Heating water without shore power?

[a64pilot]

Is this a short time issue, one season, or likely to be a concern for years?
Short term, little Honda genny or running your engine is fine but I'd want something better if it went on every year.

[AFKASAP]

Originally Posted by Dockhead

You didn't mention what kind of heating you have.

As others have said, hydronic heat will kill two birds with one stove -- domestic hot water and heat.

You can also heat water with a generator, but it's extremely inefficient compared to using a hydronic furnace. That being said -- it can be done. My hydronic heat has been down the last couple of months (on my list of things to work on today in fact). I've been on board most of that time and mostly without shore power. I combine heating water with battery charging and other power intensive tasks, and so it's probably not all that bad efficiency-wise.

If you don't have a generator, then you can also run your main engine to make some hot water. If you put the transmission in gear to produce some load, it's not harmful, and you can charge batts at the same time. Lot of wear and tear on the machinery, however, for that one task.

Hi,

No I did not mention because I don't know exactly. Its the standard Beneteau Oceanis 40 spec electric boiler. It is 25 liters. I will check out the exact model and spec when I get back onboard in an hour or so.

On a side note, the marina charges me EUR 0.30 cents per Kilowatt. I also want to figure out how much electricity the boiler will use and in turn how much it will cost to run. So I will need to some how convert the specs of the boiler into a cost of running per day. The marina have provided me with an inline meter which can help. But that is also including the usage of all my other equipment.

This feels a bit back to front, but my initial question stemmed from me wanting to find a cheaper way (less thanEUR 0.30 cents per Kilowatt) to heat my water.

[anacapaisland42]

Have a look at zoda.com
Bill



[QUOTE=AFKASAP;1946232]How do you heat your water for showers etc when staying aboard long term? I am staying aboard my Beneteau Oceanis 40 for the European winter months.

[anacapaisland42]

OOPS

zodi.com


[QUOTE=anacapaisland42;1946637]Have a look at zoda.com
Bill

Originally Posted by AFKASAP

How do you heat your water for showers etc when staying aboard long term? I am staying aboard my Beneteau Oceanis 40 for the European winter months.

[a64pilot]

I think your going to find out that nothing is cheaper than shorepower

[nigel1]

My Beneteau has one of these units fitted.
Calorifier Quick Nautic Boiler 1200 or 500 Watt 25 litre or 40 litre
It is well insulated and the water is still warm 2 days after the heating element has been turned off.

As others have said, shore power is going to be the cheapest way to heat water.

[Dockhead]

Originally Posted by AFKASAP

Hi,

No I did not mention because I don't know exactly. Its the standard Beneteau Oceanis 40 spec electric boiler. It is 25 liters. I will check out the exact model and spec when I get back onboard in an hour or so.

On a side note, the marina charges me EUR 0.30 cents per Kilowatt. I also want to figure out how much electricity the boiler will use and in turn how much it will cost to run. So I will need to some how convert the specs of the boiler into a cost of running per day. The marina have provided me with an inline meter which can help. But that is also including the usage of all my other equipment.

This feels a bit back to front, but my initial question stemmed from me wanting to find a cheaper way (less thanEUR 0.30 cents per Kilowatt) to heat my water.

I meant space heating, not water heating. Do you have some kind of space heating on board?

Whatever the marina charges for electricity, it will be cheaper than burning diesel fuel and wear and tear on whatever on board system you use.

One of the main reasons why I like to be in a marina during the cold winter months is to be able to use electrical heat (and I use cheap Chinese fan heaters). It's a luxury.

If you plan to live on board in the winter without shore power, space heat is even more crucial than water heating. What do you have, or what is your plan?

If you don't have any space heat yet, then you can kill two birds with one stone by installing a hydronic heating system, which will also heat your water. This kind of system has some downsides (needs some electrical power; not user-serviceable; makes some noise) but is really efficient and doesn't occupy bulkhead or floor space. It's what 90% of sailors up here use.

The alternative is a pot burner stove like a Refleks. Upside: silent, uses no power, dead simple and user serviceable. Downside: need bulkhead space; need to install a chimney; soot on deck; difficult to distribute the heat throughout the boat. It's possible to heat water with it but not as easily as with a hydronic furnace.

[Privilege]

I cast another vote for instantaneous propane water heaters. I have one on my boat similar in style to this...


There are loads of them online and cost a few hundred dollars. I have propane onboard anyway for cooking. Showering once or twice a day, two 20lb propane tanks will last me around ten months. You need to get the kind that are fired up with a 'D' cell battery so that you don't need AC electric to use them. They are easy to install, the only downside being that you need to vent them to the outside of the boat with a 3" or 4" flue.
(I have a mushroom vent on my deck).

They don't heat the interior or leave fumes or condensation. If you have the room, I recommend them highly.

[Kokanee]

Originally Posted by AFKASAP

Hi,

This feels a bit back to front, but my initial question stemmed from me wanting to find a cheaper way (less thanEUR 0.30 cents per Kilowatt) to heat my water.

30 EUR cents per kW/hr is not too bad. You may find other slightly cheaper running costs, but once you take the up front purchase & installation costs into account, your payback period will be a lifetime.

