heater spanner but is built to be durable. |
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