Near constant hot water without a generator - Here is how i did it.


Eric Meury
 

We have an santorin with no generator but have 1000 Watts of solar.  400 of those watts are shaded -  200 is behind the main mast flexible panels and 200 is on the new hard top bimini (room for more)  The bulk of the power comes from 600 Watts on the arch. 

Here is what we did.  

1.  Added the Victron 712 Battery Monitor that is bluetooth and replaced the Amel Shunt 

2.  Changed out the AC heating element for a 600 Watt DC element (300 Watt can be used as well)

3.  Added a Victron Battery Protect -  this serves as the relay and what powers the heating element.  - ie the heating element positive cable is connected to the battery protect .
 (BPR065022000 Victron Energy BPR065022000 Smart BatteryProtect with Bluetooth 12/24V - 65A) -  $59 bucks from pkys

4.  Disconnected the thermostat wire from the heating element and attached it directly to the relay.

Here is how it works -  The BMV has a relay setting.  This is set to Default mode but i changed the settings to Invert.  The Low SOC is set to 90 and 96.  What this means is that the relay will be powered when the SOC is anything above 90%.  When it gets to 90% it will turn off and will not turn back on again until the SOC is 96% (these can be changed)  -  This send a signal to the battery protect to "turn on" thus sending power to the heating element.  The battery protect has a shutdown setting of 12.4 volts  (i can change that to really anything but this was set to be an absolule failsafe to never let the batteries go below 12.4).  It turns back on when the batteries are 12.75. I have never seen 12.4 from my bank.   The tempature sensor is set to what ever the factory setting is...i  imagine it is 105 degrees (torried marine water heater).  

So everyday and a couple of times a day depending on how much water is used, my heater will turn on automatically in the mid morning as by that time i have recovered from the nightly discharge and am now above 96%/.  The element will draw a full 600 Watts until such time that either thhe SOC is 90% OR the tempature sensor says - he we are good and have plenty of hot water.  The first time i rant it it took a good 1.5 to 2 hours to get to that tempature. but my batteries never eached 90% as i'm usually producting 400-500 Watts and only have 600 watt drain so max i see going out during the day is 200-250 watts -  (if you use a 300 Watt Element and have plenty of solar you won't go negative but will talke longer)  Since i have this it only needs to run for maybe 15 to 20 mins and occastionally longer to keep the water at the tempature set by the tempature sensor.  

We now take a hot shower everyday and my 2 year old plays in a warm baby pool almost everyday.  -  All of this is powered with solar. (and soon to be wind)   

If i'm on the hard (which i am right now) it still works just the same and If i plug in heat water just by using the battery charger.  

If you have a desire (or don't have one) to not have to run your genset to heat water daily then this is a good way to go provided you have enough solar to make it happen.  We have one fridge and one freezer and a 12 volt home built spectra watermaker.  All of the settings are controlled from my phone via the victron connect app.  I can completley turn off the water heater by accessign the battery protect  - there is a setting to disable.  

I do not have lithium batteries but my bank is large with 4 - L16 Flooded Wet Cell batteries with 840 Amp hours.  


