Article 31420 of alt.solar.thermal: Path: news.misty.com!not-for-mail From: nicksanspam@ece.villanova.edu Newsgroups: alt.solar.thermal Subject: Re: Thermal Mass equation help needed Date: 11 Nov 2008 06:26:40 -0500 Organization: Villanova University Lines: 31 Message-ID: References: <43a9b01c-9f10-404c-8c20-6415da22e544@u29g2000pro.googlegroups.com> NNTP-Posting-Host: acadia.ece.villanova.edu X-Trace: max.inside.misty.com 1226402802 23610 153.104.44.130 (11 Nov 2008 11:26:42 GMT) X-Complaints-To: abuse@misty.com NNTP-Posting-Date: Tue, 11 Nov 2008 11:26:42 +0000 (UTC) Xref: news.misty.com alt.solar.thermal:31420 wrote: >Through a combination of passive solar heating during the afternoon, >and a wood fireplace insert from late afternoon into mid evening, I am >able to maintain an early evening living room temperature of 72F with >ease. As the fire burns out overnight, I typically find the living >room temperature around 61F in the morning. > >So we are experiencing at a drop of 11F (72F-61F) over roughly 8 hours >(10 pm to 6 am). > >My goal is to reduce the overnight temperature swings. A minimum of >around 65F in mid November would suffice. I estimate this would >equate to living room minimum temp around 61F in late January, which I >can certainly live with. > >My initial plan is to add 40 lbs of water storage in the vicinity of >the fireplace insert. Not close enough to melt the plastic of course, >but maybe 5 feet away off to the side. > >I'd appreciate some help in estimating the amount of difference this >would make in compressing the overnight swings, and if I may need to >add more thermal mass. A pound of water releases 1 Btu of energy as it cools 1 F, so 40 pounds cooling from (say) 120 to 70 would store (120-70)40 = 2000 Btu. Burning a pound of dry wood at (say) 60% efficiency releases about 0.6x10K = 6K Btu, so the water might store the heat equivalent of 1/3 pound of wood. Nick