NSH on Octopus Agile

ch_152

Did have a quick look, couldn't find this addressed specifically.

I have a very old NSH wired up to a consumer unit which only runs when off-peak (the norm, I gather). I am thinking of upgrading to a Quantum or similar before this winter.

I had a smart meter installed a few weeks back and after the install I was on E7 (as pre-install). Did a check on whether the NSH had been wired up correctly to only come on at night, and it had.

I recently switched tariff to Octopus Agile, and now my meter obviously doesn't show separate day/night use. I have just checked, during the day, and the NSH doesn't turn on when switched on at the wall. 

However, I wonder if it now also won't turn on at all at night? Obviously I can and will check this manually tonight or tomorrow morning.


The question(s):

1) If I retain the old NSH, will I need to be on an E7 tariff for my off-peak consumer unit to be switched on and it charge up? (I can test this at home tonight).

2) If I get a new NSH (Quantum), I understand I can run a single "peak" supply, but I just need to make sure it's programmed not to be on during the day?

3) (Electrical question) Can the old "off-peak" consumer unit somehow be changed to operate at any time? Otherwise I will need expensive wiring changes to run a daytime supply to the new NSH.

Swipe

If you intend to use the storage heaters over winter, I'd get back on an E7 tariff ASAP.

[Deleted User]

Personally, I would not make significant (and costly) wiring changes to make use of a tariff that Octopus could withdraw/change at anytime.

ch_152

Swipe said:

If you intend to use the storage heaters over winter, I'd get back on an E7 tariff ASAP.

I do, but why do you say this? Due to the E7 tariff likely being cheaper overall (surely depends on the rest of my usage habits during the day, but I a you are probably right)?

Dolor said:

Personally, I would not make significant (and costly) wiring changes to make use of a tariff that Octopus could withdraw/change at anytime.

Yep that’s sensible and I agree. However I understand the likelihood is that I’m going to need to make those same wiring changes anyway if I get a new NSH that has a daytime function (or just requires being powered during the day).

I suppose the actual questions (updated in OP) are, therefore:

- If I retain the old NSH, will I need to be on an E7 tariff for my off-peak consumer unit to be switched on and it charge up? (I can test this at home tonight).

- If I get a new NSH (Quantum), I understand I can run a single "peak" supply, but I just need to make sure it's programmed not to be on during the day?

- (Electrical question) Can the old "off-peak" consumer unit somehow be changed to operate at any time? Otherwise I will need expensive wiring changes to run a daytime supply to the new NSH.

QrizB

You seem to know how E7 works (one meter feeding a permanently-live CU and a cheap-rate-only CU, with the cheap-rate supply switched by an aux load control switch (ALCS) which is in turn controlled by a timing signal in the meter) so I;m not going into those details.

ch_152 said:

I suppose the actual questions (updated in OP) are, therefore:

- If I retain the old NSH, will I need to be on an E7 tariff for my off-peak consumer unit to be switched on and it charge up? (I can test this at home tonight).

The old NSH has a single supply. Thay supply is currently wired into the cheap-rate-only CU, and will only be live when the meter switches the supply to live.

By default, no ALCS signal is provided by a smart meter configured for Agile. So I would be surprised if your cheap-rate CU becomes live or your NSH heats up.

You might be able to ask Octopus to enable the ALCS switch on your smart meter. I have no idea if they would be willing to do this, but I imagine the back-office smart meter team have the ability.

ch_152 said:

- If I get a new NSH (Quantum), I understand I can run a single "peak" supply, but I just need to make sure it's programmed not to be on during the day?

Yes, Quantum NSHs can run from a single supply. Other makes/models might also have this function.

A;lternatively, you could run your current NSH from a single supply if you add a suitable timeswitch. Depending on the power requirements of the NSH, an immersion heater timeswitch might be appropriate.

ch_152 said:

- (Electrical question) Can the old "off-peak" consumer unit somehow be changed to operate at any time? Otherwise I will need expensive wiring changes to run a daytime supply to the new NSH.

If you want to move away from E7 and ALCS switching, you'll need a competent electrician to arrange a permanenttly-live feed to the cheap-rate CU (or, alternatively, move the cheap-rate circuits to spare ways in your main CU). This is unlikely to take more than an hour or two or need any expensive materials, assuming the two CUs are close to one another and your wiring is otherwise in good shape.

Qyburn

ch_152 said:

3) (Electrical question) Can the old "off-peak" consumer unit somehow be changed to operate at any time? Otherwise I will need expensive wiring changes to run a daytime supply to the new NSH.

It might be fairly straight forward depending on your installation, for example if you have an isolator so this work can be done without touching the meter. At its simplest the electrician would remove the current feed into the off peak CU and join this to the feed to the daytime CU.

You'd need an electrician to do this anyway, so why not get one to have look.

[Deleted User]

Hi - as I understand it the goal here is to make your NSH work with either cheap rate Agile or night rate E7. You then want to be able to switch backwards and forwards between tariffs "at the flick of a switch" without getting an electrician in every time? Assuming I've understood what you're trying to achieve correctly, this is very easy and although you'll need to get an electrician in once, the work is usually straightforward.

