BTU calculation`s,,,window question?

[johnn]

All windows have been replaced with "PELLA" double pane,,,low E. I have insulated approx. 70% of the rough openings with foam and fiberglass as the trim work was down on these. When calculating btu loss,,,do you measure just the pane or should I include the trim boards into the measurement just for a safety margine?

Anyone familiar with the formula for calculating, cu. ft. size of firebox? (rather strange shape they are)

One more question,, The old girl does not have an upper baffle which I intend to install. Currently the outlet has a not so close manual damper which does effect the draft, however seems to serve the better purpose of blocking flames from going straight out when firing new load. The opening is 14"x2", the same volumne as a 6" round. Since fabrication is not an issue,, would I favorably influence the burn circulation pattern and the exhaust draw, past the baffle by converting the rectangle outlet to a round?

Thanks, ml

 

[johnn]

Sorry moderators and so forth,,,seems I snuck in a couple question not related to this category. Most likely can reach my own answers on those issues,,,dont really wont to clog up the air waves. Really, delete both posts if possible.

 

[dave11]

As for the heat-loss calculation, unless the areas under the trim are pretty large, they won't make a noticeable difference in the the heat-loss calculation under any circumstances. If the R-value of the trim areas is closer to the R-value of the walls, then add the trim area to the wall area. If the R-value is closer to that of the windows (the inverse of the U-value), then add the area to that of the windows.

Can't answer your other questions myself though.

 

[johnn]

Maybe I wouldn`t have figured that out for myself! THANK`s,,,makes good since,,,maybe thats why the answer evaded me!!

 

[burntime]

Either way I can't see it making a lot of difference each way. I replaced most of my windows with anderson 400 series from single panes. It make a whole lot of difference. SOme on the forum will disagree but I bet it decreased the required btu by 10-15 percent! Pella were good too, my only complaint was the screen was on the qrong side and when you close it the bugs were on the inside of the home???

 

[johnn]

You bet they make a difference,,,Love my new windows. Having lost my 182" circum. "Old Oak" shade tree,,,which shaded the south and west side`s,I elected to make my own full screens using solar screen and it keeps the bugs on the wright side!