Cold Start-up

Brian_18

I couldn't find this tid bit of info., I figure it will take a week to bring everything up to temperature. I connected my radiant floor 3-car garage last month to my house system, and after a couple of days I began nervously re-calculating because the garage was still quite cold. By the second week, the garage warmed up nicely.

Brian_18

Groundhog Day was the comissioning of my coal boiler heating system for my work shop building. 2400 sq. ft. insulated steel building, 5" concrete slab (32 yds when poured) radiant, fully foam insulated under, and perimeter.

This is a cold start-up, building temp inside 34° F, slab temp 41°F. I know it will take quite a long time to bring things up to temperature.

Question is, can anybody tell me how to calculate the BTU's required to raise the temp of the slab 1° F. ?

Assuming zero heatloss to the ground, and zero heatloss to radiation of building. I guess we're talking specific heat of concrete.

This is just my curiosity factor to know how many BTU's I will eventually pump into the slab until the biulding is up to comfort level.

Tom Blackwell_2

My reference material(ASHRAE) shows the specific heat of concrete with sand/gravel aggregate to be 0.22-0.25 based on moisture. At 150#/cubic foot the total weight would be 130,000lbs x .25 = 32400; so approx 35,000 btu/ degree rise with no loss. Hope this helps...