Immersion Heater Thermostat "Reset"

Discussion in 'Plumbers' Talk' started by harry-the-hound, May 22, 2008.

  1. harry-the-hound

    harry-the-hound New Member

    Not sure if this is a plumbing or a sparks question, but here goes:
    I have a 30 year old back boiler type heating system in a bungalow:
    Parkray Everglow gravity anthracite heats 9 radiators and an indirect hot water cylinder. System is vented to an expansion tank. The domestic hot water cylinder can boil back into main tank in the roof.

    In the summer the hot water is heated via a long immersion inserted via a boss in the top of the copper cylinder.

    The immersion lasts 5 - 10 years before splitting and thus triggering the circuit breaker.

    Last summer I had to replace the immersion for the 4th or 5th time.

    This is a bggr of a job, cos the boss is at the back of the tank, there are pipes in the way and too little headroom. I have to resort to using a mirror to see what I'm trying to do with the wiring.

    This spring I was well pleased when the 9 month old immersion failed to work. Figured it must be the thermostat that had "failed" after such a short period.

    Struggled to extract the thermostat and eventually realised that there is a darning needle sized hole marked "reset" in minute letters.

    Some time during the winter the anthracite had managed to heat the hot water hot enough for the "new" belt and braces safety system in the immersion to lock off the electrical supply.

    Guess what - I've refitted the thermostat from last summer's old scrap immersion, so problem solved for the immediate future.

    Would I be right in thinking that some civil servant got an attack of the vapours thinking about the number of unvented systems these days and so all immersions now have to be fitted with a thermal cut out ?

    Or can I still get my hands on a thermostat without the overheating cut out. I really cannot see the missus climbing into the airing cupboard with a darning needle, a mirror and a small spanner to remove the cover and then managing to "reset" the immersion's thermostat.


    PS Any one got a second hand Parkray Everglow, mine is on its last legs but I don't fancy "upgrading" to oil at 700 GBP per tonne. Might be able to make one good out of two old ones?
  2. Captain Leaky

    Captain Leaky New Member

    There have been some recent fatal accidents involving scalding water leaking from cylinders and header tanks so now all stats are redesigned to pop-off when too if your solid fuel gets the hot water too hot then ,,yes, your new immersion stat will pop out and need re-setting.
  3. smithp60

    smithp60 New Member

    Why not save yourself some money and upgrage your system???
  4. Omniscient Polymath

    Omniscient Polymath New Member

    Harry the hound,

    You sound like a intelligent bloke, especially after that very well written explanation of your problem.

    From what you say, it sounds as if you have no control over the hot water temp during winter months.

    the cheapest option would be to fit a thermostatic valve on the primary flow after the 'open vent' which will close when water to temp reaches 60 and feed back to boiler.

    However, you will need some form of temp relief in the form of a heat sink of some sort. this will relieve the problem of the thermal cut out activating.

    Best get a timeserved plumber, heating engineer, gas tech or whatever they want to call themselves lately in and have a look. but it should not be a big job.

    Do not however listen to half the 6 week clowns on here espcially WS, christ he'll have you spending thousands on a heatbank or some other new fangled literature he's been reading about. Thing is though! the stuff he talks about, I bet he's never fitted or even got his soft manicured nails dirty. Some expert eh!

    Oh! went off on one their. Sorry.
  5. harry-the-hound

    harry-the-hound New Member

    Thanks guys.

    I rather feared that would be the situation.
    If I get a bit of clinker stuck in the air intake and go to bed on a windy night I recon I can boil the whole system !

    Interesting banging noises normally put me wise to what is happening. Seriously though I only do that about one a year.

    The poor old Parkray is on its last legs. It has done 31 years, without certificates, servicing or professional assistance of any sort; so I don't think it owes me anything.

    Was rather hoping to upgrade to GSHP (old fangled Swedish technology with a mean time to failure of 22 years?) BUT step one is to upgrade my insulation - I'm having problems with dirty cavities as recorded elsewhere on this forum.
  6. Dawn

    Dawn New Member

    Hi Harry, We are in the process of buying a cottage with one of these in. (I think) Is it one where you pour the anthracite in the top? We have some pics of our one but it does look a bit sorry for itself but if you are interested please let me know


  7. Parkray

    Parkray New Member

    Hi Dawn,
    did you get in touch with Harry after all those years and did you buy the cottage?
    i own an Everglow and am keen to talk to fellow `enthusiasts`

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