Economy 7 Rewire

[cr0ft]

Hi all,

Doing my first one of these today. In the meter box there is the standard supply head (PME) and the line and neutral meter tails go into some hendy boxes.  One line meter tail then goes into the E7 radio teleswitch box and out to the old E7 consumer unit controlling the storage heaters and immersion.  The other line meter tail goes to the permanently live consumer unit and runs the remainder of the house.

My question is hopefully simple, is there a device I can fit after the E7 switch unit that will accept both line meter tails and automatically supply just one consumer unit with E7 if available or permanent supply if not.  This way the homeowner can of course run everything on E7 overnight and do away with needing 2 consumer units.

I'm sure there must be a product that does this out there, but my inexperience here is showing!

 

[Evans Electric]

if its a Radio time switch it more than likely does what you want anyway.      Whole house over to E7  and the timer puts a fed onto the heating board for 7 hours.   The E7  mileometer will kick in and the dayrate wil stop.

A pic would have been good for this one .

 

[Steve3948]

+1 What Dave has said.

 

[ProDave]

Do you not realise, that with E7, the WHOLE HOUSE gets the cheap rate at night.

So all loads connected to the "normal" CU will get the cheap rate if used at night.

What exactly are you trying to achieve? If you only have one CU, how will you ensure the storage heaters only turn on at night?

 

[SLIPSHOD & SLAPDASH]

Do you not realise, that with E7, the WHOLE HOUSE gets the cheap rate at night.

So all loads connected to the "normal" CU will get the cheap rate if used at night.

What exactly are you trying to achieve? If you only have one CU, how will you ensure the storage heaters only turn on at night?

Not necessarily Dave. Rules have changed but  a few years back if you had a 'white meter'  on E7 it was only for fixed heating. No sockets etc allowed. Rules do change though and i have not seen a duel rate white meter for years now. 

 

[ProDave]

The "white meter" was never economy 7, that was the old "off peak" tariff and yes with that only the heaters got the cheap rate.

Economy 7 replaced the old white meter at least 20 years ago. I would be surprised if there are still many white meter installs still in use, especially if it's got a modern radio teleswitch.

My last house, when I bought it in 1989 had a white meter but I had it changed for economy 7, mainly as an easy and free way of getting the meter moved.

The big give away, is the old white meter system had two physically seperate meters. E7 has one dual rate meter.

 

[cr0ft]

Hi and thanks for your advice on this everyone.  It kind of clicked after I made the post and did a bit of reading elsewhere that the radio teleswitch tells the meter to log off-peak KWh used through both line meter tails.  It's just that the old setup ran one board off the off-peak only meter tail from the radio teleswitch.  This powered the storage heaters and immersion.

On the rewire I am just running the whole lot off a 12-way consumer unit for everything.

This setup is not the old white meter system so I'm pretty happy that the way I'm re-wiring it is ok.

@Dave, I will be using timers on the immersion heater and the 3x storage heaters.  The 3x storage heaters are run on separate radial circuits from the board.  Just seems a simpler (and cheaper in terms of materials) setup to me, and saves the owner having 2 consumer units in their living room.

 

[ProDave]

So it's cheaper to have your own timers (and contactors?) to switch the off peak loads on, than it is to have a separate 4 way off peak CU and use the DNO supplied switched output?

If your timers are not precicely timed with the DNO's radio teleswitch, some of your "off peak" usage might be metered at peak rate. Pertinent as they don't publish the exact times the radio switches operate.

Why not look for one dual CU in one package to make a neat install and do it the conventional way?

 

[SLIPSHOD & SLAPDASH]

So it's cheaper to have your own timers (and contactors?) to switch the off peak loads on, than it is to have a separate 4 way off peak CU and use the DNO supplied switched output?

If your timers are not precicely timed with the DNO's radio teleswitch, some of your "off peak" usage might be metered at peak rate. Pertinent as they don't publish the exact times the radio switches operate.

Why not look for one dual CU in one package to make a neat install and do it the conventional way?

Good points. Much better to use the teleswitch output as you cant get the timing wrong

 

[steptoe]

and dont need to change it twice a year.

 

[kme]

Id split the supply within 1 enclosure, and use their timed output, as the guys have said. cheaper & easier than messing with timers, IMO

 

[Steve3948]

Easy to forget after a power cut, and over time the S/H's may well be on during peak times.

As said above use the right board for the job.

 

[ProDave]

and dont need to change it twice a year.

Even if you fit your own timer, you don't need to change it as the off peak times always stay on GMT.

 

[ProDave]

and dont need to change it twice a year.

You don't need to change them, the "on" times remain on GMT all year.

Some commercial installs have local timers and contactors for the storage heaters, to save running extra long submains to off peak CU's

 

[cr0ft]

Cheers to all for advice etc.  The idea of separate timers for the immersion heater and storage heaters just seemed to be very logical to me.  The timers are £10 for 3 so by the time you buy meter tails etc for another board it's a simpler install imo.  The customer didn't want 2 boards in the lounge which was the reason for starting this thread.

 

[revjames]

did loads of these in the 90's. Teleswitch changed tarrif on 2 rate meter and also brought in a contactor for heaters inside the MG consumer unit. Water heater had an independent timer that brought main element in at midnight.

 

[cr0ft]

 I like your hourly rates.  Very similar to mine!

 

[kme]

Timers £10 for 3?

Fixed, or "plug-in"?

If plug-in, they`re not suitable.

If fixed, its a good price, or cheap chinese nonsense.

And, either way, you`re still back to contactor control.

THEY won`t be £10 for 3....... or even £10 each.

You can get one board to do it all - one board to bind them, Frodo: you must go to Mordor. Gandalf is wa......................

Oops sorry. Got sidetracked there.......... :slap

As with many things. The kit you want does exist - you just need to find it

 

[SLIPSHOD & SLAPDASH]

The large storage heaters are rated at more than 13A, so you cant use standard timers.

 

[binky]

Why not look for one dual CU in one package to make a neat install and do it the conventional way?

use high integrity CU and extra main switch