Immersion heater: copper, Incoloy or titanium element?

[boilingpoint]

Hi,

I'm replacing a 14" copper immersion heater installed into a Fortic hot water cylinder. The heater failed after just three years.

Hoping to get more life out of the next one, I've ordered an Incoloy, but am wondering whether to go for the titanium instead. It's only an extra couple of pounds in Screwfix. That said, according to the water company, the supply is "mod. soft" with a "hardness clarke" of 5.18. (No idea what that means.) Should Incoloy even be necessary? The water quality analysis is here.

As it happens, I'm no fan of the Tesla heaters that Screwfix sells. The temperature scale on their thermostats is unhelpfully in 15 degree intervals with no graduations in-between and the installation guide for the last one wrongly showed the neutral wire connecting directly to thermostat, missing out the element completely.
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Would a titanium heater have any practical benefit over the Incoloy--or is it the case that even the Incoloy is unnecessary and that the copper should do?

 

[boilingpoint]

Anyone have any thoughts?

 

[ShaunCorbs]

How long has your existing one lasted ?

 

[boilingpoint]

It failed after three years. Don't know the reason yet as I've not had chance to drain the cylinder. The thermostat is fused with black scorch marks.

 

[SimonG]

So have you tested the immersion? Might just be the thermostat.

 

[boilingpoint]

Don't have a multimeter but did replace the thermostat with a new one. No heating even though there was voltage at both terminals of the thermostat.

Looking again just now, the site of the blow-out seems to be the heater's neutral terminal in the boss. Taking the thermostat apart, there's no damage inside. The scorch marks are on the outside only.

Have also just noticed that the neutral wire has come away from its terminal. Doubt I'd have missed that, but I'll clean it up and try with the new thermostat again.
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Actually, rather than reconnect, I'll get hold of a multimeter. If the element's shorting then connecting up again could be unpleasant.

 

[Swoopdave]

Don't have a multimeter but did replace the thermostat with a new one. No heating even though there was voltage at both terminals of the thermostat.

Looking again just now, the site of the blow-out seems to be the heater's neutral terminal in the boss. Taking the thermostat apart, there's no damage inside. The scorch marks are on the outside only.

Have also just noticed that the neutral wire has come away from its terminal. Doubt I'd have missed that, but I'll clean it up and try with the new thermostat again.
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Actually, rather than reconnect, I'll get hold of a multimeter. If the element's shorting then connecting up again could be unpleasant.

You should use an insulation tester to check whether the element is breaking down and therefore needs replacing

 

[Lou]

(Just bumping a few older threads, they will drop off what is new soon)

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