Wind being curtailed tonight

Martyn1981

Reed_Richards wrote: »

My old house was a 4 bedroom detached built in 1970. I heated radiators and hot water (tank set to 50 C) with a modulating condensing gas boiler (no immersion heater). I lived in East Anglia. My annual consumption was 18500 kWh of gas with the living-room thermostat set to ramp-up the temperature during the day to a maximum of 19.5 C. Averaged over the entire year that is over 2 kW (i.e. 2 kWh per hour) or just over 50 kWh per day. The boiler was off overnight. As it was a modulating boiler you could see how hard it was working and the time when it need its full 24 kW output was when it came on in the morning and needed to warm-up the house rapidly.

You can't see steam; I would have thought a physicist would know that.

Yep, 3kW would not be enough to warm a house up on a cold winter's day which even with hot rads is still a long time away. But, in fairness, GA has now added a bit about the boiler coming back on to help, so I think 3kW power demand has now been relegated from temp maintenance after 1min to 'average', which is of course massively different from any suggestion of coping with peaks.

Call me stupid (no go on) but I can't help but think he's describing my current set up with a 3.5kW ASHP that takes the strain when the heating demand is low. But of course it's nowhere near 3.5kW or even 3kW of input leccy. Edit - And no hope of warming nor keeping the house warm on a really cold day. Our boiler is a 28kW model, and that can tested on extremely cold days, yet our annual gas consumption is only 6-8k kWh's, so less than 1kW or around 2kW if we work on 6 months of the year.

zeupater

Martyn1981 wrote: »

So, the physicist started out at 1 minute, and now we need 2kWh, which from a 24kWh 77.5% (average of your figures) would be ~6.5 mins (not 5 mins) so already 550% greater than you first 'calculated'?

Hi

Warning:exclamati - Basic sanity test coming down the line ...

Taking GCH inhibitor manufacturer rule of thumb guidelines as a basis, a standard radiator GCH system would have a volume of 11litres/kW of boiler rating, so a 20kWh system would be expected to contain 220litres of water ... add in copper pipe (60mx15mm/30mx22mm) (25+18kg) and allow for connectors etc we're talking ~45kg ... add in ~10 radiators (5xType11/5xType21) at around 330kg the allow a further 20kg for boiler heat exchanger, valves etc and we get to somewhere around/just over 600kg (220+45+330+20) of initial thermal mass to absorb heat ....

Operating to achieve the standard deltaT50 and applying a rough rule of thumb of 1kW to raise 1tonne by 1degreeC in 1hour, we're looking at operating a 30kW boiler for >1 hour (excluding convective/radiative heat transfer) just to raise the system temperature to operating levels, so >1.5hrs for a 20kW boiler, >3hrs for a 10kW, to 10Hrs for something the size of an immersion heater! ...

Of course, as the thermal mass of the system rises, so does the heat transfer to the environment, which in turn slows the rate of heating of the thermal mass, which slows the rate of thermal mass heating (vicious circle this one! ... ), but the system will eventually reach somewhere near it's full operating temperature ... if the heat source is sufficiently powered to maintain the deltaT50 of the radiators and the radiator space heating capacity at a maintainable temperature is higher than overall energy loss to ambient conditions is higher than the property's heat loss that is! ... :whistle:

... but then again, considering that the reason for running wet GSHP & ASHP systems for extended periods is related to the initial heat-sink into thermal mass, didn't we already know that? ...

Aren't basic sanity check exercises fun! .... ... anyway, instead of running 3kW of resistance heating to provide 3kW.t of comfort, I'd have a huge preference towards doing the same with closer to 600W ... oh look, currently generating 3.39kW, and consuming 600W, knock off ~170W for baseload/TV etc and there must be something else running .... I wonder what that could be? .... ah that's right .. currently ~2.5kW of thermal mass charging, after all - it is September! .... :cool:

HTH
Z

Martyn1981

zeupater wrote: »

Hi

Warning:exclamati - Basic sanity test coming down the line ...