Matt Salatino
 

Eric,
Excellent configuration. Where do you get $C heating elements? And is there really a difference between AC and DC elements? Seems it would just be a resistance heater? Different resistance?

~~~⛵️~~~Matt

On May 17, 2020, at 10:04 AM, Eric Meury <ericmeury@...> wrote:

We have an santorin with no generator but have 1000 Watts of solar.  400 of those watts are shaded -  200 is behind the main mast flexible panels and 200 is on the new hard top bimini (room for more)  The bulk of the power comes from 600 Watts on the arch. 

Here is what we did.  

1.  Added the Victron 712 Battery Monitor that is bluetooth and replaced the Amel Shunt 

2.  Changed out the AC heating element for a 600 Watt DC element (300 Watt can be used as well)

3.  Added a Victron Battery Protect -  this serves as the relay and what powers the heating element.  - ie the heating element positive cable is connected to the battery protect .
 (BPR065022000 Victron Energy BPR065022000 Smart BatteryProtect with Bluetooth 12/24V - 65A) -  $59 bucks from pkys

4.  Disconnected the thermostat wire from the heating element and attached it directly to the relay.

Here is how it works -  The BMV has a relay setting.  This is set to Default mode but i changed the settings to Invert.  The Low SOC is set to 90 and 96.  What this means is that the relay will be powered when the SOC is anything above 90%.  When it gets to 90% it will turn off and will not turn back on again until the SOC is 96% (these can be changed)  -  This send a signal to the battery protect to "turn on" thus sending power to the heating element.  The battery protect has a shutdown setting of 12.4 volts  (i can change that to really anything but this was set to be an absolule failsafe to never let the batteries go below 12.4).  It turns back on when the batteries are 12.75. I have never seen 12.4 from my bank.   The tempature sensor is set to what ever the factory setting is...i  imagine it is 105 degrees (torried marine water heater).  

So everyday and a couple of times a day depending on how much water is used, my heater will turn on automatically in the mid morning as by that time i have recovered from the nightly discharge and am now above 96%/.  The element will draw a full 600 Watts until such time that either thhe SOC is 90% OR the tempature sensor says - he we are good and have plenty of hot water.  The first time i rant it it took a good 1.5 to 2 hours to get to that tempature. but my batteries never eached 90% as i'm usually producting 400-500 Watts and only have 600 watt drain so max i see going out during the day is 200-250 watts -  (if you use a 300 Watt Element and have plenty of solar you won't go negative but will talke longer)  Since i have this it only needs to run for maybe 15 to 20 mins and occastionally longer to keep the water at the tempature set by the tempature sensor.  

We now take a hot shower everyday and my 2 year old plays in a warm baby pool almost everyday.  -  All of this is powered with solar. (and soon to be wind)   

If i'm on the hard (which i am right now) it still works just the same and If i plug in heat water just by using the battery charger.  

If you have a desire (or don't have one) to not have to run your genset to heat water daily then this is a good way to go provided you have enough solar to make it happen.  We have one fridge and one freezer and a 12 volt home built spectra watermaker.  All of the settings are controlled from my phone via the victron connect app.  I can completley turn off the water heater by accessign the battery protect  - there is a setting to disable.  

I do not have lithium batteries but my bank is large with 4 - L16 Flooded Wet Cell batteries with 840 Amp hours.  


 

Bravo Eric. and I do not believe there is any difference in AC vs DC resistance heating element...but ask an electrician.

CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Sun, May 17, 2020 at 9:40 AM Matt Salatino via groups.io <helmsmatt=yahoo.com@groups.io> wrote:
Eric,
Excellent configuration. Where do you get $C heating elements? And is there really a difference between AC and DC elements? Seems it would just be a resistance heater? Different resistance?

~~~⛵️~~~Matt

On May 17, 2020, at 10:04 AM, Eric Meury <ericmeury@...> wrote:

We have an santorin with no generator but have 1000 Watts of solar.  400 of those watts are shaded -  200 is behind the main mast flexible panels and 200 is on the new hard top bimini (room for more)  The bulk of the power comes from 600 Watts on the arch. 

Here is what we did.  

1.  Added the Victron 712 Battery Monitor that is bluetooth and replaced the Amel Shunt 

2.  Changed out the AC heating element for a 600 Watt DC element (300 Watt can be used as well)

3.  Added a Victron Battery Protect -  this serves as the relay and what powers the heating element.  - ie the heating element positive cable is connected to the battery protect .
 (BPR065022000 Victron Energy BPR065022000 Smart BatteryProtect with Bluetooth 12/24V - 65A) -  $59 bucks from pkys

4.  Disconnected the thermostat wire from the heating element and attached it directly to the relay.

Here is how it works -  The BMV has a relay setting.  This is set to Default mode but i changed the settings to Invert.  The Low SOC is set to 90 and 96.  What this means is that the relay will be powered when the SOC is anything above 90%.  When it gets to 90% it will turn off and will not turn back on again until the SOC is 96% (these can be changed)  -  This send a signal to the battery protect to "turn on" thus sending power to the heating element.  The battery protect has a shutdown setting of 12.4 volts  (i can change that to really anything but this was set to be an absolule failsafe to never let the batteries go below 12.4).  It turns back on when the batteries are 12.75. I have never seen 12.4 from my bank.   The tempature sensor is set to what ever the factory setting is...i  imagine it is 105 degrees (torried marine water heater).  

