Smart switch for old storage heaters?

[foxhole]

The basic E7 manual control, is to simply to turn them to off, either on the heater itself, or at the isolator next to it. What the OP wants, is to be able to remotely decide whether they need to be on, or not.

But that means predicting accurately the next day temperature, a big ask.

 

[Harry Bloomfield]

But that means predicting accurately the next day temperature, a big ask.

No need to predict it, use the weather forecast. It could even be automated, by a system reading the forecast, then switching the storage heater charge up time, to suit the forecast.

 

[foxhole]

No need to predict it, use the weather forecast. It could even be automated, by a system reading the forecast, then switching the storage heater charge up time, to suit the forecast.

Isn't the weather forecast a prediction?

 

[Harry Bloomfield]

Isn't the weather forecast a prediction?

Of course, there are no guarantees - but generally the forecasts are reasonably accurate, especially as close as the next day. Do you have some a better idea?

 

[Norfolk Broad]

What the OP wants, is to be able to remotely decide whether they need to be on, or not.

That's right, Harry

I returned to the flat yesterday afternoon after an absence of several days. I wish I was able to have switched the heating on the night before!

Anyway, below is a photo of my meter cabinet. Hopefully it makes sense.

View media item 107229
Many thanks
NB

 

[Harry Bloomfield]

I returned to the flat yesterday afternoon after an absence of several days. I wish I was able to have switched the heating on the night before!

Anyway, below is a photo of my meter cabinet. Hopefully it makes sense.

from that, I would guess that the meter in the photo is doing the switching of the off-peak dis-board, so the easiest way would be to add a contactor interrupting the feeds to each storage heater, with the contactor coil fed from a smart switch or plug. If there are no more than three storage heater, then just one three phase contactor, with a 240v coil would be the easy way to set it up.

 

[Norfolk Broad]

Thanks for that, Harry.


Yes, I believe the meter is doing the switching, and there are only two storage heaters at the flat.

However I would like to control them independently, if possible.
The lounge is south facing, and gets a good deal of warmth on a sunny winter's day (like today), so it might be useful to switch this heater off, or at least limit its operating period.

I guess a couple of these contactors,
https://www.screwfix.com/p/british-...ctor-no/6654P?tc=GB5&ds_kid=92700055281954493
plus a couple of the Shelly 1 driving contactors that Special K recommended should do the trick?


Or... (sorry to be a pain)
...could I use a single 2-channel Shelly 2.5 to operate the two separate contactors?
https://shellystore.co.uk/product/shelly-25/


Thanks again
NB

 

[Harry Bloomfield]

Or... (sorry to be a pain)
...could I use a single 2-channel Shelly 2.5 to operate the two separate contactors?
https://shellystore.co.uk/product/shelly-25/

The spec. suggests it should work, but not having any practical experience of the units....

You will need some means to mount those din contactors and the above, unless there is space in the existing board. Keep in mind that wifi will not work into a metal box.

 

[Norfolk Broad]

Thanks Harry

Here's the plan (picture = thousand words, earth omitted for clarity, etc, etc).

Question - on the proposed plan, does the contactor come before the MCB, or the MCB before the contactor?

Thanks in advance

NB

View media item 107234
View media item 107233

 

[Harry Bloomfield]

Contactor comes after MCB's, exactly as you have drawn your second diagram.

 

[MeldrewsMate]

SonOff supply a wi-fi controlled switch which can be set to switch on a time based schedule or on a temperature based schedule, or both. It is called the TH10. It will not, however, be capable of switching the multiple loads that you have with storage heaters.
Let me suggest a solution....assuming you have wi-fi in the premises.

Buy one of the 25A wi-fi controlled contactors for each storage heater.
Buy one TH10 for each area that you want temperature measurement, perhaps only one for the whole premises, but they are only about £15 each. The TH10s will be powered continuously, the contactors only from the economy seven supply. The TH10 uses a plug-in thermistor which can have it's lead extended within reason, so you can effectively hide the TH10 away.
The items will all connect to the EweLink application via wi-fi. You can then use what they call 'scenes' to combine one or more attributes such as time and temperature to automatically switch on one or more of the contactors, knowing that they will all turn off at the end of the cheaper electricity period.
The ability to monitor the room temperature(s) remotely will be available around the clock.
The use of additional apps such as IFTTT will enable you to 'predict' a cold snap by virtue of the online weather forecasts.

MM

 

[Norfolk Broad]

Contactor comes after MCB's, exactly as you have drawn your second diagram.

Thanks Harry. I figured that was the case, but you mentioned using a 3-phase contactor to control all of the heaters, so I wasn't sure if the circuit protection would be affected by having all radials on or off.

Apologies also to you and MeldrewsMate for taking so long to get back to you. Shortly after my last message I ordered a pair of 20A contactors from Screwfix, as well as a 6A MCB for the control circuit.
I also found this two-gang switch on Amazon for a reasonable price:
https://www.amazon.co.uk/gp/product/B07PGYKF4M/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

I already had some spare cable and a pattress box so, for under £40, I have everything I need to control the storage heaters remotely. Of course, I won't be able to set the input/output dials on the heaters, but at least I can get them up and running the night before I stay at the flat, or switch them off when this weather improves!).

I've prepared a breadboard prototype of the circuits and connected the switch to the Wifi (once I figured it out, it connected first time, and the app works well, even via Google Home).
The contactors make a reassuring thud when activated, and a bit of a buzz, but this shouldn't be a problem once fitted in the CU and the cupboard door closed.

The biggest challenge now will be the feeds between the two CUs, and back to the neutral busbar in the main CU. The knockouts in the bottom of each CU are virtually inaccessible, and space is tight.
Details.... details...


Thanks again for all your help.
NB

 

[Harry Bloomfield]

Thanks for your update, all sounds fine. Good this wifi control, innit? I keeping thinking of new uses for it.