24 volt water heater

jkis · Veteran Member

24 volt water heater

Peter_n_Margaret · Guru

Seems like a lot of trouble and expense to get a worse performing product.
I suggest you simply buy a 1200W inverter and run it on 240V.

That tank is 22L. At 600W it will take 30 minutes or more to heat. What is your battery capacity and how do you recharge them?

It is also a calorifier. What is the vehicle it is in? We have a calorifier the same size as that one (different brand). We heat it via the engine while driving or via the diesel heater. It has a 750W 240V element, but we would never heat it with electricity unless we have a lot of excess solar.

Cheers,
Peter

jkis · Veteran Member

Thank you peter The vehicle is a 1418 mercedes coach and will heat the water. While on the road I'm about to start on the solar i can fit about 2500 watts and more later if i need. I thought there would be less loss without the inverter and one less to think about Cheers stuart

jkis · Veteran Member

Sorry about the pics. Cant see eere to attach. Im using a mobile phone any clues Cheers stuart

Peter_n_Margaret · Guru

With 2.5kW of solar (or more) I would definitely stay with 220/240V and 1200W for heating the HWS via an inverter (when it is not hot from driving) as well as diesel.
And I would have no gas in the vehicle at all.
Cook with a 220V induction cook top.

To attach pics, go to the "Advanced Editor" at the bottom of the post box.

Cheers,
Peter

jkis · Veteran Member

On the bottom of my screen it had activeboard mobile sn then itd white can't scroll it Cheers stuart

T1 Terry · Guru

jkis wrote:
I have a ati water heater model bb2212x it used to have a 1200 watt 240ac element. I'm wanting to fit a 24vdc 600 watt element. A couple of things I'm not sure about is will the 600 watt heat the water in a good time frame. the old element has the thermostate fitted to it. I would have to use a seperate thermostate and its a very tight space. Will try and put some pics up later in the day. Cheers stuart

Hi Stuart, we commonly use this method to use solar that would be otherwise wasted and it works a treat. We use part of the Plasmatronics Dingo to control a solid state relay so it only turns on when the battery reaches a certain voltage and turns off again when the battery voltage drops below a certain point, but I guess most good solar regulators would have a load circuit that could be programmed the same way. Who cares if it takes half a day to heat the water, it was still heated for free and no need to mess with switching inverters on/off/on. Only worth doing the 240vac method if it's too hard to change the element or get the 6B&S cabling to the water heater, the 24v 600w element is a lot cheaper than a 1500w inverter, the size needed to drive a 1200w element without over loading it. Of course, if you already have an iverter big enough to do the job running 24/7 then just a 240vac solid state relay switched by the solar controller will work fine.

As far as a thermostat for the 24v idea, Jaycar have various temp thermostats that can easily be attached to the side of the tank near where the element goes it and this can be wired into the loop from the solar controller that controls the solid state relay, that way the relay doesn't turn on once the water is up to temp.

T1 Terry

jkis · Veteran Member

Thank you terry I was startting to think ssr relay. And wondering if i can wire in a temp gauge and its own controller. If i build it i should be able to repair it. I cannot fix an inverter. I'd also like to keep it seperate from the solar controller if i have a problem down the track. Cheers stuart

T1 Terry · Guru

No real problem with manually turning the heater on/off, just easier not to have to think about it and accidentally leaving it switched on over night and draining the battery excessively. Not a big issue programming the solar controller load terminals, if you PM me the try of controller you have I'm happy to guide you through the process.

T1 Terry

Peter_n_Margaret · Guru

Julian (who posts on caravaners forum) switches his HWS on and off via signals based on battery SOC. From memory, on at 99% SOC and off at 97% SOC.
He uses a dedicated 240V inverter for the HWS.
I switch mine manually, but not often. It is a 750W 240V element powered by a 1300W inverter that also powers all our other 240V stuff.
We have no 240V shore power plug-in capability, relying completely on solar (plus alternator for very rare emergency back up charging) and Stuart won't need any either and that simplifies the 240V side of things.

With 2.5kW of solar, I expect you will use nominal 250W household panels? What controller(s) do you propose. Might be worth splitting the system into a couple of pieces to provide some redundancy?