So everyday and a couple of times a day depending on how much water is used, my heater will turn on automatically in the mid morning as by that time i have recovered from the nightly discharge and am now above 96%/.  The element will draw a full 600 Watts until such time that either thhe SOC is 90% OR the tempature sensor says - he we are good and have plenty of hot water.  The first time i rant it it took a good 1.5 to 2 hours to get to that tempature. but my batteries never eached 90% as i'm usually producting 400-500 Watts and only have 600 watt drain so max i see going out during the day is 200-250 watts -  (if you use a 300 Watt Element and have plenty of solar you won't go negative but will talke longer)  Since i have this it only needs to run for maybe 15 to 20 mins and occastionally longer to keep the water at the tempature set by the tempature sensor.  

We now take a hot shower everyday and my 2 year old plays in a warm baby pool almost everyday.  -  All of this is powered with solar. (and soon to be wind)   

If i'm on the hard (which i am right now) it still works just the same and If i plug in heat water just by using the battery charger.  

If you have a desire (or don't have one) to not have to run your genset to heat water daily then this is a good way to go provided you have enough solar to make it happen.  We have one fridge and one freezer and a 12 volt home built spectra watermaker.  All of the settings are controlled from my phone via the victron connect app.  I can completley turn off the water heater by accessign the battery protect  - there is a setting to disable.  

I do not have lithium batteries but my bank is large with 4 - L16 Flooded Wet Cell batteries with 840 Amp hours.  


Eric Meury
 

hey matt. 

im not 100% sure if there is a difference but i do know that my AC element way to many watts going out.  This is the unit i purchased.  https://globalsolarsupply.com/product/diversion-load-water-heating-element-60a12v-30a24v/

it will work for 12 or 24 volt.  I think if you goole the type of water heater you have you can find out the size of the element.   You will most likely need the professional tool to remove the water heater element.  The cheap home ones will simply not do the job.  at least on my tank that was the case.  ...What brand of water heater do you have?


Matt Salatino
 

Our water heater is an Isotherm.
I haven’t looked at the element nut size.

~~~⛵️~~~Matt

On May 18, 2020, at 7:36 AM, Eric Meury <ericmeury@...> wrote:

hey matt. 

im not 100% sure if there is a difference but i do know that my AC element way to many watts going out.  This is the unit i purchased.  https://globalsolarsupply.com/product/diversion-load-water-heating-element-60a12v-30a24v/

it will work for 12 or 24 volt.  I think if you goole the type of water heater you have you can find out the size of the element.   You will most likely need the professional tool to remove the water heater element.  The cheap home ones will simply not do the job.  at least on my tank that was the case.  ...What brand of water heater do you have?


Ryan Meador
 

There's nothing special about "AC" vs "DC" for these heater elements, but the voltage does matter, and in common boating usage these current types imply a voltage as well.  The element is just a resistor, so to achieve the desired number of watts, the resistance is sized for a specific voltage.  If you run a 240V element at 24V, you'll get 1/10th the rated output (and vice versa will likely explode).  The other electronics involved (like the thermostat) may actually care about AC vs DC and the voltage; I'm not sure.

Some marine water heaters have two ports so you can have both AC and DC elements at the same time.  I've heard using a DC water heater element as a wind generator's dump load works well.

Ryan and Kelly
SM 233 Iteration
Boston, MA, USA


On Mon, May 18, 2020 at 3:25 AM Matt Salatino via groups.io <helmsmatt=yahoo.com@groups.io> wrote:
Our water heater is an Isotherm.
I haven’t looked at the element nut size.

