SolarImmersion

mickyduck

What a good idea "Z" actually had never crossed my mind to do that to heat more of the cylinder.

zeupater

mickyduck wrote: »

What a good idea "Z" actually had never crossed my mind to do that to heat more of the cylinder.

Hi

Our cylinder is taller than me and designed to encourage thermal stratification of the contents - I'd doubt that they'd have a standard element that long ..... . However, it really could be an issue in cylinders which have been specified for the main heating provision to be GCH or E7, with a switchable immersion being only for a quick 'top-up' .... I'm pretty sure that this is the case in a number of posts which mention that there's not enough DHW and should therefore be taken into consideration.

It's really the same as using a twin-coil cylinder ... our solar thermal heats a coil near the bottom, which heats the lower (cooler) part of the cylinder to a point where there's thermal equilibrium throughout the cylinder, then continues to raise the temperature of the whole until the thermostat at the top reaches it's set-point. A second coil sits about 4' higher in the cylinder which is connected to the GCH and is used to 'top-up' the heat in the winter or if there's been a long dull period. The idea of this setup being that you're still using whatever solar thermal which can be collected to at least raise the temperature of the cold feed, whilst the GCH duty is restricted to only heating the upper part. This way, we can use the GCH to heat the top of the tank (which is probably as large as a normal cylinder) to 'hot' whilst still warming the cold fill during the winter ... of course, with it being a cylinder designed to retain as much heat as possible, it's got about double the standard thickness of insulation .... it's absolutely huge - MrsZ lost her entire airing cupboard when it was installed, so I fitted some shelving in the utility room which greatly increased the ironing productivity ....

HTH
Z

Martyn1981

lisyloo wrote: »

I was told by one company it would save 50p per day and I reckon it's closer to 15p and for me it wouldn't be worth paying for the device.

Hi. Just to say that I was nodding along to that yesterday, and the potential for these items to be oversold or missold (which was (I believe) the intention behind Willemm1's posts). But then along comes Chopper:

ChopperST wrote: »

There is two of us having showers in the morning and the Mrs has a bath most nights. On good days the Immersun will dump 10-11 kWh to the tank.

Taking efficiency losses of a boiler into account, that probably equates to about 14kWhs of gas, which at around 3.5 to 4p is ~50p. Though I'm sure this varies.

I guess the lesson is you have to look to your own personal consumption of DHW to decide if these switches offer a reasonable ROI, and do your best to favour the PV via the thermostat settings.

All interesting stuff.

Mart.

Dave_Fowler

Last October I posted the following figures:

http://forums.moneysavingexpert.com/showpost.php?p=63373233&postcount=424

Whilst these figures are for three summer months, the 'feel' of the system suggests that the annual savings run along similar lines. I've only used the gas central heating boiler to heat the hot water on 4 days since the beginning of March when there was insufficient sun to heat the water via the proportional unit.

Dave F

ChopperST

The Immersun simply uses our current cost of heating the hot water (gas) and displays the savings it has made in both kWh and £/p

We currently pay 5.9p for gas.

50p a day is a reasonable estimation on our 210litre tank with a 4kW array but bear in mind this is only when we have sun all day.

travellerboy

This thread has gone a little off-track. The original question was - anyone with experience of the SolarImmersion Proportional Controller. I have already evaluated that it makes good economic sense and my use of Hot water definitely exceeds that of willemm1

mpn226

Hi I purchased my Immersun of eBay, got my friendly electrician to install in exchange for coffee and choccy biccs, boy does it do what it says on the tin installed July last year, and did not have to use any oil to heat my water until late September. I even had some (a little) diverted leccy on the shortest day of the year. I have it set up to heat a small towel rail when the water is hot,.
A great product and would thoroughly recommend it.

Cardew

ChopperST wrote: »

The Immersun simply uses our current cost of heating the hot water (gas) and displays the savings it has made in both kWh and £/p

We currently pay 5.9p for gas.

50p a day is a reasonable estimation on our 210litre tank with a 4kW array but bear in mind this is only when we have sun all day.

5.9p/kWh for gas?


Are you sure that isn't the old Tier 1 price for gas?


Now with all(new) gas tariffs having a daily standing charge. a more representative figure is between 3.5p to 4p - I pay 3.15p/kWh(including VAT)

mnbvcxz

theboylard wrote: »

Cheaper than that

Pray tell. How?

ed110220

Cardew wrote: »

5.9p/kWh for gas?


Are you sure that isn't the old Tier 1 price for gas?


Now with all(new) gas tariffs having a daily standing charge. a more representative figure is between 3.5p to 4p - I pay 3.15p/kWh(including VAT)

I think it depends how much gas you use. I found the cheapest supplier for us (excluding one or two with awful reviews) has a higher price than that per kWh but lower standing charge and this works out cheaper for us as we use under 10 000 kWh/year. If you use more, it will work out cheaper to pay less per kWh and more standing charge.

Ed