Economy 7 or Single Rate?

Gerry1

GasAttacK77 said:

I can only see one rather chunky supply cable coming from the Quantum heaters to the hard wired on / off switch.

That can be highly problematic: it's a cheapskate way of wiring them up.  Ideally there should be two supplies, one being an overnight cheap rate E7 supply that delivers the charging current and is switched by the meter, and the other being a 24h supply that powers the fan and the control electronics.

Councils and other organisations often cut corners by failing to install the second supply cable.  They convert the E7 supply to 24h and change the new heater's internal wiring so that its programmer tries to mimic the meter's E7 times. This bodge often happens when an old Box of Bricks NSH is upgraded to a more efficient High Heat Retention one such as a Quantum which doesn't waste heat all night long (and all day if out at work), blowing heat out only at times when it's needed.

Unfortunately, unless this is done by a resident anorak it's more than likely to be wrong.  The organisation gets the cost savings but the user gets higher bills forever if the job has been done less than perfectly.  Even then, years later a new smart meter (or tariff) can quietly knock things out of kilter.

The risk is that some or even most of the charging takes place during peak hours, so the user ends up paying far more than is necessary.  Ideally, prevent problems by installing the second cable, otherwise there are two things that must be done.

• Find out exactly when the meter starts and finishes the cheap rate, noting that some may have a two-hour peak period during the night, typically 0030 - 0230.  Forget what the web or anyone tells you, all that counts is what your meter actually does, not what it's supposed to do.  Unfortunately, unless one socket has a neon indicator (or there's an accurate IHD) that means looking at the meter very late at night and early in the morning to see exactly when it changes over.  It's unlikely the installer attended at those times.
• Then program the Quantum accordingly, noting that it may have to stop charging at midnight and then start again immediately afterwards.  Search online using the exact model number to get the detailed instructions.

GasAttacK77 said:
The immersion heater is set to come on for an hour in the night (off peak) and an hour in the day (around 6pm).

That seems like a big mistake, why pay peak rate (even more expensive than single rate) when you don't need to?  Set the local timer to use only the cheap overnight rate.

QrizB

The OFTM fixed rate deals are looking quite competitive at the moment. They don't seem to be offering E7, just a single rate, unless I'm failing to find E7 rates on their website (which is possible).

Slightly less than 20p/kWh and fixed for up to 2 years could be attractive to many people.

GasAttacK77

Thanks Gerry. That's annoying about the Quantum NSH. I can't say I fancy sitting outside all night checking my meter every 5 minutes. None of the sockets have neon indicators unfortunately.

If I contacted an electrician and told them what you detailed above, would they know what I was talking about and how to put it right? I'm guessing it's not a 5 minute job so would cost a few £'s.

If I did that would it automatically charge at off peak times, meaning I don't have to worry about any potential peak period at night?

I guess there is a chance it is charging at the correct times and I'd have paid out quite a lot unnecessarily.

Might it be easier to go with the Outfox The Market single rate tariff at 18.65p/kWh which would save me money based on 50/50 usage, even though that 50/50 usage might be wrong?

I'm not sure how much it would cost to have put right, or indeed if I could trust them to do it correctly.

With regards to the immersion, we also need hot water in the evening and it was going cold by about 4pm. I tried having it on for longer overnight but it still wasn't staying hot into the evening. I'm not sure whether leaving it on for even longer overnight would have made any difference. In the end I decided 1 hour in the day was marginally better than an extra 2 hours at night. 

Gerry1

You may find the IHD has a countdown display showing when cheap rate kicks in.

Otherwise just check the meter on the wall at 15 minute intervals starting around 11pm.  Once you've narrowed it down to a 15-minute slot you can watch it continuously the next night to find the exact switchover time.

Then check it again 7 hours later to make sure that's when peak rate resumes.  If it doesn't switch back it probably has the 'split shift' times, so check again 2 hours later.

If you don't have the second cable installed that's the only way to be sure.  You can then program the Quantum with the confirmed times.

Alternatively, for complete peace of mind a good electrician should be able to run a switched E7 supply to each heater and change the internal wiring connections.  Just give him a copy of the wiring instructions you'll find online.  If in doubt, ask Dimplex to recommend one of their suppliers.  Also get him to fit one of the new E7 outlets with a neon indicator so that you'll be able to see at a glance precisely when E7 is live.

