Best hot water system for a cruising boat..?

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Oen

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The only thing I find slightly disappointing about my new boat is that the domestic hot water system (a big calorifier/immersion) only produces the goods after a while at high engine revs (other than when on shore power).

Now, this is irksome, as I like to be at anchor and to maximise sailing time and minimise motoring time, yet with a number of folk on board and decent grub, we need plenty of hot water for showers, washing up, etc.

So, what advice would the panel give about alternative (or additional) hot water systems, please? Or can I do something to get my MD22 to heat the calorifier up when at idle?
 
I'm in the process of fitting a Rinnai Gas water heater, (£195 from a caravan shop, or similar from marine chandlers). Seems to be the answer to instant & continuous hot water.

Cheers
 
I ahve the Paloma type, works well, though means I cannot do without gas on board. Having said that, it uses very little of the stuff.
 
Yep, the Paloma is very good - but wouldn't sit comfortably in my Phillipe Starck interior! I need something that will hide in the lazarette or a locker...? ...and ideally heats the tank, not just an instant supply...
 
You cannot beat the Rinnai Gas water heater, by far the best.
Provided it's well ventilated and has a Draught Diverter there should not be any gas safety issues. Fit a Gas dectector and Carbon Monoxide detector for absolute peace of mind.
One thing that gas is far better at, and cheaper, than other forms of energy, is hot water heating.
Most calorifiers/immersions are slow.
It the same in a Caravan. If you use the electric immersion element it'll take ages.
When on gas it heats up in five to ten minutes.
You could consider also reducing the size of the unit you have, which would make it more efficient, but you would then have less stored hot water.

Steve.
 
The upside to having inadequate seawater cooling flow through the engine is rapid hot water in the calorifier. My Volvo 2003 can't seem to push enough seawater to stop steaming in the exhaust though I've checked the thermostat, cleaned out the mixing elbow and Heat exchanger, changed the impeller ...

Maybe you can modify the raw water flow so not too much flows through the heat exchanger until the calorifier is well heated up, perhaps another thermostat?

Just a thought, concealing a plea for ideas what I should try next.

Regards,
Derek
 
Our Webasto water based heating system is used to heat up the water in our calorifier. It uses domestic central heating controls so we can switch between heating/hot water or both. We have found it a great system for cruising.
 
The "best" is an eberspacher water heater but they are expensive. Can be plumbed in to heat the calorifier when the engine is not running. Simple switch in cabin. Turn on and 15 minutes later piping hot water. You can also put one on a timer to heat water to wake up to. Will consume about 4 amps current when running but it's not continuous and a lot cheaper on diesel than any gas heater.
 
Sorry, yes! Didn't read your post before replying.. Wabasto heaters do roughly the same thing. I prefer the Eberspacher but now't wrong with Wabasto if you choose to go that way.
 
First, we too have a MD22 engine and it has no probs heating the hot water in the calorifier/immersion heater to very high temps even when at idle and that surprisingly quickly. We therefore time our big hot water usage for during the charging runs of the engine with the hot water cylinder left hot for the rest of the day - it holds temp well overnight. With big freezer, refrigerator, etc we normally need two hours of charge time split over 2 runs a day so we end up with plenty of hot water.

We also have a gas fuelled flow thru' calorifier which we never use and I would not put another on a boat of my own as it is wasteful of water and chews through the gas (even though we carry 20kg LPG).

As Mike has suggested an Eber or similar is the way to go and is something we may do in the future, but as above we find that we manage fine using the engine charge runs and here don't really need the space heating as well.

John
 
When I fitted a calorifer to my boat I was advised to make certain that there was a fall to the calorifer, or it would not heat the water quickly. Is this the problem with your boat? Ships Cat seems to have no trouble with an MD22 /forums/images/graemlins/confused.gif. Alternatively there may be an air lock in the system.
 
This
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Any idea if gas systems use standard fittings? I've got some old nasty gas water heater on mine that's died this winter and a Rinnai could be the answer, but I am not sure if I should try to be a gas engineer...
Wish I could afford an Eber water heater- I have an Eber air heater, but that's died too- previous owner was not known for his maintenance habits (was in fact known for the lack of it turns out).
Have heard rumours though of someone on eBay that does Eber exchanges and cheap sales of used units. Maybe they'd do water heaters too.
Jem.
 
You need the carver system ... like a small immersion heater tank under bunk with calrific gas / 12v / 240v elements. It has to have a flued exhaust - but works well. Available in various sizes from 10ltr upwards ....

Here is a small bit of chat I had with a "Caravan Breakers" some time ago about these units .... worth you contacting them - as they know so much more than most about the subject !! >>>

Quote :

From: "caravan breakers" <info@caravanbreakers.net>
To: "Solent-life" <nluther@solent-life.co.uk>
Subject: Re: Contact from the Caravanninglinks.com website


hello carver cascade m2 runs on gas and 12v and 240v
we sell these with 3 months warr delivered to your door£290
however these are sidevented so if put below water line i think u might sink! unless yuo have a large deck,
also which might be better option is wall mounted unit with top flue but out of stock at this time these are cheaper but need bigger pump to run as they need higher pressure to work
hot water systems we always sell out of and we are getting low on these units
please advise
www.caravanbreakers.net
01495 792700


Good luck.
 
Many thanks for all the replies so far...

I'm now investigating why, although the engine reaches and maintains 80 deg perfectly well, and the pipes to the calorifier seem hot (I'm not sure what the temperature drop is across the calorifier though), I'm not getting the piping hot water from it...

It's a 10 gal calorifier, so perhaps there's a problem with the volume of water it's heating (I could do some clever sums I suppose).

Or, perhaps there's a problem with scale or something else which is making the calorifer inefficient at transferring heat from the engine water circuit to the water in the tank.

Any ideas, anyone?
 
As I mentioned earlier, we have a MD22 and it has no problem heating the hotwater in the calorifier.

I don't recall what volume the calorifier is but it is certainly not less than the 10 gals you mention and probably more. So I suspect that you have an equipment or arrangement problem.

While it is unlikely that there is a difference in where the coolant is taken from the engine in your installation compared to ours (and I cannot see anything about it in the workshop manual), I will be on the boat Tues/Weds so PM me if it would be any help if I sent you a photo.

John
 
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