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Fast corrosion waterheater Isotemp 40HXCV

Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 461 / 470
Forum Description: 461 / 470 Hints and Tips
URL: https://www.myhanse.com/forum_posts.asp?TID=10337
Printed Date: 27 March 2026 at 03:40
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com


Topic: Fast corrosion waterheater Isotemp 40HXCV
Posted By: tobo2
Subject: Fast corrosion waterheater Isotemp 40HXCV
Date Posted: 30 June 2017 at 13:46
We have big problems with our waterheater. On the Hanse 470e (2007) that boiler is installed above the engine. When there is a leakage in the heating coil the boilerwater dripps into the freshwater cooling system of the engine and the expansion bowl overflows. All our boilers from Indel-Webasto didn't hold longer than 3-4 years, one of them even only 1 year! Now #4 is corroded again after 3 years of use even though we don't heat it electrically to exclude electrolytical processes! This last type even had anodes inside, at least they promised it. So far the company (Indel Webasto Italy) replaced them on warranty or courtesy. 
Webasto suspects the water quality to cause this fast corrosion. I don't really think so as we had this phenoneme in four different marinas being our base. (Croatia/Punat & Kastela, Gouvia Marina Greece and Kos Marina). Does anybody with a 470 have similar experiences?
This time the company argues that my warranty has expired long ago even though they give a 5 years warranty on inner corrosion of the stainless steel tank. Quote: "The warranty on our heaters is 5 years from the date of launch of the boat so the warranty for your first heater, and all the replacements after,  ended in 2012. We are now in 2017 so we are 5 years over the standard warranty."
 
I really can't follow this point of view. We must find the mistake, I cannot replace the waterheater every three years! All suggestions are welcome! (Grounding has been tested and no foul current was found).



Replies:
Posted By: bovine
Date Posted: 30 June 2017 at 17:14
Interesting , my 430 from 2007 is still on the original and no problems .
You say the boats been in various locations , so fresh water quality probably not to blame.
The engine coolant could be causing the problem though, I would use distilled water plus the correct antifreeze .
Also dismantle the old water heater to see exactly what's going on.
David


Posted By: Rubato
Date Posted: 30 June 2017 at 17:23
Same experience as Bovine with our 400, no problem so far after 10 years.

I understand Webasto's point of view though. It is quite common that a replacement given under warranty is guaranteed only for the remainder of the original warranty period, the warranty period does not reset. If you pay for another heater, you will have a full 5 year warranty. As a consumer, this is annoying and not "best in class" customer service but it is quite common. I actually give them high marks for replacing it so many times already. (Porbably not what you want to hear, but it's just my opinion)

Cheers, good luck
Steve


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Steve

Hanse 400e, #168


Posted By: sailkoop
Date Posted: 02 July 2017 at 06:25
Hi tobo,
I've still the first waterheater in Place. No Issue at all. If the grounding is correct, you should analyse the Cooling Water by a Laboratory to find the rootcause of that Failure!

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best regards

Bjoern





Posted By: tobo2
Date Posted: 02 July 2017 at 18:22
Dear sailkoop

Thank you for your suggestions. Are you talking about the cooling system water INSIDE the heating coil (cooling system water with anti-freeze)  or the water from the water tanks which runs OUTSIDE around the heating coil in the water heater? These are two pair of shoes!  Am I really the only 470 with this problem?? There were quite a few postings in earlier years stating that Isotemp/Webasto is delivering boilers with minor quality! (bad inox quality, no anodes inside)


Posted By: sailkoop
Date Posted: 02 July 2017 at 18:34
Hi tobo,
I am talking about the water from the cooling System. I am not believing that the water from the tanks have an influence! The tanks himself are out of stainless steel and the tubes are out of plastic! Therefor they have no influence into the cause....

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best regards

Bjoern





Posted By: High Time
Date Posted: 04 July 2017 at 10:33
It sounds to me as though the failures are more likely due to electrolysis rather than chemical corrosion.

Is a mains electric heater fitted to the boiler? If so, have you checked the wiring, particularly the earthing arrangements, for this? Is there any electric circuit (wires or fixing brackets etc) between the boiler and the engine for instance?



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Roger

High Time (415 #038)


Posted By: tobo2
Date Posted: 05 July 2017 at 12:28
Dear Hightime

My electrician in Kos is now carefully testing the waterheater for stray current and mounting a proper grounding if missing. I will let you know. By the way: this is now the first time that someone is really interested in finding the mistake and not only exchanging the waterheater. We should have done that before when in 2013 #3 failed after only one year of use. But this was in Croatia (Kastela marina) with a terrible technical service.

It turned out that there is no Galvanic isolator installed. (s. pic in thread "galavnic Isolator") and the grounding has been tested. The new boiler Isotemp Basic 40 has now two anodes. We really hope that the problems are solved now!



