PV immersion heater proportional control

[brian wright22]

Thanks Yorkshiremike. Retro fit its quite clear 20% vat then.

 

[Gavin A]

Thanks Yorkshiremike. Retro fit its quite clear 20% vat then.

top line - hot water controls.

it's 20% for the equipment only, 5% if professionally installed.

 

[sly_dog_jonah]

My understanding is the same as Gavin A's, 5% if it's installed professionally as it qualifies as a hot water controller.

pwboston, thanks for the your comment about amount of E7 you use. A couple of questions if you don't mind: How big is your tank? What temperature do you heat it to?

 

[yorkshiremike]

Thanks Gavin, I hadn't considered the heating controls paragraph, I guess the Immersun is an 'electronic timer'. On the HMRC site paragraph 2.6 is:

[h=2]2.6 Controls for central heating and hot water systems [/h]Central heating and hot water system controls include manual or electronic timers, thermostats, mechanical or electronic valves, including thermostatic radiator valves.

 

[sly_dog_jonah]

Thanks Gavin, I hadn't considered the heating controls paragraph, I guess the Immersun is an 'electronic timer'. On the HMRC site paragraph 2.6 is:

2.6 Controls for central heating and hot water systems

Central heating and hot water system controls include manual or electronic timers, thermostats, mechanical or electronic valves, including thermostatic radiator valves.

The Immersun is much more than an electronic timer, although that is one of its many functions. It's primary use-case is as a dynamic load controller, optimising diversion of exported power to a local load (usually an immersion) to maximise benefit from microgeneration while remaining grid-independent. Given the finite capacity of any heat storage, the device can't eliminate export, but it can certainly reduce a household's carbon footprint by reducing gas consumption (or electric heating).

On that basis it should certainly qualify for the 5% VAT.

 

[MicraShed]

Finally got my act together (and finished my IV antibiotics!) and ordered my ImmerSun install.

Bit of a shame its going to be the back end of the month before Im free to sort out the install, so Im heading into the wrong bit of the year - but Im still sure I'll see some benefit even now - and of course there is next summer to look forward to!

 

[pwboston]

My understanding is the same as Gavin A's, 5% if it's installed professionally as it qualifies as a hot water controller.

pwboston, thanks for the your comment about amount of E7 you use. A couple of questions if you don't mind: How big is your tank? What temperature do you heat it to?

It is a 140l tank, but the temperature is 2/3rds of the dial (no temperature reading on stat) however its hot enough not to have your hand under it.

 

[brian wright22]

sly_dog_jonah
QUOTE

Re: PV immersion heater proportional control
Brian, Would be interesting to compare those figures with your Gas savings over the same period (or similar period depending on when your meters were read by you/EDF).

Yesterday sent EDF my meter readings. Today the costs came back with a full 32 days worth of using the IMMERSUN . The Gas saving is for the 32 days so far £20.35..
This late September burst of Solar power is great for the bank balance

http://www.immersun.co.uk/downloads/...ide%20v1.0.pdf Section 5.4​

Read more: http://www.electriciansforums.net/newreply.php?do=newreply&p=598333#ixzz25nh1t6mB​

 

[nowty]

I got my Immersun today, there is not much to them so I am sure these are going to come down in price significantly over time. I am putting in a preheat tank for my water but probably won’t get round to it for a while yet. However I temporarily installed it from a wall socket, connected the sensor clamp and connected a £20 2kw electric heater (non fan type) to it.

The set up is easy peasy, whole job including the set up took about 10 mins. When I installed it after work I only had about 1 hr of sunlight left and I was generating about 1kw with the house using about 300w. It dumped about 600w into the heater and I monitored the house usage and PV generation on a combined energy meter I have got.

I have to say my first impressions are very very impressed. It settled down quite quickly and my energy meter was reading practically zero import / export. I played about with the heater controls as the one I bought has two heating elements 1250w and 720w which you can independently switch on or off. I was quite amazed that it deals within seconds with varying heater loads and adjusts its output to dump the same available power to different heater ratings.

