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Solar Heating Dump Kit 12v & 240v immersion Heater


Clodi

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Has anyone fitted the Solar Heating Dump Kit - With 12V And 240V Twin Immersion Heater - 2 1/4" BSP from Bimble solar? it's more the 12V And 240V Twin Immersion Heater - 2 1/4" BSP I'm interested in. I'm in the process of moving my horizontal calorifier to the engine bay and pondering fitting one of these whilst it's easy to get to.

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I feed my excess solar to the mains immersion heater via the inverter and a thyristor.

 

It's a fixed resistive load so the voltage dictates the power output.

 

I can dial in anywhere between about 50 and 240 volts depending on how much spare electric my panels provide.

 

At lower powers - 200 watts or so - it doesn't really heat the water but it offsets the cooling so it stays hotter for longer.  At medium power - 400 watts or so - it will eventually heat from cold but takes all day to get there.  I try and remember not to turn it up to 1kW on the inverter ....

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Add:

 

I did it this way because I don't always have a "spare" 300W (the rating of the 12V element) of solar and it seems daft to flatten the batteries for the sake of warmer water.

 

A friend with a much larger solar array copied my idea and he just relies on getting enough power during the day to heat water until the immersion heater switches off and then charge his batteries after that.

  • Greenie 1
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  • 4 months later...

Hi @TheBiscuits could you possibly share more details of your setup? You've done exactly what I want to do. Did you use a thyristor regulator module of some sort or build something yourself? How does the inverter handle the setup? Really keen to get something sorted so would appreciate any and all info! 

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  • 10 months later...

I'm just opening up this thread again as I'm interested in doing this.

 

Once my batteries are charged, which on a sunny day is not long at all, my controller goes into float mode and I feel like I'm wasting available sunshine. If I put the washing machine on for example, the controller will see the current being drawn and allow the panels to start charging the batteries again. I'm usually down to around 97% SoC after the wash cycle has finished and then within an hour or so on a sunny day the batteries are fully charged again.

 

So which one of these Bimble dump load immersion heaters should I be looking at? My current mains immersion heater is 1kW which I think it's the standard 2 & 1/4" BSP fitting? 

 

Water Heaters and Dump Loads (bimblesolar.com)

 

I assume the 300w/12v units are connected directly to the controller's load output, but I don't really understand how the twin mains/12v units work or what the separate relays are for?

 

Also, if the controller is set to switch the immersion on when it drops down to 13.6v then what happens when some clouds are overhead and the batteries aren't fully charged and the controller hasn't really gone into float mode, it just isn't getting enough sunshine to complete the charge cycle?

 

It's a 60amp Epever Tracer AN series MPPT controller. 6415AN

Edited by blackrose
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43 minutes ago, blackrose said:

but I don't really understand how the twin mains/12v units work

It's one unit with separate 12V and 240 V heaters, so you can use either or both at the same time depending on the availability of 12V and 240V electricity sources.

The 12V 300W heater will draw a current of around 25A, which is more than you can switch with a typical thermostat, so you use the thermostat to switch the relay which turns off the heater when the water is up to temperature.

Edited by David Mack
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16 minutes ago, David Mack said:

It's one unit with separate 12V and 240 V heaters, so you can use either or both at the same time depending on the availability of 12V and 240V electricity sources.

The 12V 300W heater will draw a current of around 25A, which is more than you can switch with a typical thermostat, so you use the thermostat to switch the relay which turns off the heater when the water is up to temperature.

 

Ok I see. That makes sense. Only why didn't they build the relay into the immersion unit rather than making you buy and install a separate relay?

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7 minutes ago, blackrose said:

 

Ok I see. That makes sense. Only why didn't they build the relay into the immersion unit rather than making you buy and install a separate relay?

Probably because there isn't enough space in the head of the unit alongside the 240V connections, the 12V connections and the necessary physical and electrical safety separation between them.

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41 minutes ago, robtheplod said:

shame its for horizontal calorifiers only otherwise I'd be interested!

 

Where does it say that? Have I missed it?

 

What difference can the orientation of the calorifier make to the installation/operation of these things?

Edited by blackrose
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2 hours ago, Loddon said:

Heat rises 🤔

 

 

Exactly! My immerson heater is at the bottom of my vertical calorifier - isn't everyones'?

