New WaterHeater needed (Now updated)
Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 370 / 375
Forum Description: 370 / 375 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=12672
Printed Date: 27 March 2026 at 03:41
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: New WaterHeater needed (Now updated)
Posted By: H8jer
Subject: New WaterHeater needed (Now updated)
Date Posted: 17 April 2021 at 17:09
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Hi Which WaterHeater (stainless) will be a drop-in replacement for the Isotherm Budget? All fittings are completely dry but somehow pink engine coolant build up underneath the heater.  ------------- Hanse 370#487 30HP 3-cabin |
Replies:
Posted By: H8jer
Date Posted: 17 April 2021 at 17:25
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I am thinking going for a new Isotherm in Stainless steel with mixer is best option. SVB got 20L and it looks to be same dimentions as the old one... https://www.svb24.com/en/isotherm-slim-hot-water-boiler-230v-750w.html" rel="nofollow - https://www.svb24.com/en/isotherm-slim-hot-water-boiler-230v-750w.html ------------- Hanse 370#487 30HP 3-cabin |
Posted By: H8jer
Date Posted: 28 June 2021 at 16:04
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Now the new Boiler is installed. The new boiler Isotherm Slim Stainless has the same dimensions, but different connections. The old boiler used some pipe extensions, but the new has valves instead. I could not find the same hose connectors, but got new 1/2 bends and such to replace the old fittings. The most difficult part was the fact that the 1/2 bends did not point in the right direction when tighten. With the use of Plumbing Hemp and Tec7 it was possible to have the bends point in the right direction. The old Isotherm Budget Boiler from 2007 was a mess... The underside was completely destroyed  Old boilder inside. Filled with calcium and rust. There where also a fluid looking like oil, but heavier than water.  New Boiler with mixer valve and Over-pressure/drain valve  The boiler has been tested and the shower felt great after changing it in the summer heat. /H8jer ------------- Hanse 370#487 30HP 3-cabin |
Posted By: Saltair
Date Posted: 12 October 2024 at 07:37
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Hi, I have a 2007 400e with a rust water heater, what water capacity fits best - a 20lt or 25lt? It looks like you have some space, but i realise the height of the unit is the limiting factor! cheers
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Posted By: H8jer
Date Posted: 12 October 2024 at 07:44
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Hi i have a 370. Perhaps your 400 has more space? But 20L is max size for a 370. ------------- Hanse 370#487 30HP 3-cabin |
Posted By: Rock
Date Posted: 12 October 2024 at 09:55
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In practice there really isn’t much excess space. I replaced with the stainless (from standard enamel) 20L BR Peter
------------- Hanse 400e "M-square2" #0241 |
Posted By: Martin&Rene
Date Posted: 13 October 2024 at 16:33
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Re H8jer comments about the outlet elbows not lining up with existing pipe, I finally solved it by using loctite to set the elbow in the right direction. ------------- Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland |
Posted By: sgrhma2
Date Posted: 16 February 2025 at 19:33
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When I first fitted the webasto water heater I was using the original 20L hot water tank. Initially I fitted a shuttle valve T joint as the original tank only had a single heat exchange coil. This allowed me to have the engine and the heater connected and enabled either the engine or the webasto to heat the water. I had a major problem with this setup as the heater kept shutting down early before fully heating the water because the coil in the Isotherm tank had far to small a heat exchange area that the heater beat the heat loss in the circuit and shut down early. To overcome early shut down I removed the shuttle in the T piece and allowed the heater to heat the engine as well. This gave sufficient area/ volume for it to dump the heat it was making. Shortly afterwards the Isotherm cylinder started to leak (it’s an extremely poor design which is only made to last slightly longer than the warranty period, it even has an internal anode to ensure this). I decided to replace it with a system that was properly designed for its location in the boat, to have two separate coils each capable of transferring 8Kw of heat and to give me as much additional hot water capacity as possible. To give me as much space for the tank I cut out the bottom of the glass fibre recess that the standard tank fits in, this gave me additional depth and allowed me to have a tank made with a 29L capacity giving an extra 45% of hot water. I decided to do away with the over pressure valve as I viewed this as a future failure point, but in doing this I had to fit a pressure bottle in the system. This is an absolute must if the pressure relief valve is done away with, it’s also a really useful thing to add to the water system to prevent over pressurisation when the water is heated and to maximise the life of the water pump. With the base of the moulding cut away the new hot water tank sits on the hull skin and it is held firmly in place by using pu foam around it in the cavity. To ensure the pu foam didn’t bond to the hull plastic sheet is placed down and taped to the side of the recess the tank sits in when this is done connect the plumbing, test and then pu foam around the edges to secure in place (use extremely small amount of foam, let it cure and if required add more. It’s a nightmare to clear up if you use too much). I’ve had this fitted in my 370 for the last 13 years and it has worked perfectly and to date has lasted almost twice as long as the original Isotherm unit. As a point of interest, at the time my one off cylinder was about 2/3 of the cost of a new isotherm the same as had been fitted. Hope this is useful to anyone thinking of doing something similar. As I mentioned earlier in this topic, I think having easy hot water as one of the best things I’ve done to the boat for ease of living aboard. Simon
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Posted By: sgrhma2
Date Posted: 16 February 2025 at 19:43
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My last post should have been in this topic, but is applicable to the discussion here https://www.myhanse.com/hydronic-heating-and-hot-water-install_topic14988.html#123083" rel="nofollow - https://www.myhanse.com/hydronic-heating-and-hot-water-install_topic14988.html#123083 Oooppps Simon
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Posted By: pearson.henry2
Date Posted: 16 February 2025 at 22:18
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Simon - very useful - we did consider cutting out the bottom of the original locker. But we decided it was easier to just move it aft and put it in the garage. On reflection I think we made good call, the original locker is now available for storage and also doesn't heat up the bunk. But we agree, a 30L dual coil calorifier with a webasto/hydronic unit really is the way to go. We've fired it up and very happy with it. Nice hot air to cabins and heads, 20 mins for a tank of hot water. And being able to do diagnostics via old eberspacher EDITH software is a nice bonus.
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