Yanmar 4JH57 water heater (calorifier) shutoff

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   Just to remind all. The accumulator can go anywhere there is a hot water pipe. Under a sink, under a floor board, etc. I was able to cut the pipe and insert a T barb fitting with a heat gun and hose clamps. 

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Arcadia Members Profile Send Private Message Find Members Posts Add to Buddy List Admiral Joined: 27 November 2017 Location: Sag Harbor, USA Status: Offline Points: 1112	Post Options Post Reply Quote Arcadia Report Post Thanks(0) Quote Reply Posted: 25 November 2025 at 23:58
	Just to remind all. The accumulator can go anywhere there is a hot water pipe. Under a sink, under a floor board, etc. I was able to cut the pipe and insert a T barb fitting with a heat gun and hose clamps.
	Leon / ARCADIA 2018 Hanse 588 Sag Harbor, NY

32mike Members Profile Send Private Message Find Members Posts Add to Buddy List Commadore Joined: 26 March 2020 Location: FLorida, US Status: Offline Points: 453	Post Options Post Reply Quote 32mike Report Post Thanks(0) Quote Reply Posted: 26 November 2025 at 13:16
	Here’s a link: https://www.heatso.com/surejust-2-litre-expansion-tank/?utm_source=google&utm_campaign=&utm_medium=cpc&utm_content=&utm_term=&device=c&product=856&gad_source=1&gad_campaignid=20032553275&gbraid=0AAAAADc83YbpGFM_9PFgRkcpsxhrBbZ7i&gclid=EAIaIQobChMI0NWM2u-PkQMVQbdaBR3skThwEAQYAiABEgItGfD_BwE It’s a 2 liter tank with a brand name of “SureJust” - British product. The company in the link is “Heatso” and they say they are out of Costa Mesa, Ca. There’s also this: https://www.supplyhouse.com/Zilmet-ZS2-Inox-Pro-Stainless-Steel-Expansion-Tank-0-53-Gal This tank is “Zilmet”, 1/2 gallon from US based Supply Warehouse. If you buy it and have luck with the install, it might give me inspiration to give it a go. Mike
	Mike S/V Dulces Sueños 458 #087 Tampa, FL

marsella Members Profile Send Private Message Find Members Posts Add to Buddy List Rear Admiral Joined: 21 June 2022 Location: Antigua Jolly H Status: Offline Points: 592	Post Options Post Reply Quote marsella Report Post Thanks(0) Quote Reply Posted: 26 November 2025 at 13:55
	Thanks Mike, this should fit our boats! My only concern is that these tanks are designed for household water pipes where typical water pressure is 40-60 PSI, and those tanks are precharged with similar pressure. Whether this will help us to absorb excess pressure during the hot water expansion in our boats, I am not sure. This excess pressure may still find its way to expand into faucet plastic cartrige and damage it. The trick when you open the hot water tab during motoring looks much better since the hot water pipe is open to the air in this way and there is no problem for hot water to expand. My thinking is that you would need to reduce the precharged pressure in that expansion tank by a lot to make it really work for a boat water system. PS. Actually found Seaflo, only 0.75l, very compact and precharged with 10PSI air pressure Edited by marsella - 26 November 2025 at 15:19

Lyn Members Profile Send Private Message Find Members Posts Add to Buddy List Captain Joined: 04 February 2022 Location: Hampton, VA Status: Offline Points: 190	Post Options Post Reply Quote Lyn Report Post Thanks(0) Quote Reply Posted: 26 November 2025 at 15:35
	The expansion tanks may come pre-charged, but the means to adjust is via a Schrader valve (auto or bike tire type). So you can let air out or charge it to your desire. You'll just need a small pump and a gauge. Under advice from Arcadia, I also added a 5 gallon accumulator to the cold water side. Keep in mind the actual water resident in the tank is somewhere around 50% of the capacity. Once you master a hot water expansion tank, I highly recommend it! Hard part is finding room if you go big -- I put mine in the starboard quarter near the deck shower. Freshwater pump cycling is at a minimum & flow is smooth. Edited by Lyn - 26 November 2025 at 15:35
	Jon S/V Lyn 2017 Hanse 588 \| Hull 19 \| Deep draft \| 150hp \| 220v & 110v systems \| Lithium House Bank

