Post
by ericmark »
Fri Oct 17, 2014 11:52 pm
Economy 7 is a tariff not a supply type. Over the years the method of using the tariff has changed. It all started with the white meter with two independent supplies but this mean you could not run items like tumble driers and washing machines from the cheap rate supply so today it's all a single meter and the timing has been down to the customer to ensure is correct.
There has been may intermediate systems but they all have the same tariff name.
There is no reason why one can't have two consumer units with henley blocks joining them but since the consumer unit is only rated at 100A where there is no separate fuse then the total supply is limited to 100A.
With 6 x 3kW used for heating that just leaves 5kW or 22A for all other appliances. Once the heating has fired up then one would expect it to start to cycle on and off to maintain heat and once this cyclic switching has started then no problem. But it you switch off the heating when for example at work then switch back on when for example arriving home then all units could demand together and mean using a cooker could blow the main fuse.
The whole idea of the Economy 7 is the heating did not get any power until 11 pm by which time there was very little other demand on the system. What has happened is a move to use water rather than bricks to store the heat. The problem with bricks is the temperatures used means it's very hard to stop the heat leaking out during the day. Problem with water is a larger size is required as the temperature is lower. However it does not in theory need to be inside the house.
One of the main reasons for the move to water is solar panels, wind turbines and solid fuel fires can all add energy to the system. It uses standard water radiators and once the circulation pump is off the heat loss is minimal.
My brother-in-law has the system in his house with two huge cylinders which store the hot water. When he goes abroad for a week the old power used if by the anti-freezing system so on return home he has 2 days before he needs to either light wood burner or run the LPG boiler.
But the installation price would be huge in his case fitted when house was built but I looked into using wood burners efficiently and because of particular emissions a wood burner until all wood has become charcoal has to be run at a set rate and in the main you don't want that much heat released into the house so only method is to store the heat for latter use.
So although a wood burner can be bought for £150 to make it run environmentally friendly and economically costs more like £15,000 and at the price of wood it's unlikely to pay for it's self within ones life time.
There is also a Economy 10 tariff which has a afternoon boost.
So yes you can have the two systems combined to one but likely it will not be as simple as just putting both sets of tails into a henley block. Likely electricians will want the installation to comply with current regulations so will want RCD protection so could very well mean new consumer units if not already RCD protected.
I have seen claims that getting rid of Economy 7 can save money but it's all down to when heat is required. My friend lives in a timber frame house and like a caravan it does not hold heat in the walls so once fire goes out then it gets cold quickly. So when going out to work and heat is off during the day the water pipes can freeze where as in my brick house having heat off all day the house will never cool down enough to cause pipes to freeze.
If you can switch off all heating during the day then yes moving from Economy 7 can save money but if you need heat during the day then unlikely to save money.
There are some wild claims but remember unless you use heat pumps it does not matter what electric heater you use it will use same amount of power. There is of course the radiant heater which glows red and heats any objects within it's line of sight rather than the air directly used a lot in garages where the air is changed every time the door is opened but near impossible to control any thermostat measures air temperature not heat felt on the human body so you can't switch radiant heaters off and on like a radiator once off it becomes cold straight away.
There is the combination of the two types of heating of course. Using tungsten bulbs means radiant heat from the bulb supplements the convected heat from radiators. When I swapped from tungsten to LED I also had to raise the central heating temperature 2 degrees. The LED only saves energy if the heat is not required. In most houses they do save money because gas is cheaper than electric but they don't save energy as we used the heat from the light bulb it was not waisted.