Next I turned on the kettle and the heater stopped instantly with the Immersun display saying “waiting”. Turned the kettle off and the power returned to the heater again within seconds. Need to wait tomorrow to see how it copes with 3kw+ excess generation.

 

[regen]

Hi There,

I have been looking at both the imersun and the sola controller but which would be best for my application?

I have a 4kw pv limited to 3.6 via inverter which reguarly runs for several hours at 3.6 when sun shines and hoping to install a 1 to 2 kw hydro system on a stream with variable flow rates giving a max input of 5.6kw. This will be all fed via 2 immersion heaters into a 300 litre thermal store. Although 5.6 is max it is unlikely to be achieved with 4.5kw being the expected max for most of the time.

Regen

 

[sly_dog_jonah]

ImmerSUN have updated their FAQ recently: Frequently Asked Questions :: immerSUN :: Use 100% generated free electricity :: A 4eco Product

What is the minimum amount of export required for the immerSUN to start heating the water?

The immerSUN will wait for around 130W of export before any power is delivered to the immersion heater, once the water heating begins, however, the unit will be able control power in 1% steps, so for a 3kW heating element, the minimum power output is about 30W.

Our immersion element was replaced under warranty yesterday and from 10am onwards the ImmerSUN diverted 5kWh of power into the immersion rather than allowing it to be exported Our generation after 10am was 7.8kWh so we would have otherwise exported 64% of our generation. The tank didn't reach 60C (or 45C which is the boiler control thermostat setting) but considering it was completely cold at 10am after being refilled I'm pretty happy with the first day's result. The boiler kicked in at 6pm to top the temperature up to 45C. Grey dull day today so doubt we'll have much spare generation.

 

[sly_dog_jonah]

Hi There,

I have been looking at both the imersun and the sola controller but which would be best for my application?

I have a 4kw pv limited to 3.6 via inverter which reguarly runs for several hours at 3.6 when sun shines and hoping to install a 1 to 2 kw hydro system on a stream with variable flow rates giving a max input of 5.6kw. This will be all fed via 2 immersion heaters into a 300 litre thermal store. Although 5.6 is max it is unlikely to be achieved with 4.5kw being the expected max for most of the time.

Regen

Am not too familiar with the Sola controller but the ImmerSUN sounds suitable as it can power multiple loads of up to 3kW at any one time. Since your hydro will presumably run 24/7 you will probably have sufficient excess generation to keep your large thermal store permanently hot.

 

[goretex73]

I must thank everyone for their comments on this thread. I saw the immersun offered online and have been in touch with the company that installed my PV system is it right that you need to be a qualified spark to fit this or is this unit a job for the home owner to do ? If it is a spark job anyone in the Manchester area ??

 

[Gavin A]

We're installing a unit in preston on Wednesday, so could come across to Manchester after that, if we could get a unit in time.

 

[MicraShed]

it right that you need to be a qualified spark to fit this or is this unit a job for the home owner to do ?

I qualified in electrical engineering back in the 80's and I wouldnt dream of installing this myself.
Its not overly complicated when you look at the wiring diagram, but I imagine it will need a P cert.
I would rather do a couple of extra shifts at work and pay someone and know its safe and my house insurance will pay out in the event of anything going wrong than chance it to save a few quid.

 

[Sunshine777]

Yes Sly, Its been averaging 3.3kw hours per day for the past 32 days.


By this comparison, either the gas boiler is very inefficient or the calculation of the Immersun is somewhat inaccurate? I must say that using recognised formular to calculate the heat required to raise the amount of water in my tank seems to indicated that I need more kwh's than the Immersun indicates!

Any more thoughts on the accuracy of the Immersun's reporting?

 

[Martyfox]

Does anybody have any good data on Immersun running in real life, including import/export over a decent length of time?

