[Phys-L] Re: Natural Gas vs Electricity

[betwys1 at SBCGLOBAL.NET (Brian Whatcott)]

At 01:48 PM 10/27/2005, Rick Tarara wrote:
> A note on thermostats--I seem to buy a new one every 5 years.  The latest
> ($50-60) seems to have a couple interesting features.
> ///
> There is another thing that this thermostat does (and I think the previous
> one did as well) but older ones did not.  A couple minutes after running the
> burners and the fan, the fan runs again for about 15 seconds.  That is
> somewhat irritating to me (I still hear pretty well and the one-speed fan is
> reasonably loud).  But I think the reason for that is to clear out any
> uncombusted gas from the burner section.

///

> Richard W. Tarara


There should be no path between house air and the combustion flue.
The combustion CO content, though low is hazardous.
I expect Rick notices that the fan which senses a burner case
temperature, switches off when the case has cooled sufficiently.
The case may then recover in a heat soak effect.
  The other effect sometimes noticed, is that the burner fires up
  for a little while before the fan starts - the case  heating provides
  a lag.  A CO monitor is always helpful in a house gas-heated with
  blown air.


Brian Whatcott    Altus OK    Eureka!