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Discuss Horizontal cylinder indirect immersion heating element burnt out in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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Hi


We recently had a horizontal cylinder installed with a main hot water supply from a gas boiler. The immersion heater was hooked up to a solar panel diverter to utilise excess power generated by the panels. This worked great for the first few months, but suddenly the diverter was reporting a problem with the immersion heater.


After sending the diverter off for testing and three new thermostats the issue was still not resolved, so I eventually convinced the heating engineer that the heating element must be at fault and he replaced it the other day.


The old element was completely burnt out and the engineer said that diverter must be supplying too much power which cause the burn out. During the replacement I noticed that the engineer has rotated the cylinder so that immersion unit is now at the bottom of the tank whereas before it was at the top.


So would the diverter have burnt out the element, as the engineer suggests or would the fact the heating element was near the top of the cylinder (and possibly not submerge) have been the cause?


Thanks


Paul
 
I highly doubt your solar panels have enough power to burn out an immersion heater.

I don't think the element been placed towards the top would burn it out either, the position of the element is to give you maximum hot water usage, not prolong the life of it.

If anything I would say that if your in a hard water area, the wrong immersion had been used or possible faulty thermostat or maybe set too high.
 
Is the cylinder actually designed to go horizontally? I have come across a similar problem where someone had installed a regular unvented cylinder in a horizontal position, the main problem being that the cylinder is not able to fill properly and some of the element can remain not fully submerged.
Whatever the cylinder, the orientation is critical when fitted horizontally- get it checked by someone who knows what they are doing or you will have problems.
 
The old element was completely burnt out and the engineer said that diverter must be supplying too much power which cause the burn out. During the replacement I noticed that the engineer has rotated the cylinder so that immersion unit is now at the bottom of the tank whereas before it was at the top.

Have you got a photo of the burned out element?
 
If its the standard elements it wont last .
On solar PV they are a different element, ask the manufacturer for the correct part no.
 
Thanks all for you replies.

The cylinder is designed to be horizontal and was installed by heating engineer and the solar diverter by an electrician, so it's not something I have attempted myself.

The diverter is the Apollo GEM-C and it does state that it works with any standard immersion heater. The immersion is rated as 3kw and the diverter supplies variable power from 50w - 3kw depending on what the panels are generating, so not sure why it would need a special element.

I have attached a picture of the element.

Cheers

element1.jpg


element2.jpg
 
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I’d still be checking with the manufacturer that the immersion is suitable for solar. Manufacturers guidance wins out and all that
 
At the time it stopped working it was only 3 months old and when it was pulled out a couple of days ago it had been in about a year.

I live in North Yorkshire, which is a soft water area (30 ppm).
 
Well the new immersion heater is inncoloy which has better corrosion resistance then the copper one that was removed.
I presume you are on a gravity system and not unvented?
 
To me, that photo looks like a copper immersion heater that's failed due to electrolytic corrosion. (The corrosion seems to worsens as you get towards to the flange, which is closest to the tank.) If so, the replacement needs to be a type recommended by the cylinder manufacturer.
 
Why aren’t we asking the manufacturer what they recommend??? Then the onus is on them for the correct info.
 
I would be approaching the cylinder manufacturer and asking A if the cylinder is suitable for solar and B if it is what immersion they recommend to work with that set up. Speaking from experience their unvented cylinders usually have the immersion heater on the top when it’s a horizontal cylinder
 
Just read through this and was very confused at first. Then I realised 'diverter' meant inverter!

Seeing that the cylinder is a copper cylinder, as Riley has said, I would def bounce it back to RM for advice.

It looks to me like quite a cheap element (RM are pretty cheap) and if the inverter is pushing out a slightly higher voltage than it should and the immersion is perm on then it would not surprise me to see what's happened. Normally when an element goes, its caused by a local hot spot or ten with a root in calcification. This looks to me like it's just overheated and gone.

Once you get the correct type of element that should be installed, I'd a) buy a (much) better quality version from elsewhere and b) get the inverter output voltages checked to see they don't exceed 240vac when the panels are generating and there is no load.
 
The solar PV isn't connected directly to the hot water cylinder in anyway. It works by using a sensor that detects if power is being export or imported to the grid, so if the Solar PV is generating more than is being used in the house power will be exported to grid. There is a control box that sits between the mains and the immersion heater and depending on the amount of power being exported allows between 50w – 3kw to the immersion. The idea is that no excess power is exported to the grid and is utilised to heat water in the cyclinder.

Regarding the position of the immersion, my first thought was would the level of the water drop below the elements at any point which sounds like it wouldn’t from the replies. It does not look like sufficient heat was being dispersed as mentioned earlier.

I am going to contact RM today and see what advice they give.

Thanks
 

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