You can then program the Quantums to give heat only when it's needed, secure in the knowledge that they can never again charge at peak rate.  Best to do this yourself so that you're fully clued up and can tweak them in the autumn if necessary.

Scot_39

https://www.dimplex.co.uk/sites/g/files/emiian551/files/media_import/medias/docus/14/08_83324_0-3 QMRF Online G13 23-023.pdf

Scan through the settings.

A badly configured NSH or HW immersion can use a good few kWh per hour at peak rate if not careful.

And an undercharging or under rated NSH for the room - can leave you reliant on boosting heat at peak rate.

One way of perhaps confirming if they are single wired or dual wired - is that dual wired wont normally use preset charge times (see p33).  But if their is only one wire one switch visible chances are you are wired into a single live feed.

So timings should match.

If you check the preset times - you can then check your meter or the power in some way as @Gerry1 - something that many IHDs make easy.  Right now my IHD is telling me its 50 mins to my cheap rate period starts at 12 GMT / 1 am DST

RedFraggle

If the Quantums are using the fan regularly then they're likely not storing energy or not storing enough.

The fan will only activate if:
It's running out of stored heat and pushing the last bit out
It's rapidly heating up a room at the start of a heating cycle
It's operating in boost mode as a standard fan heater.

We are also not far off 50:50 but the whole flat is at 20 from 8 am to 10 pm as I work from home and have arthritis. My office has a panel heater (small room so not crazy) and we run an oil filled rad in the bedroom. 

QrizB

GasAttacK77 said:

If I contacted an electrician and told them what you detailed above, would they know what I was talking about and how to put it right? I'm guessing it's not a 5 minute job so would cost a few £'s.

It will involve some new circuits. I'd guess more than £1k but less than £2k.

Depending on how it's installed, you might need to do some redecoration afterwards too.

GasAttacK77 said:

Might it be easier to go with the Outfox The Market single rate tariff at 18.65p/kWh which would save me money based on 50/50 usage, even though that 50/50 usage might be wrong?

A two year fix with OFTM at ~19p/kWh will save you money and give you time to decide whether to rewire or not.

And on a single rate tariff, your heater timings won't make any difference.

GasAttacK77

I've checked my charge times as suggested by Scot.

00.00 to 07.00 - Period 1
07.00 to 07.00 - Period 2
07.00 to 07.00 - Period 3
07.00 to 07.00 - Period 4

It sound like that confirms a single live feed.

It's annoying, and no doubt costing me money, but I don't think it's worth paying £2k to have it corrected, plus additional decorating costs.

Sounds like I might have to try and work out when the night read on my meter starts and stops ticking over. Does anyone have an idea what those times are likely to be? I'm guessing 23:00 to 01.00 Start and 06.00 to 08.00 finish. Does that sound about right? I know I'll have to check my meter to be sure but it would give me an idea of when to start.

I set my Quantum NSH to come on for 4 periods during the day at a temp of 21. Will the heaters automatically store enough heat overnight to maintain that temp at those times? 

06.30 to 09.30
11.30 to 14.00
16.00 to 18.30
20.00 to 23.00 

That's the 2 downstairs NSH, the upstairs heater is set to different times to also pump out heat during the night.

Swipe

The most common E7 times will likely be 00:30-0730 GMT but it does vary by region. If you have a smart meter you could install the Bright phone app and it should pick up your tariff rate times from the smart meter (to the nearest half hour) once registered with your In Home Display device GUID. Most E7 meters' actual switch timings are offset (delayed) by 0-10 mins. As Gerry said, if you have an In Home Display device (depending on the model) you may be able to watch the active tariff menu screen change when the time switches. This feature is available on the Chameleon HD3 IHD. Failing that, you'd have to watch for the active tariff rate on the smart meter screen to change.

Scot_39

No that's sounds like a likely e7 off peak window.

And is how it should be for e7 and single wired.

But they do vary regionally.  So worth checking.

And meters may even have a small offset - so 0000 might not switch over to say 0010.

Not sure if Qyantyms have a switch option for gnt / dst - check the manual  - at least one brand I thought about could be set to.  Your meter normally doesn't- many stay gmt (so in summer your likely now 1am and 8am clock time if want to look at meter to check)