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Hot shower all year round


big d

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14 hours ago, Detling said:

The reason most domestic showers are 7kW or more is to get the water hot enough at a reasonable flow rate. 

It’s surprising how few folk appreciate that that’s a hefty power requirement.
 

There used to be a dry ice fog machine used in theatres called the ‘Londoner Fog’. It had three 3kW kettle elements inside (so 9kW) to heat the water quickly and to try to keep it hot once you’d dropped a quantity of CO2 at -78C into it. Getting 3 x 13A sockets on a board with a 40A feed, despite asking clearly in advance, was invariably difficult. Nobody believed that it truly required a 40A 230V supply. 

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5 minutes ago, WotEver said:

It’s surprising how few folk appreciate that that’s a hefty power requirement.

We had a caravan owner come and complain about the electric continually tripping, upon investigation, he had removed the old shower and installed an 11Kw unit.

With a 16a supply its little wonder - According to him, he was previously an electrician (mind you, from his alleged employment history he must have been 500 years old) and it should have been OK.

 

Left him to it.

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Years ago while working on tv show, we dropped off air when studio went dark, turns out the lighting crew had switched on a kettle, the show required a large ice rink and 15 plus cameras and full rig. One kettle on the wrong ring was the straw! 

  • Happy 1
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Am I missing something here? Is the answer not, as has already been said, a 1kw immersion heater running from the shore supply?  No need for more than the perfectly adequate, ubiquitous narrowboat 240v 1kw immersion; easily coped with by even a 6 amp shore supply with a bit of thought before flashing up the kettle, microwave, or whatever; no need to involve the inverter; no need to go for a 12v immersion with huge cables; no need to start bothering the batteries.

 

Apologies if I've misread the OP's situation. :)

 

  • Greenie 2
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26 minutes ago, Sea Dog said:

Am I missing something here? Is the answer not, as has already been said, a 1kw immersion heater running from the shore supply?  No need for more than the perfectly adequate, ubiquitous narrowboat 240v 1kw immersion; easily coped with by even a 6 amp shore supply with a bit of thought before flashing up the kettle, microwave, or whatever; no need to involve the inverter; no need to go for a 12v immersion with huge cables; no need to start bothering the batteries.

 

Apologies if I've misread the OP's situation. :)

 

Eggsactly (post #3)

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36 minutes ago, Sea Dog said:

Am I missing something here? Is the answer not, as has already been said, a 1kw immersion heater running from the shore supply?  No need for more than the perfectly adequate, ubiquitous narrowboat 240v 1kw immersion; easily coped with by even a 6 amp shore supply with a bit of thought before flashing up the kettle, microwave, or whatever; no need to involve the inverter; no need to go for a 12v immersion with huge cables; no need to start bothering the batteries.

 

Apologies if I've misread the OP's situation. :)

 

That's the route I will go down, I like to use as much free power from the sun as possible but the time factor for me sold the 240 1kw immersion. Right now in summer all I have is cold water so a timer and mains means when I need it in morning the water will be hot as needs, if when out cruising I can strain bats or just run bubble as when cruising the through air keeps cabin cool. Thank for brain picking, as always saves me coming up with 15 different solutions before getting right one 

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No I think you are exactly right.

 

Assuming they have a calorifier and mains connection, using or fitting an immersion heater is a very sensible and practical option. Using a 1kw 'travel spec' immersion, or a 3kw normal domestic spec one, would depend in anticipated water usage and or shore connection. If the calorifier needs replacing to install an immersion that is another battle, but I understand reasonably unlikely assuming a fairly modern boat.

 

The smaller immersion would give more scope to run it off the 3.5kw inverter alongside other loads, but heating water using power from an inverter is not something to be taken lightly, and while a 120A 12v (1.4kw) alternator might just about be able to keep pace, you would have little joy taking that much out of most battery banks.

 

 

Daniel

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36 minutes ago, DHutch said:

No I think you are exactly right.

 

Assuming they have a calorifier and mains connection, using or fitting an immersion heater is a very sensible and practical option. Using a 1kw 'travel spec' immersion, or a 3kw normal domestic spec one, would depend in anticipated water usage and or shore connection. If the calorifier needs replacing to install an immersion that is another battle, but I understand reasonably unlikely assuming a fairly modern boat.

 

The smaller immersion would give more scope to run it off the 3.5kw inverter alongside other loads, but heating water using power from an inverter is not something to be taken lightly, and while a 120A 12v (1.4kw) alternator might just about be able to keep pace, you would have little joy taking that much out of most battery banks.

