water heating options

[blackrose]

9 hours ago, Alan de Enfield said:

 

Would it not be worth changing it so it doesn't ?

 

Thanks I'll change it! 😋

[booke23]

13 hours ago, blackrose said:

I guess I could just use the timer on my immersion heater on days I'm away from the boat if the forecast is for sun, but if it clouds over I don't really want to use the batteries to heat water.

 

Yes that's the problem if happens to get cloudy when you're not around. However after a bit of digging on google I found this https://www.bimblesolar.com/digital-voltage-relay?tracking=60c4aee677342 

 

Looks like you can set it up to disconnect any load once the battery voltage drops to a value set by the user. I guess you could set it to cut off if the batteries drop below about 13.5v (assuming LFP) to preserve charge. Quite cost effective too....the unit + 200amp relay is £30. 

 

 

[blackrose]

3 hours ago, booke23 said:

 

Yes that's the problem if happens to get cloudy when you're not around. However after a bit of digging on google I found this https://www.bimblesolar.com/digital-voltage-relay?tracking=60c4aee677342 

 

Looks like you can set it up to disconnect any load once the battery voltage drops to a value set by the user. I guess you could set it to cut off if the batteries drop below about 13.5v (assuming LFP) to preserve charge. Quite cost effective too....the unit + 200amp relay is £30. 

 

 

 

That's interesting. I had a look at the manual and the wiring diagram but it's a bit confusing. Someone would need to explain exactly how I connect it to the immersion.

[IanD]

1 hour ago, blackrose said:

 

That's interesting. I had a look at the manual and the wiring diagram but it's a bit confusing. Someone would need to explain exactly how I connect it to the immersion.

Do you have a Victron Multiplus or Quattro? If so you can wire the immersion heater directly to ACOUT2, see earlier post.

[booke23]

3 hours ago, blackrose said:

 

That's interesting. I had a look at the manual and the wiring diagram but it's a bit confusing. Someone would need to explain exactly how I connect it to the immersion.

 

Actually I've just read the manual and it looks like it can switch up to 277v/10amps. So I think you could set it up to run on and monitor the battery voltage while switching the 240v immersion directly. So once the battery bank voltage drops it turns off the immersion only. But I could be misreading it.  

[blackrose]

15 hours ago, IanD said:

Do you have a Victron Multiplus or Quattro? If so you can wire the immersion heater directly to ACOUT2, see earlier post.

 

No I don't, I have a standalone Sterling 2kW inverter.

[MtB]

14 hours ago, booke23 said:

Actually I've just read the manual and it looks like it can switch up to 277v/10amps.

 

I doubt 10 Amps is enough. Surely a 12V immersion heater draws more current than that? 

 

I think a relay will be required.

 

 

[Alan de Enfield]

1 hour ago, MtB said:

 

I doubt 10 Amps is enough. Surely a 12V immersion heater draws more current than that? 

 

I think a relay will be required.

 

 

 

Roughly - A 120w immersion (which won't do a great deal) will draw 10 amps.

A typical 1000 watt immersion will draw 80 odd amps

[booke23]

2 hours ago, MtB said:

 

I doubt 10 Amps is enough. Surely a 12V immersion heater draws more current than that? 

 

No, but his immersion is 1kW mains so it'll be more than enough, assuming the device can safely switch 230v. 

[Tony1]

 

Apologies if I'm repeating stuff, I dont have time to read all the replies made so far.

You need different solutions at different times of year.

For example, I get enough solar energy from my 1.4kw of panels to heat a tank of water above washing temp between mid-march and mid-Sept. It can vary of course. If you moor under trees or on heavily overcast days you might not get enough solar to heat the water. But most days you will, and certainly between April and Aug, if you have 1 to 1.5 kw of panels.  So that's the summer hot water taken care of.

In the marginal months, where you use diesel CH to give you the odd blast of heat on a chilly morning or evening, you can use the CH to heat the water if its set up that way on your boat. 

In the colder months (say Nov-Feb), I've had to run my engine to charge the batteries, and that heats the water anyway.

But it does add a lot of running hours to the engine. So next winter I'm thinking of getting a generator instead to do the battery charging. If I do that I'll need an alternative to the heat provided by the engine running every day. 

