Immersion Heater - PV electricity

[Maurice Sauer]

Thanks Duplada.
Yeah, I mailed a number of companies some months back about availability of the NO, but nothing was on offer. Don't know whether I tried chinaeproducts though - will check this out. I also have this as saved search on ebay.
What is your take on the hysteresis though - is this a problem in practise, to the extent that you are now using another thermostat type or feel a change would be worthwhile?
I also found these KSD301's while searching for KDS9700 switches, but I was put off by the fact that they are 240v AC and the need for safety casing etc.
cheers, Mo

Hi Maurice,

When I purchased my KSD9700 NC/NO switches from eBay, I looked for a seller who listed a NC version and then asked them if they also had a NO version. I suggest you do the same. Search for a seller chinaeproducts (they don't have any listed at the moment) send them an email and tell them what you want, this is where I purchased mine.

Alternatively you could use these, search on ebay for KSD301 60 these switches have better hysteresis than the KDS9700. The KDS9700 switch at 60 +/- 5 degrees and reset at 40 +/- 10 Degrees. The KSD301 switch at 60 +/- 3 Degrees and reset at 45 +/- 5 Degrees. The KSD301 also have two lugs which you can use to secure to the tank with elastic.

Hope this helps.

regards Duplada

 

[Duplada]

Thanks Duplada.
Yeah, I mailed a number of companies some months back about availability of the NO, but nothing was on offer. Don't know whether I tried chinaeproducts though - will check this out. I also have this as saved search on ebay.
What is your take on the hysteresis though - is this a problem in practise, to the extent that you are now using another thermostat type or feel a change would be worthwhile?
I also found these KSD301's while searching for KDS9700 switches, but I was put off by the fact that they are 240v AC and the need for safety casing etc.
cheers, Mo

Hi Maurice,

I am still using the KDS9700 switches which work without issue. They do have a wider hysteresis band than the KSD301's but they work fine. Ideally the KSD301's should work better as they will recover to their default state more quickly. I would buy those if I was doing it again. There should be no issue strapping the KSD301's direct to your tank as you are only using 12v. The KSD9700 are rated 250v also and work fine without the plastic cap glued to the tank.

regards Duplada

 

[jimbro]

Hi I am a retired Elec Eng and have been following your discussion with pauldreed about using excess solar pv power as I would like to build a power diverter circuit for my 3.655kW array. I have two CTs and have considered either using a Picaxe or OP Amp front end and would prefer to have system which will follow the input/output power difference as closely as possible. Would you mind sharing your circuit diagram with me?

 

[echase]

@OldGrouser from what I recall (can't find it now on the Engensa site), their Solar 24 IS an ImmerSUN.

Solar 24 is definitely not an Immersun. The Immersun is a burst fire device that is illegal because it does not pass the mandatory flicker specification, so can cause your and your neighbours lights to flicker. Because of this no one is allowed to sell or install them so why are you?

The Solar 24 works differently, is cheaper and legal. Its performance is as good as or better than any other.

 

[kiani8822]

hi i i think idealy best is to fit longer immersion heater ( 27 inch ) as with ( 11 inch immersion ) it would mainly heat the top part of the cylinder beside that as have 1kw immersion heater you would need at least about 5 hrs to heat 100 litter cylinder to 60 c

 

[suntrap]

The Immersun is a burst fire device that is illegal because it does not pass the mandatory flicker specification, so can cause your and your neighbours lights to flicker.

What a shame - these things should be allowed to be fitted subject to an impedance test of the mains supply. I know they wouldn't cause my lights to flicker.

 

[Worcester]

Hi I am a retired Elec Eng and have been following your discussion with pauldreed about using excess solar pv power as I would like to build a power diverter circuit for my 3.655kW array. I have two CTs and have considered either using a Picaxe or OP Amp front end and would prefer to have system which will follow the input/output power difference as closely as possible. Would you mind sharing your circuit diagram with me?

Go have a look here: circuits, sketches etc all available for you to build yourself:
Solar PV Monitoring System | OpenEnergyMonitor
and
Mk2a PV Router (lean, mean and fast!!) | OpenEnergyMonitor

 

[echase]

What a shame - these things should be allowed to be fitted subject to an impedance test of the mains supply. I know they wouldn't cause my lights to flicker.

Not that familiar with the flicker regs but I believe that in industrial installations you can do an impedance test to prove it’s OK, but in domestic use not so. Unless your mains is almost a tenth of the standard impedance used in the spec I doubt even your house would be OK with a 3kW burst fire controller as they fail that badly.

 

[Worcester]

The Immersun is a burst fire device that is illegal because it does not pass the mandatory flicker specification, so can cause your and your neighbours lights to flicker. Because of this no one is allowed to sell or install them so why are you?

The Solar 24 works differently, is cheaper and legal. Its performance is as good as or better than any other.

@echase Could you point me to the 'mandatory flicker specification' that you refer to and I'll forward it to the designers.

There are only 2 methods of proportional power control, burst fire or phase angle, the phase angle has horrendous issues with harmonics, and requires extensive testing and filtering...

What is so special about the Solar 24 - what method does it use?

 

[old grouser]

The Immersun is a burst fire device that is illegal because it does not pass the mandatory flicker specification. Because of this no one is allowed to sell or install them so why are you?

