<div><span style="font-family:Helvetica,Arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">John:</span></div><div><span style="font-family:Helvetica,Arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><br>
</span></div><div><span style="font-family:Helvetica,Arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">"The grid cares about the total size of the electric load (resistive or inductive) and the peakiness of it."</span></div>
<div><span style="font-family:Helvetica,Arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)"><br></span></div><div><span style="font-family:Helvetica,Arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Yes, I agree. Especially when a cold front comes in and temperatures and thermostats drop drastically. Simultaneous switching on of baseboards puts a heavy load on the grid. </span><span style="background-color:rgb(255,255,255);font-family:Helvetica,Arial,sans-serif;font-size:13px">Let's call this "The EastEnders Effect" </span><span style="background-color:rgb(255,255,255);font-family:Helvetica,Arial,sans-serif;font-size:13px"> </span><a href="http://www.bbc.co.uk/learningzone/clips/monitoring-and-responding-to-the-demand-for-electricity/7977.html" target="_blank">http://www.bbc.co.uk/learningzone/clips/monitoring-and-responding-to-the-demand-for-electricity/7977.html</a></div>
<div>When outside temperatures are static, you'll have random switching on and off with no peakiness and no need for the grid to "cope". Billions of dollars in "coping" infrastructure sit idle most of the time just to deal with these swings in demand. Pumped storage and peaker plants should not be looked at as the first line of defence. Demand-side management will go a long way to help right-size the grid. For example: "<span style="background-color:rgb(255,255,255);font-family:Arial">Pumped storage projects are net consumers of energy in that for every one kWh of energy generated during peak periods, more than one kWh of off-peak energy is required for pumping. </span><span style="background-color:rgb(255,255,255);font-family:Arial,Helvetica"></span><span style="background-color:rgb(255,255,255);font-family:Arial">Due to evaporation losses from the exposed water surface and mechanical efficiency losses during conversion, only between <font size="4">70% and 85%</font> of the electrical energy used to pump the water into the elevated reservoir can be regained in this process."</span><a href="http://uspowerpartners.org/Topics/SECTION2Topic-PumpedStorage.htm">http://uspowerpartners.org/Topics/SECTION2Topic-PumpedStorage.htm</a>. So, we end up inflating our base load infrastructure to deal with the peaks! That's why I don't worry too much about the minimal thermal loses on my well insulated 375 watt water heater and think triacs have a place in helping an overburdened grid.</div>
<div><br></div><div>Cheers,</div><div><br></div><div>Richard</div><div><br></div>
<br>=====================================================================================<br><div class="gmail_quote">On Mon, Dec 19, 2011 at 8:01 PM, John Straube <span dir="ltr"><<a href="mailto:jfstraube@gmail.com" target="_blank">jfstraube@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Modulating electric heaters WONT save money if you discount the
unproven (and unlikely in my opinion) comfort savings. Exact same
energy will be delivered.<br>
All that changes with any strategy is temperature stability.<br>
It is quite easy to buy a new electronic thermostat for baseboards
that control +/-0.5. The built-in thermostat that often come with
baseboards often are +/-1.5F.<br>
<br>
I sure would not recommend these for most space heating
applications. For special applications, they are neat.<div><br>
<br>
Dr John Straube, P.Eng.<br>
<a href="http://www.BuildingScience.com" target="_blank">www.BuildingScience.com</a><br>
<br>
<br></div><div>
On 11-12-19 6:13 PM, Corwyn wrote:<br>
<span style="white-space:pre-wrap">> On 12/19/2011 5:32 PM, John
Straube wrote:<br>
>> You cant use a normal on-off thermostat with a modulating
control. <br>
>> The simplest thermostat for use with an SCR or TRIAC
would have<br>
>> what is called proportional control. For example, if the<br>
>> temperature fell below 68F by 0.1 F, 100W would be
delivered to the<br>
>> heater, of the temperature dropped to 67.8F, 200W would
be provided<br>
>> and if it dropped to 67F, 1000W would be delivered.
Because a<br>
>> smaller amount of heat is added with small temperature
drops, the<br>
>> temperature does not oscilate as much as an on-off
control with a<br>
>> 3F deadband as described in the example.<br>
> <br>
> But, it isn't, in fact, delivering 100W to the heater. It is<br>
> delivering 1000W to the heater for 1 second out of 10. Or
perhaps<br>
> 0.1 seconds out of 1 second. I guess that is the point I am
trying<br>
> to make.<br>
> <br>
> Since I have trouble believing that anyone *needs* within
0.1F<br>
> stability in their house temperature; a thermostat upgrade
will get<br>
> most of the accuracy improvement anyway; and since no one has
shown<br>
> energy savings, I would recommend these only if the lifecycle<br>
> benefits make them cheaper.<br>
> <br>
> <br>
> Thank You Kindly,<br>
> <br>
> Corwyn<br>
> </span><br>
<br>
</div></div>
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