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Marine hot water cylinder recommendations


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One of the items on Mrs FLC wishlist for the new boat is a hot shower.

I'm not keen on gas califonts inside hulls, we don't have the battery capacity for an instant electric water heater so I'm left looking at engine heated storage/supply options.

I understand cylinders ideally need to be lower than but close the motor, so I'm thinking of putting something in the pantry aft of galley (Farr 1020)

Engine is Yanmar 3ym 20

Anyone had good/bad experiences with particular brands/models?

Thinking 25/30 litre. (We aren't in a Marina so not fussed on 240v backup types)

Cheers

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13 minutes ago, funlovincriminal said:

One of the items on Mrs FLC wishlist for the new boat is a hot shower.

I'm not keen on gas califonts inside hulls, we don't have the battery capacity for an instant electric water heater so I'm left looking at engine heated storage/supply options.

I understand cylinders ideally need to be lower than but close the motor, so I'm thinking of putting something in the pantry aft of galley (Farr 1020)

Engine is Yanmar 3ym 20

Anyone had good/bad experiences with particular brands/models?

Thinking 25/30 litre. (We aren't in a Marina so not fussed on 240v backup types)

Cheers

The cylinder does not need to be lower than the engine, the water pump will push the coolant around just fine. 

Here is another potential supplier

https://www.superheat.co.nz/marine-water-cylinders/

Fridgetech are the distributors for Isotemp.

Best to get a copper pressure cylinder, you will need to add a pressure reducing valve in the supply line

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I have a second hand 26L kuuma cylinder with heat exchanger fittings that you could have really cheap. Its 110v for the heating element but as you said it doesn't need to be hooked up to power. 

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1 hour ago, Fish said:

$20 and no installation, sorted!

Solar Shower - Army & Outdoors (armyandoutdoors.co.nz)

Can get surprisingly warm if you leave them in the sun all day.

the other option is a visit to your local Mitre 10/Bunnings and buy the bits to make one of these

https://www.amazon.com/CLICIC-Pressure-Sprayer-Removable-Traveling/dp/B07TS6Z1YV/ref=sr_1_7?crid=2JD0UZJPSNM27&dchild=1&keywords=camp+shower+pump+sprayer&qid=1620775323&sprefix=camp+shower+pump%2Caps%2C339&sr=8-7

if there is limited sun just boil the kettle to get the right temp. Paint it black so you can leave it in the sun to warm up on a sunny day

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Be wary of air locks if fitting cylinder above the header tank. 

There is a reason the radiator cap is the highest point. 

 

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We have one but don't run the engine enough to have hot water often enough.

My only takeaway advice is to pay attention to the R-Value, or it's inverse U-Value of the insulation on the tank. This makes a huge difference. I think it's worth paying more for a well insulated tank. I put a picture in of our current install

I also had one of these on a converted OSTAR boat and it worked great. That one had extra spray foam insulation heaped over and around it, a bit of a mess but worked very well.

 

3GM30F Engine shots 2017 (10).JPG

3GM30F Engine shots 2017 (11).JPG

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A lot going on in that space!

Very clean engine bay, something we are a ways from at present. So if you are running your motor and using hot water (say a shower) at the same time, does the cylinder keep up with demand or do you end up with water that gradually loses its temp?

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12 hours ago, funlovincriminal said:

A lot going on in that space!

Very clean engine bay, something we are a ways from at present. So if you are running your motor and using hot water (say a shower) at the same time, does the cylinder keep up with demand or do you end up with water that gradually loses its temp?

Depends Nigel, thermostat needs to be open for heating to work. So if she gets up in the morning after being at anchor all night then you will need to get engine up to temp before it will start to heat. Also depends on flow rate and cylinder capacity, ours is 60ltr and we get about 4 quick showers before the cylinder temp gets down to a point where you have full hot on but your out of luck if your #5. Running the engine if you’ve just motored for a couple of hours will probably mean you will need to run the watermaker to keep up.

We have a ball valve in the line from the motor into the cylinder that we can either regulate or shut off if we are motoring for a long time as the water gets stupid hot.

 

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1 hour ago, Young Entertainer said:

my one (not sure of brand is in the seat in front of the galley so a run of at least 3+ metres,  works to well most of the time.  Have to be careful not to turn on just hot water 

 

33 minutes ago, Jon said:

We have a ball valve in the line from the motor into the cylinder that we can either regulate or shut off if we are motoring for a long time as the water gets stupid hot.

tempering valves would fix that...

