Electric Heating/Hot Water Conundrum

Scot_39

Its a common misconception that you need heat a whole tank every day.

You essentially heat what you have run in plus losses.

You don't - for my size of tank - and it's a small one - would take c6kWh to heat just the water itself 15-60, 6.5kWh to heat 15-65 - 2-3x the energy I think I use.

Heat loss can be non trivial - depending on age and design of tank - estimates start around 1kWh for small conventional etc.  Which don't occur with combi's - but both share common ones like running off cold from the tap before - and leaving hot water in the pipes when shut the tap off.  It can literally be litres each time on a longer run more than you use hot - I haven't measured it explicitly - but have ran with the basin stopper in a couple of times - it's not a quick trickle.

Edit : I rememberd posting that and just filled a 1l jug twice with cold to tepid before I let it start filling my c10l washing up basin for dishes.  I poured the third into basin. So 2l in 9-10l non trivial.  A smaller use say quick hand rinse more so.

So another plus for kettle on demand for those on SR anyway with the patience.

But in winter - any heat losses from water in the pipes is in some cases internal - and from the tank itself - just adds to the heat from heaters - like the pipes running under upstairs floors for me. So I don't then think of it all as a hard loss.

markin

If they expect to be in the house 10-20 years then it makes sense to spend on a new tank, new shower fed from it, Maybe a wet room in case they ever need a wheelchair or walking frames.

 And consider £5K on a Solar PV system, No battery needed, would knock around 5,000 kwh of the yearly bill, And be around  a 6 year payback. Maybe faster with a higher day peak rate.


But if not a small 30lt tank under the kitchen sink on a timer?

tim_p

markin said:

 And consider £5K on a Solar PV system, No battery needed, would knock around 5,000 kwh of the yearly bill, And be around  a 6 year payback. Maybe faster with a higher day peak rate.

Going to struggle to use that much, particularly without a battery or EV. 

markin

tim_p said:

markin said:

 And consider £5K on a Solar PV system, No battery needed, would knock around 5,000 kwh of the yearly bill, And be around  a 6 year payback. Maybe faster with a higher day peak rate.

Going to struggle to use that much, particularly without a battery or EV. 

No you sell it and bank the money for winter, But they are more likely to be home in the day to use what they don't sell and that will be at peak prices.

And we don't know if they still have a car and they could still have a new or second hand EV in the next 5 years.

Sell 5000kwh at 15p 7 year payback.
Use 1000 at a peak of say 35p, And sell 4000 at 15p, 5.5 year payback.
Use 2000 and sell 3000, payback 4.5 year.

Callyb69

@CrizB

This is the fuse board, might sell it to a museum! 🤣

QrizB

Interesting!

There are two separate dumb meters (one analogue, one digital). I think the digital meter is capable of supporting a split-rate tariff by itself, which makes me wonder what the onld analogue meter is for. Does the property have one of those odd three-rate tariffs - day, night and heat?

And two separate fuse boxes (one black with visible MCBs, one beige with the cover in place that probably contains rewirable fuses). I'd guess the beige one will contain the fuses for the storage heaters.

I don't know why the electrician thinks he can't replace both.

lohr500

Someone will hopefully be able to shed more light on the meter set up, but it looks a little confusing to me.
The paper tag on the right hand meter is hiding the routing for some of the wires, but I think the setup is something like this.

The left hand meter feeds the top set of circuit breakers that will provide a 24 hour supply to the labelled circuits.

The right hand meter, more than likely supplies power to the white fuse box in the photo. If you remove the plastic cover hiding the fuses it will be possible to see how fuses are in place and hopefully the circuits will be labelled. I suspect these will be the fuses for the storage heaters and immersion heater.

What puzzles me though is how the right hand meter receives any signal to energise the off peak rate. The meter model is a 5246B which according to the specification has no built in Economy 10 time switch or radio switch. It has a relay to energise the 5th terminal connection, but this would need an external Economy 10 time signal switch to energise it. There doesn't appear to be any external radio teleswitch or timer in the photo.
The small black box to the right of the white fuse box looks like a door bell transformer or similar. It might even be a transformer for the alarm system fed off the fuse marked Alarm on the top panel.

In the absence of any Eco10 time clock or radio signal switch controlling the white meter, the only way to regulate when the storage heaters and immersion tank should use Eco 10 is if there are seperate time clocks on each storage heater or the immersion heater. Or possibly a high current time switch somewhere out of view fed from the white fuse box which provides power to the storage heaters and/or immersion heater.

