Reply
 
Thread Tools Display Modes
 
Old 07-03-2016, 07:34 PM   #1
Senior Member
 
Simi 60's Avatar
 
City: Queensland
Country: Australia
Vessel Model: Milkraft 60 converted trawler
Join Date: Jul 2016
Posts: 385
Hot Water System

New boat has a perfectly adequate HWS on board for when attached to a marina berth.
A Rheem household 140 litre with 240v supply
As we plan on actually using the boat and unattached we need an alternative.

The boat will mainly be used in warmer climates mainly with two people on board.
We have had boats before so are used to short showers so not much hot water required for showering, some months even cold showers will be the norm.
Main water usage will be hot water for washing up.

One thought was to use the existing tank as storage and try and set up a recirculating water supply getting heat from the primary engine when running and then kept warm by the genset when running for an hour a day while supplementing solar charging.
I think in reality this will not work.

On demand gas is considered, but laws in Australia mean that only certain systems meet approval so that will be a $1000 PLUS installation plus gas is not always readily available

That leaves small 240v and off engine systems.

I was looking at this would appear to be the simplest install once I remove the existing electric HWS as power and water are already there.
Duoetto 12Volt-240Volt Electric 10Litre Hot Water Heater
https://www.keoghsmarine.com.au/HOT-...er-Motor-Yacht

Next was this unit and while it has some advantages it will be a more difficult install.
Kuuma / Force 10 24 Litre Water Heater
https://www.whitworths.com.au/main_i...tAbsolutePage=

Any thoughts or is there something better I am missing?
__________________
Advertisement

Simi 60 is offline   Reply With Quote
Old 07-04-2016, 02:52 AM   #2
TF Site Team
 
ksanders's Avatar
 
City: SEWARD ALASKA
Country: USA
Vessel Name: LISAS WAY
Vessel Model: BAYLINER 4788
Join Date: Feb 2011
Posts: 3,644
we have a standard marine water heater. it gets geat from the engine while cruising. otherwise it heats the water using 120 V from either the generator or shore power.

we just came back from a weeklong cruise and never wanted for hot water. I can't imagine things would be different as A full-time cruiser, or live aboard.
__________________

__________________
Kevin Sanders
Bayliner 4788
Seward, Alaska
www.mvlisasway.com
ksanders is offline   Reply With Quote
Old 07-04-2016, 03:41 AM   #3
Guru
 
caltexflanc's Avatar
 
City: North Carolina for now
Country: USA
Vessel Name: Small Incentive
Vessel Model: Boston Whaler 130 Sport
Join Date: Aug 2011
Posts: 3,460
When we were living aboard and cruising full time we had a set up identical in size and configuration as the OP. We found the water heater kept water hot for at least a day without power. An hour or two a day from the genset was enough to keep it just fine. My advice would be to do nothing, go for a cruise and see how it works for you.
__________________
George

"There's the Right Way, the Wrong Way, and what some guy says he's gotten away with"
caltexflanc is offline   Reply With Quote
Old 07-04-2016, 05:13 AM   #4
Senior Member
 
Simi 60's Avatar
 
City: Queensland
Country: Australia
Vessel Model: Milkraft 60 converted trawler
Join Date: Jul 2016
Posts: 385
Quote:
Originally Posted by caltexflanc View Post
My advice would be to do nothing, go for a cruise and see how it works for you.
Sounds like fair advice, thanks
Simi 60 is offline   Reply With Quote
Old 07-04-2016, 06:02 AM   #5
TF Site Team
 
Bay Pelican's Avatar
 
City: Chicago, IL
Country: USA
Vessel Name: Bay Pelican
Vessel Model: Krogen 42
Join Date: Oct 2007
Posts: 2,563
Quality marine water heaters (ours is Isotherm) will keep water hot for 24 hrs. Their insulation is designed for storage. Isotherm sells 240v 50 hertz units.

We anchor out for months and find that a 25 liter unit provides all the hot water we need. The water is heated whenever the generator or main engine is on which is usually once or twice a day.

Choosing the wattage for a six gallon unit is an important decision. Using a 120v US based system we have had both a 1,500 watt unit and now a 750 watt unit. The time required to heat the water has changed from approximately 15 minutes of generator run time to approximately 30 minutes of generator run time with the 750 watt unit.

