On Dec 10, 9:48 pm, "Edwin Pawlowski" wrote:
wrote in message

Nonsense. Any setback saves energy, no matter how short.

This is 300-year-old high-school physics :-)

Nick


Assuming, as someone earlier pointed out, that fuel costs are
constant, which is usually the case. For example, if you had a
situation with a heat pump where by turning it down too much it
resulted in secondary electric kicking in during recovery, it could
negate the cost savings. Or if you had differing rates for
electricity for a heat pump during different periods, etc.


Is there any limit to what the setback temperature should be?

Only what you can tolerate from a comfort level when you're there and
what the house can tolerate when you're not. If I'm away for an
extended period, I set it down to 45. One factor is as the house
cycles, you may get more drywall cracking do to expansion/contraction.