Immersion heater gone again.

  • Thread starter Thread starter RAI
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savageseadog said:
The engine is likely to be true earth via propeller etc, mains earth can have a potential difference and yes, currents will flow from one to the other via cooling water. It does raise another issue regarding corrosion of the saildrive and propeller.
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Well that may well be it I suppose. A pontoon earth voltage setting up a current through the copper outer of the heater element (and the SS calorifier) through the calorifier spiral into the engine cooling circuit and down the prop shaft to the zinc shaft anode. If I connect the pontoon earth line to the engine the current will have a shorter less resistant path to the shaft anode. Is this a good idea? Hmmm. Alternatives?

Oddly, there is no sign of corrosion on the copper element. There must be some sort of erosive tunnelling going on.
 
I helped a pontoon neighbour with this problem last year. His heating element had failed after only a couple of years after the original lasted around the same time. We found that some makes have an anode intended to eliminate this problem, whereas others do not. The titanium one sounds like another option if not too expensive, titanium has excellent resistence to most forms of corrosion.
 
RAI said:
Tony, how did you fit those anodes inside the calorifier? My heater element has no space available. Did you mount them into the calorifier cylinder?
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Fortunately the heating element assembly has a stainless steel plate over the element, I had another stainless steel plate welded at right angles to this and I mounted the two anodes on that. The whole heating element assembly is electrically connected to the outer case when installed.
 

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Thanks Tony, unfortunately I can't match that, my heater element is on a 1.25 inch BSP mounting and the folded element pretty much takes up the diameter.
 
Sorry to resurrect this thread but previously talked about water analysis and the choice of immersion heater sheathing. Another factor I have discovered is the material of the calorifier tank.

Copper sheathed elements are only suitable for copper tanks. If the tank is stainless steel Incoloy ( or titanium) must be used .
 
VicS said:
Sorry to resurrect this thread but previously talked about water analysis and the choice of immersion heater sheathing. Another factor I have discovered is the material of the calorifier tank.

Copper sheathed elements are only suitable for copper tanks. If the tank is stainless steel Incoloy ( or titanium) must be used .
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Dang! It looks like it's stainless and the only element I've found so far is copper. And it's sold as being a replacement for exactly this tank.
 
Titanium one from Screwfix (if 2 1/4 BSP) and a reducer to drop it to 1kw, available from solar energy outlets, I get mine from a company that makes nothing else powerreducer.co .. The whole ensemble comes to around the same as a dedicated low wattage "marine" unit.
 
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Contact http://www.heatrod.com/
Talk to a chap called Brian Rix
Whatever type of element you want they will make out of stock parts, matching diameter of cap, number of thermowells, overall length and number of folds in the elements, sheath material etc. - I had a couple of "specials" made at no extra cost - had to wait about a week though as the wee laddie that did the welding was on holiday.
 
cliff said:
Contact http://www.heatrod.com/
Talk to a chap called Alan Rix
Whatever type of element you want they will make out of stock parts, matching diameter of cap, number of thermowells, overall length and number of folds in the elements, sheath material etc. - I had a couple of "specials" made at no extra cost - had to wait about a week though as the wee laddie that did the welding was on holiday.
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nigelmercier said:
Does he drop his trousers?
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Correction - chap's name is Alan Rix - what was I thinking?
 
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