It was our preference to drop to the 750 watt unit to reduce the load on our generator during the first 15 minutes when both chargers are at full output. Ours is a 8kw generator. With a larger generator or only one charger this would not be an issue.
__________________
Marty
Bay Pelican is offline   Reply With Quote
Old 07-04-2016, 06:45 AM   #6
Guru
 
angus99's Avatar
 
City: Signal Mtn., TN
Country: US
Vessel Name: Stella Maris
Vessel Model: Defever 44
Join Date: Feb 2012
Posts: 1,168
We have an Isotemp Spa 30 (about 8 gallons). It has multiple mounting options--ours is fixed to a bulkhead--and it can be mounted horizontally or vetically. A mixing valve prevents scalding while extending the volume of hot water, which otherwise would be overheated by the engine coolant loop. It has a polypropylene case so it's a little less pricey than the stainless shells. The tank is 316 stainless. They also make a Spa 40--about 11 gallons--if you have the space.
Attached Thumbnails
Click image for larger version

Name:	image.jpg
Views:	78
Size:	121.3 KB
ID:	53812  
angus99 is offline   Reply With Quote
Old 07-08-2016, 06:53 AM   #7
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 15,604
The solar shower (a plastic bag) works fine , and can be carried below easily if your shy on deck showering.

Just for dish washing using the stove to heat a quart is fast and simple.

No need for hot to rinse soap off.

Underway boats can feed some of the sea water coolant to an always on sink spout.

Great for checking the engine cooling underway and does well at rinsing , or even washing and showering .
FF is offline   Reply With Quote
Old 07-08-2016, 08:44 AM   #8
Senior Member
 
DeniseO30's Avatar
 
City: Bristol PA
Country: USA
Join Date: Jul 2016
Posts: 137
Simi, you can keep the larger tank and use a typical engine heated WH that will heat all the water via thermo-siphon (gravity flow, one to the other) I would take longer to heat it all but if the engine is running.... and running....

You could use designated external engine heat exchanger but that is what is inside a marine water and would cost about the same.
DeniseO30 is offline   Reply With Quote
Old 07-08-2016, 09:04 AM   #9
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 5,924
Quote:
Originally Posted by caltexflanc View Post
When we were living aboard and cruising full time we had a set up identical in size and configuration as the OP. We found the water heater kept water hot for at least a day without power. An hour or two a day from the genset was enough to keep it just fine. My advice would be to do nothing, go for a cruise and see how it works for you.
sunchaser is offline   Reply With Quote
Old 07-08-2016, 09:16 AM   #10
Veteran Member
 
Trundlebug's Avatar
 
City: River Trent
Country: UK
Vessel Model: Profile 33
Join Date: Jul 2015
Posts: 27
When we first bought our boat it had a 25litre hot water tank with engine heated coil calorifier and 240v immersion heater (2kw).

After using the boat for a while we discovered that the 25 litre hot water tank wasn't really big enough. 2 people could have a shower, with just enough left over to wash up with, but that was about it.

So I decided to add another 35 litre calorifier next to the existing one in the engine bay (there was plenty of room at the aft end), and plumb it in series with the existing one. So the HW take off is from the original tank, and that tank gets heated first, the new (second) tank is connected in series so starts to heat up when the first tank has nearly equalised.

It's been fantastic. We have what seems like unlimited hot water for 36 hours after a decent run of 2-4 hours. It means we don't have to worry about running out of hot water when having a shower. There's now enough to shower 4 people in succession and still have enough to wash up and have a shave the next morning.

In your position I would advise doing exactly the same, but wire it so you can heat it up by immersion from the generator on the first tank if you need it. We don't have a generator so I can't do that. But it would be the easiest solution instead of a complete re-installation.
Trundlebug is offline   Reply With Quote
Old 07-08-2016, 10:30 AM   #11
Senior Member
 
DeniseO30's Avatar
 
City: Bristol PA
Country: USA
Join Date: Jul 2016
Posts: 137
Quote:
Originally Posted by Trundlebug View Post
When we first bought our boat it had a 25litre hot water tank with engine heated coil calorifier and 240v immersion heater (2kw).

After using the boat for a while we discovered that the 25 litre hot water tank wasn't really big enough. 2 people could have a shower, with just enough left over to wash up with, but that was about it.

So I decided to add another 35 litre calorifier next to the existing one in the engine bay (there was plenty of room at the aft end), and plumb it in series with the existing one. So the HW take off is from the original tank, and that tank gets heated first, the new (second) tank is connected in series so starts to heat up when the first tank has nearly equalised.