~~~⛵️~~~Matt

On May 18, 2020, at 7:36 AM, Eric Meury <ericmeury@...> wrote:

hey matt. 

im not 100% sure if there is a difference but i do know that my AC element way to many watts going out.  This is the unit i purchased.  https://globalsolarsupply.com/product/diversion-load-water-heating-element-60a12v-30a24v/

it will work for 12 or 24 volt.  I think if you goole the type of water heater you have you can find out the size of the element.   You will most likely need the professional tool to remove the water heater element.  The cheap home ones will simply not do the job.  at least on my tank that was the case.  ...What brand of water heater do you have?


JOSE PRIETO
 

Does anyone know where to find the 24 volt element in Europe?
I would love to mount this system on my boat.

--
Jose Prieto
SV Wayag, SM 323
Currently Alicante, Spain


Alan Leslie
 
Edited

1.The Isotherm element is not a one-nut job - Google it you'll see - not an easy substitute - in fact probably impossible-it's a simple element with two nuts bolted to a flange -  I know, I've changed a few over the last 20 years.
2.Power (W) is a square function of voltage so a reduction to one tenth of voltage equates to a 100th reduction in power (W=Vsqd/R)  so if you ran your 240V 750W element on 24V you'd get 7.5W
Sorry to burst your bubbles

Cheers
Alan
Elyse SM437


Craig Briggs
 

The original Isotemp heaters did use the standard 1" element - they had orange insulating jackets and mine from 2002 is still ticking, with many patches and replaced elements. The current silver-jacketed model uses a different (proprietary?) element as Alan describes. Btw, Indel-Webasto uses the Isotherm brand name for their refrigeration equipment and Isotemp for the water heaters - same company (probably part of Dometic). The water heaters were originally a product of Thermoproduktur AB in Sweden.

Anyway, here's a link to a DC standard 1" element, with a 12v 200w version and a 24v 600w version. The arithmetic would say those would draw 16.6 and 25 amps respectively. The seller has a specific warning: "DO NOT USE GRID POWER AS IT WILL IMMEDIATELY DESTROY THE ELEMENT!" 
https://windandsolar.com/6-inch-dc-submersible-water-heater-element/

The thermostats are simply bi-metal snap-open temperature switches and do not care about AC vs DC. 
--
Craig Briggs - s/v Sangaris / SN68  Tropic Isle Harbor, FL


JOSE PRIETO
 

I will try!

Thanks Craig!
By the way, I found some elements 24 vdc on Chinese websites.

Cheers,

JP
--
Jose Prieto
SV Wayag, SM 323
Currently Alicante, Spain


JOSE PRIETO
 

I sent Eric a message, but I believe he is no longer in the group perhaps.  One of my doubts about the system he built refers to the 12 volt element he installed, in my case the boiler is from the quick brand, and the thermostat is installed over the element through a hole in the element's head.  The question is how to control the water temperature, or the “on/off” of the electric current at a given temperature, if I can't install the thermostat in the new non-original quick element?
Any suggestion?

JP
--
Jose Prieto
SV Wayag, SM 323
Currently Menorca, Spain


Davi Rozgonyi
 

I have a tangentially related question I'd like to add on if I may. Running the main engine heats the hot water tank by diverting some hot cooling water into it's body. Has anyone teed the generator's cooling water into the hot water tank? And if not, why not? l run the generator every few days for bigger things like laundry, dive compressor, etc, and it would be nice to have a little shot of warm water in there.... Incidentally, with a good battery bank (we have simple agms) and decent solar (800W) you can just run the hot water heater off it, it pulls 8 percent out of the battery bank from cold to hot, which is pretty doable on a nice sunny day to replace in a few hours. But the automated safety system above definitely sounds cool, so to speak :)