 

2 hours ago, David Mack said:

From your Bimble website link:

Screenshot_20230418-151450_SamsungInternet.jpg.065d6beb90879c4b66d79c2706d6d83e.jpg

 

Why would you fit an immerson heater at top of a vertical calorifier?

Edited by blackrose
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5 hours ago, blackrose said:

I'm usually down to around 97% SoC after the wash cycle has finished and then within an hour or so on a sunny day the batteries are fully charged again.

 

Just a side note really, but if your daily practice in sunny weather is to maintain the batteries at 100% for many hours at a time, you might end up reducing their longevity. 

Other people like Ian and Nick will know the latest data on this, but my general understanding was that to maximise the lifespan of the batteries, the 'full' level should be regarded as being 90% or less (at least on a day to day basis). 

I personally use a SoC of about 85% as my day to day 'full' value, so my MPPTs will switch off at that point.

Its a shame to waste solar energy, but if I understand it right, the batteries will be less stressed if I keep them below 90% on a routine basis. 

Apparently the other side of looking after them is running them down to around 10% every so often, to stretch their legs a bit.  

 

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40 minutes ago, blackrose said:

 

Exactly! My immerson heater is at the bottom of my vertical calorifier - isn't everyones'?

 

 

Why would you fit an immerson heater at top of a vertical calorifier?

Because many are made that way 😱

Mine is at the top I believe to get the coils in as they are the primary heating source.

If yours is at the bottom then you will be OK 

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11 minutes ago, Tony1 said:

 

Just a side note really, but if your daily practice in sunny weather is to maintain the batteries at 100% for many hours at a time, you might end up reducing their longevity. 

Other people like Ian and Nick will know the latest data on this, but my general understanding was that to maximise the lifespan of the batteries, the 'full' level should be regarded as being 90% or less (at least on a day to day basis). 

I personally use a SoC of about 85% as my day to day 'full' value, so my MPPTs will switch off at that point.

Its a shame to waste solar energy, but if I understand it right, the batteries will be less stressed if I keep them below 90% on a routine basis. 

Apparently the other side of looking after them is running them down to around 10% every so often, to stretch their legs a bit.  

 

 

 

That is true if you have Lithiums - do you know if @blackrose has them or does he have FLA ?

Edited by Alan de Enfield
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50 minutes ago, Alan de Enfield said:

I'd have thought that in 'vertical' cauliflowers it is only common sense (and thermo dynamics) that the heater element MUST be near the bottom of the tank.

 

 

Mine :

 

 

 

CAM00321.jpg

You'd think that wouldnt you.... my vertical cauliflower has a top entry and when replacing i need to buy the very long elements.... 

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23 minutes ago, Alan de Enfield said:

 

That is true if you have Lithiums - do you know if @blackrose has them or does he have FLA ?

 

FLA. My mains battery charger used to keep them at 100% SoC on float giving them a weekly charge cycle if no activity was detected. My first set lasted for 10 years. I don't see why a solar controller keeping them at 100% should be any different? 

 

34 minutes ago, Tony1 said:

Just a side note really, but if your daily practice in sunny weather is to maintain the batteries at 100% for many hours at a time, you might end up reducing their longevity. 

 

 

Not according to Trojan or anything else I've read. Perhaps as Alan says, you're referring to lithium batteries.

Edited by blackrose
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  • 1 month later...

Beautiful sunny weather here today. I switched on my 1kW mains immersion heater to make use of the sun. Had 55A coming in from the MPPT and 30A coming from the batteries. Left it on for 2 hours for a full tank of hot water. By that time the batteries were down to 76% on my Smartgauge. I switched the immersion off and ran a 30C wash cycle on my washing machine. Batteries were still drawing 55A from the MPPT and easily coped with the washing machine and then charged to 100% after a couple of hours. 

 

So I've decided not to bother fitting a 12v dump load immersion in my calorifier. Instead I've decided just to set the timer for a couple of hours daily on my AC immersion and look at the weather forecast. If it looks like being a sunny day I'll switch the timer on so if I'm not working from home I can go to work and will have a tank of hot water when I get back. It won't be quite as efficient as the 12v dump load as I wouldn't run the mains immersion on a cloudy day, but it's not a bad compromise

Edited by blackrose
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