 

In the cold months the SF stove is on most of the time, so my thinking is that I could use a tall stock pot to heat water for washing. like this one from Argos:

https://www.argos.co.uk/product/8355238?istCompanyId=a74d8886-5df9-4baa-b776-166b3bf9111c&istFeedId=c290d9a9-b5d6-423c-841d-2a559621874c&istItemId=ixwliqmit&istBid=t&utm_custom6=PLA&deeplink=true&&cmpid=GS001&_$ja=tsid:59157|acid:898-274-0554|cid:20247640952|agid:|tid:|crid:|nw:x|rnd:7453860963325015905|dvc:c|adp:|mt:|loc:9222618&utm_source=Google&utm_medium=cpc&utm_campaign=20247640952&utm_term=8355238&utm_content=shopping&utm_custom1=&utm_custom2=898-274-0554&GPDP=true&gad_source=1&gad_campaignid=19663889715&gbraid=0AAAAAD9II9kQNv3gc0411rOdThE2GGn8Q&gclid=Cj0KCQjwt8zABhDKARIsAHXuD7Yd3dAjF7gRuxX9upDbP6YGWZPSaXPdNGA9vr60kT4mk40JBSZ7VDAaAopeEALw_wcB&gclsrc=aw.ds

 

It will (very slowly) heat 10 litres close to boiling, and that can be diluted about 50/50 with cold water - and that's enough to get a very good strip wash. I'm thinking of doing this myself next winter, and I'll only ever use the pot for body washing water, and never for cooking. 

 

As an alternative, one chap I met recently uses a 3500 watt MXR genny with the charge running into his shoreline socket, and that gives enough electricity to heat his water up to maybe 60 degrees in about an hour. 

But if you dont want to run the engine every day, the SF stove seems the most cost effective, as it is usually on anyway in winter. 

 

Edited May 1 by Tony1

[blackrose]

Carrying large pots of nearly boiling water around the boat sounds a bit dodgy and a bit of a faff. In winter I usually run the Webasto for an hour first thing in the morning to heat the boat up as the fire has died down overnight so that gives me a tank of water. Either that or I can use the gas water heater or switch on the immersion heater if I'm charging the batteries from the generator. Anyway I don't think I want to carry big pots of water around. Sooner or later it's bound to end in disaster. Either that or you're strip washing by the stove which doesn't sound ideal.

[Tony1]

21 minutes ago, blackrose said:

Carrying large pots of nearly boiling water around the boat sounds a bit dodgy and a bit of a faff. In winter I usually run the Webasto for an hour first thing in the morning to heat the boat up as the fire has died down overnight so that gives me a tank of water. Either that or I can use the gas water heater or switch on the immersion heater if I'm charging the batteries from the generator. Anyway I don't think I want to carry big pots of water around. Sooner or later it's bound to end in disaster. Either that or you're strip washing by the stove which doesn't sound ideal.

 

Tbh, I say nearly boiling but on the times I've tried it, I seldom wait that long. Most times its about 60 degrees, which is plenty hot enough to wash. 

I think the risk of carrying a 10 litre pot of hot water from the stove to the sink (about 10-15 feet?) is not nearly as great as the risks I already run by working locks in wet or icy conditions. Boaters carry pots and pans of very hot food from their stoves to their worktops on a daily basis during winter. Personally,  I'm not convinced there is a significant safety issue.

In winter I leave the stove ticking over during the night, so there is no need to use the CH in the morning. 

And if have the SF stove on anyway, I'm not going to waste a litre of diesel (and get the boat too hot) by running the CH at the same time.    

 

Edited May 1 by Tony1

[blackrose]

10 hours ago, Tony1 said:

 

Tbh, I say nearly boiling but on the times I've tried it, I seldom wait that long. Most times its about 60 degrees, which is plenty hot enough to wash. 

I think the risk of carrying a 10 litre pot of hot water from the stove to the sink (about 10-15 feet?) is not nearly as great as the risks I already run by working locks in wet or icy conditions. Boaters carry pots and pans of very hot food from their stoves to their worktops on a daily basis during winter. Personally,  I'm not convinced there is a significant safety issue.

In winter I leave the stove ticking over during the night, so there is no need to use the CH in the morning. 

And if have the SF stove on anyway, I'm not going to waste a litre of diesel (and get the boat too hot) by running the CH at the same time.    

 

 

Ok first you said "close to boiling" and then 60C. If it's the latter then the risk is significantly reduced. Boaters don't generally carry pots of hot food 30ft down the boat, they just move it from the stove to an adjacent worktop and put it on a plate or in a bowl and it wouldn't be nearly as heavy or have the free surface effect as that huge stock pot, so there is a difference.

