[OpenTRV-interest] [OpenTRV-dev] Storage heating, dynamic demand, and OpenTRV
Damon Hart-Davis
EMAIL ADDRESS HIDDEN
Mon Sep 8 11:55:53 BST 2014
Hi,
Oh I agree that it’s a crime against exergy to do it in bulk (esp given that the UK FiT scheme assumes that you’ll be spilling excess to the grid), but maybe the very controllability of electricity is being used properly here for balancing purposes. (Burning gas for heat in bulk is still 2.5x less horrific than bulk electric resistance heating…)
I will go and burn myself for heresy in due course, feeding the energy into a suitable thermal store, natch.
Rgds
Damon
PS. I’m all for heat-pump and PV combo with some resistance-heating garnish: see late on in this thread with suggestion of PV-powered ASHP to get water to 35C then lift rest of the way with controllable electric shower: http://www.ebuild.co.uk/topic/14185-heating-and-dhw-using-an-ashp-or-immersion-based-system-a-comparison/
On 8 Sep 2014, at 11:25, John Stumbles <EMAIL ADDRESS HIDDEN> wrote:
> On 08/09/14 11:06, Bo Herrmannsen wrote:
>> it was an electric storage heater i had in mind.... cylinder with water
>> in it and and some point an electric heating element
>
> If you really did want to commit the thermodynamic crime* of burning high quality electric energy to produce low grade heat energy and you have a wet central heating system then a heat bank or thermal store would be the sensible way to go. DIY-able with old HW cylinder, plate heat exchanger & CH circulator pump.
>
> Here's a starting point to show the general principles, though this is for DHW http://wiki.diyfaq.org.uk/index.php?title=DIY_Heat_Bank.
>
> Probably most fruitful given availability of PV in warmer seasons when you don't need the CH would be to pre-heat water for the combi using PV-generated heat stored in the thermal store. You'd need the DHW + pump to allow you to use a cheap vented cylinder on a pressurised sealed primary heating system; alternatively could use an unvented cylinder directly but building regs cover installation of unvented so you'd need a qualified installer to do it to be legal.
>
> * (c) David MacKay, although he was talking of burning gas for heat
>
>>
>> at buttom 2 pipe connections... water in and out...
>>
>> 2014-09-08 12:00 GMT+02:00 Damon Hart-Davis <EMAIL ADDRESS HIDDEN
>> <mailto:EMAIL ADDRESS HIDDEN>>:
>>
>> Hi,
>>
>> The key thing I’m aiming for here is short-term controllability to
>> balance second-by-second flows in/out of the house, plus storage to
>> carry that energy to a more useful time.
>>
>> Thus an electric storage heater rather than a normal one.
>>
>> Your DHW idea is in principle fine if done right, but storage in
>> water isn’t plausible for everyone.
>>
>> Anyhow, only a thought experiment, so good to thrash it out!
>>
>> Rgds
>>
>> Damon
>>
>>
>> On 8 Sep 2014, at 10:57, Bo Herrmannsen <EMAIL ADDRESS HIDDEN
>> <mailto:EMAIL ADDRESS HIDDEN>> wrote:
>>
>> > my thought of a tank with electric heater is simply just that i
>> did not know any other hardware that could do the job
>> >
>> > maybe there are a electric heater you just plumb in?
>> >
>> > 2014-09-08 11:43 GMT+02:00 Damon Hart-Davis <EMAIL ADDRESS HIDDEN
>> <mailto:EMAIL ADDRESS HIDDEN>>:
>> > Hi,
>> >
>> > Sorry, not sure if I missed this one or not.
>> >
>> > My thought experiment is for situations such as mine with solar
>> PV and ‘instant’ DHW (no tank, and no solar thermal), which I sure
>> is not unique!
>> >
>> > Thanks for everyone’s feedback: very helpful!
>> >
>> > Rgds
>> >
>> > Damon
>> >
>> >
>> > On 7 Sep 2014, at 15:57, Bo Herrmannsen <EMAIL ADDRESS HIDDEN
>> <mailto:EMAIL ADDRESS HIDDEN>> wrote:
>> >
>> > > hmmm
>> > >
>> > > just on top of my head.... an well insulated hot water cylinder
>> with an electric heating element in series with the rad loop..? then
>> both the gas heater and the electric can heat up the water at the
>> same time...
>> > >
>> > > of course you have to wire in the electric heating element so
>> the system will not boil...
>> > >
>> > >
>> > > in denmark the cylinder normally hold 100 liters of water, not
>> sure if there are space enough in an UK home for that... but if you
>> can get them in 50 liters you could pick 2 of them and place them
>> where there is space
>> > >
>> > >
>> > > but will the gas heater make hot drinking water from that same
>> loop? if not my idea is not worth much....
>> > >
>> > >
>> > >
>> > > 2014-09-07 13:00 GMT+02:00 Damon Hart-Davis <EMAIL ADDRESS HIDDEN
>> <mailto:EMAIL ADDRESS HIDDEN>>:
>> > > Hi,
>> > >
>> > > I have a thought in the back of my mind about carefully making
>> some use of residual exported solar PV generation in winter with
>> highly-efficient storage heaters controllable by an extension of
>> OpenTRV to supplement a gas-fired system. This would also help with
>> grid balancing.
>> > >
>> > > (Yes, I am allergic to electric resistance heating in most
>> circumstances, but if done carefully this might be virtuous.)
>> > >
>> > > Does anyone know of off-the-shelf UK storage heaters that have
>> electronically-controllable fans/vents and that can retain the bulk
>> of their heat for much more than a day, preferably a week.
>> > >
>> > > Rgds
>> > >
>> > > Damon
>> > >
>> > >
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>> > >
>> > > --
>> > > |||||
>> > > @(~Ô^Ô~)@
>> > > -------------oOo---U---oOo-------------
>> > > | |
>> > > | Bo Herrmannsen |
>> > > | |
>> > > | |
>> > > | "blessed are the "cracked", |
>> > > | for its they who let in the light" |
>> > > | Ooo |
>> > > |_________________ooO____( )________|
>> > > ( ) ) /
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>> > --
>> > |||||
>> > @(~Ô^Ô~)@
>> > -------------oOo---U---oOo-------------
>> > | |
>> > | Bo Herrmannsen |
>> > | |
>> > | |
>> > | "blessed are the "cracked", |
>> > | for its they who let in the light" |
>> > | Ooo |
>> > |_________________ooO____( )________|
>> > ( ) ) /
>> > \ ( (_/
>> > \_)
>> >
>> >
>> >
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>> --
>>
>> |||||
>> @(~Ô^Ô~)@
>> -------------oOo---U---oOo-------------
>> | |
>> | Bo Herrmannsen |
>> | |
>> | |
>> | "blessed are the "cracked", |
>> | for its they who let in the light" |
>> | Ooo |
>> |_________________ooO____( )________|
>> ( ) ) /
>> \ ( (_/
>> \_)
>>
>>
>>
>>
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>
> --
> John Stumbles http://stumbles.org.uk
> :-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:
>
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