Economy 7

[hard-work]

A meter in the basement of a block of flats. The CU is in the flats fed by 25mm cables. Unable to run any cables from flats to basement. What is the usual arrangement to have economy 7 in this situation?

thx

 

[SUNRAY]

A meter in the basement of a block of flats. The CU is in the flats fed by 25mm cables. Unable to run any cables from flats to basement. What is the usual arrangement to have economy 7 in this situation?

thx

Use time switches

 

[ericmark]

Economy 7 is a tariff not a system, there are many systems which use Economy 7 from the old white meter to simply having timers on all items used. In some cases there is a signal sent to tell an appliance when it can switch on, but also you can simply set a delay timer on for example your washing machine.

 

[hard-work]

I recall Economy 7 storage heaters which had a separate CU and (white coloured) meter, and only the heaters were on the cheaper overnight electricity.

 

[ericmark]

Yes that was the original system, however people wanted to also run washing machines, dishwashers, and tumble driers on the cheap rate, but when required still able to use them during the day.

I know at one point there was an extra wire to storage heaters that told them when to come on, however the storage heater idea does not really work, there are systems that do, brother-in-laws house had two huge very well insulated water tanks, these had a huge advantage over the simple storage heater, one they would not release heat when not required, and two you could use multi fuels, his used solar panels, wood burner, LPG gas, and electric. These units can say hot for weeks, with central heating turned down he could go on holiday for two weeks in winter and the heating would maintain house above freezing not costing a penny and as it sensed his phone was within 80 miles range would auto turn up the heating for his return.

Two major draw backs, one installation cost, and two you need the room for the storage tanks.

So many have realised the Economy 7 does not work for them. With some one in the home all day it may still work out well, but where people go to work in the day then you are heating the home when not required. Much depends on how well insulated the home is, this house when outside is below zero turn off heating at 9 pm and by 6 am it has only dropped 4 degrees. Both good insulation and heat held in fabric of building means having central heating change temperature through the day saves very little. Although I still do it.

So although the storage radiators do have some controls, they tend to heat home too much in the day and not enough in the evening, and you can't just keep the warm in case it's a cold day. The economy of an electric heater with exception of heat pumps and inferred is measured buy the amount of time it needs to be on, compared with time room is used. So same heater in a room used 24/7 and a room used for 2 hours a day could well be 100% and 60% efficient, the latter if it needs to be on one hour before room is used.

However an oil filled radiator maintains the temperature with very little hysteresis where a fan heater will likely have a high hysteresis and noisy. So not just maths.

But with electric heaters used as an when required, with thermostatic control so never goes over temperature then in many homes a single tariff works out cheaper. Although I don't use them for heating, I have sockets and plug in controllers which can be set to use geofencing, that means when I am within a set distance from house they switch on. You can't do this with storage radiators.

There is Economy 10 where you get a boost during the day, but unless retired or young mother with baby in the main Economy 7/10 does not save enough to be worth it. Even with a semi-detached house the heat from next door can make a huge difference. We were told turn heating down 2 degrees saves you a fortune and it did, until next door moved out, she had heating set to 22 we had ours set to 18 and there is no cavity between houses so her heating kept our house warm.

So a whole block of flats with Economy 7 it may seem to work, but one flat and during the day your heating neighbours flat and at night your cold. OK if you have the room for the water tanks then that may work, but spending out converting to Economy 7 now I would say in the main is a bad move.

 

[SUNRAY]

I recall Economy 7 storage heaters which had a separate CU and (white coloured) meter, and only they were on the cheaper overnight electricity.

I haven't seen that system for a long time but I dare say there are still some around.
Any new installation will be a meter with 2 sets of readings and automatically change over at relevant times. the L&N tails from the meter will be the sole supply and there will be a contact on the meter which can be used to operate eternal switch gear such as a big contactor and it is this contactor which will 'replace' the white meter.