Craig Briggs
 

Hi Davi,
With only one engine water heat exchanging coil inside the tank you can only use either the propulsion engine or the generator; not both as their cooling circuits would be tied together. If the generator is running turn on the electric element - your generator will probably appreciate the added load.
I suppose you could gin up an isolating plumbing circuit with check valves but that would seriously violate the KISS principle.
--
Craig Briggs - s/v Sangaris / SN68  Tropic Isle Harbor, FL


 

You could install one of these and connect both the Onan and the main engine:

Isotemp Basic 40L 230V Water Heater w/Dual Heat Exchangers & Mix Valve

CW Bill Rouse Amel Owners Yacht School
720 Winnie, Galveston Island, Texas 77550 
   


On Sun, Jun 12, 2022 at 6:55 AM Craig Briggs <sangaris68@...> wrote:
Hi Davi,
With only one engine water heat exchanging coil inside the tank you can only use either the propulsion engine or the generator; not both as their cooling circuits would be tied together. If the generator is running turn on the electric element - your generator will probably appreciate the added load.
I suppose you could gin up an isolating plumbing circuit with check valves but that would seriously violate the KISS principle.
--
Craig Briggs - s/v Sangaris / SN68  Tropic Isle Harbor, FL


Mark Erdos
 

 

Davi,

Cream Puff's water heater heat exchanger is plumbed to the generator. IMO - It makes a lot more sense than having it plumbed to the engine. There are some water heaters that allow for 2 heat exchangers to be used, so a person could plumb both the engine and genset. However, I don't see this as much of an advantage.

With best regards,

 

Mark

 

Skipper

Sailing Vessel - Cream Puff - SM2K - #275

Currently cruising - French Polynesia

www.creampuff.us


On 6/11/2022 6:27 PM, Davi Rozgonyi wrote:
I have a tangentially related question I'd like to add on if I may. Running the main engine heats the hot water tank by diverting some hot cooling water into it's body. Has anyone teed the generator's cooling water into the hot water tank? And if not, why not? l run the generator every few days for bigger things like laundry, dive compressor, etc, and it would be nice to have a little shot of warm water in there.... Incidentally, with a good battery bank (we have simple agms) and decent solar (800W) you can just run the hot water heater off it, it pulls 8 percent out of the battery bank from cold to hot, which is pretty doable on a nice sunny day to replace in a few hours. But the automated safety system above definitely sounds cool, so to speak :)


Eric Meury
 

Jose.  I'm still in the group.  although i don't own an amel any longer (went to a garcia passoa 50) and i'm on land because of my fathers health conditions.  The system i built can be turned "on/off" via the victron battery protect on your smartphone via the victron app.  In fact all of the adjustments of the SOC and voltage are adjusted via the victron app.  This makes it easy to adjust the settings.  The thermostat is still the original one that came with my torrid marine water heater.  Its basic and when the temperature is reached the circuit opens meaning that no more power is going to the element - when this happens the victron app for the battery protect will say "disabled by remote".  I did have a problem with a failed battery protect  ibut this got sorted out and a new one was installed when i sold the boat.   (the battery protect showed no signs of failure btw)

Davi - with regard to hooking up to a generator.  Yes you can do this if you want but i think you would have to have two exchanges in the tank.  I had torrid marine build me one with two exchangers because at  the time i was thinking of doing a hydronic heating system in the santorin and though adding the ability to heat the water in the tank would be good.  

You could also look at this.  but so far it is only for 12 volt.  - my system described above is pretty slick and i plan to do something similar on the garcia at some point. - probably when i go lithium.  




On Fri, Jun 10, 2022 at 7:58 AM JOSE PRIETO <prietomd11@...> wrote:

I sent Eric a message, but I believe he is no longer in the group perhaps.  One of my doubts about the system he built refers to the 12 volt element he installed, in my case the boiler is from the quick brand, and the thermostat is installed over the element through a hole in the element's head.  The question is how to control the water temperature, or the “on/off” of the electric current at a given temperature, if I can't install the thermostat in the new non-original quick element?
Any suggestion?

JP
--
Jose Prieto
SV Wayag, SM 323
Currently Menorca, Spain