Gas and Oil Home Heating Furnaces - Propane rate of use.

We had a new heat pump w/ a propane furnace backup system installed over the summer. The propane furnace is set to kick on when the outdoor temp goes below 35F, and we have a 100 gallon propane tank. We turned our heat on approximately 6 weeks ago, and the temperature started going below 35 regularly at night approximately 3 weeks ago (we live outside of Philadelphia PA). We woke up to a cold house over the weekend and I discovered our propane tank was bone dry (0 PSI). I find it very hard to believe that we ran through 100 gallons of gas in this time period. Of course the gas company said we "were on the schedule to be refilled last week", which obviously never happened.

Does this sound like a typical rate of use for 100 gallons of propane in a back up system?

35˚ lock out is too high.. I would bump it down lower..

What is the make/model of t-stat you have there?

Also, when the tank goes that low/empty, I would have someone check your heat exchanger to make sure it didn't get all shooted up from the burners.

Anything else in the house on gas?

How much lower would your reccomend? We used to have an electric strip backup heat pump, and we couldn't stand the electric bills during cold spells. I was hoping the propane would be a nice upgrade w/ the new system being installed, but at this rate I'm starting to wonder.

Our t-stat is a Honeywell TB8220U or TB8321. I'm not at home right now to verify, but after a quick search online I'm pretty sure it's one of those models.

We have all electric appliances, nothing else uses this this propane.

How much lower would your reccomend?

I would start off at 15˚ and if you don't feel the comfort, then you can bring it up more if needed.

I was hoping the propane would be a nice upgrade w/ the new system being installed, but at this rate I'm starting to wonder.

Well, the 100 gallon tank isn't very big.. So yeah, it's going to run out faster.. What do you have for a furnace?

Our t-stat is a Honeywell TB8220U or TB8321.

You mean TH8320.... TB is used in commerical buildings.

Is it a DIY task to switch the setpoint where the furnace takes over for the heat pump? I've pored over the t-stat manual and see nothing about a setting for this.

Our t-stat is actually the Honeywell VisionPRO IAQ Dual Fuel model (http://yourhome.honeywell.com/Consumer/Cultures/en-US/Products/Thermostats/Programmable/Professionally-Installed/VisionPRO+IAQ/Default.htm). We have a Trane XL14i Heat Pump, and a Trane XR90 Gas Furnace.

Here is the manual. (http://customer.honeywell.com/techlit/pdf/69-0000s/69-1816EFS.pdf)

You can make changes of your set point.

Just for kicks, why don't ya make notes of what settings is what, and I'll be happy to go over it with you to make sure it's all good.