Using a TRIAC, does the Immersun not import power some of the time, and export the rest, or have i misunderstood something... :6:

 

[Worcester]

@MartyFox

No, from a user point of view the ImmerSUN doesn't import any power EXCEPT if you use the overide timers or boost control. From a technical viepoint, it porportionally switches the resistive load on and off using burst fire. The electricity meters response criteria are such that they balance out the full power import / export over the very short period so they work just fine.

 

[series530]

I've built my own proportional control unit and am continuing operational trials at the moment.

It wasn't cheap but it gave me some experience of programming micro controllers and reading current and voltage using them. I also wanted a unit which gave me a wireless based visual indication of what was happening because the controller is far away in the garage. I suspect that, for somebody who wasn't bothered about the learning experience or the visual indicator, provided you know what you are doing, a unit can be built for about £70 without installation costs.

It's too early to say at the moment but, on a reasonable day, the system will heat a whole hot water tank for free so I suspect that it wont take long to pay for itself.

 

[Worcester]

@series530

Sounds good, can you share your ideas? So that others that want to spend the time and trouble building one for themseleves are able to follow your example.

For those that want to build one themselves, there is a fair bit of information, including step by step construction details and progarmming instructions, here: Home | OpenEnergyMonitor and specifically here: Solar PV Monitoring System | OpenEnergyMonitor and here: Labs | OpenEnergyMonitor (see the section entitled, Solar PV to Immersion heater control.

I know that one is very well researched - would be interested to see photos ond diagrams of how yours works.

 

[MicraShed]

I now have an ImmerSun and despite rain of Biblical proportions it is dumping (some) electricity into the hot water tank (well the immersion heater obviously - not just dumping raw power into the tank!).

Roll on the sunshine!

 

[Scobo]

Must say, the Immersun looks a good quality piece of kit going by that photo.
Might consider upgrading from my cheapo controller if the price comes down a bit.

 

[series530]

Hi Worcester,

that's a very useful site and one I stumbled upon by accident about two months ago. It's no co-incidence, therefore, that my design is based upon designs and hardware from that site. What I have done is to take a solution offered by one of those members and have added additional functionality to it.

The past month or so has been full of week long business trips and I haven't been in a position to finalise my solution and publish it. Rest assured that, with a bit of luck, I will publish something on that site and link to it on here in the coming week or so. The whole point of the site is that it is open source and thus available for anybody to freely use provided written recognition is given to the original designer if code is used.

For those who are interested, and as a simple introduction, if you are reasonably handy with a soldering iron and can follow simple instructions to program a micro controller, it's quite easy to build a controller. Pretty well all of the parts are available at reasonable prices through the open energy monitor site and the software is simply down loadable (the beauty being that the contributors offer what they have written as open source).

For most of us, and I know that this cuts across best practise in the electrical industry, the only rub is intercepting the mains feed to the immersion heater. What many build as a solution may not be seen as industrial enough for a qualified electrician to put his name against installing. It doesn't mean that what is offered for installation is unsafe, far from it. It's just that the mains interface may not always be something that an electrician would naturally buy from a wholesaler. More industrial solutions for the mains interface can be purchased but this does increase the end price somewhat.

 

[MicraShed]

PV Update - last week with its Biblical rain storms saw a reduced PV generation of just 41kWh for the week and an increased household use to 9kWh/day. Still as the days shorten I have to expect this.

Today the ImmerSun managed to dump 0.85kWh in total (though at one point it was pushing 1.2kW into the tank for a short time, the 0.85 is the total) into the immersion heater which saw water at the tap reaching a flesh melting 67 degrees.
Now given I have smallish children I dont want it set this high.
Thanks to W2G's advice I isolated the immersion from the mains whan I got in from work and whipped the cap off - its been 17 years at least since I saw this last, in fact Im fairly sure dad wired it up not me.

Set originally at the 70 degree(ish) mark I felt it click at the 65 degree mark (so the taps are at 67 degrees at the moment).
I have turned it down to about 60 degrees, hoping that it might be about 57 degrees ish at the taps but I suspect there will be further mucking about to do to fine tune it.

