rancherburn said:
I have an owb heating two seperate buildings one has in floor the other is forced air. I recently did some temp drops on the underground lines they're 125' to each building 250' all together. I'm seeing a 5 degree temp drop on both lines when there is no load. with grundfos pump on low i'm guessing about 7 gpm. so that would mean my boiller temp is dropping 5 degrees every 15 minutes. so i was thinking about zone valves only circulating when there is a load the rest of the time circulating just the boiler. i've seen wireless thermostats on line wondering if this would be an easy fix. or don't you guys think i will see enough savings to mess with it. any input would be greatly appreciated.
Well here's the math........
7gpm x 8.33 x 5 x 60 = 17,493 btu's lost per hour ........Egad!!
17493 x 24 = 419,832 (per day)
419,832 x 7 = 2,938,824 (per week)
Avg btu content per cord = 21,000,000
21,000,000 x .50 (efficiency....generous for an OWB) = 10,500,000 btu's
10,500,000 / 2,938,824 = 3.58 so.....
Every 3-1/2 weeks you are burning an extra cord of wood provided the info on temp drop and flow are correct.
So what does a cord of wood cost you?
A Honeywell wireless programmable t-stat will set you back around $300 m/l (YTH6320R1009)
A couple 1" zone valves will be around $130 m/l (V8043E5079)
You'll have somewhere in the neighborhood of $5-600 in the stat and ZV's (good pro grade stuff)
So again.........what does a cord of wood cost you?
Hope that helps