[DMCantor]

You also might want to rethink the need for daily showers. Its a habit many of us have established when living on shore, but is it really necessary? Our ancestors managed with annual baths. I'm not advocating that, but you can really reduce the need for hot water by going to an every 2nd or 3rd day schedule. In cool climates, no one will notice.

We have avoided this problem altogether by spending our winter months in the Caribbean.

One final comment, it takes a surprisingly long time for an idling main engine to bring the water heater to temp. They just don't generate that much heat unless they are under load.

[CaptTom]

Originally Posted by AFKASAP

...the marina charges me EUR 0.30 cents per Kilowatt. I also want to figure out how much electricity the boiler will use and in turn how much it will cost to run. So I will need to some how convert the specs of the boiler into a cost of running per day.

Originally Posted by Dockhead

Whatever the marina charges for electricity, it will be cheaper than burning diesel fuel and wear and tear on whatever on board system you use.

I assume Dockhead meant it will be cheaper to run than either a generator or running the main, and cheaper to install. He also suggested a hydronic system that burns diesel, which is probably the cheapest to run. Propane may or may not be cheaper, but it's certainly a simple solution.

You can get some good numbers if you leave a meter attached for 24 hours of typical use. I've found it takes about 30 minutes at 1250W to heat my 11 Gallons (41.5 liters) of water from stone cold to hot. That's 625 Watt-Hours, or a little over a half a KWH, or around .19 Euro. You can do that several times a day and never pay back the cost of a more efficient system.

Again, that's just for water. If you're going to heat the boat, that's a totally different calculation, and shore power will be one of the most expensive options.

[Dockhead]

Originally Posted by Privilege

I cast another vote for instantaneous propane water heaters. I have one on my boat similar in style to this...


There are loads of them online and cost a few hundred dollars. I have propane onboard anyway for cooking. Showering once or twice a day, two 20lb propane tanks will last me around ten months. You need to get the kind that are fired up with a 'D' cell battery so that you don't need AC electric to use them. They are easy to install, the only downside being that you need to vent them to the outside of the boat with a 3" or 4" flue.
(I have a mushroom vent on my deck).

They don't heat the interior or leave fumes or condensation. If you have the room, I recommend them highly.

Everyone will have to make up his own mind about the safety aspects of such devices.

Just keep in mind that they are not designed for marine use, where a propane leak can be disastrous (which is very different from the situation in a house, where a propane leak will generally dissipate harmlessly to the outside). And therefore violate all codes that I know.

A word to the wise.

If you have some way of mounting it outside of the main hull volume, these concerns might not apply.

[Dockhead]

Originally Posted by CaptTom

I assume Dockhead meant it will be cheaper to run than either a generator or running the main, and cheaper to install. He also suggested a hydronic system that burns diesel, which is probably the cheapest to run. Propane may or may not be cheaper, but it's certainly a simple solution.

You can get some good numbers if you leave a meter attached for 24 hours of typical use. I've found it takes about 30 minutes at 1250W to heat my 11 Gallons (41.5 liters) of water from stone cold to hot. That's 625 Watt-Hours, or a little over a half a KWH, or around .19 Euro. You can do that several times a day and never pay back the cost of a more efficient system.

Again, that's just for water. If you're going to heat the boat, that's a totally different calculation, and shore power will be one of the most expensive options.

In my opinion, electric heat powered by shore power is always going to be cheaper in the end than heating with diesel fuel, although of course the marginal cost vary depending on fuel cost, cost of power, etc.

My Eber D10 uses .6 liters per hour while on "low", producing nominally 1.5kW of power. It will make up to 10kW but spends most of its time on "low". The fuel consumption per unit of output goes down at higher settings.

One of the problems with this type of heat is that a lot of the heat produced goes out the exhaust, or doesn't make it to where you want it. I guess I get 1 kW maybe when my heater is running on "low", which means at 1 GBP per liter for fuel (say; that also varies a lot) then 1 kW/h of heat costs me 60p, which is about 80 euro cents.

That does not compare favorably to 30 euro cents per kW/h of electrical power. One beautiful thing about electric heat is that it is absolutely 100% efficient; every bit of heat goes where you want it.

But the other beautiful thing about electrical heat is that you can produce it with a $50 Chinese fan heater which has zero maintenance.

Diesel heaters need to be cleaned and serviced on a regular basis; several hundred dollars for only some hundreds of hours of operation. So when you add the maintenance costs -- which probably cost close to what the fuel costs -- then shore power becomes a no-brainer.

And all that is assuming you are paying .30 euro cents per kW/h of metered consumption as in the OP's question. Here in the UK South Coast, only a few marinas are metering power. Unlimited electrical power is usually included in the berthing cost.

[Mithril Bham]

I discovered on-demand propane in Europe in the early 70's. Works great. Get rid of hot water tank

[Mikado]

I haven't seen anyone post who's 120v water heater runs on their inverter when off shore power and generator power? My hot water system is well insulated so only runs for a few minutes every couple of hours unless we use a lot of hot water. It's just another component as part of our power consumption plan.