Baggywrinkle
Well-Known Member
This is the basic layout of a boat water system.
adding a hot water system to a cold water only sailboat
- Thread starter Marceline
- Start date
This is the basic layout of a boat water system.
Marceline
Well-Known Member
thanks so much Baggywrinkle - that's quite a helpful illustrative diagram 
Daverw
Well-Known Member
I would add the hot water mixing valve and sometimes fitted the hot water expansion tankthanks so much Baggywrinkle - that's quite a helpful illustrative diagram
Baggywrinkle
Well-Known Member
Mixer would be a very good idea, engine heated water gets extremely hot .... mixer valve mixes cold water with the exiting hot water (can even get them thermostatically controlled) and the diagram looks like this ...
rogerthebodger
Well-Known Member
I have a thermostatic mixing valve in my shower out only as SWMBO would like hotter water at the gally simk for washinh up dishes.
The other outlets have mixer taps that allow individual mixing of hot and cold waiter as does my outdoor shower
The other outlets have mixer taps that allow individual mixing of hot and cold waiter as does my outdoor shower
Daverw
Well-Known Member
You can have both, just set the clorifier one higher to stop potentially scalding someone as 60 degree water is rather hot
Grith
Well-Known Member
Our unusual 28foot trailerable cruising yacht is outboard powered so no heat exchanger solution for us.
Just a thought on an alternative to many solutions outlined here.
We have a 22litre 240v marine electric storage hot water service which we power via solar panels through a portable EcoFlow lithium power bank which is hooked into our shore power supply line with a change over switch.
This gives us shore power like 240v whilst remote cruising.
We cook via induction and have separate 12/240v compressor fridge and freezer which we power via the units 12v outlet saving the inverter losses.
Yes we have fitted a significant solar array but it means if we limit our engine use we can stay out a significant time without resupply.
The yacht still has its regular house and engine agm batteries for normal yachting systems and lighting limiting any rewiring needs.
The drop in portable lithium power banks are just hooked through the yachts shore power system with the main additional wiring just being bringing extra solar feed wires down to it.
When the outboard is in use any surplus alternator power is also feed into the powerbank units.
Mid winter we can carry a portable gas generator but in the more more usual sunnier sailing times we generate enough solar to leave this behind.
The extra bonus of our solution is the lithium powerbank easily removes for both use in our motorhome style slide on truck camper and also does duty at home as our solar charged power source for our electrically pumped house water supply.
Just a thought on an alternative to many solutions outlined here.
We have a 22litre 240v marine electric storage hot water service which we power via solar panels through a portable EcoFlow lithium power bank which is hooked into our shore power supply line with a change over switch.
This gives us shore power like 240v whilst remote cruising.
We cook via induction and have separate 12/240v compressor fridge and freezer which we power via the units 12v outlet saving the inverter losses.
Yes we have fitted a significant solar array but it means if we limit our engine use we can stay out a significant time without resupply.
The yacht still has its regular house and engine agm batteries for normal yachting systems and lighting limiting any rewiring needs.
The drop in portable lithium power banks are just hooked through the yachts shore power system with the main additional wiring just being bringing extra solar feed wires down to it.
When the outboard is in use any surplus alternator power is also feed into the powerbank units.
Mid winter we can carry a portable gas generator but in the more more usual sunnier sailing times we generate enough solar to leave this behind.
The extra bonus of our solution is the lithium powerbank easily removes for both use in our motorhome style slide on truck camper and also does duty at home as our solar charged power source for our electrically pumped house water supply.
Marceline
Well-Known Member
oh wow - thanks Grith for sharing that and an interesting alternative solution, especially as I do already have a portable Poweroak/Bluetti 2kw power bank that has 2kw sinewave and solar charger/inverter/12v/240 options. I'll do more research based on yoursuggestions too.
Baggywrinkle
Well-Known Member
Bear in mind that heating 40L water from 16°C to 50°C takes 1,5kWh ... your average Lithium power bank is around 2kWh ... so 75% of it's capacity will be gone heating one 40l tank of water - if you are long-term cruising you need to replace this energy every day with solar, shore-power, engine or generator.
