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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> Immersion Heater repeated failure https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1504277613 Message started by Charmwah on Sep 1^st, 2017, 3:53pm

Title: Immersion Heater repeated failure
Post by Charmwah on Sep 1^st, 2017, 3:53pm

Hi all

I've got an issue with a persistent immersion heater issue which I think may be related to something other than the heater itself. I might add that I live on a narrowboat, but that the electric supply is normal mains as i'm hooked up to a shoreline. The immersion heater itself is a 1kw type.

In September of last year my immersion heater failed (I came home to find breaker tripped on my consumer board and the main breaker on the shoreline post). After checking to see whether it was the thermostat (it wasn't), I replaced the immersion heater element and all was good, no issues.

Fast forward to April of this year, the new immersion heater failed in exactly the same manner. I bought a new multimeter and diagnosed a ground fault on the immersion heater, so replaced the heater once more for new. This lasted until the weekend where the same problem has developed, only this time I was there when the heater tripped out the breakers.

The only other thing of possible relevance is that I have an electronic timer which plugs into the mains socket, to which I then plug the immersion heater into. This of course then turns on the immersion heater for a few hours each morning and afternoon.

My concern is that there is some issue which is causing the heating element to fail, since it seems unlikely that I would have 2 elements fail in relatively quick succession.

Is there anything anybody can suggest I do? I'm thinking i'll replace the wiring from element to plug, on the assumption that the cable may have an issue?

Thanks in advance!!

Title: Re: Immersion Heater repeated failure
Post by thescruff on Sep 1^st, 2017, 9:36pm

What is failing the element or the stat.

Is the element permanently in water.

Title: Re: Immersion Heater repeated failure
Post by Lectrician on Sep 2^nd, 2017, 7:53am

What is your water source? There are titanium elements available. Some tanks can have sacrificial anodes fitted, usually magnesium.

Title: Re: Immersion Heater repeated failure
Post by scotspark on Sep 3^rd, 2017, 4:09pm

Sounds like electrolytic action corroding the elemen

Title: Re: Immersion Heater repeated failure
Post by CWatters on Sep 4^th, 2017, 2:06pm

Quote:

breaker tripped on my consumer board and the main breaker on the shoreline post

Sorry of this is a daft question but are you sure the immersion elements are failing?

Does the breaker on your board supply anything else? You mentioned a plug so is the immersion element plugged into a circuit that feeds other outlets?

Title: Re: Immersion Heater repeated failure
Post by The_Trician on Sep 4^th, 2017, 6:15pm

Could be a spike when the plug-in timer switches off.

You could try the heater without the timer for a period if practical (you'd obviously have to stay with it to see if it worked ok)

Title: Re: Immersion Heater repeated failure
Post by Charmwah on Sep 5^th, 2017, 9:54am

Hi all

Thanks for your responses. To answer the queries:

* I'm diagnosing a ground failure on the element itself.
* The element is permanently in water.
* The element type is an Ecotherm HE111A (available at www.heatrodshop.com) and uses an alloy element, so very unlikely to have corroded so quickly.
* The water source is my water tank (approximately 250l capacity), which is then filled manually from a standpipe on shore.
* The breaker on the consumer board only supplies one double plug socket. The other socket is in use by my battery charger (Sterling type, 40A smart charger). This charge is used to smart charge my 2 120Ah leisure batteries. I would note that this is not a new addition, and has been used on the boat for the last 5 years without any issue, until recently of course.
* The trip occurred when the timer switched the immersion heater on, not when the timer was switching the heater off.

I'm wondering whether there could be anything else at fault, such as the wiring having a split, or something else which could cause a power surge and blow the element?

Thanks again for your time all!

Title: Re: Immersion Heater repeated failure
Post by CWatters on Sep 6^th, 2017, 8:33pm

Re: "I'm diagnosing a ground failure on the element itself."

They appear to have a 12 month warranty so would be interesting to see what the manufacturer says.

Title: Re: Immersion Heater repeated failure
Post by Charmwah on Sep 7^th, 2017, 7:51am

I called and they've asked first for photos of the element that i've removed. My guess is that they'll eventually ask for the element to be returned for further testing.

I'm not calling into question the reliability of the element, and i'm happy to have any shortcomings of the system shown up. When I spoke to them they suggested that the element may have been dry, but since my element is in the bottom of the tank, and the system is pressurized so that as soon as any water leaves the system the pump kicks in, I can't see how it could have run dry without my knowing about it...?

Title: Re: Immersion Heater repeated failure
Post by thescruff on Sep 7^th, 2017, 2:20pm

That was my first thought, Is there a chance the cylinder is full of scale.

Title: Re: Immersion Heater repeated failure
Post by Charmwah on Sep 12^th, 2017, 12:23pm

To respond specifically to thescruff's comment, No the tank isn't full of scale, no issue there at all.

After further conversations with the element manufacture i've been sent a 3rd element to try out...