Cheers,
Peter

jkis · Veteran Member

Terry I'd like to automate the switching on and off with an overide to be able to turn it on. But would like to keep it seperate from the solar controller. Incause i have to fault find. I like the pwm type controllers most probly plastronics. Peter I'm thinking of using the house rail type so i can replace or update the panell easy. A s/h house system would be the way I'd like to go. But see on ebay there are 325 watt panels out now. If i mount them east west. 4 bolts to replace a panel. I'm on a tight buget so a lot will be a work in progress as i need it. Very sorry for the spelling mistakes in the earlyer posts. Lack of sleep we ill do that Cheers stuart

jkis · Veteran Member

I picked up a jaycar book the over day. Hard to belive how much gear they have. It will take me awhile to search it out. Cheers stuart

T1 Terry · Guru

jkis wrote:
I picked up a jaycar book the over day. Hard to belive how much gear they have. It will take me awhile to search it out. Cheers stuart

Here ya go, https://www.jaycar.com.au/70-c-thermal-circuit-breaker-switch/p/ST3823 there are different temperatures available but you are looking for an N/C (Normally Closed) model that will open at the specified temp, give or take a few degrees C and probably a difference (hysteresis) of 5*C between off and back on again.

T1 Terry

jkis · Veteran Member

I did see them in the book. Wondering if i can take the locating ring of and stick it onto the heater. Theers not much room were the element goes. Would i need epoxy sikaflex or something else Cheers stuart

T1 Terry · Guru

jkis wrote:
I did see them in the book. Wondering if i can take the locating ring of and stick it onto the heater. Theers not much room were the element goes. Would i need epoxy sikaflex or something else Cheers stuart

You just need an adhesive with an upper range heat tolerance above 70*C, something like 100*C would be ideal. Then apply a bit of heatsink paste to the base of the thermostat and apply a good thick layer of adhesive around the locating ring so it will stick to the side of the metal tank about level with the thermostat or maybe just above it. If you can make a piece of springy stainless steel into some sort of spring loaded retainer and attach it to the heater element bolts if it's a 4 bolt type or using a hose clamp if it's the round/hexagon head screw in type so it applies pressure to the wings on the thermostat then the job is done. Once the water temp at the level of the thermostat reaches the thermostat temp the SSR will be switched off so the element will no longer be powered until that part of the tank cools enough for the thermostat to close again. If you are concerned about the temp at the top of the tank getting too high then use a thermostat with a lower temp, they go down to 50*C and that is about as low as you can adjust a household electric hot water thermostat, something to do will being hot enough to kill off the nasties I believe.

T1 Terry

jkis · Veteran Member

Yes it is the screw in type 1 1/4 bsp. Heat idea on the spring clip and paste. Cheers and many thanks to terry and peter

Peter_n_Margaret · Guru

If the calorifier is plumbed to the engine, it will get up to 85C consistently, and often higher. Adhesives, hoses etc should be good for well in excess of 100C.
Mine has a separate thermostat built in as standard equipment for the 240V heating. It is adjustable. Ours is set to 70C.
It also has a built in tempering valve (that is also adjustable). John Guest pipes and fittings will fail if they cop water at 85C, or even close. Ours is set to 45C, determined by getting water to the wash up sink at a good temperature for washing dishes.
65C is typically the lowest set point recommended for bug killing.

Cheers,
Peter

-- Edited by Peter_n_Margaret on Monday 23rd of July 2018 07:25:21 PM

jkis · Veteran Member

I have to order the tempvalve kit. Will do that today. Mine will also run of the motor. It runs at 80C acording to the gauge. Thanks for the tip on the john guest pipe. My intention was to set the temp for the shower around 37C run a single pipe and tap for the shower (off/on) to save water And heat up some warter for the washup. Next time I'm in town will chase up some household type pipe. Guys you have been a great help. Cheers stuart

jkis · Veteran Member

The original thermostate would of made life easy. And i thought because these were intended for boats. That i would of been able to get 12/24 volt heating element easy. Just order it. Not so easy Cheers stuart