Do immersun type devices work

[robertevans68]

Our tank is already insulated with foam jacket from the factory, but the tank cupboard was always really warm. Last week I fitted an additional red jacket from BQ and now the cupboard is cool so this must be a good thing.

 

[liquidity]

When you say without a jacket do you mean just a bare copper cylinder? My post above is referring to a 20 year old copper cylinder with perhaps 1.5 inches of hard foam insulation bonded to the cylinder at the time of manufacture.

 

[FB.]

Our tank is already insulated with foam jacket from the factory, but the tank cupboard was always really warm. Last week I fitted an additional red jacket from BQ and now the cupboard is cool so this must be a good thing.

The tank I mentioned earlier had a tough foam-like, pale greenish coating on it, maybe 2cm thick. It wasn't bare copper.

Adding the jacket to the hard-foam-coating roughly halved the power consumption or roughly doubled the time between reheating.
Had it been bare copper I expect it would be doubled again.

 

[Digon]

I've been using a home made proportional controller, similar to the Imersun, with my 4kWp system since April and can say they are definately worthwhile.
How much you can get out can vary a lot depending on how you set things up.
My system was a standard 120L tank with 27" immersion and because I have a toddler in the house I had to limit the thermostat to 60 DegC, which was probably still too high. For the last 3 1/2 months this setup has been shutting down at about 11 am on good days and 1pm on cloudy days. This was adequate without supplimentary heat for 2 x evening baths plus general kitchen use or 1 x evening bath and 1x morning shower. I've logged the (true) energy sent to the immersion and it's been pretty consistent at 185 kWh/ month from about 350 - 430 kWh/ month generated.
Two weeks ago I modified my system and it's made a big difference so far with 7 -11 kWh/ day now going to the immersion, conditions permitting of course.
The mods I made where to fit a larger 150L tank (second hand off Ebay), 36" immersion which reaches to within a few inches of the concave tank bottom and a thermostatic temperature control on the tank outlet so I can run the tank hotter without scald risks at the taps.
I also switched the washing machine and dishwasher to hot fill and carefully time there use. Currently the washing machine goes on about 9- 10 am as it will drain whats left of the previous days heated water before the rinse cycles.
The dishwasher which doesn't use anywhere near as much water goes on about 1- 2 pm and uses enough water to re-engage the immersion thermostat to use some more of the afternoon sun.
The thermostat will still cut out by about 5pm on good days but the only way I could store any more energy in my current setup would be to use a pump for tank stirring which would not be easy plumb in to my system.
I may put a second hand storage heater on a relay linked to the thermostat but I don't think there will be enough spare energy during the winter months when it will be needed.

 

[liquidity]

Digon - thanks for sharing your actual results to date. Can you post a link to any design info on the controller?

 

[Digon]

It is a design by a member of this forum, Pmcalli. There was a long thread on here discussing the design of these devices but I can't find it right now. as I'm not on aPC.

 

[MicraShed]

The only flaw I can see in your calculations is perhaps not factoring in what time of the day the gas use takes place.

Both my heating and hot water are controlled by a thermostat only. No time clocks.
So when the room stat calls for heat the boiler fires up and delivers heat (with surplus heat being dumped into the cylinder via the gravity hot water set up) TRV's shut off when individual rooms get up to temp.

If however the cylinder calls for heat, then the boiler fires up and delivers the heat via the gravity feed set up to the cylinder.
The downside of the gravity set up is that there is a very long run on the pipes so heat is wasted there, and the boiler ends up cycling as the heat does not disappate fast enough into the cylinder.

The cylinder is 17 years old and insulated by both a foam jacket and red jacket.
Pipes are insulated as well as they can be by foam.

 

[nicksgonesurfin]

4 KW of PV produces 4 x 900 units in the south west 850 in norfolk 800 in scotland. 3600

ten units a day at best during the winter its going to be more like 3-4 units which is when you use any hot water for heating.
This device will certainly cover hot water usage in the summer but i dont think it will achieve as much. Ideally you need a heat store Large well insulated thermal store to keep the heat in. You also need a range of immersion heaters as most are at least 2KW most are 3 KW. So if your exporting 1 KW and your 3 KW immersion kicks in then your using two units of electricty at 14p per unit =28p rather than Gas ' 4.2 p per unit x 2 = 8.4p that means it could cost you 60p a day extra

 

[Worcester]

You also need a range of immersion heaters as most are at least 2KW most are 3 KW. So if your exporting 1 KW and your 3 KW immersion kicks in then your using two units of electricty at 14p per unit =28p rather than Gas ' 4.2 p per unit x 2 = 8.4p that means it could cost you 60p a day extra

@niskgonesurfin, That's the whole purpose of inmmersun type devices, the PROPORTIONALLY control the power to the immersun so YOU DON'T import, and if you've only got 751 watts available that's all it will send to the 3kW immersion:

This ImmerSun was installed on the 22nd December 2012:

 

[danesol]

4 KW of PV produces 4 x 900 units in the south west 850 in norfolk 800 in scotland. 3600

ten units a day at best during the winter its going to be more like 3-4 units which is when you use any hot water for heating.
This device will certainly cover hot water usage in the summer but i dont think it will achieve as much. Ideally you need a heat store Large well insulated thermal store to keep the heat in. You also need a range of immersion heaters as most are at least 2KW most are 3 KW. So if your exporting 1 KW and your 3 KW immersion kicks in then your using two units of electricty at 14p per unit =28p rather than Gas ' 4.2 p per unit x 2 = 8.4p that means it could cost you 60p a day extra

Given that is you heat your hot water cylinder with electric, I thought most ppl used GCH like me ??

If you do use GCH - the benefit could be less but still rewarding, again its all about knowing your systems, your needs and whats possible with your system, especially figs like whats your export rate to grid to work out ultimately your ROI !

