I can't see what the contactor does in that drawing, apart from holding off the heater out of low peal times. Just a timer on the heaters would do.
The contactor control wire is operated by the grid's timer?
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Economy 7
- Thread starter hard-work
- Start date
The contactor control wire is operated by the grid's timer?
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The saving (once one has exceeded the 'break-even' point) due to having E7 will obviously increase as one's consumption of cheap-rate electricity increases, but that does not alter the fact that the (seemingly very strange) changes my supplier made in April will, for any amount of consumption, appreciably reduce that saving. The changes (all figures include VAT) were:
Day Rate: from 16.34p to 17.147p per kWh (an increase of 4.94%)
Night Rate: from 6.89p to 7.844p per kWh (an increase of 13.85%)
Put another way, the Night rate increased from being just over 42% of the Day rate to being nearly 46% of the Day rate.
Much as I would have moaned, I could have 'understood' an 'across-the-board' (similar for day and night) increase, but what they actually did seems to be working against their (one assumes) wish/need to encourage use of a higher proportion of electricity at low-demand times of day!
Kind Regards, John
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it turns on the off peak cu at the time set by the dno via the switch live to the contactor coil
It connects the supply (from the meter) to the off-peak CU (hence the storage heaters) only during the off-peak times of day.
Think of it just as a 'time-switch', with the actual 'time information' being provided by the meter.
Kind Regards, John
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You are - but since the contactor uses so little power (in comparison with the heating) I suspect that you would struggle to actually notice the very little you would be paying.
A typical contactor coil for such use consumes 5W or less when energised. At 7 hours per day for 365 days per year, that would be about 12 kWh (maybe about £2) per year.
Kind regards, John
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First the contactor is energised only during off peak. whether is costs the customer is dependant on the way it's set-up. if you look at the picture, the brown and blue tails from the cut-out are there for control and on the unmetered side. If a contactor were to be fitted in the flat, on the metered side, then the cost of operating it would be by the customer.
This would be at off peak time.
So they pay for the energy to open the contactor.
So they pay for the energy to OPERATE (close) the contactor, so it only uses energy during off peak time.
Yes, I'd overlooked the fact that the contactor might be activated by unmetered electricity (as used to be the case with time switches). However, as I recently wrote, even if the customer were paying, it would probably be no more than a couple of quid per year.
Kind Regards, John
Daytime electricity with E7 is much more expensive than 'single tariff' electricity - so very many people would end up paying much more if they had E7.
As I recently wrote, unless one's night-time use is at least about 35% of the total used, one will pay more with e7.
Kind regards, John
True, I'd overlooked that, too (not my day1)! ... so, even if the customer were paying, it would probably be less than £1 per year (at 'cheap rate').
Kind Regards, John
Indeed but it is not always like this. If the contactor were to be elsewhere in the system (several floors above the meter) which is fairly common for retro fitted systems it will be costing.
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