If you are installing night storage heaters, they can be purchased with integral time switches. Many appliances (washing machines etc) can be programmed to run at a particular time. All of which make it unnecessary to have a separate CU for the cheap time.

 

[hard-work]

I haven't seen that system for a long time but I dare say there are still some around.
Any new installation will be a meter with 2 sets of readings and automatically change over at relevant times. the L&N tails from the meter will be the sole supply and there will be a contact on the meter which can be used to operate eternal switch gear such as a big contactor and it is this contactor which will 'replace' the white meter.

If you are installing night storage heaters, they can be purchased with integral time switches. Many appliances (washing machines etc) can be programmed to run at a particular time. All of which make it unnecessary to have a separate CU for the cheap time.

So it is only on time. So during the night all electricity used is on a cheaper rate?
I am confused about the contactor.

 

[SUNRAY]

Yes that was the original system, however people wanted to also run washing machines, dishwashers, and tumble driers on the cheap rate, but when required still able to use them during the day.

I know at one point there was an extra wire to storage heaters that told them when to come on, however the storage heater idea does not really work, there are systems that do, brother-in-laws house had two huge very well insulated water tanks, these had a huge advantage over the simple storage heater, one they would not release heat when not required, and two you could use multi fuels, his used solar panels, wood burner, LPG gas, and electric. These units can say hot for weeks, with central heating turned down he could go on holiday for two weeks in winter and the heating would maintain house above freezing not costing a penny and as it sensed his phone was within 80 miles range would auto turn up the heating for his return.

Two major draw backs, one installation cost, and two you need the room for the storage tanks.

So many have realised the Economy 7 does not work for them. With some one in the home all day it may still work out well, but where people go to work in the day then you are heating the home when not required. Much depends on how well insulated the home is, this house when outside is below zero turn off heating at 9 pm and by 6 am it has only dropped 4 degrees. Both good insulation and heat held in fabric of building means having central heating change temperature through the day saves very little. Although I still do it.

So although the storage radiators do have some controls, they tend to heat home too much in the day and not enough in the evening, and you can't just keep the warm in case it's a cold day. The economy of an electric heater with exception of heat pumps and inferred is measured buy the amount of time it needs to be on, compared with time room is used. So same heater in a room used 24/7 and a room used for 2 hours a day could well be 100% and 60% efficient, the latter if it needs to be on one hour before room is used.

However an oil filled radiator maintains the temperature with very little hysteresis where a fan heater will likely have a high hysteresis and noisy. So not just maths.

But with electric heaters used as an when required, with thermostatic control so never goes over temperature then in many homes a single tariff works out cheaper. Although I don't use them for heating, I have sockets and plug in controllers which can be set to use geofencing, that means when I am within a set distance from house they switch on. You can't do this with storage radiators.

There is Economy 10 where you get a boost during the day, but unless retired or young mother with baby in the main Economy 7/10 does not save enough to be worth it. Even with a semi-detached house the heat from next door can make a huge difference. We were told turn heating down 2 degrees saves you a fortune and it did, until next door moved out, she had heating set to 22 we had ours set to 18 and there is no cavity between houses so her heating kept our house warm.

So a whole block of flats with Economy 7 it may seem to work, but one flat and during the day your heating neighbours flat and at night your cold. OK if you have the room for the water tanks then that may work, but spending out converting to Economy 7 now I would say in the main is a bad move.

I've never lived in a property with E7 so don't have the operating costs experience. I'll certainly agree with the benefit of neighbours heat as I own some rental flats, one of which was empty for December and January with no heating running and it stayed between 12&17'C. The previous tenant recons he only used the lounge heater in boost mode as the room was baking before he went to work at 2pm and there was never enough heat left by 10pm when he got home. I was debating removing the 28 year old storage heaters as they were quite tatty but the decorator did a pretty good job of respraying them (removed covers and did the job off site).

 

[jg321]

Yeah mine was based on time, all electric cheap once the meter switched over. In the three installations I've experienced, the contactor was used to signal to the storage heaters to come on - but they shared the same (typically split con) cable as the normal supply (it was usually a smallish T+E, often fused, run alongside the main feed for the contactor).

