Water heater for shower

poter

poter

Well-Known Member
Joined
4 Feb 2002
Messages
2,127
Location
Still going south currently in Corsica for winter
www.fairhead.com
Ok, having done quite a lot of investigation into hot water heating for a shower, I have hit several road blocks.....,.
First I thought about a small electric calorifier running through an inverter but a 30 litre cylinder requires 1250 watts (5.4 amp) and would drain my battery bank in short order and the cost of wind/solar power to replace would be in the thousands of pounds, and a small generator, a much cheaper alternative would need to be outside and is heavy (25 kg) to lug about the boat every time I want a shower, also its not waterproof.
So, a gas water heater....nope! cos it comes under the " Boat safety scheme" and they wont even talk to me.
Need a solution guys....she who must be obeyed wont sail without hot water.....help!!
 
Only really practical solution is a calorifier using the cooling water from the engine plus an immersion heater for when you are hooked up to mains electricity.
 
Or use a diesel hydronic heating system and a dual coil calorifier?
Positives; hot water as well as heating and less disruptive to install as only 2 small pipes needed.
Negatives; each air outlet needs a blower and matrix and more amps are used and takes longer to warm up (heating).
I opted for the eber hydronic to get hot water as well (previous boat had a Webasto hydronic which was also very good)
 
DipperToo said:
Or use a diesel hydronic heating system and a dual coil calorifier?
Positives; hot water as well as heating and less disruptive to install as only 2 small pipes needed.
Negatives; each air outlet needs a blower and matrix and more amps are used and takes longer to warm up (heating).
I opted for the eber hydronic to get hot water as well (previous boat had a Webasto hydronic which was also very good)
Click to expand...

The OP is in the Med, so installing a sophisticated heating system such as you suggest just to have a hot shower is probably not high on his list of priorities!
 
I have used those solar bags they do heat the water but a shower well you do eventially get wet all over!
I had thought of making my own and using the pump from the boat to pressure it when showering. My best solution so far was jump overboard get out soap jump in again then rinse off with fresh water. Actually it is very refreshing. My boat is in the med though dont think i would try it very often in uk waters.
 
poter said:
OK thanks all,
got all the details from Tek Tank on their C-Warm Hot water heater which I can plug into the engine cooling system. Now I have to figure out how to break into the engine pipework...oh dear.
Click to expand...
Traditionally, we have used a small saw. :D
 
Can you not run the inverter while the engine is running?

Is your Alternator man enough to run it? Should be 55 Amp/h which produces over 600W...
 
poter said:
OK thanks all,
got all the details from Tek Tank on their C-Warm Hot water heater which I can plug into the engine cooling system. Now I have to figure out how to break into the engine pipework...oh dear.
Click to expand...

You'll probably find that Surecal calorifiers are a bit cheaper and very good.
 
No Regrets said:
Can you not run the inverter while the engine is running?

Is your Alternator man enough to run it? Should be 55 Amp/h which produces over 600W...
Click to expand...

600w at 12v, as opposed to 1250w @ 240v, without factoring in any inverter inefficiencies. Very, very, round figures the water will take 40-50ah to heat up to shower temp, which the engine can't keep up with, so the batteries take a big hit. If the battery bank is not sufficient the batteries will be overly discharged. Either way, the engine will need to be run for an hour or so to even come close to re-charging the batteries, but even then they won't be truly fully charged. With plenty of solar panels an inverter would be more viable.

The engine would need to be run for much less than that to heat the water via a calorifier. The calorifier can be used with shore power in a marina. Often, some motoring is done during a voyage, that gives a completely free tank of water.
 
The idea of heating the water electrically using anything other than shore power is a complete non starter. Just don't go there. Heat it directly using a fossil fuel, or the sun.

A couple of years ago there was a PBO article about making a small solar thermal panel for a boat, nice project but I don't know how practical it would be.
 
In the old days, more medium sized boats had generators. So you could use immersion and the generator cooling circuit to heat the calrofier.

20 minutes motoring will give hot water for a quick shower, but the engine needs to be working, not idling.
 
CLB said:
As a matter of interest, why is the BSS relevant to a sailing boat in the med?
Click to expand...

We use a Bosch gas water heater, have done for 20 years. Instant hot water. We do have a desal unit, lots of solar and a windgen. Very civilised. As far as I can ascertain we are both still alive and kicking (and have 2 hot, Navy, showers a day).

As correctly mentioned we would often motor into an anchorage and I have thus wondered about engine heat but then have wondered what those with calorifiers do if they anchor in some idyllic spot for a week. Or are they the people who run their engines for 3 hours a day, or worse, don't shower. We have reached the age when cold showers lose their attraction. So enlighten me - you are in NW Scotland, just added another Munro to the list - and no hot water?

Jonathan
 
As said forget electric heating. My parents used to have a 3 phase instantaneous electric hot water heater. 15 amps per phase at 240v gives 4.25kw times 3 or 13kw of power. A storage hot water system can run at lower power but takes time to heat up. I think if it is a small boat you might consider a tank either above the shower or via a pump that can be filled with hot water from the cooker. Has the advantage of being conservative on fresh water supply. But she may not like it. olewill
 
PaulRainbow said:
600w at 12v, as opposed to 1250w @ 240v, without factoring in any inverter inefficiencies. Very, very, round figures the water will take 40-50ah to heat up to shower temp, which the engine can't keep up with, so the batteries take a big hit. If the battery bank is not sufficient the batteries will be overly discharged. Either way, the engine will need to be run for an hour or so to even come close to re-charging the batteries, but even then they won't be truly fully charged. With plenty of solar panels an inverter would be more viable.

The engine would need to be run for much less than that to heat the water via a calorifier. The calorifier can be used with shore power in a marina. Often, some motoring is done during a voyage, that gives a completely free tank of water.
Click to expand...

Ah, You're right Paul. Just looked at inverter specs, and the current draw from the batteries is a tenth of the power being used, so 1250W would need a 125A alternator to match the draw.

Worth looking into a high power alternator given the cost of Calorifier installed, but I would personally just use a 2Kw generator which is £400 9I have a Stanley which works fine!)
 
You must log in or register to reply here.

Share this page

Top