"George Patterson" wrote in message news:%S2Ig.1420$pX3.1301@trnddc07...
Pszemol wrote:

What temperature drops have you observed and how fast ?

This was years ago, but, IIRC, the outside temperature was in the single digits.
The drop of temperature in the house went from the low 70s to the low 50s or
high 40s in the space of 45 minutes. My tank was either 100 gallons or 125 (I
upgraded during that period). The temperature drop was about 6 degrees, maybe more.

I had no idea a whole house can cool down 20F or more in 45 minutes...
But the 100 galons tank going down 6 degrees in the same 45 minutes is a real mistery.

However, even if your termometer was not broken and these numbers are real,
I would still not use the back up power to run heaters... they are not that critical.