Timers can work but you run the risk of summer time changes/things going bad and the heaters coming on in peak hours. If you can't run cables for a contactor though you have no choice than to find an alternative.

 

[hard-work]

So if the meter is in the basement and there is a long run to the CU in the flat, and no way to put new cable between, then you are stuffed?

 

[jg321]

Just use timers once you've found out what the times are?

 

[ericmark]

Ask supplier (DNO) as they use to use radio 4 time signal so maybe the timer can be in flat. As said the problem is if in error a heater switches on in the day.

 

[SUNRAY]

So it is only on time. So during the night all electricity used is on a cheaper rate?
I am confused about the contactor.

These days all 'off peak' is at the cheaper price and a contactor is, or can be, used to create the power which would have been provided by the white meter.
The only image I have available on this PC is not ideal but it may help, I have done a sketch which shows a comparison of this system and the white meter system with corresponding wire designations for explanation.

The control wire is the picture below is blue, the contactor is the clear lid with white labels.
As has already been said, the contactor is not essential to the operation of E7 tariff.

 

[JohnW2]

I've never lived in a property with E7 so don't have the operating costs experience.

AS I've commented recently ...

I've has E7 for the past 30+ years. At least with my supplier (E.ON), the benefit of having E7 reduced considerably a few months ago (having been fairly constant for most of the preceding 30 years). Traditionally, the 'break-even' point with E7 was reached when one used at least ~33% of one's electricity at cheap rate. Tariff changes in April have moved that up to about 40%, which many might struggle to achieve. Since I generally manage to run between 45% and 50% (see **), it is still worthwhile for me to have E7, but it looks as if the yearly saving resulting from my having it may well have reduced from ~£250 per year to not much over £100 per year.

As I've observed, it seems very odd that a supplier should reduce the incentive to (have E7 and) use more electricity at low-demand times at a time when adequacy of peak supply availability is becoming an increasing concerned - but that's what has happened.

[ ** I would show you some graphs and give actual figures, but the situation during the past few months has become totally confused by the weather. Since the lion's share of my cheap-rate usage is to heat stored hot water, a combination of the very extensive insulation of the tank and the very high ambient temperatures has reduced heat losses from the hot water during the daytime, so my night-time usage during recent times has fallen to an all-time low - something which I can illustrate with graphs (the immersion is usually the only appreciable load on Phase 2 - and the 'sublime and ridiculous' of the temperatures we have encountered this year allow me to illustrate 'the extremes')...

It remains to be seen, once ambient temps have become a bit more 'normal', what my ongoing saving due to having E7 will actually be.

Kind Regards, John

 

[SUNRAY]

AS I've commented recently ...

I've has E7 for the past 30+ years. At least with my supplier (E.ON), the benefit of having E7 reduced considerably a few months ago (having been fairly constant for most of the preceding 30 years). Traditionally, the 'break-even' point with E7 was reached when one used at least ~33% of one's electricity at cheap rate. Tariff changes in April have moved that up to about 40%, which many might struggle to achieve. Since I generally manage to run between 45% and 50% (see **), it is still worthwhile for me to have E7, but it looks as if the yearly saving resulting from my having it may well have reduced from ~£250 per year to not much over £100 per year.



Kind Regards, John

Interesting stuff, it would be useful to see the comparison in a cold winter.
I've never really given any thought to it as I've never been in the situation. I know I installed loads of storage heater circuits in the 70's in new build all electric properties as it was supposed to be the bees knees, as was gas fired warm air heating - warm air into a room at floor level and extracted at ceiling level

My elderly FIL currently has storage heating in sheltered accommodation and he seems to get on OK with it. They are supposed to be installing GF radiators, from a central boiler, for the last 4 years but the logistics of that many dwellings in one go is causing too many problems. They have already done most of the external properties (bungalows separate from the main building) and the residents love the change.