Storage heater dual supply for a panel heater?

[Bwip]

Ah yes, "If you can find out how the metered price changes, it will make your question, and the answer, clearer.

I’ve kept an eye on what the meter is up to at the point the tarrifs change for the 24hr circuit - it seems to be clean switches of the whole load between ‘normal’ and ‘low’ (that’s how the meter is labelled).

So it’s one or t’other (unlike Total Heating Total Control which has the additional circuit/tarrif for 24hr heating)

 

[Bwip]

Now I'm confused on how your system works as the Teleswitch seems to switch the power to the NSH CU on the flexible rate and also control the E7 which seems to feed the 24Hr CU. I don't know enough about Teleswitches to know if they are capable of doing those two services at different times.

I was confused too as there didn’t seem to be enough tails for the teleswitch to be controlling both meters. But I just noticed an additional smaller cable connecting the teleswitch and 24hr meter (picture attached). It’s too small to carry much load so I assume it’s used for triggering the 24hr meter to switch between ‘normal’ and ‘low’

 

[JohnD]

I’ve kept an eye on what the meter is up to at the point the tarrifs change for the 24hr circuit - it seems to be clean switches of the whole load between ‘normal’ and ‘low’ (that’s how the meter is labelled).

So it’s one or t’other (unlike Total Heating Total Control which has the additional circuit/tarrif for 24hr heating)

If I understand correctly, that means there is no need for a changeover switch.

 

[Bwip]

My apologies. When I said “one or t’other” I only meant the two rates on the 24hr meter. The storage heater circuit is independent of those. Both meters appear to be controlled by the same teleswitch but their schedules are independent. I probably confused matters by dropping Total Heating Total Control into the conversation earlier.

If you have a look at my previous post with the tarrifs/ times you’ll see that there are many times of the day that the storage heater circuit is available during 24hr peak rate. Even during off-peak, the storage heater tarrif is a bit cheaper.

It might be penny pinching but it’s irksome to think that if I wire the panel heater only to the 24hr supply then several times a day there will be electricity available behind a blank plate a few centimetres away that costs about half the price!

 

[JohnD]

I can see how to draw the logic for the contactor. If supply circuit "B" is energised, changover from supply "A" to supply "B." Else use supply "A"
Break before make.

there will be a bit of a voltage surge, though, as it snaps across.

 

[SUNRAY]

If I understand correctly, that means there is no need for a changeover switch.

That was my first thought but to maintain heating throughout the day at the cheapest available, I think will need to be switched between 18p and variable during the hours it's live.

For example to run the heater from 16:00 to 01:00
16:00 to 16:30 24Hr Peak rate
16:30 to 17:30 Heating
17:30 to 22:00 24Hr Peak rate
22:00 to 24:00 Heating
24:00 to 01:00 24Hr cheap rate

Sounds like a classic aplication for one of those auto generator changeover units that Big Clive pulled apart.

 

[JohnD]

If I have grasped the logic correctly, the contactor needs no knowledge of time.

 

[EFLImpudence]

Have we deduced (or not) that the whole supply changes to cheap rate during the cheap times?

 

[SUNRAY]

I can see how to draw the logic for the contactor. If supply circuit "B" is energised, changover from supply "A" to supply "B." Else use supply "A"
Break before make.

there will be a bit of a voltage surge, though, as it snaps across.

Oops crossed in the post again.

There is going to be negligable voltage surge, if any, if the two services were linked together momentarily. The only real issue would be a shock hazard if the 24Hr CU were isolated and being worked on.
There will likely be a momentary cut in voltage but for a panel heater it wont matter at all.

Simply controlled by the heating supply it is a simple thing to do for me but I'll not offer advice to someone on this matter if they have to ask as there is room for error within dual supply systems. I've been caught out a couple of times with unknown systems.

 

[SUNRAY]

Have we deduced (or not) that the whole supply changes to cheap rate during the cheap times?

Which supply are you referring to?

 

[SUNRAY]

If I have grasped the logic correctly, the contactor needs no knowledge of time.

Correct, simply controlled by the 'heating' power.

 

[EFLImpudence]

Which supply are you referring to?

All of it - the whole installation.

Does everything go to cheap rate during the relevant times?

 

[SUNRAY]

All of it - the whole installation.

Does everything go to cheap rate during the relevant times?

There are 2 meters and a Teleswitch, this is the info supplied by OP

Below are the supply times, and the tariff details are in the attached image.

Off-peak

• 23:30 - 07:30

Storage heaters

• 01.30 to 03.30
• 08:00 to 11:00
• 16:30 to 17:30
• 22:00 to 24:00

 

[Bwip]

If I have grasped the logic correctly, the contactor needs no knowledge of time.

That seems to be the case, and the storage heater circuit is sometimes activated at different times of day depending on local weather conditions.

Have we deduced (or not) that the whole supply changes to cheap rate during the cheap times?

Currently there are three different rates:

• 24hr
  • Day: 18.89p
  • Night: 11.25p
• Storage
  • 11.43p

To add to the logic fun, I've just noticed EDF have this month increased the storage heater rate so it is actually slightly more expensive than the 'night' rate!

 

[EFLImpudence]

To add to the logic fun, I've just noticed EDF have this month increased the storage heater rate so it is actually slightly more expensive than the 'night' rate!

Yes but it allows their use for a few hours in the day.

However, that means what I had in mind wouldn't work.