It's been fantastic. We have what seems like unlimited hot water for 36 hours after a decent run of 2-4 hours. It means we don't have to worry about running out of hot water when having a shower. There's now enough to shower 4 people in succession and still have enough to wash up and have a shave the next morning.

In your position I would advise doing exactly the same, but wire it so you can heat it up by immersion from the generator on the first tank if you need it. We don't have a generator so I can't do that. But it would be the easiest solution instead of a complete re-installation.
Funny how we said the same thing with so many different words.
__________________
Retired HVAC, wooden boat aficionado & builder of smaller craft. NOT Josie the plumber!
DeniseO30 is offline   Reply With Quote
Old 07-12-2016, 07:40 PM   #12
Senior Member
 
City: Between Oregon and Alaska
Country: US
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 359
I have a house hw 50 gal tank and surrounded it with 2" foam along with good insulation applied to all pipes (even cold) so heat isn't drawn out. I can keep water warm enough for a comfortable shower for 4 days if I'm not using much hw for other things.
With a heat exchanger you can heat with engine water. With some valves you can use either main or generator.
Lepke is offline   Reply With Quote
Old 07-12-2016, 09:10 PM   #13
Guru
 
Tidahapah's Avatar
 
City: Mooloolaba
Country: Australia
Vessel Name: Tidahapah
Vessel Model: Bert Ellis Timber motor cruiser
Join Date: Oct 2007
Posts: 1,765
Simi,
I used to have instant gas hot water but upon failure of the unit a replacement could not be used due to the new regs. ( could have but had to be installed outside)
I have chosen to go with a Force 40 lt unit and not connected to main engine cooling water, strictly 240 V.
So far I am happy but probably with your boat would go at least 90 lts. Even with my solar panels i still run my gen set an hour or so a day which is enough time to heat water and a bit longer sometimes to make water.
have just spent 2 weeks out on the Swains with 4 of us free diving a couple of times a day and heavy use on frig and freezers (freezing fish and crays and lots of fresh water washing) and still happy with the set up.
__________________
"When I die I hope my wife doesn't sell my toys for what I told her I paid for them"
Money: It's made round to go round , not flat to stack.
"Get out and do it"
Tidahapah is offline   Reply With Quote
Old 07-12-2016, 10:16 PM   #14
Senior Member
 
Simi 60's Avatar
 
City: Queensland
Country: Australia
Vessel Model: Milkraft 60 converted trawler
Join Date: Jul 2016
Posts: 385
Quote:
Originally Posted by Tidahapah View Post
I have chosen to go with a Force 40 lt unit and not connected to main engine cooling water, strictly 240 V.
So far I am happy but probably with your boat would go at least 90 lts.
Good to hear and the price is right on the 40's.
Why do you think I will need 90?
There'll only 2 of us on board 99% of the time
Simi 60 is offline   Reply With Quote
Old 07-12-2016, 11:32 PM   #15
TF Site Team
 
Peter B's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Lotus
Vessel Model: Clipper (CHB) 34 Sedan/Europa style
Join Date: Jun 2008
Posts: 6,385
Send a message via Skype™ to Peter B
Quote:
Originally Posted by Simi 60 View Post
Good to hear and the price is right on the 40's.
Why do you think I will need 90?
There'll only 2 of us on board 99% of the time
Can you refresh our memories as to why you want another cylinder at all, when you have a 140L one heated off 240v already. I agree with those who said just use what you've got heating from the genny/house bank/inverter, until you see how well it copes. If you leave the dock with it heated right up, with good insulation and that volume, topping up the heat via genny or house bank would not take all that much I would think.

