[Greenbuilding] Triac Thermostats

[John Straube]

As far as any physics I have seen, electric resistance water heaters and baseboards are both 100% efficient. Modulating the output does nothing to improve the efficiency. 
The efficiency of the grid is around 30%, so electric resistance heat is around 30% efficient. 
Use a heat pump at COP of 3 and you are now around 90% efficient.  

I won't comment on oil heat since this is a small and rapidly shrinking form of heat. 

Sent wirelessly from my BlackBerry device on the Bell network.

-----Original Message-----
From: Carmine Vasile <gfx-ch at msn.com>
Date: Wed, 21 Dec 2011 18:27:24 
To: <jfstraube at gmail.com>; GB Forum<greenbuilding at lists.bioenergylists.org>
Subject: RE: [Greenbuilding] Triac Thermostats


John: You are referring to electric resistance heating not electric hot-water heating, which can be twice as efficient, cheaper than oil, and far more comfortable.  "Exact same energy" will not be delivered because resistance baseboard heating is far more wasteful. I've  used both.Happy HoliidaysCarminegfxtechnology.com 

Date: Mon, 19 Dec 2011 20:01:43 -0500
From: jfstraube at gmail.com
To: greenbuilding at lists.bioenergylists.org
Subject: Re: [Greenbuilding] Triac Thermostats


  


    
  
  
    Modulating electric heaters WONT save money if you discount the
    unproven (and unlikely in my opinion) comfort savings.  Exact same
    energy will be delivered.

    All that changes with any strategy is temperature stability.

    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.

    

    I sure would not recommend these for most space heating
    applications.  For special applications,  they are neat.

    

    Dr John Straube, P.Eng.

    www.BuildingScience.com

    

    

    On 11-12-19 6:13 PM, Corwyn wrote:

    > On 12/19/2011 5:32 PM, John
      Straube wrote:

      >> You cant use a normal on-off thermostat with a modulating
      control. 

      >> The simplest thermostat for use with an SCR or TRIAC
      would have

      >> what is called proportional control. For example, if the

      >> temperature fell below 68F by 0.1 F, 100W would be
      delivered to the

      >> heater, of the temperature dropped to 67.8F, 200W would
      be provided

      >> and if it dropped to 67F, 1000W would be delivered.
      Because a

      >> smaller amount of heat is added with small temperature
      drops, the

      >> temperature does not oscilate as much as an on-off
      control with a

      >> 3F deadband as described in the example.

      > 

      > But, it isn't, in fact, delivering 100W to the heater. It is

      > delivering 1000W to the heater for 1 second out of 10. Or
      perhaps

      > 0.1 seconds out of 1 second. I guess that is the point I am
      trying

      > to make.

      > 

      > Since I have trouble believing that anyone *needs* within
      0.1F

      > stability in their house temperature; a thermostat upgrade
      will get

      > most of the accuracy improvement anyway; and since no one has
      shown

      > energy savings, I would recommend these only if the lifecycle

      > benefits make them cheaper.

      > 

      > 

      > Thank You Kindly,

      > 

      > Corwyn

      > 

    

  



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