economy 7 on prepaid meter for a 1.6kw heater Does this sound correct?

Scot_39

oneiloneil said:

Thank you all. Your answers have cleared up many of my wrong assumptions. 
I'll offer to check his 24hr consumption the next time he uses the heater. 
It has 2 separate power feeds, and the off peak time clock matches the off peak set up on the unit. 
From what's been said here, it will potentially draw 7 x 3.5 KW (24.5 KWh) during off peak, and release this at 1.6 KW per hour for 24 hrs (38.4 KWh). meaning it will draw a further 14 KWh from the peak rate electricity.

My advice will be to turn his unit on at least 2 days before the cold weather hits again, running it at a constant 18 degrees. When the cold arrives, his comfort override can be used when he feels he needs a boost. 

Edit

Is the person using any form of heat currently ?

I am still running 2 of my 3 NSH but on minimum - its warmer - but not warm out there - in the wind and rain (a lack of sun makes a difference to house heating - and higher wind to heat loss etc)

If so - it might not be worth waiting - until gets really cold.

And if worried about the NSH using peak - think the 5 hr limit is configurable.  See Gerry1 installation manual link.

End of Edit

Just read Gerry1 comment re 5 hours default on the peak cycle. But I guess the installer could have tweeked.

This would be via the "balancing" charge heater - so 1.1kW not 3.48 kW - so c5.5kWh.

The 1.6kWh is the nominal heat output - it may not be achieved at end of day.

But given his other comment - about that wiping out the off peak advantage - not so sure.

If were to draw 24.5kWh off peak - and 5.5kWh peak - that 82% night use ratio is still way above the typical E7 break even point (42% night - at least as was pre EPG and discount differences ? ) vs single rate.

The problem is NSH is essentially an all room heater.

It may not be as cheap as some "heat the person" / corner of room strategies (which tends to spread to whole room in a few hours anyway) - and even these smart hybrid ones are pre-configured essentially as all day "comfort" devices.

It might be the best balance in the end isn't 18 all day / night - but lower when room not in regular use - and just boost when is.

Either by programming NSH more aggressively - or using more localised heaters (e.g. fan onto person ) - but that tends to merge into whole room heating in a few hours according to some experts.

Ultimately the problem is not only the cost but the willingness / or even physical ability to survive by lowering it by lowering settings - is a very personal and property / tariff dependent balance.

Often expressed opinion by other forumites - is that it is better to use the lowest cost source - in this case the E7 night rate - for general basic background heat.

oneiloneil

He has no heating on in the property apart from the four coldest days we had. he had run the heater at 24 degrees and supplemented this with a small fan heater whilst he was awake in the room as well. the middle of the room didn't get above 17degrees. Obviously this now upsets my calculation as well. He feels the need for the extra heat which I cant advise against if its preventing him from getting hypothermia. Ill leave the topic until I get more details ie tarrif costs and kw hours of fan heater use etc. Ill also need 24 hour status readings when he next uses the storage heater. I'll update this topic when I have these details. Thanks again for you help.

Scot_39

I mentioned my ave cold snap use.

But just before then I was away for a week - and only left a small nsh on min in ds hall on as a safety net - as new winter approaching.

The unhet living room was just 12C when returned. Upstairs 13-13.5c.

It took about 15kWh extra in the first 1.5-2 days to lift house back to 17/15 and heat water - the cold snap started in earnest the next day. The first sub zero overnight that night.

Used about 15kWh 1st evening (8-10pm off peak on E10) for all 3 nsh heaters, water immersor etc - max over 10kW and a 2kW oil filled radiator for instant lr heat, 2nd day c36kWh iirc - settled closer to 25-27kWh total inc everything, despite winding up lr and ds nsh input a little further - as daytime dropped sub zero in coming days

So try persevering for a few days.

But based on your 17 vs 24 setting  above, it might just be that the room house is just very expensive toget and possibly even keep warm.

In a recent bbc sounds, one albeit perhaps industry expert was very pro heating whole house to some degree at cheapest rates (gch with lower set trv in unused rooms) - rather than just boosting one at peak electric.


Read some articles suggesting unheated rooms might get to c10C in typical UK winter conditions -  below in really cold spells / North etc.

Gerry1

oneiloneil said:

It has 2 separate power feeds, and the off peak time clock matches the off peak set up on the unit.

Provided that one is a switched E7 supply and that the heater has been internally wired and programmed correctly then the off peak settings in the Elnur can be ignored.  It won't be possible to charge up from the 24h circuit, but the top-up ('balance') heater can undo all the good work if it's often kicking in.

oneiloneil said:

From what's been said here, it will potentially draw 7 x 3.5 KW (24.5 KWh) during off peak, and release this at 1.6 KW per hour for 24 hrs (38.4 KWh). meaning it will draw a further 14 KWh from the peak rate electricity.