[Tony1]

41 minutes ago, blackrose said:

 

Ok first you said "close to boiling" and then 60C. If it's the latter then the risk is significantly reduced. Boaters don't generally carry pots of hot food 30ft down the boat, they just move it from the stove to an adjacent worktop and put it on a plate or in a bowl and it wouldn't be nearly as heavy or have the free surface effect as that huge stock pot, so there is a difference.

 

You can heat the water to the whatever temp is needed - I used the example of a strip wash but there would be several other uses for it. If personal washing it will probably be maybe 60 degrees, but even that depends on how the user wants to wash. 

 

Many boaters use their SF stove to cook and to heat water on a daily basis, whilst the stove is in use. The distance they carry their pan or pot from the SF stove to the kitchen worktop depends on the boat layout. In my case it is about 10 or 12ft. In other boats it will be longer, some will be shorter. 

 

But I do agree that carrying a 10 litre pot full of water (even at 60-70 degrees) is fairly risky, even over 10 feet.

When I thought of this idea, I envisioned the pot being about 70% full at most. I would never cook or boil on a boat with a pan or pot that is anywhere close to full.   

 

But even 7 litres of hot water is a significant volume, and I agree that it would have to be carried very carefully. I've tried it using two pans of smaller volume, but if I were to try using my pot idea, I think it might be better to use two smaller pots instead of one big one. The carrying risk doesnt bother me personally, in fact I run greater risks on rainy days when lifting my 27kg ebike from the stern onto the bank.

My problem is that I moor using fat yacht fenders to minimise the impact of bumping against the banks in windy conditions, but that method also allows the boat to bob around a bit when other boats pass by.

So in my case, the risk that bothers me most (and one that I hadn't considered before you raised the issue of risks) is that a passing boat boat could cause enough movement to shift a tall cooking pot in some way. Its not often that a boat goes past that fast in winter, but it does happen, and a tall pot of hot water on the stove seems like a potential accident waiting to happen. I'll have to give the idea some more thought.  

 

[Jen-in-Wellies]

Our ancestors had solutions to the moving hot water around the home problem, before plumbing was widespread. Water was heated on the fire, or range in a kettle, then transferred to a wash jug to take it to a wash stand for washing in a bedroom.

https://www.sellingantiques.co.uk/191786/antique-victorian-pine-wash-stand-vanity-table-with-washstand-jug-bowl-c1880/

The wide base and narrow top reduced the risk of slosh and spillage while carrying it around.

Similarly for heating on the stovd, kettles have a wide flat base and narrow to the top and spout, which again reduces slosh and spillage risks. This would also reduce the risk of slosh from boat movement as well as carrying. Anything to reduce the surface area of the water, while keeping the base wide for stability. Something to consider.

[blackrose]

If I wanted hot water from my stove I'd do it properly with a backboiler in the stove heating a calorifier. Then you don't need to mess about with pots and jugs and can just turn on a tap or even have a shower. 

Edited May 2 by blackrose

[magnetman]

I have managed without any hot water other than cooking or tea for the last 3 years.

 

Not sure what all the fuss is about. Cherry tea shop clothes now and then.

 

Navy showers are ok.

 

 

[blackrose]

That sounds like a rather frugal existence. Hot water isn't "a fuss", it's just hot water. They even have it in parts of the third world.

[magnetman]

I do not find it arduous. M&S shirts from the cheery tea shops at this time of the year for ventilation and also going in commando.

 

Maybe this is too much information 

 

It just advice for when life gets really difficult during the initial phase of world war 3 or something.

[DShK]

11 hours ago, magnetman said:

I do not find it arduous. M&S shirts from the cheery tea shops at this time of the year for ventilation and also going in commando.

 

Maybe this is too much information 

 

It just advice for when life gets really difficult during the initial phase of world war 3 or something.

Ah yes, we won't have hot water available to us but the charity shops will stay open so we can all throw away our clothes when they get smelly. Good advice.

[magnetman]

7 minutes ago, DShK said:

Ah yes, we won't have hot water available to us but the charity shops will stay open so we can all throw away our clothes when they get smelly. Good advice.

 

I wonder if it is more energy intensive to keep washing things or use them as consumables. 

 

Cotton clothes don't need to be thrown away just tear up and use as pieces as firelighters in winter. 

 

Cotton is the only material needed for clothing. 

 

Charity shops always have a lot of stuff available. 

