Quantum Dimplex Night Storage Heater Won't Charge at Max Rate

You still have a right under the Sale of Goods Act for a repair or replacement if the goods fail with within an unreasonably short period of time even though it might be outside of the warranty period. The difficulty of ‘unreasonably sort period of time’ is that it isn’t precise but for a relatively simple piece of equipment six years is usually taken to be a reasonable period.

CAB or Trading standards should be able to help but I think you have to contact the retailer in the first instance and that may or may not be possible.

Peter

(A bit of web research later...)

I think I have got to the bottom of it…  This appears to be a relevant wiring diagram for the heater:

… although mine appears to be a ‘G10 series’ not a G6.. .  According to https://electricspares.co.uk/product/dimplex-quantum-340w-element/ the 2 main elements are 340W each (x 2 = 680W which is actually what my energy app shows - not quite 700W).  There is a 3rd ‘boost’ element of maybe the same rating which gives the max input power as ~1000W as the specs sheet says.

So, I don’t think there are any issues with the unit itself, just the design in terms of some modern eco overnight tariffs which can’t make the heater heat up fully at basic cheap rates…  I doubt there is any possibility of taking advantage of, for example, Octopus Intelligent Go’s random daytime sessions and even if it were, I would almost certainly need to add the wifi hub (at another ridiculous £150, thanks very much indeed. Actually, I just found one on eBay for a ‘mere’ £80 and bought one 😊..)...

Ok, that's really useful and I can read that diagram (electronics deign engineer like forever). If your heater has an Off Peak terminal you just need to supply power to that (including the Neutral line). Two elements come off the Permanently On power and one from the Off Peak. Just give the Off Peak terminal some power. You can talk that through with an electrician. 

The only thing I'm not certain of is what the symbols mean to the left of the word PCB. They are obviously relay contacts controlled by the PCB but there are only two types. Normally Open and Normally Closed but there are three different types of symbol which has me a bit confused.

More thinking required …

Peter

The tariff is probably not the limiting factor here, but rather the charge rate or installer settings of the heater. I would check the input/charge settings and also make sure it is wired for full charging capacity. 4.2kWh/day does seem quite low for winter heating, even for a small room,

As a matter of interest ​@martinwinlow how are you switching the heater on/off to coincide with the EV tariff discount period? 

A Chinese ‘smart-breaker’ - operating on a fixed schedule to coincide with my tariff’s main, fixed night cheap rate which is only 6 hours long.  There are (as previously stated) additional daytime periods of the same cheap (7p/kWh) rates but they are random.  I might be able to make use of these with something clever like Node Red (https://nodered.org/) but that’s a learning curve I’d like to avoid climbing for the time being.

I’m afraid the tariff is most definitely one limiting factor - as clearly demonstrated by the screenshot of my energy monitoring kit above.  I have 6 hours (avoiding the tariff’s random daytime ‘on’ sessions) to charge the Quantum’s ~7kW of storage from only 680W-worth of heating element (being the other limiting factor - the ‘symbols’ you refer to are just connections… and offpeak is connected to 2 elements not 1 and they appear to be - going from the look of the PCB - to be mosfet-driven, not relay-driven).

However, there is a feature in the advanced menu which talks about programming the Quantum to store more energy than normal but it is a bit obscurely written:
“Charging Settings

If the output of the storage heater is not able to deliver the required heat demand throughout the day, it is possible to force the heater to store additional energy. This will manually adjust the charge calculation to store more electrical energy during the charging period.

This setting displays the available charge times for the Heater to store off -peak energy. It is presented like the Timer setup screen, but without a Target Temperature or Day Selection. This allows the Installer to set up to 4 charging On and Off times.

Charge Times

This setting displays the available charge times for the Heater to store off -peak energy. It is presented like the Timer setup screen, but without a Target Temperature or Day Selection. This allows the Installer to set up to 4 charging On and Off times.

Default charge times (Standalone) are:

Period 1 00:00 - 00:00

Period 2 00:00 - 00:00

Period 3 00:00 - 00:00

Period 4 00:00 - 00:00

Charge times should remain at the default settings (as shown above) for twin supply installations. This setting

should only be used in single supply installations. Values entered here always take precedent.”

Fortunately, this doesn't help because I'm still stuck with only having access to the Fixed six hours overnight for charging unless the third element can be brought into play somehow but this is where the instructions are not very clear. It reminds me of Chinese-made devices which have lots of functionality but whose user-manuals are so badly written it's next to impossible to make use of them all.
 

So I think I will be looking into Node Red after all…

I use Home Assistant on ours (Solar inverter/tariff control) which hasn’t been too bad considering that I haven’t really coded since ‘Basic’ days. The HA community is very good at sharing code.

I do know of others using Node Red but I’ve not experienced it myself

We’re getting into the realm of the configuration settings I touched on. You haven’t told us, I think, whether this installation is single- or dual-supply. It is a common arrangement for Economy 7 installations to have two supplies to a night-storage heater: one for charging, energized only during offpeak hours, and the other constantly live to power the heater’s controls, its fan and its booster element.

Since you’re apparently on a half-hourly metered Time of Use tariff, it would be natural to assume that there’s only one, constant, supply to the heater. Your statement “I'm still stuck with only having access to the Fixed six hours overnight for charging” is a bit worrying - in what way is access limited? It would be if the meter were controlling a switched charging circuit, but that doesn’t make sense with the tariff you’re on.

It looks like the instructions you were given would solve the problem you’re facing, but you’ll have to come clean about how power is currently delivered to the heater.