Posted By: perry
Date Posted: 18 July 2022 at 10:08
I have now had 2 boiler [calorifier failures. The first on my Hanse 301 when it was 12 years old. I stripped the calorifier and found the leak in a Silver Soldered [Brazed maybe] joint alowing fresh water leak. I was able to repair the failty joint. The general construction was good with stainlees materials [Inox]. I believe the new owner has had another fail which would be 6 years from my repair but I'm not aware of nature of this fail. The Calorifier was fitted with a magnesium anode in the fresh water which was 30% depleted. No expansion tank fitted.

My second Calorifier fail on my 2007 315 was a corrosion related fail/leak  after 12 yrs under the rubber gasket that seals the flange. The calorifier is an IsoTemp 20l "budget" model. The tank is mild steel with vitreous lining, fitted with a large magnesium anode approx 30% depleted. The design is typical of Ilalian made boilers sold widely for domestic use in France, using mild steel for pressure vessel with vitreous enamel lining. I have knowlegde of these French Italian boilers [Chauf Eau], they often fail in < 10 years and you can visit any plumber in france and see a large pile of them in his scrap.
In my 315 the IsoTerm budget was fitted with 6 bar pressure release valve of poor quality, no pressure expansion tank was fitted so as the water heats and the pressure rises till it blows off vents. My PRV never vented to my knowledge. This cycling of pressure in a vitreous lined pressure vessel may cause fail/crack of liner. French Chauf Eaux boilers are usually limited to 3 bar.

I am fitting a new Calorifier from Surejust [all stainless of good quality] who say its imprtant to fit Expanion tank and their PRV is set to 4 bar and pressure vessel is Stainless. I hope and expect better life from this boiler.

From a manufacturers point of view this life may be acceptable, from owners with a bill for >£500 for boiler alone plus the  problem of failure at sea, high labour cost for difficult replacement, I feel this use of less than optimum materials and build quality is akin to the many builders who still fit poor seacocks and say change them often?

Just a further thought I have recently fitted a new domestic Calorifier in my house its made of Duplex stainless steel, this grade is better in this application than 316l grades [stronger and weldable without post weld heat trealment, not subject to stress corrosion cracking etc]  and is becoming standard in these and domestic applications.
Perry


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Current Yacht Hanse 315 2007
Last Yacht Hanse 301 Round GB in 2017


Posted By: Martin&Rene
Date Posted: 18 July 2022 at 20:52
My Isotemp manual has the following comment

Quote
Important! The water heater shall be connected to the mains power supply only when it is in service.
When leaving the boat for any length of a period, it is recommended to pull out the cable connector
from the socket to also disconnect the earth protection. This should be done even if the
shore power system is shut off, as there can be a potential difference, between the earth from shore
and the sea water earth of the boat. This can seriously damage, by stray current corrosion, the immersion heater, water heater tank or the engine with its drive unit.
Installation of a insulation transformer in the shore power equipment eliminates the risk of galvanic
corrosion via the shore power connection.
Unquote

That is obviously not very good advice if you are a liveaboard.

I actually do follow the recommendation and even though my yacht does have a galvanic isolator I do take it off shore power for the 2-3 week sessions when I am not on the yacht and the yacht is based in the cold Scottish environment, so corrosion rates are lower..  In the winter the yacht is out of the water.  As previous posters have said, we have to put up with the fact that some equipment is not really designed for the life of the yacht, as so we have to take every preventative measure possible.

Just one thought, though it is not normal practice to completely isolate components (ie break all 3 wires including the earth) when switched off, perhaps in this instance it may be worth considering.  


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Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland


Posted By: perry
Date Posted: 18 July 2022 at 21:36
Thanks for that.
My H301 spent most life on an isolated mid stream mooring. Very rarely plugged into a mains. The 315 is often in marina. Both have galvanic isolators, but that doesnt help if there is earth leak current.
The 301 calorifier was clearly a deficiency in Braze/build quality. The 315 is an Isotemp buget model as I said using mild steel pressure vessel with vitreous enamel lining, the rust [and there was a lot of rust] was in beween the rubber gasket, the pressure vessel, and the header that holds the immersion heater and the thermocouple pocket for the dual over heat sensors. The magnesium anode was pretty big and only part used. I doubt if galvanic action was the cause, I have seen similar failures on French Domestic boilers, that use this mild steel pressure vessel protected by vitreous enamel coat.
This evening was speaking to a yacht chandler friend, who said his experiece of Isotemp boilers and many other calorifier manufacturers  was a 10-15 year life.


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Current Yacht Hanse 315 2007
Last Yacht Hanse 301 Round GB in 2017



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