There are different ways to achieve this, but one very straightforward way is as follows:

1. At the moment you have two sets of circuits in the house fed by different consumer units. One set of circuits is on all the time and you pay the current Agile rate. When you were on E7 you would have paid either the day or night rate depending on the time. The other set of circuits was wired so that they only came on during the E7 night rate times so you could only use those circuits at night but, because those circuits were switched on and off by the meter, you were guaranteed only to use cheap electricity for those circuits. Your NSH is connected in to one of these "cheap overnight" circuits.

2. The first thing to do is get an electrician in to rewire the feed to the "cheap overnight" consuner unit (i.e. fusebox) so it takes it's power from the same place as the "on all the time" consumer unit. This is a perfectly normal and straightforward for any electrican to do and is something they are likely to have done many times before when de-commissioning storage heaters, for example when a customer changes to gas heating. In a lot of cases (possibly most?) you're probably only looking at a couple of hours work, if that. Once this is done you will have "bog standard" house wiring with all the circuits powered up all the time, like they are in a non-E7 house. You may have a few fused outlets from previous storage heaters that you want the electrician to change to normal sockets at the same time.

3. The second thing you need to do is to make the NSH only switch itself on when Agile is cheap or during the E7 night hours depending on which tariff you're on at the time. This can easily be done by wiring your existing NSH through a timeswitch (it needs to be a heavy duty one of the type you'd use for an immersion heater, for example). You can then set the timeswitch according to the tariff. A little bit of thought is needed when the clocks change and you also need to allow for the possibility of the time on the timeswitch drifting but it's clear from your original post and questions this isn't something you're going to struggle with. When you're on Agile, you might find that the best timings are 4 or 5 hours overnight and 2 or 3 hours in the afternoon. At the moment, assuming you only have a single NSH and use a "normal" amount of electricity at other times (and lots of other caveats), you'll probably find that you can save quite a bit of money by using Agile over E7.  Presumably you are aware of and that's why you're asking.

I realise I haven't answered your questions directly but I hope this helps. FWIW, from your questions I'm sure you're heading in the right direction with this. Mike.

ch_152

Thanks very much, very useful replies. I assumed it was doable, and also had thought it was probably not going to require too much in terms of major works - will get an electrician in to have a look.

I'll see if the existing NSH works tonight. Given what @QrizB has said, and as I had thought probably the case, it seems unlikely that the cheap rate CU would activate.

So that necessitates either: a switch back to an E7 tariff (based on my current usage, Agile is an absolute no brainer); or getting the cheap rate CU wired up to just be on 24/7 and having choice between changing the existing NSH for a smart one with timers and programming, or a timeswitch for the existing NSH.

The latter being a discussion for a new thread entirely!


Cheers all.

ch_152

Interesting(ish) update on this, the NSH does work during the night-time on the current tariff.

I think I'd still like to get a time switch on it to avoid the more expensive morning periods during agile. Something smart/programmable via an app or with IFTTT etc. would be good. Any suggestions @[Deleted User] ? I know you are a fan of this stuff!

[Deleted User]

I have a number of these which have proved rock-solid reliable and also have the advantage of power monitoring:

https://www.amazon.co.uk/gp/product/B09XB3RZB9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

You can control them with the basic eWelink app, which is free. If you want to use IFTTT at some stage you either need the paid version of the app which costs ca. $10 per year or you can integrate them with a smart home system such as Home Assistant (which is what I have done).

There are other options. These sonoff devices are fairly inexpensive but not the cheapest. I chose them because they are widely used and supported and they're rated at 20A which makes switching immersion heaters and the like well within their capacity.

A "gotcha" to be aware of - not a showstopper but something to consider. These things need to be powered up so you can program them, control them and download any data. No problem in switching them on and off outside E7 cheap hours, but you'll either have to set them up overnight or move them to a 24 hour live supply to configure them.

Also, without wanting to get into the die-we're-all-going-to-die H&S hysteria that this kind of post sometimes attracts, do be aware that although wiring these in is a perfectly feasible DIY proposition, these are high-current devices and as such the fire risks associated with slightly dodgy wiring are increased. Personally, I have no qualms about wiring these in but still get them checked over by an electrician friend, and I'm also fastidious about checking the smoke alarm batteries. From your earlier posts I'm sure you don't need me to say this, but you never know who else is going to read this.

Let us know how you get on and any other questions, just ask.

[Deleted User]

Also, without wanting to get into the die-we're-all-going-to-die H&S hysteria that this kind of post sometimes attracts, do be aware that although wiring these in is a perfectly feasible DIY proposition, these are high-current devices and as such the fire risks associated with slightly dodgy wiring are increased. Personally, I have no qualms about wiring these in but still get them checked over by an electrician friend, and I'm also fastidious about checking the smoke alarm batteries. From your earlier posts I'm sure you don't need me to say this, but you never know who else is going to read this.

I am not sure that it has got anything to do with H&S hysteria but it has more to do with Part P of Building Regulations and the Law. The risk of doing it yourself and getting it wrong is that it could well invalidate home insurance were something to go wrong. ‘I had working smoke alarms’ isn’t much of a defence.