How much power for water heating

[Homer J]

I have a 38 foot yacht with a water heater - I can remember what capacity it is but suspect around 20 litres - it is a Jeanneau SO 37. It's on a mid-river pontoon without electricity and I use it during the winter. I would love to have hot water available so I was thinking of getting a generator but they are noisy and smell and dont always start.

I've seen battery banks available like this " Anker 757 1229Wh with 1,500 watt max output". Would this be sufficient to heat my water? I can take it ashore daily to charge it - apparently 80% charge in 1 hr and I have solar panels sufficient to cover my other needs so I am wondering if this is a (expensive) solution?

I've broken my leg so I can't get onto the boat to check the actual size or power consumption so I am wondering if anyone on here can give me a bit of guidance.

 

[Momac]

We just use the gas kettle to make hot water when away from shore power . Obviously not in any great quantity.

I have a 1500W generator which over loads and stalls if I put the low wattage immersion heater on so would guess the battery pack you suggest could be over loaded also.

 

[PaulRainbow]

I doubt it would heat 20 ltrs of water very hot.

For small amounts a gas kettle is a good solution.

 

[Homer J]

Thanks - it's never really enough to tackle the washing up and leaves a lot of water vapour in the air - I guess I need to check the wattage of the immersion heater and/or look for a larger battery bank

 

[Homer J]

Do we think this one would be man enough for the job? 4.5hrs from empty to full charge

Bluetti PowerOak AC200P Portable Power Station

• 2000W (Surge 4800W) Battery capacity 2000Wh

 

[BabaYaga]

I've seen battery banks available like this " Anker 757 1229Wh with 1,500 watt max output". Would this be sufficient to heat my water? I can take it ashore daily to charge it - apparently 80% charge in 1 hr and I have solar panels sufficient to cover my other needs so I am wondering if this is a (expensive) solution?

To heat 1 litre of water 1 degree C takes something like 1.16 Wh, therefore heating 20 litres by say 30 degrees (5 > 35) would require ≈ 700 Wh. So theoretically, yes, that device would hold the amount of stored energy required. If it is practical is another question.

 

[penfold]

If you need a longterm solution it's worth looking at a wet heater from eberspacher etc, carrying a can of diesel once a week is less onerous than lugging a battery daily.

 

[Beneteau381]

Do we think this one would be man enough for the job? 4.5hrs from empty to full charge

Bluetti PowerOak AC200P Portable Power Station

• 2000W (Surge 4800W) Battery capacity 2000Wh

I tried a 1.2 kwhr genny on my Bene 381. It stalled. I believe my heater is 1.5 kw. I have since been given a Honda 2.0i which is rated continuous 1.6kw. I t grunts a bit but copes admirably. So you probably need an over 1.5 kw provision with a 2kw surge? So this would probably work, but follow Paul Rainbows advice

 

[sailaboutvic]

On our other boat we heated it throught our nverter and out lithium batteries bank .Once the batteries where charge throight the panels on went the hot water heater.
Job this winter start work on a new bank of life PO4.

 

[Homer J]

On our other boat we heated it throught our nverter and out lithium batteries bank .Once the batteries where charge throight the panels on went the hot water heater.
Job this winter start work on a new bank of life PO4.

Thanks VIC - I was hoping not to mess with the boat battery bank. In any case I would still have the same issue - I don't want to be sitting there using the engine to charge the batteries (even though it heats the water too) and I have no access to shore power and have limited space for more solar panels.

A silent battery pack that I can take ashore / home and charge that will allow me a weekend on the boat mid-river is very tempting if I can get it to work. It seems like a big battery powerhouse would work at 2000W & 200Wh as B183 comments suggest. It would also be nice to have this on an anchorage - sounds more socially acceptable than a genny - problem is the £1,500 cost of it

 

[Homer J]

On our other boat we heated it throught our nverter and out lithium batteries bank .Once the batteries where charge throight the panels on went the hot water heater.
Job this winter start work on a new bank of life PO4.

Thanks for your post - that's really helpful - I am sure our set ups would be remarkably similar and suggests that this battery pack would do what I want it to without noise and stink - probably a similar price to a Honda genny

 

[PaulRainbow]

Why not just run the engine at fast idle, in gear, for a while. Charge the batteries and heat the water at the same time.

 

[geem]

If you are thinking of using a generator and it's a bit small for your immersion heater, you can use a Variac to lower the voltage to the immersion heater. I feed solar into my calorifier via the inverter and Variac. The generator and Variac might be the winter solution and solar and Variac with an inverter the summer solution

 

[pandos]

Do you have a diesel hot air heater? If so these guys do a heat exchanger that will allow you heat your water from it.

