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Calorifier size.


NbPlod

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Provided you shower using the boat method (get wet, switch of shower, soap up, switch on shower to rinse quickly) a 50l one should be enough (bigger if you have more room as Tony says). Add extra insulation it you have room - use a standard set of house insulation panel - should fill the cupboard its in!

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You don't really explain how you intend to heat it most of the time, although mention of an immersion suggests that it may often be from a 230V land-line possibly?

 

I would say that if most of the time you are heating from a land-line, or even a coal or gas fired boiler, that absolute size isn't that important, and certainly something like 50L will be fine.

 

To me the benefits of a much larger calorifier only kick in when you are cruising and using the engine to heat it, as you will get more "free" hot water for longer after you finish a day's boating. If you are regularly on the move, I'd fit as large as practical, but only if you are regularly using the engine as the heat source.

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I find my 22l is good for a couple of quick showers or a shower and a wash up. I chose a small one as it is heated by an Alde gas heater and I did not want to waste gas heating loads of water that I would not use.

 

If you have 'free' heat from the engine it might be better to get something big, but as I suspect, you will be using electric to heat it, I'd be tempted to go small.

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I'd suggest that, given your basin/shower fit out is the same, you'll use the same amount of hot water on your 36' as you would in any boat with 2 people on it, such as my 57' where I have a 55ltr calorifier heated by engine, Eberspacher or shore supply electric immersion. Assuming you have space to fit a range of sizes (or you wouldn't be asking) I'd agree that bigger is generally more useful, the limiting factor being your ability to heat it.

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Hi,

hate to break in on this topic, but I'm having a bit of a discussion with my boat builder. I am kitting out a livaaboard and as I'm not havimg a bath, it's important to me to have a really decent shower. I am insisting on at least 13l per minute pump and a 75 Litre water tank to cover a 10 minute shower. Heating it would be via engine, boiler (Webasto) or a 2 Kw imersion heater powered by a 4Kw generator. Dors this sound ok to everyone or am I beimg prissey?

Thanks for any cöear ups.

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Your heating proposals will work - but -

 

Just remember that unlike a house, you do not have an unlimited supply of water.

 

A 10 minute shower at 13 litres per minute would be 130 litres, but add that to all your other usage (washing pots, drinking, flushing toilet etc) you will be looking for somewhere to refill your tank every couple of days. Not so much of a problem when cruising everyday, but come winter time and potentially iced up canal, you may be struggling.

 

A 'boat shower' consists of a 'quick-squirt' to get wet, get soaped up, then a 'quick-squirt' to wash off the soap.

10 minute showers are unheard of.

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We have;

1300 litre water tank, 141 litre calorifier, heated by built in generator cooling system while battery charging for an hour or so. Corner bath. Luxury.

Boats can be frugal and minimalist - usually are - but they don't have to be. Just sayin'.

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Amen! I have a 900 Litre tank. Don't forget in the shower flow to build in a ratio of 60-40% hot to cold. That means at 13l/m you only use 78 Litres of hot in a ten minute shower. Am definately not interested in the 'boat shower'! Ok for holidays but not a liveaboard.

The problem seems to be finding a shower pump that will do 13l/m on a 10 amp system. Any advice? The other issue he raised was the difficulty of heating the water in a 75 litre tank, but Surecal seem to think 30 mins of engine or boiler will heat the whole tank, and a 2kw immersion heater should do the job in two hours of genny running.

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Amen! I have a 900 Litre tank. Don't forget in the shower flow to build in a ratio of 60-40% hot to cold.

Very true - but it also depends on what temperature you set the thermostat, and, if you set the thermostat 'high' (maybe 85o then it takes longer to heat up, also remember that as you take the hot water out of the cauliflower, you are replacing it with cold water and reducing the temperature of the remaining water, and will need to reduce you cold water ratio.

 

That means at 13l/m you only use 78 Litres of hot in a ten minute shower.

I was not talking about the amount of 'hot water' I said that the total taken out of your tank will be 10 x 13 litres, That is why you will need to refill your tank regularly.

 

Am definately not interested in the 'boat shower'! Ok for holidays but not a liveaboard.

The problem seems to be finding a shower pump that will do 13l/m on a 10 amp system. Any advice?

Is there any reason why you are limited to 10 amps ?

 

The other issue he raised was the difficulty of heating the water in a 75 litre tank, but Surecal seem to think 30 mins of engine or boiler will heat the whole tank, and a 2kw immersion heater should do the job in two hours of genny running.

According to the 'water heating calculations' (easily found on Google), heating 75 litres of water from 10oC to 85oC using a 2kw immersion heater will take 197 minutes.

I would suggest that the engine run time of "30 minutes" is very optimistic and would be nearer the hour (in my experience) unless you were really 'thrashing' it and running against the tide.

 

I am not suggesting that life as aliveaboard should be like living in a cave and 'roughing it', but one also needs to face facts that a boat is not a 'floating flat' - unless it is a 'houseboat' permanently connected to the utilities.

Edited by Alan de Enfield
  • Greenie 2
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Obviously it will differ from boat to boat, engine to engine, and upon exact installation details, but I would be surprised if many Surecal calorifiers of that size are fully heated in only half an hour. Certainly you will have significant hot water after half an hour, but normally I would say not a whole tank full unless the engine i working hard. If you are moored up and running at "battery charging speeds" then I would say generally a lot longer will be needed.

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. If you are moored up and running at "battery charging speeds" then I would say generally a lot longer will be needed.

I wouldn't have a tank full in 2 hours doing that. I dont know how long it takes cruising but as you say you soon have some hot water.

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I live in a house and couldn't imagine spending more than 5 minutes in the shower - once you are clean there is no real benefit to being in there any longer than necessary.

 

On the boat we use a shower with a trigger in the handset, saves no end of water.

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Guys! The issue is not necessarily how long you spend in a shower. There may well be two or three people wanting to shower and then it would be three minutes each. The point is getting a decent flow rate so it's a nice experience even in winter and how to get the water hot. In the winter the boiler will be on for a couple of hours in the morning and the genny for a couple of hours too. Shouldn't be a problem. Whilst cruising the engine will get 75 litres hot, but in the summer it will just be the genny running the 2 kw immersion and I'm a bit worried that won't be enough.

Not very good at electrics but The limit for a water pump on my loom is for a 14 amp fuse. Does that make sense?

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Another way of heating water is to use a decent heat exchanger after the calorfier with the heat source of your choice (like a ebersplutter), this way you'll get instant (ish) hot water without having to wait for the calorfier to warm up. Most boat heaters tend to be around the 4kw mark so the water will need to warm first, but the heat exchanger will top it up by this amount.

 

The system works better ofcourse if you have a heater in the 12kw+ range and a thermostat on the exchanger to turn the boiler on.

Edited by Robbo
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