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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.<br>
<br>
Dr John Straube, P.Eng.<br>
<a class="moz-txt-link-abbreviated" href="http://www.BuildingScience.com">www.BuildingScience.com</a><br>
<br>
<br>
On 11-12-19 6:13 PM, Corwyn wrote:<br>
<span style="white-space: pre;">> 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>
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