Solar Immersions and Megaflow CL tank

DATMAN_2

Hi all,

Have had the Solar Immersions device connected to my Megaflow tank via the fusebox in the garage and it appears to be useless!

The Megaflow it is fired up on the gas boiler at 5am for an hour and this normally stores all the hot water we need for the day.

The Megaflow also has a socket switch next to boiler which is on off and only used rarely to heat up tank - twice in 2 years.

When the switch is put on - the Megaflow sucks in 3kw of elecy whether it is being produced or not!

I expected the Solar Immersion device to control the tank switch so it only switched on when 3kw (or say 2.75kw if the device can be programmed) of excess energy is being produced.

Emailed Solar Immersion (never answer phones) with no reply!

Anyone managed to get the Megaflow working on PV?

thanks

EricMears

DATMAN wrote: »

Anyone managed to get the Megaflow working on PV?

I have neither - though I am aware of how a megaflow should work and have read a few leaflets on devices such as Immersun before settling for the simplified setup of 'Optiplug' and a 115V immersin heater element.

The only significant difference between a Megaflow and my 'Heatbank' (or indeed a conventional storage cylinder) is that the Megaflow is kept at mains pressure and everything else is vented. No reason at all why that should stop it working with one of the diversion devices.

A device like yours is supposed to measure your excess generation then attenuate the voltage to your immersion coil such that it demands all of that (or works at 230V if there's an even bigger excess than coil's maximum demand). It doesn't sound as though that's happening so your problem should be directed towards supplier.

If they won't answer you and you paid by credit card, you may be able to ask credit card company to make a full refund.

Cardew

DATMAN wrote: »

Hi all,


When the switch is put on - the Megaflow sucks in 3kw of elecy whether it is being produced or not!

Hi,

Not sure what you mean by that statement.

A guy called Albert Einstien said, and the First law of Themodynamics states, the 'Energy cannot be created or destroyed'

Thus, if by 'sucks in 3kW' you mean 3kW is being consumed, then it must be producing heat.

EricMears

Cardew wrote: »

A guy called Albert Einstien said, and the First law of Themodynamics states, the 'Energy cannot be created or destroyed'

Thus, if by 'sucks in 3kW' you mean 3kW is being consumed, then it must be producing heat.

That is indeed a Law of Thermodynamics but Einstein was the chap who pointed out that energy can be created - by converting it from matter.

And I'm pretty sure that Datman was saying that his immersion heater would be switched on without modulation regardless of the generation status.

DATMAN_2

EricMears wrote: »

I have neither - though I am aware of how a megaflow should work and have read a few leaflets on devices such as Immersun before settling for the simplified setup of 'Optiplug' and a 115V immersin heater element.

The only significant difference between a Megaflow and my 'Heatbank' (or indeed a conventional storage cylinder) is that the Megaflow is kept at mains pressure and everything else is vented. No reason at all why that should stop it working with one of the diversion devices.

A device like yours is supposed to measure your excess generation then attenuate the voltage to your immersion coil such that it demands all of that (or works at 230V if there's an even bigger excess than coil's maximum demand). It doesn't sound as though that's happening so your problem should be directed towards supplier.

If they won't answer you and you paid by credit card, you may be able to ask credit card company to make a full refund.

Thanks re next post...exactly what I meant. When the Megaflow is switched on it pulls 3kw of elecy from the pv or grid irrespective what is being produced by the PV. It's a simple all or nothing switch at 3kw! It's has stayed off since PV and solar immersion (similar to immersion sun) was installed.

Going back to your reply, could you simplify your second paragraph please! Layman here. The Megaflow has 3kw heater built inside. If I am say producing 900w of excess energy, is this sufficient to get the 3kw heater up and running - and producing some heat warm up water?

Please also give further info re 115v thing!!


cheers

EricMears

DATMAN wrote: »

Going back to your reply, could you simplify your second paragraph please! Layman here. The Megaflow has 3kw heater built inside. If I am say producing 900w of excess energy, is this sufficient to get the 3kw heater up and running - and producing some heat warm up water?

