Low Wattage Immersion Heater

[shaunb]

Hi,

Have any of you seen the solar PV related immersion controllers that people are building/designing on other forums?

In a nutshell, they monitor the house energy consumption and PV generation and then the balance (i.e. that would normally be exported to grid) is instead used to power the immersion heater. The clever part is that they vary the power to the immersion rod - it's not just ON or OFF, it only ever gets given the "spare" power (or nothing). So, unless your hot water tank thermostat tells it not to (because its warm enough), then all excess power is dumped into the immersion. That means your normal boiler doesn't have to do as much work (if any) to heat the tank and it automatically steps down (or switches off) if you turn on other devices in the house.

These devices sound a bit like home made versions of EMMA. Even the PLC-based one (which sounds almost like plug & play off the shelf components) should come in at less than a third of the price of EMMA for the parts.

Some links to other threads I've been reading:

http://www.electriciansforums.co.uk/cen ... icity.html

http://www.navitron.org.uk/forum/index. ... 072.0.html

http://www.navitron.org.uk/forum/index. ... 239.0.html

http://www.navitron.org.uk/forum/index. ... 296.0.html

Hope these are useful!

Shaun.

[thushar]

I have been using the automatic solar immersion heater and 1 kw immersion heater from http://solarimmersionheaterswitch.co.uk ( the same on ebay at http://stores.ebay.co.uk/Fair-Trade-Hub-Shop ) . It's working perfectly for the last two months providing me with a full tank of hot water during sunny days (gas boiler keeps silent!) and effectively preheats the water on dull days - so the boiler has to work less - saving on gas. It's a good investment, pays for itself in an year (I hope) and get better ROI on the solar panel investment.

Excellent idea, as it uses only the spare electricity generated by the solar panels, so no electricity is imported from Grid. Also the export meter reading unaffected. Easy to install as well - just a clip on sensor will do the trick.

[itshardbeinggreen]

I've found an affordable product which works with my 1k Watt Immersion Heater. It will monitor how much energy my house is consuming and how much power I am getting from my solar panels. It will switch on my immersion heater when enough surplus energy is being generated.

Have a look at www.totalpowershop.com and their TP-S610A power management unit

Apparently, it will work with the energy generated by wind turbines as well. And its only £300!! It should pay for itself as well although it may take a year or two to get the money back. And it will make sure that I'm not consuming anymore power than I want to.

[emordnilap]

What is it about low-wattage immersion heaters that attract one-post wonders?

Not you, I'm sure, itshardbeinggreen - welcome to the forum.

[JohnB]

I've got something better than a low wattage immersion heater. It's called a kettle, and only heats water when needed and to the temperature required .

[MatthewBragg]

I have a PV system and have been trying to find a 1000 or 1500 watt storage heater. I would have this connected to the normal electricity circuit rather than the white meter, and have it switched on during the day so that it can make use of the excess power generated by the PV system, and provide heating in the evening. Does anyone know where I can get one from ???

[emordnilap]

I have a PV system and have been trying to find a 1000 or 1500 watt storage heater. I would have this connected to the normal electricity circuit rather than the white meter, and have it switched on during the day so that it can make use of the excess power generated by the PV system, and provide heating in the evening. Does anyone know where I can get one from ???

Welcome to the forum, Matthew.

Our resident electrickster, adam2, addressed this very question nearly four years ago here. Have a look.

[itshardbeinggreen]

I recently found that I could buy them from these two companies:

http://www.surecal.co.uk/Product/ImmersionHeaters.aspx

http://www.howden-electroheating.com/

[MatthewBragg]

Thanks - I've emailed these companies, but I think their only storage heaters are for heating stored water. I'm after a convector heater for heating a room, just like the normal night storage heaters but lower power and heating up during the day.

[adam2]

What you require can be done but is by no means a simple matter.
Before proceeding furthur, one should consider is the idea even viable, remembering that during the heating season the output of a PV system will be limited and perhaps better used for applications that need electricty rather than low grade heat.
You may find exporting the power to the grid, and buying gas or firewood for heating is more economical.
Alternativey, solar thermal collectors that heat a large hot water tank might be better. This stored hot water being used to heat standard hot water radiators when required.

Small electric thermal storage heaters are readily available, but are unlikey to meet your requirements without modification.

[thushar]

Just found it on ebay :

http://stores.ebay.co.uk/t-sassociates? ... 7675.l2563


They also sell solar immersion controller/ divert (proportional based surplus diverting switch for free hot water ) from http://solarimmersion.co.uk/

[mikepepler]

What about other ways us using the excess power?

Our system is off-grid, and we have solar thermal too, so when the batteries are full there's nowhere for the power to go... I've been putting the freezer on 'boost' during the day so it can have several hours off when the sun goes down to reduce battery drain, and have been putting the washing machine on during the day, but with the run of sunny weather we're having there is still power being dumped by the controller...

[verytricky]

There are two options.

You can buy 1kw imersion heaters from places like ASAP or BES. Check the thread size suits you, they are all different.

You can buy a yellow builders transformer 3kw 110v output. You connect this to the inversion heater of 3kw and you draw power from the input of around 900w or 0.9kw. The drop in voltage makes this work. You need to use the 240v immersion heater! Providing half the voltage quarters the draw on the input line.

[RenewableCandy]

While doing a spot of online Xmas shopping perusal I came across this:
http://www.nigelsecostore.com/acatalog/ ... iplug.html

Also, the ever-trendy WattsOn now comes complete with solar power detection!

[mikepepler]

I've found that I *can* get a gadget to plug into my solar charge controller that can switch up to 4 relays on and off according to various voltages and other variables in the controller. It's about £100, and I *think* that I'm probably losing about £60 worth of electricity because I can't use it when it's generated at the moment.

The question is, what else is there I could usefully power when there's excess energy? In such a situation I'm already running:
- fridge
- freezer
- solar water heating pump
- internet/phone
- computer
- washing machine

In terms of manually controlled things:
- the cooker's not an option, for wiring reasons and its demand is too high.
- kettle, iron, vacuum cleaner demand is too high.
- microwave and toaster are OK, but only if you want some food!
- strimmer is OK, if there's stuff to do in the garden.

But I'm stuck for thinking of things I could power automatically, given that water heating is out (plenty coming from the solar thermal). It annoys me to have the power going to waste...