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Calorifier heater element – IsoTemp type 0400

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  • #656

    This is for information:

    I had a problem with the immersion heater in the calorifier on my 2002 321.
    The calorifier is an IsoTemp type 0400 (orange coloured unit) which is now
    no longer produced.

    When the immersion heater was switched on it tripped both the boat’s 240 Volt
    RCCB, but also the RCCB in the marina pontoon shorepower box.

    I removed the earth wire directly on the heater terminals and the unit then
    stayed on – this implied that the immersion heater element had a leakage
    to earth which is what tripped the RCCB.
    I ordered a new heater element from Evesham Marina (01386 768500  ) They are
    distributors for Webasto products.

    It turns out that IsoTemp is a brand of Indel Marine of Italy. Webasto, a
    German company, in turn owns Indel.

    I had to wait months for the part since it seems the supply chain is
    not very good, however Evesham were very helpful.

    The element is part no. SEE00002HA and it cost about £58 including P&P.

    The old Suppliers list suggested Norfolk Marine but their price was rather
    higher. The list gave the element part number so I guess this element
    failure may be a common issue.

    Fitting is not easy on a 321 because the only access is via a locker under the main saloon seating where you have to crouch down in a very confined space. It was clear the only way the old element could be
    removed was by having a suitable large box spanner to unscrew it. I had to order a 41mm box spanner from a tool supplier and it cost about £20.

    However when I tried to get the spanner onto the existing element in situ the spanner fouled on the rod which is welded to the unit to attach the electrical cover by a nut. As a result I had to hacksaw off just over 1 flat of the box spanner by about 6mm so that I could turn it one flat at a time. My first attempt was unsuccessful because I could not get the old unit to move. On a second attempt I increased the effective length of the spanner by ‘plugging’ another box spanner into the first one. This meant it stuck out a lot further (about a foot) and meant I could get a better leverage using a very long screwdriver as a tommy bar.

    The next problem was the old unit would not come through the hole, the width of the elements was wider than the hole diameter. Eventually I got it out by ‘unscrewing’ it via the hole threads . Amazingly the new element just popped in OK and I put it all back together again in just a few minutes.

    Previously I had drained down the whole calorifier tank and then had to pump it back full of water which took quite a long time.

    So overall one of the worst jobs I have done on the boat……


    Picture attached of element in situ


    Box spanners


    Old element

    John Crump

    I also had recently to replace the immersion heater in my 2001 331. Thanks to Richard for recording his experience. I obtained my replacement element from JPC Direct. Brundall, Norfolk. The part was supplied within 2 days of placing the order and I saved carriage charges by also ordering a Sidepower Bowthruster Anode. A very useful and recommended supplier!
    I separately ordered a 41mm box spanner – but this proved unnecessary since I managed to unscrew the element with a sturdy adjustable spanner applied “end-on”.

    However, having replaced the element, I am still unable to achieve hot water in the heads/shower compartment; it always only tepid and needs to be supplemented from a hot kettle. There is a temperature regulation valve at the outlet of the calorifier that mixes cold water with the hot output. No matter how it is adjusted, the water at my taps is always much cooler than at the tank. Presumable the pipes were not lagged but other owners seem to have no problems. Any ideas?

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