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

[Mark Wigmore]

Hi Damon,

I had storage heaters until a year ago when I switched to gas central
heating. I had some fairly modern storage heaters and their design is such
that there is a constant air flow through the core. There are dampers to
increase the flow ('boost') but I don't know of any design that will stay
hot for more than a couple of days. Having said that, I can see that they
could be used in conjunction with PV as a kind of reverse Economy 7,
heating up during the day when there's surplus generation to provide warmth
in the early evening. As you say, +/- one or two months around the winter
solstice there might be little benefit, but in spring and autumn there
could be something. The alternative is to dump the energy into the hot
water system via an immersion heater, as that's used all year round, but if
you're going to do that it might be better to use solar-thermal panels
instead.

One thing I have noticed since removing the storage heaters is that in the
summer there is a much wider variation in room temperature. I think they
were actually stabilising the temperature by acting as a sink in the day
and a heater at night. I kept the boost dampers open from spring to autumn
to enhance the airflow for this effect.

Hope this is of interest,

Mark

PS I still have the storage heaters if you want to experiment.

PPS Another thought that's just occurred to me is to use the excess PV to
run a reversible heat pump, maybe using storage heater bricks on one side
of the pump?


On 7 September 2014 12:28, Damon Hart-Davis <EMAIL ADDRESS HIDDEN> wrote:

> Hi,
>
> This isn’t particularly about money (or indeed carbon yet), though given
> the ratio of export to retail tariffs it might pay off.  And the generation
> component is paid just the same.  And many people’s export is ‘deemed’
> anyway.
>
> This is about attempting to minimise grid flows to/from a house which has
> some virtues of its own, and looks trickier than I had expected given how
> fast power generation from PV varies from my own measurements.
>
> Note that in our case because of our E- and W- facing PV we generate
> relatively little power in winter, but still probably only get to consume
> about 50% of it in house because of timing, and a resistive heating dump is
> probably the most robust thing to practice on!
>
> Rgds
>
> Damon
>
>
> On 7 Sep 2014, at 12:21, John Stumbles <EMAIL ADDRESS HIDDEN> wrote:
>
> > On 07/09/14 12:00, Damon Hart-Davis wrote:
> >> 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.
> >
> > Wouldn't you get more money selling PV 'leccy back to the grid than it
> would be worth to you as heat?
> >
> >
> > --
> > John Stumbles                                    http://stumbles.org.uk
> > :-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:
> >
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