The Solar 24 works differently, is cheaper and legal. Its performance is as good as or better than any other.

Thanks, Echase. I can assure you I'm not fitting or selling or advocating ImmerSUNs. I'm just trying to find the best device of its kind to fit to my own system, and hoping that by the spring someone will have identified an efficient solution which gives a 100% return on investment in less than five years.

 

[inie meanie]

Seems a shame that the burst fire is a problem because when we have the power you don't need the lights on!

 

[Worcester]

I'm not sure that burst fire is a problem - it's phase angle that does havock with harmonics and EMF.

I'm still waiting for @echase to point me to the regulations / guidance note.. and to explain how / why the Solar 24 is different...

I know that there are already over 2000 Immersuns installed, and I am not aware of any complaints.

Certainly we see no flickering, and running an oscilloscope on the power supply nor do we notice anything untoward...

 

[Gavin A]

I know that there are already over 2000 Immersuns installed, and I am not aware of any complaints.

really?

we've got one install where the flicker is pretty serious, and immersun said they were aware of problems in a small percentage of cases IIRC, though I might have got that wrong, it presumably must be up to dozens by now.

The regs are these ones, which they confirm they meet, but I'm not entirely convinced they do. Even if they technically do, then the flicker from the units is definitely unacceptable in situations where the local grid network as large volt swings / high impedance - this one's in the countryside at the end of quite a long single phase line.

BS EN 61000-6-1 Electromagnetic compatibility (EMC). Generic standards. Immunity for residential, commercial and light-industrial environments 2007BS EN 61000-6-3 Electromagnetic compatibility (EMC). Generic standards. Emission standard for residential, commercial and light-industrial environments 2007

The issue can be resolved for the customer by using LED lights or CFLs in place of halogens / incandescants, but that doesn't solve the issue for the neighbours.

We've backtracked a lot on installing these units, and won't do it where there's a risk of high volt swings. It's a right pain in the arse as we were about to offer them to all our existing customer base, but couldn't risk it after seeing how bad it was for these customers.

 

[Gavin A]

ah, hold on they're different regulations, it's BS EN 61000-3-3:2008 and EN 61000-3-11 that are the regulations in question.

this diagram explains why the Immersun can't meet those regulations, as it shouldn't be able to cause a volt swing each time it cuts in of more than just under 0.3% or around 0.7V, but the location we had it at I measured around a 2V drop from switching on a 3kW load, so effectively every time the burst fire kicks in on each cycle it's causing around a 2V drop on that cycle.

Presumably this is why dishwashers and washing machines are restricted to around a 1kW element.

EN 61000-3-3 is now mandatory under the EMC Directive for all equipment that consumes up to 16A/phase from the public 230V supply. Test laboratories use an instrument called a ‘flickermeter’ to measure to this standard. EN 61000-3-3 limits the emissions of voltage fluctuations and flicker

Design for EMC Part 6: ESD, dips and dropouts, etc.

http://www.reo.co.uk/files/handbook_en_61000-3-3_and_en_61000-3-11.pdf

I've been meaning to get back to 4-Eco about this tbh.

 

[suntrap]

Thanks - that's really interesting. Just one point though: elements in dishwashers etc are not limited to 1kW (my dishwasher element's the best part of 3kW [though it is old]; washing machine about 2kW; oven in total >3kW but interestingly it staggers the switching of its elements). However, they are not controlled by burst firing so they will only cause intermittent flickering as they switch on and off infrequently, rather than constant flickering by being switched several times a second.

 

[Gavin A]

Thanks - that's really interesting. Just one point though: elements in dishwashers etc are not limited to 1kW (my dishwasher element's the best part of 3kW [though it is old]; washing machine about 2kW; oven in total >3kW but interestingly it staggers the switching of its elements). However, they are not controlled by burst firing so they will only cause intermittent flickering as they switch on and off infrequently, rather than constant flickering by being switched several times a second.

I think it's the newer models that have smaller elements, and use the burst fire just to keep them topped up with heat, probably as they use so much less water and lower temps... not my field though, but I have stuck power meters on a few in the past to see what they're drawing.

 

[suntrap]

Oh I see - so they have smaller elements in order that they can use burst firing? With solar panels, good reason to get a new dishwasher!

 

[Worcester]

Hi GavinA,

Thanks for the detail, it must be down to some of the characteristics of the individual installation, as I say we have had no reported problems at all. Reading the documents you posted, I wouldn't be suprised if some of the supplies don't meet those specications!

 

[inie meanie]

Thanks Gavin A for the information. So where does this leave us? I have a burst fire model and a phase angle unit running, both work really well. Has anybody come up with suitable filtering for the phase angle cutting? I have used commercial two stage units , but I don't have any specific equipment to test if it is below the regulation amount of interference.

 

[TechyTim]

Hi guys,
Just had a look at latest comments on ths thread as I have now more or less dropped out of Controller market (4 left in stock if anyone interested) but this latest batch confirm my comments 6 months ago that no-one will be able to legally market a cheap proportional control due to harmonics, etc.
Hence why I was marketing the SolarHeat which was simple fixed switching but not the most efficient.
Did echase manage to get his design commercially developed?