Theory question

[mjcp]

I have done a lot of work on old furnaces and am pretty familiar with the whole theory of operation. I recently began the learning curve on my Pool Heater which operates basically the same as the furnaces I am familiar with. The pool Heater is a Millivolt system, and is able to run without a connection to the electrical system.

Why isn't this sytem used in the home furnaces? I can't think of any reason this wouldn't be workable, and I can only think of all those freezing cold nights when the power goes out in an Ice Storm. What downside am I overlooking?

Thanks for the education

[mjcp]

Thanks for the reply, I knew I was overlooking something obvious, AND I WAS!!

[heatseeker]

they do use them in homes, floor furnaces, wall furnaces and gravity furnaces. Don't forget water heaters