Please also give further info re 115v thing!!

AFAIK, your Megaflow will have a perfectly normal 3kW immersion heater element built in. I can't think of any other way it would produce 3kW of heat electrically. (There are some very obscure methods used in calorimetry of rotating a paddle in a tightly fitting space that would generate heat but nobody in their right mind would think of applying that principle in practice).

also AFAIK, there should be no minimum level of excess generation available needed. If there was (say) just 100W 'spare' then the device ought to modulate its output to the heating coil to 100W. I guess in practice it wouldn't be set to deliver a very low output as that would almost certainly mean it kept switching on & off.


My 115V thing has been described here (albeit on a different thread) before. But its simply a builder's site transformer that drops my 230V supply down to 115V. When a 230V 3000W heating element is connected to a 115V supply, it will only draw 750W.

Since my previous description that's had an Optiplug added to the circuit. So all that happens now is that the Optiplug is calibrated to switch ON if it can see a spare 750W and OFF if it can't.

Not quite as good as feeding 3000W to it if that's available or whatever we can spare if less - but a lot easier to understand, fit and use and a lot cheaper.

Cardew

EricMears wrote: »

That is indeed a Law of Thermodynamics but Einstein was the chap who pointed out that energy can be created - by converting it from matter.

He said what!!!!!

He stated:

“Energy cannot be created or destroyed, it can only be changed from one form to another.”

http://www.spiked-online.com/articles/0000000CA9B8.htm

You can change the form of energy from matter. e.g. the potential energy(PE) petrol in our car tank is changed to kinetic energy(KE)

Burning a lump of coal(matter) changes the energy from one form to another.

Anyway to the OP's question about 115v:

Yes Ohms law applies! If you apply a lower voltage to a simple resistive heater(i.e. an immersion heater) then you will use less power.

tr8

why not do the same as I have done and switch to a 1kw water heater in the tank.
I can heat the water any time I have more than 1kw excess.
Takes longer to heat the tank but if I need quick heat then that's done by the gas boiler.
Then when I have a sunny spell and not using the feed turn on the tank heater

EricMears

There's a world of difference between the mass-energy relationship postulated by Einstein and the simple 'change of state' examples well known for hundreds of years.

Before Einstein, mass was fixed and energy was something completely independent. Only since his work has the actual conversion of mass into energy been recognised

OffGridLiving

tr8 wrote: »

why not do the same as I have done and switch to a 1kw water heater in the tank.
I can heat the water any time I have more than 1kw excess.
Takes longer to heat the tank but if I need quick heat then that's done by the gas boiler.
Then when I have a sunny spell and not using the feed turn on the tank heater

This is what I've seen on other forums, people installing much smaller immersion heaters for PV. The only thing I don't understand is what happens when the spare PV energy goes above 1kw?

I've seen the blurb on the Immersun website where it tracks energy generation almost perfectly, routing spare capacity into the HW tank. I've never understood how it can do this if the spare energy can fluctuate between 100w and 4kw, because I have always thought that if you have a 4kw immersion heater, then it won't work unless you feed it 4kw of power?

Is that wrong?

Dave_Fowler

OffGridLiving wrote: »

This is what I've seen on other forums, people installing much smaller immersion heaters for PV. The only thing I don't understand is what happens when the spare PV energy goes above 1kw?

I've seen the blurb on the Immersun website where it tracks energy generation almost perfectly, routing spare capacity into the HW tank. I've never understood how it can do this if the spare energy can fluctuate between 100w and 4kw, because I have always thought that if you have a 4kw immersion heater, then it won't work unless you feed it 4kw of power?

Is that wrong?

An immersion heater is similar to a light bulb (except it produces only heat). The Immersun acts like a normal dimmer switch you can use for the lights, only the control of the 'dimmer' part is automatic.

Dave F