After a bath was run, the tank filled up with cold to replace the hot drawn and settled at 61 degrees with a couple of gallons of cold (at 16 degrees) filling it

 

[jason121]

install a TMV on the tank that way you increase the tank temperature with the immersun

 

[MicraShed]

Well yes that is an option, but in the meantime I want to aim to keep the tank temp between 55 and 57 degrees if possible until such time as I can get around to further plumbing shenanigans!
So for now fiddling with the immersion element thermostat is my option. Ultimately I want to replace this element with a modern one with thermal cut out, but again plumbing shenanigans and draining the system down - so I'll probably leave that til next summer.

The boiler feed is regulated to 55/56 degrees via a tank thermostat.

 

[Barry ugen]

there is a unit on the market called a immersun, i have not installed yet is there anyone out there who has??

 

[Worcester]

Barry, there are loads of them installed (we know, we've done a lot of them ) if you read this thread from the beggining, I know it's 127 posts long, you'll see end users actual thought processes for deciding to install it and the results they are getting.

Generally not just good reviews - GREAT reviews!

 

[MicraShed]

Barry
Admittedly my tank is already warm, and quite well insulated but despite only pushing half a kilowatt hour into the tank yesterday and 0.8kWh today it has raised the temp from 55 degrees to nearly 70 degrees with electricity that would otherwise been exported.

Raising the temp of the tank also prevents the boiler stat from triggering and making the boiler fire up to heat the water, thus saving me gas too. As the heating still isnt on yet I can ensure that the spare electric is being used rather than exported!

 

[adamcharvet]

I've just spoken to both Jo and Lee at Immersun and their product seems to be the one to go for. And in cases where the immersion isn't on its own circuit, all you have to do is run a small twinned pair cable (similar to cat 5, I guess) from the CT up to where the Immersun box is installed. They are talking about having a wireless signal from the CT available shortly too for these cases. I must admit I have no experience with the Woolridge Device, but unless they've come down in price or can demonstrate why their product is better, I'd go with Immersun, as they seem to have got the product support and documentation right.

- - - Updated - - -

I've just spoken to both Jo and Lee at Immersun and their product seems to be the one to go for. And in cases where the immersion isn't on its own circuit, all you have to do is run a small twinned pair cable (similar to cat 5, I guess) from the CT up to where the Immersun box is installed. They are talking about having a wireless signal from the CT available shortly too for these cases. I must admit I have no experience with the Woolridge Device, but unless they've come down in price or can demonstrate why their product is better, I'd go with Immersun, as they seem to have got the product support and documentation right.

 

[Graeme Harrold]

Just ordered 2 Immersun units from Edmonsons (same price as buying direct) and also spoken with Jo. They know their stuff and their customer service seems to be impeccable.

 

[echase]

Problem with Immersun is it is a burst fire device and is not approved for installation because in most installations it causes an illegal amount of lighting flicker on all houses in the area. Also the electricity supply companies do not like burst fire technology so may later make it very difficult for owners of such devices e.g. when they fit smart meters. Try Intelligent Immersion Ltd instead for a legal product. www.intelligent-immersion.co.uk

 

[JulianC]

Proof please

 

[thushar]

Immersun looks very expensive - @ £400 .

Found a new proportional / modulation control unit at an affordable price of £199 + £9 for postage at SolarImmersion ? Surplus Solar Energy Water Heater | . It will divert 100% of the surplus power to the immersion and no need to change the immersion heater or the tank.

The feature list looks very good as well

 

[series530]

Immersun looks very expensive - @ £400 .

Found a new proportional / modulation control unit at an affordable price of £199 + £9 for postage at SolarImmersion ? Surplus Solar Energy Water Heater | . It will divert 100% of the surplus power to the immersion and no need to change the immersion heater or the tank.

The feature list looks very good as well

for the money, that looks like a pretty good system. It's a little like my home grown system but without all of the effort that I had to put in building and programming it.

if nothing else it demonstrates that the cost of these units is coming down as competition increases.

