"Nancy Young" > wrote in message
>
> My furnace does not measure the heat by the dishwasher, it measures
> the heat by the thermostat. Particularly annoying when the sun comes
> through the skylight and hits the thermostat and it gets really cold in
> here because the furnace won't run.
>
>> The heating source doesn't have to be blowing onto the thermostat for
>> the heat to have an effect.
>
> No, it has to reach the thermostat.
> Of course it's warmer if you're sitting in front of the dishwasher when
> it's venting the heat. That's not what we're talking about. We're
> talking about the furnace noticing it. Maybe in your house you can
> just have one heat vent in one room because hey, the heat just homogenizes
> through the house. Me, I have a heat vent in every
> room because otherwise the heat would be uneven.

A technicality here. Even though you have vents in every room, the air does
drift around in slow currents and the currents change throughout the day as
different rooms get sunlight, heat from the shower, the stove, the furnace,
the dishwasher, the dog, you, your spouse, etc. If the particular heat
generated by the DW does not move to the thermostat, it prevents other
warmer air from moving to that area from another, maybe even where the
thermostat is.

Heat constantly seeks cooker areas. This is one of the laws of physics,
solidly founded and proven. You don't have to believe it, but you can't
change it. Take a candle and move it up and down in the stairwell and you
may see a more dramatic movement of air.

Check the temperature of you bedroom overnight compared to the rest of the
house. You will see the temperature will be a bit warmer than other rooms
because the average body gives off about 450 Btu of heat every hour.
Calories = energy. Your body burns the calories and give off heat. Crowded
stadiums in winter don't need heat, but often need cooling when you add
20,000 bodies giving off heat.

In any case, heat from an appliance is not wasted during heating season.
Body heat info
http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd102_e.html