 

 

Daniel

The boat is  old, no alternator on engine, resurrection of boat was done in the 90s so hoping I can fit a immersion if not new calirifier 

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15 hours ago, big d said:

The boat is  old, no alternator on engine, 

So, no hot water from engine because it's air cooled and NO ALTERNATOR.

The only way to keep 20 batteries charged is with your solar power when you're out and about. Might work in the Sahara, not sure about the UK.

I would say an alternator is required?

What about a solar water heater (like they stick on the roofs of houses), anyone tried that? 

Edited by Stephen Jeavons
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How is the boat going to be used?

 

If it is going to almost always be on its home mooring with a mains hook up, and just has to survive a day off-grid, or you are happy to greatly reduce consumption for the time you are off-grid till you next plug in, then you will be fine. However few moorings outside of marinas have hookup, so if you are planning to go off boating off-grid you will need to think seriously about how you put the power back in to the batteries. If you are actually moving the boat 8 hours a day, an alternator on the engine would make a big difference. If you are going to moored up static off-grig for days, the alternatives need more care and attention.

 

20 x 110Ah x 12 V = 2640 Wh (2.64kWh) so a 3.5kW inverter on high output will pull them to pancake-flat in 40 minutes. Enough to cook a roast dinner, once, or heat a tank of water once, but not both! Heating 50 litre of water from 15 to 65 deg will take 3kWh. So one hour with a 3kW element or 3 hours with a 1kW element. Or about 20% more than you battery has from full to pancake. Obviously if you take them down to pancake with any frequency at all they will need replacing fairly promptly!

 

If you have 21x70W = 1470W (1.47kW) solar running flatout out it will theoretically take 2-3 hours to refill, however in practice in the UK I understand it will take more like 3 days*.

 

*   "Average UK conditions you can expect, 1kW of panels to generate 700-900 kWh."   So you panels might average 1-1.3kWh per day, obviously more in summer, less in winter.

https://www.cat.org.uk/info-resources/free-information-service/energy/solar-photovoltaic/

 

 

Daniel

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20 minutes ago, TheBiscuits said:

Also no immersion heater, hence this thread.

 

I can see why this boat was an obvious choice to go gas-free ...

I looks to me as if in the Winter 6-months it is more 'electric free' than gas free.

 

Once 20 batteries have been killed off it will become an expensive job to replace them.

 

 

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The guy that built the boat wanted to live off grid, originally there was a diesel genny in bow, its wasn't designed to have a tv and kettle and any electric draw really except 12v pumps etc. When he stopped living off grid it went to a home mooring where it was on mains and had domestic white goods added and air con so one extreme to another, now I am trying to find a balance, I removed some stuff, added others. Been ok for the time I've had it and happy when off mooring as I don't roast a dinner and have a bath on same day. Thank you for concearn but the starter batterys are isolated cranking batterys from the rest so never drawn by anything except engine. I'm happy without gas as in winter diesels better, I just wanted ideas for hot water while on mooring in summer and the option to have when off mooring. As I originally said I don't care about judgement but thanks for putting stuff in bold capitals it really helps me read turns out that also charges my batteries like disbelief, judgement and righteousness 

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6 minutes ago, big d said:

The guy that built the boat wanted to live off grid, originally there was a diesel genny in bow, its wasn't designed to have a tv and kettle and any electric draw really except 12v pumps etc. When he stopped living off grid it went to a home mooring where it was on mains and had domestic white goods added and air con so one extreme to another, now I am trying to find a balance, I removed some stuff, added others. Been ok for the time I've had it and happy when off mooring as I don't roast a dinner and have a bath on same day. Thank you for concearn but the starter batterys are isolated cranking batterys from the rest so never drawn by anything except engine. I'm happy without gas as in winter diesels better, I just wanted ideas for hot water while on mooring in summer and the option to have when off mooring. As I originally said I don't care about judgement but thanks for putting stuff in bold capitals it really helps me read turns out that also charges my batteries like disbelief, judgement and righteousness 

Electrical heating of water from batteries is going to kill them off rapidly as @DHutch has shown in his sums a few replies back without a way of supplying it from another source pretty much as it is being used. If you aren't going to install either a high output engine alternator, or a generator, or cover every inch of the roof with photovoltaic panels, then this isn't practical off grid. Cooking by electric off grid will make the life of your batteries short, even if it seems to work OK.

Your options seem to be. Install a generator, install a high output alternator, or mains travelpower on the engine, install solar thermal hot water heating.

The last is the method I use, with the stove back boiler in the winter. Lashings of hot water all year round, except for a few annoying days in spring and autumn, when it is too warm for a fire, but not warm enough to get much hot water.