Nope.

The point about HHR NSHs is that they only release heat at times when it's needed, by blowing it out with a fan.  It's not like the old plain box of bricks which let heat escape throughout the 24 hours, it's more like a vacuum flask than a hot water bottle.  It would be well worth programming it so that it matches his lifestyle accurately: no point in having the fan pumping out heat at full blast when he's in bed.

IFF (sic) programmed correctly, there should seldom if ever be any need to use the top up heater unless a 'bomb cyclone' suddenly arrives one morning or he returns after being away having not programmed in an absence.  It must be emphasised that it really is critical to program an HHR NSH for optimum performance otherwise its smartness can work against the user's best interests.

Gerry1

ariarnia said:

and if the vents are closed first thing in the morning and opened when it starts to get dark then it wont release the heat until later in the evening. or you can even open them a bit in the morning then close them down and not open them again until evening.

Nope.

That's only true of the old 'box of bricks' NSHs.  HHR NSHs are well insulated and there aren't any simple vents and flaps as such.  The heat is blown out via a fan only when it is needed to keep the room at the temperature that has been programmed for that time of day.  Once optimally programmed it shouldn't need much further adjustment unless the occupant's lifestyle or requirements change.

Scot_39

Medics articles seem to suggest real physical changes start to kick in c18  - so things like circulation to hands feet etc to protect core, blood pressure etc.

NHS suggest ranges 18-21C for vulnerable - infants, ill, elderly.

Age uk 21C etc. 

So easy to understand why 17 - even if well wrapped - would not be comfortable or good for many peoples health.

And for dampness as high as 14C seems to be mentioned in some articles for preventing mould risk.  Another reason to heat other rooms a bit - like main bedroom, bathroom.


But sadly have known many poor e.g. pensioners who lived in one room - long before recent price hikes.

ariarnia

Gerry1 said:

ariarnia said:

and if the vents are closed first thing in the morning and opened when it starts to get dark then it wont release the heat until later in the evening. or you can even open them a bit in the morning then close them down and not open them again until evening.

Nope.

That's only true of the old 'box of bricks' NSHs.  HHR NSHs are well insulated and there aren't any simple vents and flaps as such.  The heat is blown out via a fan only when it is needed to keep the room at the temperature that has been programmed for that time of day.  Once optimally programmed it shouldn't need much further adjustment unless the occupant's lifestyle or requirements change.

okay. if the fan programmed so its only on the first thing in the morning and again when it starts to get colder or just when the room is occupied...

my point was that theres differnt controls for input and output so more complex than the op was suggesting with the heating overnight and then releasing heat during the day.  

oneiloneil

Jannuary update
Elnur hhr40 
The unit was switched on on thursday (4 days ago)
The current status in the settings menu is as follows;
heat called for  =  24 degrees c   (Maximum)
room temp = 20 degrees c
core temperature = 176 degrees c
air temperature at grille = 48 degrees c
charge percentage from previous night = 80%
time which balancing element was used for = 00:21  

EssexHebridean

20C from 24C output temperature sounds a little lower than I would expect - I am assuming here that the Elnur runs - as my Quantum does - on an output temperature rather than more like a thermostat. The Quantum usually gives a room temperature of around 2 degrees below where the output temp is set - that is a relatively small heater in a relatively small space.

I would also say that it is FAR harder to warm a place up using storage heaters from stone cold - for a start I find that all ours regardless of type (new/old) take a good 48 hours - 2 charge cycles - to "settle in" and really start producing heat and retaining it fully - even the Quantum. Add into the equation walls that have developed a chill from not having any heating running and it could easily take close to a week to see things beginning to stabilise on temperature I would think? 

Scot_39

oneiloneil said:

Jannuary update
Elnur hhr40 
The unit was switched on on thursday (4 days ago)
The current status in the settings menu is as follows;
heat called for  =  24 degrees c   (Maximum)
room temp = 20 degrees c
core temperature = 176 degrees c
air temperature at grille = 48 degrees c
charge percentage from previous night = 80%
time which balancing element was used for = 00:21  

Thanks for the update - let us know how get on with actual power consumption.

And actual room temperature - or was that the 20C above - in the status ?

But if the balancing element only used for 21 minutes looks like the main element - and if configured correctly for connections hopefully the E7 economy rate - taking a lot of the strain.

As one of my posts above - it is probably going to be scary - as heat house - on any initial turn on.  Hopefully settles after a couple of days.

Neighbour clearly more resillient - I turned 2 of my NSH up a bit - and put the 3rd on low  starting 10 days ago - but turned LR and DSH up again on Thursday. 

It was interesting to read @EssexHebridean comment regarding the two charge cycles - for the heater.

So hopefully neighbour will have seen some improvement over the last few days.

Be good to know if happy with output for room size / type - as you don't mention previous problem re 17 mid room including fan heater.