 

[Worcester]

Proof please

echase has only posted on threads relating to immersion heater controls and has consistently berated the immersun and various other products, and then all of a sudden reactivates an old thread and then promotes a product from a company only registered in October last year, and a website regsitered in December 2012, draw your own conclusions...


Or maybe it's just me being biased the other way ......

 

[JulianC]

Yes, my "competitor bashing" alarm had triggered... along with my bulls**t detector.

 

[Worcester]

@Series530 / @thushar, at least those guys have been round the blok a while, here are their earlier incarnations: Intelligent Solar PV Immersion Heater Switch - Use Surplus PV Power to Heat Water (csroll down the page to view Versions I, II and now III )

 

[series530]

I have no axe to grind - I don't know this company and I have no issue with the Immersun product either.

On face value alone, it makes it an interesting proposition. That said, I'm amazed that they can turn out a product at that price and still offer a two year warranty. I know that what I have built myself has grown in complexity and now does a whole lot more than many offerings on the market. That said, I suspect that, all in, I've probably spent as much as that unit costs building my own system.

People are waking up and realising that you don't have to install solar heat exchangers on your roof to heat water provided you already have a PV system. Add to that the fact that you are giving away something that you could use yourself and still be paid for - these PV dump systems provide a compelling proposition and should be a decent earner for both consumer and installer in the future.

If this company can make the product, sell it and properly support it then good luck to them. If I were in the market to buy a PV dump system I would be very cautious, especially in light of what has been posted very recently on this thread.

 

[Worcester]

@series530, no critiscism meant, sorry if you took it that way. It's good to see other products coming on the market.

We had long chats with various inverter manufacturers early last year about what was needed in the market place and gave them a reatil price point of £200.

Considering what you can by 3.6kW inverter for, getting these to a price point of £200 retail for an inverter manufacturer should neve have been an issue, especially for the chinese ones

 

[series530]

Hi Worcester,

I was probably being a little over sensitive and mistook the intention. Apologies for that.

I guess that we have been too used to seeing relatively new products with an early adopter price tag. The relative cost of an inverter, as you sensibly mentioned, puts things into perspective.

I just wonder how, unless such a company took a huge punt and bought in the thousands, the price point could be squeezed enough and a decent margin with some after sales service thrown in could be attained so as to make it viable. I suppose it could be Fred in a shed with a windfall just buying these units in bulk from Asia and putting them in a cardboard box, attaching a stamp and keeping his fingers crossed. It is interesting to note that their previous offerings all boasted a union jack. This one does not.

We'll see in six months or a year from now if they are still around. I hope for all concerned that they are. It would be a shame to take people's money and then not be in a position to support them afterwards.

 

[jason121]

Where is solarimmersion made and does it use the same technology as the immersion ???

 

[lydart]

Website clearly states that the item is designed and made in the UK.

 

[jason121]

looks familiar

 

[thushar]

these guys have been in the solar switch innovations for some time: Intelligent Solar PV Immersion Heater Switch - Use Surplus PV Power to Heat Water (scroll down the page to view Versions I, II and now III )

mark I came out in 2011, Mark II in April 2012 and Mark III in Jan 2013 . Mark I monitors only pv output, Mark II is differential but switched, Mark III is proportional .

details of Mark III is on dedicated site - SolarImmersion ? Surplus Solar Energy Water Heater |

Looks like they have a good track history

 

[series530]

Website clearly states that the item is designed and made in the UK.

I take back what I said - even more astounding that they can make a decent margin using UK production!

 

[thushar]

I take back what I said - even more astounding that they can make a decent margin using UK production!

Yes - Wonder how they could manage that. Suspect the price will go up after the pre-order.

 

[jason121]

does it work the same as the immersion

 

[puddy]

does it work the same as the immersion

I don't have hot water cylinder but have a boilermate 2000, I am buying a new car this year and was looking at Vauxhall Ampera hybrid car could charge it when not used with is device?

 

[jason121]

If the design is like the immersion then no, it wouldn’t be able to charge your car.
Needs resistive loads only with no electronics or switching devices.