Can you check to see what fuses are behind the cover on the white fuse box (switch off 1st using the switch on the right of the white box). Are they labelled?

Are there any timers on the storage heaters and/or immersion tank heater?

A photo of the connections to the white meter (hidden by the paper label) would also help. There may be a smaller relay wire going into the meter which carries the ECO10 switching signal from a timer or radio teleswitch located somewhere else in the property.

Edited to change references from Economy 7 to Economy 10 as noticed OPs 1st post refers to Economy 10.

Callyb69

lohr500 said:

Someone will hopefully be able to shed more light on the meter set up, but it looks a little confusing to me.
The paper tag on the right hand meter is hiding the routing for some of the wires, but I think the setup is something like this.

The left hand meter feeds the top set of circuit breakers that will provide a 24 hour supply to the labelled circuits.

The right hand meter, more than likely supplies power to the white fuse box in the photo. If you remove the plastic cover hiding the fuses it will be possible to see how fuses are in place and hopefully the circuits will be labelled. I suspect these will be the fuses for the storage heaters and immersion heater.

What puzzles me though is how the right hand meter receives any signal to energise the off peak rate. The meter model is a 5246B which according to the specification has no built in Economy 10 time switch or radio switch. It has a relay to energise the 5th terminal connection, but this would need an external Economy 10 time signal switch to energise it. There doesn't appear to be any external radio teleswitch or timer in the photo.
The small black box to the right of the white fuse box looks like a door bell transformer or similar. It might even be a transformer for the alarm system fed off the fuse marked Alarm on the top panel.

In the absence of any Eco10 time clock or radio signal switch controlling the white meter, the only way to regulate when the storage heaters and immersion tank should use Eco 10 is if there are seperate time clocks on each storage heater or the immersion heater. Or possibly a high current time switch somewhere out of view fed from the white fuse box which provides power to the storage heaters and/or immersion heater.

Can you check to see what fuses are behind the cover on the white fuse box (switch off 1st using the switch on the right of the white box). Are they labelled?

Are there any timers on the storage heaters and/or immersion tank heater?

A photo of the connections to the white meter (hidden by the paper label) would also help. There may be a smaller relay wire going into the meter which carries the ECO10 switching signal from a timer or radio teleswitch located somewhere else in the property.

Edited to change references from Economy 7 to Economy 10 as noticed OPs 1st post refers to Economy 10.

Thanks for the detailed post @lohr500.
It all looks ancient and confusing to me, let alone a pensioner, and maybe even the electrician! 🤣

I'll get a few more detailed photos of each, but might be a few days.
Out of curiosity, should I be contacting the energy supplier to find out any info about timers and how it switches etc?
The purchase was a probate sale so the owner passed away, but was living in it, so guess it 'should' have been working. But no way to check as the family didn't live there. 

I've not noticed any additional timers anywhere, unless the water one would be hidden under the jacket of the boiler, but certainly nothing obvious. All NSHs just have the standard enclosed/mains connections and dials to control output. So again, nothing obvious as a timer. 

Callyb69

QrizB said:

Interesting!

There are two separate dumb meters (one analogue, one digital). I think the digital meter is capable of supporting a split-rate tariff by itself, which makes me wonder what the onld analogue meter is for. Does the property have one of those odd three-rate tariffs - day, night and heat?

And two separate fuse boxes (one black with visible MCBs, one beige with the cover in place that probably contains rewirable fuses). I'd guess the beige one will contain the fuses for the storage heaters.

I don't know why the electrician thinks he can't replace both.

The supplier told us it was eco10 and no more. Originally assumed it was eco 7 because of the NSH but they supplied 3 times for off peak.
Maybe my mum should have held out for a gas supplied property, stuck to what we both know!  🤦‍♀️

littleteapot

I'd be more concerned about that ancient little black box to the top right with the bell wire and T+E going to it than the ancient CU and slightly confusing metering setup.

No idea what it actually does but I can't read the writing on it and it's an odd arrangement to have in a meter/CU cupboard. My biggest concern would be whether it is connected to a suitably rated protective device to prevent the wires smoking or glowing red hot if a short circuit were to occurr...

And then what other 'interesting' electrical arrangements are around the house.