cost to operate boiler systems

Mike T_4

I am building a barn/apartment/office that is approximately 6000 sq.ft. I live in the country and have thousands of trees on our property. I was considering having in floor heat and using a wood gasification bioler as a heat source (possibly a HS Tarm product). Additionally, I might consider a dual fuel unit. Based on heat loss calculations, I need a unit that supplies 148,000 BTU/Hr. Here's my question: What do you think about boiler systems (wood) as a heat source? Also, does anyone know the cost to operate a gas boiler system? I'm only looking for a ball park as I understand that the cost to operate depends on many factors. Any input would be appreciated.

Mike

Brad White

Getting heat from your wood, twice...

My dad always said that should I be splitting any wood.

If you know your location's design temperature and degree-days, you can get pretty close. The formula is:

Heat Loss in Btuh)x(degree-days)x(24 hours)

(Design "Delta-T" Ti-To)x(Eff.)x(Fuel Units)

All of this is multiplied by a Cd factor, an empirical adjustment that takes into account solar gains, internal gains and other variables. This averages between 0.4 and 0.7. For my area of about 5,500 DD's it is about 0.6.


Say you have 148,000 BTUH heat loss at an indoor temperature of 70 and outdoor temperature of zero. You burn gas at 100,000 BTU's per therm and at 80 percent efficiency. You have 6,000 degree days. (Don't get excited! So does your neighbor.) Say your Cd factor is 0.60.

This works out to 2,283.4 therms burned per year times your cost per therm in your area.

The cost of wood? Heck. I dunno.

Let me know roughly where you live and I can narrow down your actual degree-days and design temperatures.