 

Jen

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15 minutes ago, big d said:

The guy that built the boat wanted to live off grid, originally there was a diesel genny in bow,

That would make a huge difference, but I don't think you had mentioned it earlier.  Did you remove it or did the previous owner?

 

 Fitting a water cooled genset to the boat would solve most of the issues discussed in this thread, as would replacing the engine with one that is water cooled and has a decent alternator.  

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1 hour ago, Jen-in-Wellies said:

or cover every inch of the roof with photovoltaic panels

That's may boat! 

 

1 hour ago, TheBiscuits said:

  Did you remove it or did the previous owner?

Yes, I removed wiring as it was suspect but the fuel line is blanked off but still there although I wielded over the vent.   the previous "owner" was the relative of the guy that built it, also the reason it was left neglected for so long. A lot of stuff including batteries were taken from boat after I'd put an offer in with broker after mates were allowed to take it from boat. 

 

Ive been gradually getting the boat to where it suits me. The solar is great, I can't have spent £100 on shore electric and fridge I still 12v so summer sun keeps the ice cream cool and when solar drops off ice a cold pantry in bow that Keeps milk cool in winter. 

 

I removed composting toilet and full bath. Also it had full set of white goods, dish washer, washing machine, fridge and freezer plus aircon unit, had gone from full offgrid to house on water. All removed as I didn't need 

 

Ive learnt as Ive gone with the bubble, it's on all winter and keeps boat and water hot, no roof wood or coal required. I can do coffee pot on it and many a stew has

spent the day perfecting on it. Underfloor heating and rads can be switched off in summer and when cruising bubble will do water heat while not overheating cabin while when on home mooring hookup can do immersion hopefully, it's a balancing act to get it to suit me.

 

not going to mess with gas as don't have it and don't feel I need it. 

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as this thread is similar to what I am researching at the moment because of the boat I'm watching has an air cooled lister and without starting a new one off, I have seen some of the things the americans are doing with twin use solar panels.

 

solar panels get hot, they can;t help it and when hot they lose efficiency, I was surprised to see our house panels lost around 40% of their capability during the super hot spells we had during the past few summers, cooling them down keeps them efficient. our panels were also designed for low UV climates so they gathered more energy from winter light.

 

so how to cool them down - basically put a water pipe behind the panel and then a back on that with a circulation pump into the cauliflower. the yanks have done it with silicone pipe, hope pipe, plastic pipe, aluminium and copper pipe. I haven't tried it out but intend to, there are also some dome shaped collectors that use standard black corrugate cable trunking so I assume it copes with the temperatures well enough. in theory it doesn't need a pump either as it should thermal siphon into the cauliflower. the only weak point I see is like when I plumbed in the wetback boiler at home - you probably need a heat sink somewhere or something to stop it blowing if left unchecked..

 

If I was going to moor south facing or leave the boat empty for a while I would even consider a DIY solar air heater i've seen made from beer cans.,

 

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1 hour ago, crazydave said:

as this thread is similar to what I am researching at the moment because of the boat I'm watching has an air cooled lister and without starting a new one off, I have seen some of the things the americans are doing with twin use solar panels.

 

solar panels get hot, they can;t help it and when hot they lose efficiency, I was surprised to see our house panels lost around 40% of their capability during the super hot spells we had during the past few summers, cooling them down keeps them efficient. our panels were also designed for low UV climates so they gathered more energy from winter light.

 

so how to cool them down - basically put a water pipe behind the panel and then a back on that with a circulation pump into the cauliflower. the yanks have done it with silicone pipe, hope pipe, plastic pipe, aluminium and copper pipe. I haven't tried it out but intend to, there are also some dome shaped collectors that use standard black corrugate cable trunking so I assume it copes with the temperatures well enough. in theory it doesn't need a pump either as it should thermal siphon into the cauliflower. the only weak point I see is like when I plumbed in the wetback boiler at home - you probably need a heat sink somewhere or something to stop it blowing if left unchecked..

 

If I was going to moor south facing or leave the boat empty for a while I would even consider a DIY solar air heater i've seen made from beer cans.,

 

 

Never a more appropriate username!
 

 

:giggles:

 

 

 

 

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8 hours ago, crazydave said:

as this thread is similar to what I am researching at the moment because of the boat I'm watching has an air cooled lister and without starting a new one off, I have seen some of the things the americans are doing with twin use solar panels.

 

solar panels get hot, they can;t help it and when hot they lose efficiency, I was surprised to see our house panels lost around 40% of their capability during the super hot spells we had during the past few summers, cooling them down keeps them efficient. our panels were also designed for low UV climates so they gathered more energy from winter light.