FWIW, we have no 240v on our boat when away from the dock, but a quick 30 min preheat off 240v while getting ready is sufficient to get it quite hot, then engine heat keeps it that way, but it stays hot at anchor wth no heat input for at least 48 hours. (Isotherm 42L with engine heat exchanger)
__________________
Pete
Peter B is offline   Reply With Quote
Old 07-13-2016, 12:14 AM   #16
Senior Member
 
Simi 60's Avatar
 
City: Queensland
Country: Australia
Vessel Model: Milkraft 60 converted trawler
Join Date: Jul 2016
Posts: 385
Quote:
Originally Posted by Peter B View Post
Can you refresh our memories as to why you want another cylinder at all, when you have a 140L one heated off 240v already.
I dont want "another" one, but as the existing unit is 10 years old it may not have much life left anyway

Quote:
I agree with those who said just use what you've got heating from the genny/house bank/inverter, until you see how well it copes.
As did I.
I wont be replacing it unless the batteries cant cope or the system dies.
I certainly wont be running the genny for several hours a day just for hot water.
Quote:
If you leave the dock with it heated right up, with good insulation and that volume, topping up the heat via genny or house bank would not take all that much I would think
FWIW, we have no 240v on our boat when away from the dock, but a quick 30 min preheat off 240v while getting ready is sufficient to get it quite hot, then engine heat keeps it that way, but it stays hot at anchor wth no heat input for at least 48 hours. (Isotherm 42L with engine heat exchanger).
Once I leave the dock I dont plan to be back on one for at least a year.
That means once it goes back in the water next month thats it, no more shore power.
Simi 60 is offline   Reply With Quote
Old 07-13-2016, 12:22 AM   #17
Guru
 
BruceK's Avatar
 
Join Date: Oct 2011
Posts: 6,901
Marine HWS are often 10gal/40L. Is your issue you want engine heat as well as 240v input?
You can run the existing 240v water heater when the genny is doing other things, eg batts, eutectic fridge, etc, they like a good load. But if you aim to use solar more and genset less, maybe a new HWS both tapping engine heat, and using 240v, is better.
You could see how it goes. Or hold off replacement until the Rheem dies. The PO must have managed ok,a domestic Rheem is a less common system, maybe some thought went into it. You might find it works for you too.
PS. In view of your new post about prolonged cruising, what`s your water capacity, do you have a desalinator?
__________________
BruceK
Island Gypsy 36 Europa "Doriana"
Sydney Australia
BruceK is offline   Reply With Quote
Old 07-13-2016, 12:35 AM   #18
Guru
 
Tidahapah's Avatar
 
City: Mooloolaba
Country: Australia
Vessel Name: Tidahapah
Vessel Model: Bert Ellis Timber motor cruiser
Join Date: Oct 2007
Posts: 1,765
Simi,
My rational behind the 90 lts is just more holding capacity and hot water for longer when shut down.
Not using engine is just a personal thing of mine , it is really just another water connection that can fail either causing hot water heater problems or engine problems.
Look I have been at sea as a Chief Engineer for over 40 years and still like to keep things simple and have less problems , I can make enough of these myself with the places I go.
__________________
"When I die I hope my wife doesn't sell my toys for what I told her I paid for them"
Money: It's made round to go round , not flat to stack.
"Get out and do it"
Tidahapah is offline   Reply With Quote
Old 07-13-2016, 12:38 AM   #19
Senior Member
 
Simi 60's Avatar
 
City: Queensland
Country: Australia
Vessel Model: Milkraft 60 converted trawler
Join Date: Jul 2016
Posts: 385
Quote:
Originally Posted by BruceK View Post
The PO must have managed ok,a domestic Rheem is a less common system, maybe some thought went into it. You might find it works for you too.
The PO only used her on weekends and even then may not have left the dock, so he had plenty of power.
Quote:
PS. In view of your new post about prolonged cruising, what`s your water capacity, do you have a desalinator?
No desal but 4500L worth of water tankage and 7000L of fuel
Simi 60 is offline   Reply With Quote
Old 07-13-2016, 12:45 AM   #20
Senior Member
 
Simi 60's Avatar
 
City: Queensland
Country: Australia
Vessel Model: Milkraft 60 converted trawler
Join Date: Jul 2016
Posts: 385
Quote:
Originally Posted by Tidahapah View Post
Simi,
My rational behind the 90 lts is just more holding capacity and hot water for longer when shut down.
Not using engine is just a personal thing of mine , it is really just another water connection that can fail either causing hot water heater problems or engine problems.
Look I have been at sea as a Chief Engineer for over 40 years and still like to keep things simple and have less problems , I can make enough of these myself with the places I go.
Same here, would rather not use engine heater and will only be motoring for several hours a week anyway.

But I do have a good deal on 2300W of solar going on the roof to keep 800ah of 24v batts charged and hopefully not needing the genset as much.
There should be enough power to run a smaller HWS system as often as it needs when the time arrives .
__________________

Simi 60 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 01:14 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012