32mike Members Profile Send Private Message Find Members Posts Add to Buddy List Commadore Joined: 26 March 2020 Location: FLorida, US Status: Offline Points: 453	Post Options Post Reply Quote 32mike Report Post Thanks(0) Quote Reply Posted: 26 November 2025 at 15:42
	Yeah, the Zilmet tank comes pre charged to 50 psi. The SureJust tank recommends 5 psi above pump pressure or 30 psi if you don’t know it. I think with either tank the valve is a standard bicycle type schrader valve that’s easy to depressurize or pump up with a hand pump. Currently I forget what the water tank pump pressurizes to but it’s printed on the pump label I believe - I think 40 psi. Mike
	Mike S/V Dulces Sueños 458 #087 Tampa, FL

marsella Members Profile Send Private Message Find Members Posts Add to Buddy List Rear Admiral Joined: 21 June 2022 Location: Antigua Jolly H Status: Offline Points: 592	Post Options Post Reply Quote marsella Report Post Thanks(0) Quote Reply Posted: 26 November 2025 at 16:33
	Agree that recalibrating the tank air pressure to correct fresh water pressure in our system may do the trick. Plus correct plumbing of standard 1/2 in something tank inlet to nonstandard European Prineto which may need an intermediate PEX adapter since we know how to connect PEX to Prineto. Will keep this for a possible future project, as it looks doable. Edited by marsella - 26 November 2025 at 22:26

Tranquillity Members Profile Send Private Message Find Members Posts Add to Buddy List Captain Joined: 01 December 2018 Location: Hamble, UK Status: Offline Points: 267	Post Options Post Reply Quote Tranquillity Report Post Thanks(0) Quote Reply Posted: 26 November 2025 at 18:57
	https://www.myhanse.com/forum_posts.asp?TID=12280&title=leaking-head-faucet-tap-fix You may find this stream on expansion tanks useful ? Lots details that helped our installation.

marsella Members Profile Send Private Message Find Members Posts Add to Buddy List Rear Admiral Joined: 21 June 2022 Location: Antigua Jolly H Status: Offline Points: 592	Post Options Post Reply Quote marsella Report Post Thanks(0) Quote Reply Posted: 26 November 2025 at 20:07
	Thanks for pointing to this thread which gives the same conclusion regarding the air pressure setting to be the same as delivered by the pump.

Martin&Rene Members Profile Send Private Message Find Members Posts Add to Buddy List Vice Admiral Joined: 06 December 2009 Location: United Kingdom Status: Offline Points: 967	Post Options Post Reply Quote Martin&Rene Report Post Thanks(0) Quote Reply Posted: 27 November 2025 at 12:23
	This is where I made some general comments in the past. https://www.myhanse.com/hot-water-boiler-dropping_topic11929_post98132.html?KW=calorifier#98132 Actually nowadays, when starting the engine or switching the water heater on, we turn off the fresh water pump, run a tap until no more water comes out and then shut the tap. We then just switch the water pump on later after the water will have been heated and when you want some water and you can then leave the pump on, unless you have used a very large amount of hot water. The pressure increase leakage problem only arises when the water is first being heated from cold. So Mike, you do not need to keep doing actions continually and I think that my one-off action routine is a lot easier than having to reach into the engine compartment to turn a valve. The interesting test is to do the first bit and then when the water has been heated open the hot water tap without switching the pump on and only a small volume of water will come out demonstrating the increase in volume and pressure. With water being incompressible and the piping being thick walled, it does not take much increase in water volume to increase the pressure. If you are interested. then there is a accumulator sizing calculator https://www.accumulators.com/tool/accumulator-size-calculator/ If you just guess some representative values and if you just do the thermal expansion calc, then it comes out with quite small accumulator sizes. These are the typical accumulators sold by a UK chandlers from 0.6l upwards. https://www.force4.co.uk/department/chandlery-below-deck/pumps-water-systems/accumulator-tanks On the calorifier, I have put a section of small diameter plastic tubing onto the overpressure valve outlet, secured with a jubilee clip, and then taken this up to the plastimo shower outlet in the transom in which I had drilled a small hole and just secured the tube with sikaflex. So any leakage goes over the side. When I drain the system in winter, there is normally very little, or even zero, water in this pipe. Having only a 341, I could not work out where to put even a small accumulator, but thankfully my setup means I do not need one.
	Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland

marsella Members Profile Send Private Message Find Members Posts Add to Buddy List Rear Admiral Joined: 21 June 2022 Location: Antigua Jolly H Status: Offline Points: 592	Post Options Post Reply Quote marsella Report Post Thanks(0) Quote Reply Posted: 27 November 2025 at 13:46
	Interesting. Martin pointed to the past thread where actual volume expansion was estimated for a typical 40l boiler to be 0.5l or so although using the value of thermal expansion of water 0.0002 which is only correct at 20C. The thermal expansion of water is T depedent and goes to 0.0006 around 80C therefore if one uses a mean value of 0.0004, it produces 1l of extra volume of water. Dont remember what size of water heater we have, something around 50l, so certainly any expansion tank less than 1l will not work and probably 2l tank should be ok. Likely not a big deal to find a place for such tanks in 60 feet boats but could be a challenge in a 40 footer.



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