 

so how to cool them down - basically put a water pipe behind the panel and then a back on that with a circulation pump into the cauliflower. the yanks have done it with silicone pipe, hope pipe, plastic pipe, aluminium and copper pipe. I haven't tried it out but intend to, there are also some dome shaped collectors that use standard black corrugate cable trunking so I assume it copes with the temperatures well enough. in theory it doesn't need a pump either as it should thermal siphon into the cauliflower. the only weak point I see is like when I plumbed in the wetback boiler at home - you probably need a heat sink somewhere or something to stop it blowing if left unchecked..

 

If I was going to moor south facing or leave the boat empty for a while I would even consider a DIY solar air heater i've seen made from beer cans.,

 

Atone point you could buy solar panels that already had cooling pipes, they were expensive so never took of. However my mate Richard that sold them said they did work well, unless your cauliflower is above the panels you will need a pump a solar one will work fine.

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12 hours ago, crazydave said:

so how to cool them down - basically put a water pipe behind the panel and then a back on that with a circulation pump into the cauliflower. the yanks have done it with silicone pipe, hope pipe, plastic pipe, aluminium and copper pipe. I haven't tried it out but intend to, there are also some dome shaped collectors that use standard black corrugate cable trunking so I assume it copes with the temperatures well enough. in theory it doesn't need a pump either as it should thermal siphon into the cauliflower. the only weak point I see is like when I plumbed in the wetback boiler at home - you probably need a heat sink somewhere or something to stop it blowing if left unchecked..

Should be pretty easy to do. As @peterboat says, it won't thermosyphon on its own without a pump as the hot bit is higher than the cool end (cauliflower), but it doesn't need a big pump. I've quite bit of experience with solar thermal on my boat. I would think that without a transparent cover over the photovoltaic panels you'll only get a significant output of warm water on the very hottest days. As the water in the cauliflower heats up, then the return coolant back to the panels will get warmer and eventually you'll run in to the reduced pv efficiency problem anyway. If the calorifier is already warmed up, then you might end up with reduced electrical output. Might be better to have the coolant going to a small skin tank to dump the heat in to the canal.

 

This may well be more expensive to set up than just adding an extra panel or two to compensate for the loss. If the panel array is sized to give you enough power during the summer, then on a hot day it will be over producing anyway. Twelve years ago I had a gadget that swung the two panels I had in an arc automatically to track the sun. Cost £250 to buy, but was worth it as an extra panel was £400 at the time. I eventually replaced it with another panel for £70 and mounted all of them flat to the roof and still got more output. Since then, panel costs have continued to drop.

 

Jen

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13 minutes ago, Jen-in-Wellies said:

If the panel array is sized to give you enough power during the summer, then on a hot day it will be over producing anyway.

I feel that this is most pertinent. So what if the efficiency is reduced if you already have more power than you can use?

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thanks for the comments and no intention to hijack the thread as I am brand new here - with regards the thermosyphoning I agree usually the heat source is lower but that sis a convection rather than a thermosyphon effect, however I spent the last year working out how to combine a pressurised central heating system with a vented wet back boiler stove using a plate heat exchanger. while I pumped both sides of the exchanger for efficiancy I did see several (again US) references to putting the plate exchanger on top of the water tank and that would work naturally with no pumps. while odd and counter intuitive they say it works. but I can't vouch for it until I've tried it.

 

at to making all you need in the summer so loss of output doesn't matter - well I guess that depends on what you are running and where you are to catch the sun. I found a 3.5kw south facing solar array only worked at full speed for around 6 hours a day and it was very easy to not export a thing as the hot water tank could swallow 9kw per day easy. during the summer appliances like fridges use more power and one thing I would like to have is a full size fridge freezer for personal ease. and electric appliances as I don't want to live in the 1970s in my future floating apartment top explore the cut with on my own terms for once, I also use fans to help me sleep even in winter. 

 

so I am approaching this from previous experiences rather than the boat learning curve which is coming sooner than I expected or indeed wanted. at the  moment it is keeping me sane redesigning a boat layout and services in my head.. so I am looking at gas less and probably wood/coal less too intending to go solar/electric and diesel. so the learning curve is battery banks and how to abuse them as the voltages are different to what I have learnt to deal with.

 

this was what got me thinking at the time and I have a few other websites saved  if I ever get my other laptops back. I was trying to introduce a second heat source into the system so I had gravity circuit from my boiler to the heat sink then the secondary circuit into the heating loop via the plate exchanger using the existing boiler circuits and valves to dump heat into the water first and then into the house rads. 

 

 

 

Edited by crazydave
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