Immersion Heaters

[MickBrown]

I have fitted 2 immersions to the same cylinder in the last 8 months. Both have blown. They are 11in and bottom immersions on a huge cylinder that takes 3 hours to drain down. My electrician friend has checked it and cannot give an electrical reason for this to happen. Has this happened to anybody else? Anybody any advice? There didn't appear to be a lot of scale in the bottom of the cylinder, however both times it was getting late so did not investigate fully.

 

[lame plumber]

cheap immersions and acidic water often combine to fail early. try one of these 11in Incoloy Immersion Heater | NoLinkingToThis

 

[chris watkins]

De-scaled before installing new one's ?????????

 

[snowhead]

How many more immersions does it have?
If the cylinder takes 3hrs to drain, either the drain off cock needs looking at or it needs a few more kw of heating in the cylinder.

 

[SimonJohns]

How many more immersions does it have?
If the cylinder takes 3hrs to drain, either the drain off cock needs looking at or it needs a few more kw of heating in the cylinder.

Or it could be a unvented cylinder and he's not draining it correctly

 

[snowhead]

Or it could be a unvented cylinder and he's not draining it correctly

And he shouldn't be working on it

 

[SimonG]

Some sort of electrolytic action or cheap and nastie immersions.

 

[Zippymark]

I think the quality of a lot of immersion heaters is just really poor these days. I used to work in a plumber's merchant and we got them returned faulty almost more than anything else.

 

[MickBrown]

It is not unvented. Large vented around 250 ltrs, has top immersion and bottom economy 7 immersion. It is normally heated by oil boiler but in the summer the clients use the economy 7 immersion.
The house is quite large and a long landing before stairs. Cylinder starts draining okay initially but then slows to a trickle for the last 6 or 7 inches which take ages.

 

[Cello]

What was the mode of failure? e.g. was it scaled up, was it corroded, was the element open circuit? Knowing how exactly it failed will give clues as to why it failed.