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Well known electric car brand immersion heater problems

aligarjon

Hi Guys.

Has anyone else had problems with the above .  I got called to a job a couple of weeks ago, tenant had no hot water.  They had an unvented cylinder in the roof with dual immersion heaters that were both not working. Supply was a single supply via Horstman off peak timer with boost function for the top element in the day.

I could get power to both elements by manually adjusting the clock or boost but neither worked . Both thermostats seemed to work ok and overheat stat had not operated.  

Plumber came in and replaced both elements. We then had the same issue, power to the elements, but no hot water. The strange thing is my clamp meter was reading that they were drawing 12.6 amps each when tested and the tenant (a student with an energy usage gismo in his lounge) was charged £4.00 on his meter over a few hours and still got no hot water.  You could see his readings going up and down as i turned the elements on and off.  

I wondered if the clock was faulty, possibly something happened when the original elements blew and was cutting out as he said it didn't hold good time so i replaced it. We had the same issue.

I came back with the plumber and he replaced both the new elements, one with the same brand as above and the other with a different brand,(because that was all he could get because they are not a standard thread apparently) the different brand (off peak element) is now working perfectly, The new one from the same brand that is in the top for a boost still does not work although appears to draw power.    

    We appear to have had 3 brand new faulty elements.  ( The overheat stat had not tripped on any of the new stats and there was power directly onto the spades on the back when operating the thermostat.  I forgot to mention The thermostat was a plug in type. The spades on the back that connect to the element appear to make a good connection, i even tried giving them a squeeze with some pliers to make sure but they seemed ok  )  The different brand is also plug in. 

How can it use energy if it isn't actually heating up?

Anyone else had problems with these things?

edit to add i was getting 18.6 ohms across the new elements

I was beginning to doubt my sanity

Gary                                                                                                                                    

  • 0

    If a water heating element is absorbing about 3 kw, and for long enough to consume £4 worth of electricity then I fail to see how it does not heat the water. Where else can this energy go except into warming the water ?  

  • 0 in reply to broadgage

    I have no idea. There was a bit of luke warm water coming out of the taps for a brief period apparently. I tried it myself and that is all it was. Turning the thermostat up and down on the element also showed the water was still pretty much  cold because it clicked in the same place , at the lower scale on the stat.  I am completely baffled. 

    Gary

  • 0

    Maybe its a plumbing issue? So for example the water physically in the cylinder was getting heated, but the water coming out of the tap was being supplied from somewhere else due to some sort of faulty diverter valve issue (that's just wild hand-waving on my part).

  • 0

    If you are getting around 19 ohms between the element terminals, the resistance between the live terminals and earth is 2 mega ohms+, and you know it is using power, then there is no fault.

    Maybe, as the water was cold, it was just taking a long time to warm up?

  • 0

    As others have said, all that heat must be going somewhere.  So I would suspect a plumbing issue.

    • Excessively long pipe run from the tank to the hot tap.
    • A leak of hot water somewhere, so the hot water is disappearing as fast as it gets heated.
    • A thermostatic mixer valve hidden somewhere in the system.  I have seen these used to prevent scalding by hot water straight from the tank.
    • Botched plumbing, e.g. cold water goes in the top of the tank, and hot comes out the bottom.

    If you can grab hold of the hot water pipe as it leaves the top of the tank, then that might tell you something.

  • 0

    Perhaps hot water is leaking in some hidden area. A relatively small but continual leak would prevent the water from ever getting properly hot. As the system uses a non vented hot water cylinder, perhaps there is a safety valve stuck open.

  • 0

    Occam's razor might help.

    First, it would be very odd if both immersion heaters failed at the same time.

    Second, I agree that the issue is a plumbing one. Has somebody left a hot tap open? Is there a burst pipe below floor level such that any leakage might not be obvious?

    If there is a water meter, is it moving when everything is apparently off.

  • 0

    The only similar incident I recall was when a 240v element was connected to 110v, took an age to heat up

  • 0 in reply to Chris Pearson

    Well you could test that theory by turning off the cold feed to the cylinder, nothing can come out then. If the t&p or pressure relief valves were letting by you would see it in the tundish.

  • 0

    I really don't know what is going on. As i said they are now getting hot water with a different brand element in the bottom of the tank. The tank was completely drained to change them so starting from cold and they had hot water in two and a half hours as the plumber told them to ring him after that time and see what they had.  The run is not particularly long to the taps, i would estimate maybe 10 to 15m max. Thinking about it he changed what looked like an air release valve at the top of the tank, he used it to let the air out as the tank filled. It had a slight drip into a drain off pipe that was quite annoying. I can't see what was coming out being enough to drain the tank of hot water though, i believe he said it was cold anyway.   I am glad i was not being completely stupid though so thanks for the replies.

    Gary

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