Should I switch to Economy 7?

danrv

Hi
After extensive research into updating my E10 electric warm air system, it looks like Dimplex Quantum NSH’s on Economy 7 would be the cheapest to run for electric heating. Possibly similar to the warm air system. 
Property is 3 bed semi detached so would use electric radiators for bedrooms.
Just wondering as the heaters are expensive, how future proof storage heating is and the Economy 7 tariff. 
Without it, the heaters would be expensive to run.
Just thought I’d get some some idea before buying them.
Any help appreciated.

Neil_Jones

Eco 7 is only cost effective if you can shift the bulk of your usage to the off-peak hours, typically anywhere between 11:30pm-8am.

All electric-only properties are expensive to run regardless of what tariff you're on, unfortunately.

Gerry1

Neil_Jones said:

Eco 7 is only cost effective if you can shift the bulk of your usage to the off-peak hours, typically anywhere between 11:30pm-8am.

Not necessarily, E7 can be slightly cheaper with night usage as low as about 20% with some suppliers.  I don't have NSHs but I switch between E7 and standard rate depending on who is cheaper at the time.

Gerry1

It's probably as good as it gets for a retro fit unless you install oil (which may not stay cheap for ever).  Heat pumps seem to be expensive to install, noisy and slow to respond so that's quite an upheaval.  Dimplex Quantum seem good compared to the old box or bricks because less heat is wasted overnight (and during the day if you're always out).

Use of EVs probably means that there will always be night tariffs that are cheaper.

danrv

Gerry1 said:

Use of EVs probably means that there will always be night tariffs that are cheaper.

Yes, was thinking about EVs and charging. I guess there’ll still be cheap rate power available even with the shift towards wind turbine and greener power plants.

macman

They are not going to abolish E7, if that's what you mean. If anything, it will become more popular with growing electric car sales: people will want to charge them overnight on cheap rate.
It would be daft to fit convectors in the bedrooms, as these will then be running on peak rate E7. Use NSH's throughout.

danrv

macman said:

It would be daft to fit convectors in the bedrooms, as these will then be running on peak rate E7. Use NSH's throughout.

Yes, have thought about that.
A complete Quantum system throughout (six heaters) would replicate the warm air storage heater efficiency. Not sure if multiple storage heater installations are or were common in 3 bed, 2 storey properties.
Most I’ve heard of is 4.
My house is most certainly suited to central heating but there’s no mains gas.

macman

The usual practice is to have one NSH per room, of the appropriate size. A large living room might need 2. 
If not all 3 bedrooms are occupied permanently, then you could use convectors as long as usage is not regular.
You are also presumably putting in an immersion heater if not already installed.
It is still possible to buy the old-style NSH's which only require one connection to the E7 side of the metering. While banned for new sale, there are available as refurbs, supposedly for replacing existing older units. Obviously these lack a boost feature.

danrv

macman said:

The usual practice is to have one NSH per room, of the appropriate size. A large living room might need 2. 
If not all 3 bedrooms are occupied permanently, then you could use convectors as long as usage is not regular.
You are also presumably putting in an immersion heater if not already installed.
It is still possible to buy the old-style NSH's which only require one connection to the E7 side of the metering. While banned for new sale, there are available as refurbs, supposedly for replacing existing older units. Obviously these lack a boost feature.

Thanks. Yes, I have an immersion tank for hot water. 
With six seperate heaters, it would be good to have some sort of zone control. If all Quantum or Quantum + QRads, the Dimplex hub would allow this.
Refurbished NSH’s will probably have to be controlled individually.

Will need to think about power supply too as there’s no E7 in any of the rooms. There’s just 32A ring mains plus a seperate supply for the warm air heater, all on E10.
Ideally the heater supply would be used for all the new storage heaters.

macman

You need to run a radial circuit to each room/NSH.

danrv

macman said:

You need to run a radial circuit to each room/NSH.

Ok thanks. There’s eight spaces on the consumer unit, four labelled ‘spare’.
Don’t have a 24/7 supply though for the boost function. 
Two supplies are required normally for modern NSH’s.

As I see it, the large mechanical timer switches over the digital dual rate meter,
warm air heater and all sockets. 
The heater is not marked on the CU, instead has a seperate isolation switch possibly wired direct to the timer. There’s also another one near the unit which isn’t really necessary.
An electrician has had a look as I inadvertently turned it off once.
Will get advice if going ahead but like to get an idea anyway.