What's your summer energy use?

[Adsibob]

2 minutes ago, Marvin said:

I assume you don't have a bare copper or stainless steel 309ltr tank? That would be criminal.

No, Telford Tempest. It is insulated, but I was surprised the energy rating was only something like a C. Apparently a C is plenty good enough, but it is still acting like a giant radiator that is making my pump room a couple of degrees too warm. Our MVHR machine and ducting is in there, so I need to insulate it better.

Should have done more research before I bought it. Oh well.

[George]

5 hours ago, AliG said:

We use massive amounts compared to you guys. My base usage of electricity is around 800W.

 

 

Oh this is very much my summer usage.

 

Winter is much, much more. 

[SteamyTea]

7 hours ago, Adsibob said:

Fill both with equal amounts of ice. Leave one closed for 8 hrs. Open the other one for 1 minute every hour. I bet the amount of thawing vs ice will be quite different across the two boxes. A pocket of cool air is a good insulator. Displace that with warmer air every time you open a fridge/freezer, and you will quickly see heat  gains.

Now you are into latent heat of fusion.  You would not see the difference.  How the first ice stores stayed cool for months.

 

[AliG]

10 hours ago, Adsibob said:

Ok, that makes sense. Except for one point: why is your boiler only 80% efficient? 

My guess at 80% efficiency includes any heat lost in the pumps and pipework between the boiler and the tank. I calculated it by heating the tank up and comparing the increase in temperature in the tank with the amount of gas used.

 

If you read this article, however, it appears that the 90%+ quoted efficiency requires the boiler to run at 45C. Whilst I could run it at this temperature for heating, it is impossible to run it this low for hot water.

 

Thus when heating hot water it is likely that most people’s boiler has efficiency in the 80s and I suspect losses around the pipework reduce this further.

 

https://theintergasshop.co.uk/content/187-why-your-new-gas-boiler-isnt-efficient

[LaCurandera]

On 22/08/2022 at 08:57, SteamyTea said:

So do I, much quicker if you put the right amount of water in.

 

How so, an induction hob is more efficient.

 

This years usage

 

Last weeks usage.

 

And the percentage of time that I draw no power at all, I think this is the real secret.

Sorry, @SteamyTea, it might be elsewhere but what do you use to collect the data and create these graphs? Is it manual (they look like Excel?) or automated?

[dpmiller]

Isn't quoted boiler efficiency combustion efficiency?

 

Certainly the average combustion analyser gives efficiency numbers based purely on this, it cares not what the water temperature is...

[SteamyTea]

1 hour ago, LaCurandera said:

Sorry, @SteamyTea, it might be elsewhere but what do you use to collect the data and create these graphs? Is it manual (they look like Excel?) or automated?

I cobbled together a logger using an old CurrentCost monitor and a raspberry pi. Then analysed the data in a spreadsheet.

Also put this together to make a logger.

https://forum.buildhub.org.uk/blogs/entry/946-the-energy-meter-experiment/

[AliG]

1 hour ago, dpmiller said:

Isn't quoted boiler efficiency combustion efficiency?

 

Certainly the average combustion analyser gives efficiency numbers based purely on this, it cares not what the water temperature is...

The efficiency includes the benefits of condensing.

 

The return temperature has to be below 55/56 for condensing to happen. Otherwise your boiler is around 8% less efficient.

 

As the return temperature drops from 55 towards 45 the condensing continues to get more efficient. This would apparently be where the 90%+ efficiency would come.

 

If you set your boiler flow much above 65C then it will rarely condense and efficiency will fall considerably.

 

Mine is set at 64C, as I need this to heat my hot water to 55C. This seems to give me a temperature at the taps of around 49C max, so I don't want to set it any lower, it seems to be condensing at this setting.

 

My boiler, a fairly standard Worcester Bosch, only has one temperature, so I have to set a flow that suits DHW and heating.

[SteamyTea]

2 minutes ago, AliG said:

seems to be condensing at this setting.

How do you know it is condensing?

I had a condensing combi when I lived up country. It used to make snow when it was really cold outside.

[Radian]

38 minutes ago, AliG said:

Mine is set at 64C, as I need this to heat my hot water to 55C. This seems to give me a temperature at the taps of around 49C max, so I don't want to set it any lower, it seems to be condensing at this setting.

 

I started a new topic about this if anyone's interested...

 

[AliG]

1 hour ago, SteamyTea said:

How do you know it is condensing?

I had a condensing combi when I lived up country. It used to make snow when it was really cold outside.

When the burner stops firing the temperature steadily drops into the low 50s so it should be condensing

[SteamyTea]

5 minutes ago, AliG said:

When the burner stops firing the temperature steadily drops into the low 50s so it should be condensing

Interesting.

I don't know enough about condensing boilers to know how they work, or are meant to work.

[joe90]

Just had my lecky bill fir sept, all electric (apart from bottled gas for hob) £94.

[SteamyTea]

23 minutes ago, joe90 said:

Just had my lecky bill fir sept, all electric (apart from bottled gas for hob) £94.

How many kWh was that for?

 

Just paid mine, £122.55, I was £0.75 in credit.

All electric, even cooking.

I used, in total 305 kWh over 86 days.  So with everything included, it works out at 40p/kWh.  It is the 55.1p/day standing charge that is killing me.

Just power would have been 23.4p/kWh.

This period last year, I used 479 kWh, this year, 305 kWh, so putting only the top heater on in the 200 lt immersion heater has saved me nearly 200 kWh.  Cost about 20 quid, so far has saved me about 37 quid.

Only had a couple of luke warm showers, one was last night.

Edited September 7, 2022 by SteamyTea

[SimonD]

The energy ratings of boilers isn't entirely straighforwards as the total ErP score depends on the boiler, the installed controls and how they're configured. Typically a boiler on its own will only be about 89% efficient but controls are then graded in terms of Erp classes which add to the boiler efficiency. 

 

Class 1 is on/off thermostat which adds only 1% to the boiler efficiency. A class VIII control (fully modulating and zoned) will add 5%.

[joe90]

2 hours ago, SteamyTea said:

How many kWh was that for?

Energy Used 296.0 kWh @ 27.05p/kWh 28 days @ 48.91p/day
£80.07 £13.69
 Loyal Octopus 28 days @ 13.15p/day -£3.69‡

[SteamyTea]

1 minute ago, joe90 said:

Energy Used 296.0 kWh @ 27.05p/kWh 28 days @ 48.91p/day
£80.07 £13.69
 Loyal Octopus 28 days @ 13.15p/day -£3.69‡

Can you just divide the total amount payable by the number of units.

Too hard for me to work out while sitting on the beach.