If I was you if look out for an engine preheater from a landrover discovery and do some googling on the campervan YouTube's for the way to run these without a landrover...

WATER HEATERS | Bobil Vans

 

[RupertW]

If you are thinking of using a generator and it's a bit small for your immersion heater, you can use a Variac to lower the voltage to the immersion heater. I feed solar into my calorifier via the inverter and Variac. The generator and Variac might be the winter solution and solar and Variac with an inverter the summer solution

Similarly, for my solar powered solution I use a builder’s portable 220V-110V transformer which means the 12V batteries only draw 30Amps instead of 120. Same Wh still needed in total but over a longer time period.

 

[Momac]

I think the portable power pack is a good concept especially if coupled with a portable solar panel for summer use .
I would hope it could be used for other things like extending the capacity of the boat domestic bank by running the fridge from it .
The cost is a deterrent but could be worth considering for those longer stays on board.

PS
The Bluetti weight is 27.5kg so no light weight

 

[sailaboutvic]

To be honest I think the best solution posted was Paul in #12 ,
If you can run the engine in gear all the better.
It's the easiest and a quick way to get hot water in the condition your in with your leg.

 

[Tranona]

To be honest I think the best solution posted was Paul in #12 ,
If you can run the engine in gear all the better.
It's the easiest and a quick way to get hot water in the condition your in with your leg.

Agree. good for the engine as well to have a run under load periodically throughout the winter.

 

[ylop]

Do you have a diesel hot air heater? If so these guys do a heat exchanger that will allow you heat your water from it.

If I was you if look out for an engine preheater from a landrover discovery and do some googling on the campervan YouTube's for the way to run these without a landrover...

WATER HEATERS | Bobil Vans

I'm pretty sure when I was looking at the eberspacher copies the next step up was essentially a central heating system which if you plumbed it in correctly could also heat your water tank. Would be higher up my priority list than a generator or what is essentially a very expensive lithium battery with charger and inverter. Personally, I'm happy with running the engine / shore power / kettle depending on how much hot water I need and where. In terms of steam from the kettle: if you take if off before its at a full boil it will make a lot less steam; if you have one with a whistle on the spout it contains a lot of the steam; I wonder if you want 3L of 50 deg water to do dishes if it is better (from a steam perspective) to heat a kettle full to near boiling and add cold water or to heat the total amount you need in a big pan (with a lid) to 50 deg? I suspect the latter makes less after vapour in the cabin?

 

[sailaboutvic]

I'm pretty sure when I was looking at the eberspacher copies the next step up was essentially a central heating system which if you plumbed it in correctly could also heat your water tank. Would be higher up my priority list than a generator or what is essentially a very expensive lithium battery with charger and inverter. Personally, I'm happy with running the engine / shore power / kettle depending on how much hot water I need and where. In terms of steam from the kettle: if you take if off before its at a full boil it will make a lot less steam; if you have one with a whistle on the spout it contains a lot of the steam; I wonder if you want 3L of 50 deg water to do dishes if it is better (from a steam perspective) to heat a kettle full to near boiling and add cold water or to heat the total amount you need in a big pan (with a lid) to 50 deg? I suspect the latter makes less after vapour in the cabin?

I'm guessing if he on board full time hot water for a shower will be first on his list.
As for lithium I spend about 2.5k all in including inverter and mine wasn't the cheapest of batteries cells , with the help of solar we did everything including microwave, kettle, induction hob, hot water and charging PC,phones ipad even my shaver 2.5k well spent ,
Which I plain to do on my new to me boat over winter.

Edit I forgot to mention an oil filled electrical rad.

 

[yoda]

I have a 38 foot yacht with a water heater - I can remember what capacity it is but suspect around 20 litres - it is a Jeanneau SO 37. It's on a mid-river pontoon without electricity and I use it during the winter. I would love to have hot water available so I was thinking of getting a generator but they are noisy and smell and dont always start.

I've seen battery banks available like this " Anker 757 1229Wh with 1,500 watt max output". Would this be sufficient to heat my water? I can take it ashore daily to charge it - apparently 80% charge in 1 hr and I have solar panels sufficient to cover my other needs so I am wondering if this is a (expensive) solution?

I've broken my leg so I can't get onto the boat to check the actual size or power consumption so I am wondering if anyone on here can give me a bit of guidance.

I found that I used 20% of the capacity from a 560Ah 12v battery to run the inverter and heat the 15 Litre calorifier from cold to hot cut off. I guess your idea would just about work.