[OpenTRV-interest] [OpenTRV-dev] Storage heating, dynamic demand, and OpenTRV

John Stumbles EMAIL ADDRESS HIDDEN
Mon Sep 8 11:25:25 BST 2014


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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