Hudler wrote:You really aren't saving any money by dropping the thermostat when your not home. Think about it,how much longer is your furnace running when you get home to get it to a temp that is comfortable? In most cases I've seen it's running longer than it would beif you kept it at the temp you liked best.
I install and service furnace and AC systems for a living and two of the biggest misconceptions out there are the one above and closing off rooms will save you money. A high efficiancy furnace is designed to push a set amount of air volume and shutting off rooms can play hell with it sometimes,besides that,most interior walls are not insulated which is gonna cool off the rooms you are still heating faster.
If you keep your house at a warmer temp during the day, you're going to lose more heat to the outside. Yes, the furnace runs longer when you get home, but it shouldn't run basically all day in a climate like St. Louis. I doubt most days that my house even drops to the low 50's while I'm gone.
I can see your point with shutting off rooms adversely affecting the HVAC, but in my case both rooms I shut in are on the same duct run. I don't think I'm really affecting my flow to other vents. If it was shutting off a vent at the end of a run, I could see that it doesn't do much good--you might as well let the vent open. As for losing heat to those rooms, it's better to lose some heat to the rooms from the rest of the house than to be consistently heating that extra volume of air, no?
(I'm not spouting off out of complete ignorance either. I've had a few thermodynamics courses in my day, so I stick with the general principles of volume of air I'm heating and where I'm losing heat out of the system. But I'll defer to your judgement on HVAC matters--I've steered clear of HVAC systems in my career.)