HTH
Z

Flipping heck Z, how are we supposed to have fun if you're going to bring physics (and maths) into this.

Trust me I'm a brain scientist, I know what I'm twalking abouts.

Martyn1981

zeupater wrote: »

Hi

Operating to achieve the standard deltaT50 and applying a rough rule of thumb of 1kW to raise 1tonne by 1degreeC in 1hour, we're looking at operating a 30kW boiler for >1 hour (excluding convective/radiative heat transfer) just to raise the system temperature to operating levels, so >1.5hrs for a 20kW boiler, >3hrs for a 10kW, to 10Hrs for something the size of an immersion heater! ...

HTH
Z

Just a suggestion, but a potential alternative to BIG power (and I'm just dreaming away here), would be higher insulation, thermal store, and a much more efficient heating source (possibly 24hrs if needed) that could make use of local heat ...... out of thin air (or thick soil)?

Well, we can all dream I suppose.

zeupater

Martyn1981 wrote: »

Just a suggestion, but a potential alternative to BIG power (and I'm just dreaming away here), would be higher insulation, thermal store, and a much more efficient heating source (possibly 24hrs if needed) that could make use of local heat ...... out of thin air (or thick soil)?

Well, we can all dream I suppose.

Hi

Dream on, it's the solution we're all looking for, get those 'BIG power' bills as low as possible using some form of witchcraft that science doesn't understand yet .... <looks up> ... bu**er!, were did that come from? ... and that! ... I wonder what this does? ... I think I'll need to do some research as it must have come from somewhere ... MrsZ, do you know anything about this? .... interesting ... :cool:

Anyway, jest aside, if everyone could achieve a similar level of efficiency to ourselves, you'd be pretty close to being able to electrify domestic heating & accommodate EVs as a direct replacement to ICEVs without impacting too much on overall centralised electricity generation demand ... all it takes is an open mind, the ability to recognise various dialects of Trollanese & a willingness to do what makes sense when it makes sense! ...

HTH
Z

1961Nick

zeupater wrote: »

........Operating to achieve the standard deltaT50 and applying a rough rule of thumb of 1kW to raise 1tonne by 1degreeC in 1hour, we're looking at operating a 30kW boiler for >1 hour (excluding convective/radiative heat transfer) just to raise the system temperature to operating levels, so >1.5hrs for a 20kW boiler, >3hrs for a 10kW, to 10Hrs for something the size of an immersion heater! .........


HTH
Z

Crikey.....a primate could die of hypothermia waiting for a 3kWh system to reach anything near deltaT50!

zeupater

1961Nick wrote: »

Crikey.....a primate could die of hypothermia waiting for a 3kWh system to reach anything near deltaT50!

Hi

3kWh over what period? ....

HTH
Z

Martyn1981

zeupater wrote: »

Hi

Anyway, jest aside, if everyone could achieve a similar level of efficiency to ourselves, you'd be pretty close to being able to electrify domestic heating & accommodate EVs as a direct replacement to ICEVs without impacting too much on overall centralised electricity generation demand ... all it takes is an open mind, the ability to recognise various dialects of Trollanese & a willingness to do what makes sense when it makes sense! ...

HTH
Z

I know I'm talking net not realtime, but a while back when I was looking into ASHP for the whole house heating, it occurred to me that with the addition of those 4 south panels I keep dreaming about, my annual gen would be around 6MWh. Allowing 3MWh for non heating, that would leave 3MWh for heating and DHW. As we use about 7MWh of gas pa, that might make us close to net zero.

I appreciate PV and heating don't overlap well, but the possibilities are fun, and then I can point to wind (and other RE) investments. It all adds up I suppose.

Transport is of course more again, but i suppose that would help me personally balance some summer PV gen against external wind gen. Baby steps.

GreatApe

Another night and marginal green is being curtailed

If we had more wind we would just be curtailing it

We need heat only tariffs ASAP 3p a unit to displace gas boilers during excess wind times like tonight