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41 minutes ago, Jon said:

Depends Nigel, thermostat needs to be open for heating to work. So if she gets up in the morning after being at anchor all night then you will need to get engine up to temp before it will start to heat. Also depends on flow rate and cylinder capacity, ours is 60ltr and we get about 4 quick showers before the cylinder temp gets down to a point where you have full hot on but your out of luck if your #5. Running the engine if you’ve just motored for a couple of hours will probably mean you will need to run the watermaker to keep up.

We have a ball valve in the line from the motor into the cylinder that we can either regulate or shut off if we are motoring for a long time as the water gets stupid hot.

 

Good info thanks Jon

Yes I can see water capacity being the next hurdle! One reason I don't want an instant water heater. At least with a cylinder it kind of 'Polices' shower durations. Have a 12 yo boy who finds comfort in Long meditation sessions in the shower at home, we are on tank water so wears a bit thin!

We survived 5 xmas cruises with no pressure water and a 20L water tank, splashed out and put 100L bladder in the 930 last year and I swear it lasted about the same time. The new boat appears to have about 270L and I wager once the tribe get used to pressure water and hot showers it'll probably need refilling after 4 days 😅

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1 hour ago, funlovincriminal said:

Good info thanks Jon

Yes I can see water capacity being the next hurdle! One reason I don't want an instant water heater. At least with a cylinder it kind of 'Polices' shower durations. Have a 12 yo boy who finds comfort in Long meditation sessions in the shower at home, we are on tank water so wears a bit thin!

We survived 5 xmas cruises with no pressure water and a 20L water tank, splashed out and put 100L bladder in the 930 last year and I swear it lasted about the same time. The new boat appears to have about 270L and I wager once the tribe get used to pressure water and hot showers it'll probably need refilling after 4 days 😅

You are on the money there... the more you give, the more is taken

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1 hour ago, funlovincriminal said:

Good info thanks Jon

Yes I can see water capacity being the next hurdle! One reason I don't want an instant water heater. At least with a cylinder it kind of 'Polices' shower durations. Have a 12 yo boy who finds comfort in Long meditation sessions in the shower at home, we are on tank water so wears a bit thin!

We survived 5 xmas cruises with no pressure water and a 20L water tank, splashed out and put 100L bladder in the 930 last year and I swear it lasted about the same time. The new boat appears to have about 270L and I wager once the tribe get used to pressure water and hot showers it'll probably need refilling after 4 days 😅

My shower water drains into a sump with a float activated discharge pump. Rule is when the pump comes on, about 2 minutes, that's the end of your shower😀

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15 hours ago, funlovincriminal said:

A lot going on in that space!

Very clean engine bay, something we are a ways from at present. So if you are running your motor and using hot water (say a shower) at the same time, does the cylinder keep up with demand or do you end up with water that gradually loses its temp?

Sooo... At the top of the tank there is a tempering valve (has a black knob on the left hand side). Don't set one of these up without one because getting scalded is a real possibility.

On the lower left is a Tn'P valve (Temp & pressure release) plumbed to the outside world via the cockpit drains. My old system used to routinely blow and reset that valve so I recommend an "Industrial" rated Tn'P valve which cost 3X as much but will reseal properly 100% of the time. But take all this with a grain of salt because I don't like problems and breakages aboard and do the very best possible 'damn the cost'  That Tn'P valve should be at the top of the tank, but with a tank this small (round and on its side) it doesn't matter that much and it didn't work out in the real plumbing world.

The rest looks so damn tight because that is a truly tiny tank you are looking at.

I have no idea how running the engine would effect things because we hate to run the engine, Engine is 21 years old and we have 990 hours on the engine with full time cruising for the last four years, so we would never run the engine just to take a shower. However… Starting from a cold tank it only takes about ten minutes to have hot water and 15 minutes to have super-hot (in need of the tempering valve )water;  so running the engine would make a big difference with a 15 minute shower and would extend the run time.  Our tank stays hot enough overnight to take a full shower the next day, again… not enough for my wife’s showers.

I would NEVER install a tank this small again,  never, never. I was an idiot to think it would hold enough hot water and I rue the day I installed it every time wifie takes a shower. It has plenty of water for me but not my wife with her super long hair and longer time in the shower.  I truly wish I had the space for a tank 50-100% larger but “Nehenehe”  is a trimaran and there is a dearth of space for these sorts of amenities. In fact, I have overloaded the poor girl with this first world stuff.

Hope this helps!

 

3GM30F Engine shots 2017 (11).JPG

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