Immersion Heater - PV electricity

brianboru · Jun 25, 2011

Millerman said:
Ray you have my email address, lets coresspond via external means.

As long as the PV system has been fitted a certain way and you can put the equipment in a "box"
(to suit your location) . Not installations have the room to mount everything. The rest is easy.

Andy

Hi Andy
We've just had a PV system installed by Rayotec (commissioned on 9th June) with generation meter etc. in the porch and tails going direct to outside meter box. Like Ray I'm not an electrician but reasonably competent and very interested in assembling and installing the controls you have described in these posts. We have an indirect hot water cylinder fitted with with 3 kW immersion heaters top and bottom formerly controlled by Horstman Economy 7 timer. Would you be able to supply the bits and instructions? Thanks, Brian

Millerman · Jun 27, 2011

Brian, See posts 90 and 74 for contact details

brianboru · Jun 27, 2011

Thanks Andy. I'll be in touch.

MBE Contracting · Jun 27, 2011

wow, that sounds like a product that could do very well. Could you please give some more details. Kind regards Mick. MBE solar.

Millerman · Jun 27, 2011

Mick, please contact me via post 90 / 74

Andy

echase · Jun 30, 2011

Like a drill speed controller or light dimmer a phase angle controlled immersion is going to radiate some electrical interference, only worse because of the larger current and long cable between the immersion and fuse box. What sort of suppression is going to be needed to stop interference with say radios and TVs?

inie meanie · Jun 30, 2011

Well a drill has an arc across the com that is suppressed by a capacitor, but I am not sure that there will be any problem with this. I have been testing my circuit on 3 kw immersion heater with the triac control and have had no problem at all.

pauldreed · Jun 30, 2011

echase said:
Like a drill speed controller or light dimmer a phase angle controlled immersion is going to radiate some electrical interference, only worse because of the larger current and long cable between the immersion and fuse box. What sort of suppression is going to be needed to stop interference with say radios and TVs?

This is an interesting article which discusses this aspect http://------/m1sLDY
I think that it's not so bad with resistive loads.

Millerman · Jul 4, 2011

burst firing is the way to go no problem with EMC. Talking to a company to develop a unit,,,,, more later

inie meanie · Jul 4, 2011

Hi Millerman. Forgive me but burst firing will pull full power for a determined number of cycles. (see Burst firing ) This will then give a draw from the grid and then the cycles shut off for another set period. This is only useful for the power control of a heater temperature not what you need for balancing a load. I have just completed my circuit that measures the two power levels ( current coils, no need to phase reference if you go on output from dist board, several cores can fit through one coil no problem, remember to only use one from each ring circuit ) compares them and provides an output via the triac. It keeps the house just exporting a small amount of power whilst dumping what else is free into any resistive heating load. I used a 741 to compare the two signals, pass this onto another 741 which adds a reference voltage ( zero point ) and adjusted the gain via pot on feedback gain to alter the slope, thus totally analogue and very cheap. No problem with EMC at all. It can only do this by working at a cycle level. Burst mode will cost you power consumption sorry.

Millerman · Jul 5, 2011

inie hi

well it must be the way i have it working with my PLC because there is no consumpstion from the Grid.

inie meanie · Jul 5, 2011

You can see how that burst mode by definition will fire at full power for a time period? Have you accurately measured the current at the meter with a scope or with a phase referenced meter? The reason you may have not seen it is because you may have had a generous supply from the pv at the time. You will see a draw from the grid under more difficult conditions i.e. when you only have a couple of hundred watts to spare from the pv and you then load up your immersion heater.

Millerman · Jul 5, 2011

As of yet i have not put my scope on the grid supply and have only set the unit to "work" when there has be 700watts free.

bigbob1 · Jul 5, 2011

Tell me more Mr Millerman, don't suppose it's called an EMMA? link me to your website i may be a mass customer. Before you change your tank and mess about with it have you tried leaving your immersion turned on and seeing if it heats up? because you might be surprised that in 6 hours it will be hot enough to have a shower etc that is if you just want a tank full of water. try it.