Variables you can play with are the hot water tank size, taking it down to 20L will half the energy required, or reducing the max temperature, which will also reduce the energy required - both come at the expense of convenience.
My experience is 40l is about right for a couple swimming, showering and washing up on a boat. Both shore-power and the engine will heat the water to a useable temperature in around 30min to 1 hr dependent on the heating element/engine. I did have a honda generator for a while but while it was one of the quietest on the market it still made a hell of a racket in quiet anchorages and I sold it as I rarely used it after fitting solar panels.
Then there is the energy/solar question in general. My 36ft boat with one fridge and typical electrics/autopilot needed 300W of solar to be self-sufficient in energy in the Adriatic - about 0,9kWh per day which I easily got from 300W of solar panels. In northern climes this will be considerably reduced. Calculator here: MPPT Calculator - Victron Energy
To replace normal daily energy usage of around 0,9kWh (Fridge, Electrics and Electronics) including water heating on top (1,5kWh) on the west coast of Scotland you would need around 2,5kWh from solar from April to September. That is around 1000W of solar in Oban in Scotland - which is difficult to fit on a 30ft boat.
For heating go for a diesel heater IMO.
If I were you I'd do an energy calculation based on your electrical system, water usage etc. before spending large amounts of money on electrical equipment to heat water.
For reference, my electrical system looked like this ... the water heater (not shown) was 40l (either 800W Shore Power or engine cooling water powered) and was not something that ever irritated me. We did not heat water with solar derived electrical energy - almost all our hot water came from running the engine (getting in and out of anchorages) - and we boiled a kettle of water for washing up when necessary. I would not fit a gas water heater on a boat but that is a personal choice.
Variables you can play with are the hot water tank size, taking it down to 20L will half the energy required, or reducing the max temperature, which will also reduce the energy required - both come at the expense of convenience.
My experience is 40l is about right for a couple swimming, showering and washing up on a boat. Both shore-power and the engine will heat the water to a useable temperature in around 30min to 1 hr dependent on the heating element/engine. I did have a honda generator for a while but while it was one of the quietest on the market it still made a hell of a racket in quiet anchorages and I sold it as I rarely used it after fitting solar panels.
Then there is the energy/solar question in general. My 36ft boat with one fridge and typical electrics/autopilot needed 300W of solar to be self-sufficient in energy in the Adriatic - about 0,9kWh per day which I easily got from 300W of solar panels. In northern climes this will be considerably reduced. Calculator here: MPPT Calculator - Victron Energy
To replace normal daily energy usage of around 0,9kWh (Fridge, Electrics and Electronics) including water heating on top (1,5kWh) on the west coast of Scotland you would need around 2,5kWh from solar from April to September. That is around 1000W of solar in Oban in Scotland - which is difficult to fit on a 30ft boat.
For heating go for a diesel heater IMO.
If I were you I'd do an energy calculation based on your electrical system, water usage etc. before spending large amounts of money on electrical equipment to heat water.
For reference, my electrical system looked like this ... the water heater (not shown) was 40l (either 800W Shore Power or engine cooling water powered) and was not something that ever irritated me. We did not heat water with solar derived electrical energy - almost all our hot water came from running the engine (getting in and out of anchorages) - and we boiled a kettle of water for washing up when necessary. I would not fit a gas water heater on a boat but that is a personal choice.
Tranona
Well-Known Member
Remember Grith is in Australia where they tend to have more sun than we do here. Generally in the UK the limited sun is more useful for topping up batteries than trying to heat water through the expensive conversion media that he describes. Using the waste heat from the engine is far and away the most effective method . 30 minutes run time gives you enough water for all day usage. You can of course use the sun for heating a shower's worth of water by hanging a solar shower bag in the rigging.
Marceline
Well-Known Member
cheers so much and thanks for the steer - this is all really helpful (especially with it all so new to us) and thanks ever so much to everyone for the replies and advice
oldmanofthehills
Well-Known Member
Tried that and Navigator squealed as the not-warm water landed on her. Particularly not impressed as she had auto applied shampoo to hair before cold water shock set in. Still have the bag somewhere but she insists on proper built facilities.