 

[Worcester]

I thought most ppl used GCH like me ??

Not round here! - the majority are on liquid gold aka oil, and turn their boilers off from May - October.

like whats your export rate to grid to work out

Irrelevant when deemed.

 

[danesol]

Not round here! - the majority are on liquid gold aka oil, and turn their boilers off from May - October.

Yes I would agree it would make total sense if had no GAS and were using electric, Oil etc

Irrelevant when deemed.

How can it be irrelevant if you use every last kwh from your Solar array ( ie. use more or less every thing you generate ) - these types of device simply wont return anything then as they wont switch on so I dont understand your comment - explain ??


I'm just doing the calculations now for our household and although we export only 33% of our total generation and use GCH for the primary source to heat the water - there is still some advantage in using one of these types of device but for us it will be along term investment ( looking atm at 8yrs at the cheaper SolarImmersion and far longer for the more expensive Immersun )

However still worth looking at as an add-on and should you get this as a Solar PV package/bundle at the right price your laughing... as i state before every little bit helps

 

[nicksgonesurfin]

Given that is you heat your hot water cylinder with electric, I thought most ppl used GCH like me ??

If you do use GCH - the benefit could be less but still rewarding, again its all about knowing your systems, your needs and whats possible with your system, especially figs



Domestic export is always based on 50export unless you have an import export meter.
Most people do not.

Then your getting paid export plus any savings you make from using more than 50%

@Worcester renewables.

Thanks I didn't know it was a proportional system .

So it will dump what ever is spare into your system?

Good too know.





like whats your export rate to grid to
work out ultimately your ROI !

Thanks for the help see answer in quote above

 

[danesol]

Thanks for the help see answer in quote above

Just not sure what you were trying to tell me then but so we are clear......

Your FITs provider currently give you 50% export payment ( based on your readings ) regardless of what you ACTUALLY provide.

However in reality you could be sending 80% of your total generation to the grid which although you are getting paid for its initial generation, you are ultimately wasting free energy you could utilise...... hence the inclusion of this device to "play the system".

If HOWEVER like me you use the vast majority of your generated electric - there is very little left to use elsewhere and this is what I am suggesting.... the more sauvy PV owner would know this by either monitoring devices or by use of PVO for example

hth

 

[Worcester]

Your PV system is giving you a return over 8 - 10 years which you thought was a good investment - so why isn't an ImmerSun type device when it gives the same return?

- - - Updated - - -

If HOWEVER like me you use the vast majority of your generated electric - there is very little left to use elsewhere and this is what I am suggesting.... the more sauvy PV owner would know this by either monitoring devices or by use of PVO for example

Correct, I agree.

 

[Worcester]

Try using the eco-eye Eco-Eye | Real Time Electricity Monitors | UK - it has an RF device and you can link it up through your pc via cosm (ex pachube) to pvoutput.org (Eco-Eye | Real Time Electricity Monitors | Eco-Eye with Microgeneration/Photovoltaic Installations Eco-Eye | Real Time Electricity Monitors | Eco-Eye used with your computer)

This one uses that system above and has an ImmerSun installed - you can wee how it tracks plus when they had breakfast and put the kettle on

 

[danesol]

Your PV system is giving you a return over 8 - 10 years which you thought was a good investment - so why isn't an ImmerSun type device when it gives the same return?

- - - Updated - - -



Correct, I agree.

No I agree, as long as it lasts that long.... however I was merely pointing out that some will gain enormously with one of these devices ( typically PV owner who uses no electric during the day when sun is out ) but others may not gain so much at all ie. me for example and the risk of achieving the return is higher.

 

[Warlord2001c]

Try using the eco-eye Eco-Eye | Real Time Electricity Monitors | UK - it has an RF device and you can link it up through your pc via cosm (ex pachube) to pvoutput.org (Eco-Eye | Real Time Electricity Monitors | Eco-Eye with Microgeneration/Photovoltaic Installations Eco-Eye | Real Time Electricity Monitors | Eco-Eye used with your computer)

This one uses that system above and has an ImmerSun installed - you can wee how it tracks plus when they had breakfast and put the kettle on

View attachment 17982

I recognise my graph when I see it! Worcester fitted my Immersun less than two weeks ago and it has so far pumped over 30kWh into my hot water tank... Not bad at all considering we've seen very little sun since that day. Most days we have returned from work to a tank of hot water and the boiler has spent almost no time on water heating since then. The tank has very good insulation and we've been able to draw a nightly bath for the young man plus morning showers before the Immersun started again for the following day.

The eco eye smartPV is also proving very accurate as I've been verifying these PVoutput figures against the inverter log and SD card storage from the device which is four second samples rather than 5 minute averages that are sent to COSM.

very happy with both Immersun and smartPV. The PV suppliers were pretty good too!

 

[Berneray]

We have installed about 15 immersun units...though most of them since December so its hard to tell how well they are working yet.

We charge £450 to supply and install if its done at the same time as the PV system. £500 if its a retrospective fit.

One small point we have found....None of the monitoring devices work with Immersun.

Wattson do a similar system Optimersion that works with their monitoring system....but we are sticking with the Immerson....(When we can get stock that is)...

 

[Warlord2001c]

One small point we have found....None of the monitoring devices work with Immersun

Do you mean they don't work at all or that they give false readings?
I use the Eco Eye unit and yes it does add the immersun draw to the grid total when running so gives an overstated grid consumption figure.
To be honest though I'm seeing that as a positive for me as when shown on PVOutput I'm getting a very clear indication of where the immersun is working to bring the PV and Grid totals in sync so I see how little of my PV generated power is going to the grid.
The figures for PV Generation are unaffected and accurate and the Grid total is monitored by my Electricity supplier anyway so not a biggy for me.