 

 

[blackrose]

On 03/05/2025 at 11:02, DShK said:

Ah yes, we won't have hot water available to us but the charity shops will stay open so we can all throw away our clothes when they get smelly. Good advice.

 

It sounds incredibly wasteful to me. I assume you must both be joking. 

On 03/05/2025 at 11:13, magnetman said:

 

I wonder if it is more energy intensive to keep washing things or use them as consumables. 

 

On 03/05/2025 at 11:13, magnetman said:

Cotton clothes don't need to be thrown away just tear up and use as pieces as firelighters in winter. 

 

A life-cycle assessment or carbon footprint study would show that washing clothes at a low temperature is far better than burning them when they get dirty. When you're looking at energy use you also have to include the embedded energy involved in manufacture of the clothes.

Edited May 4 by blackrose

[magnetman]

Yes but what about if the clothing is bought from a charity shop ie a bin shop? Charity shops are full of perfectly good clothes someone else did not want. It is they who have caused the new garments to be manufactured so buying from charity shop secondhand is effectively reusing someone else's waste products and there is zero product transport. 

 

This is a different process to buying new then burning when dirty. 

 

But I know you are right. 

 

 

[blackrose]

Yes, after a certain number of uses clothes can be said to have compensated the embedded energy used in their manufacture.

 

But you have to take it into consideration. Most people intuitively think a ceramic cup is better for the environment than a single use paper or plastic cup. But if you happen to drop and smash the ceramic cup after only a few uses then the disposable cup is far better because it's embedded energy is minimal. So these sorts of comparisons are based on lots of assumptions.

[PabloC]

On 27/04/2025 at 17:45, David Mack said:

Fit a back boiler to heat the water and maybe also the radiators. Together with a solar dump system that should provide year-round hot water.

Thank you, I've thought about a back boiler, but I'm just keen to reduce the amount of work needed to get to a solution. But I can see the benefit of it over winter.

 

On 27/04/2025 at 18:21, Stilllearning said:

In my opinion, with a modern diesel, relax and run it just above tickover, charge the batteries and have hot water.

Thanks, I'll have a look into what the engine manufacturer suggests but it is a new (relatively) engine.

 

On 27/04/2025 at 19:05, Tony Brooks said:

 Rather than that, if you have an ammeter for the domestic bank, run it at the speed that gives maximum charge. With LA batteries, the charge will drop after perhaps 20 minutes and continue to drop, so you can slow the engine down to maintain maximum charge. That way, you maximise the load the alternator puts on the engine.

Thanks, I'll try that!

 

On 27/04/2025 at 19:52, booke23 said:

 

You probably need slightly more solar for an effective solar dump.....you would get some heating from it but it might not be worth the faff with 800w. People with solar dumps usually have well over a kilowatt of solar. 

 

Yes you can go down the valve route to isolate the engine/heater. Although you do hear of webasto's on a single coil system without valves, it could be a real pain to retrofit. You'd loose a bit of heat to the engine with this setup and it could be problematic with pressurised engine cooling systems. 

Worth considering, thanks! I'll likely go down the webasto route and see some advice re fitting from an engineer.

 

On 27/04/2025 at 20:03, blackrose said:

I have twin coil calorifier from engine/Webasto, 1kW immersion heater which I can use on sunny days from solar panels/lithium batteries and instant gas water heater. I also have a 2.8kW generator so if I'm using it to run the battery charger on dull days in winter I can switch on the immersion heater at the same time. 

 

The more options you have the better. 

Very true. I can see myself getting a genny, even if only for deepest winter.

 

On 28/04/2025 at 09:30, JoeC said:

I have a heat exchanger and pump fitted to my engine to heat the radiators in winter when the engine is running. I also have a Webasto connected to the same radiator circuit so you may find your current setup could be used should you install a diesel heater. There are some posts on here about installing heat exchangers.

Thanks, that's good to know. I'll have a look into that. Obviously, the less work to get it fitted the better.

 

On 28/04/2025 at 09:42, MtB said:

 

I think it would be worthwhile. I helped a mate design and install a solar dump onto 1200W of panels over winter and it came on stream working well late feb or the beginning of March, I can't quite remember. The less solar you have, the later in the year it will come on stream and the sooner in Autumn it will stop working so more is always better, but a little will always be useful in the summer. 

 

 

I wouldn't know where to start with getting a solar dump fitted 😵‍💫

 

Thanks again for the replies!