to the Solar CollectorBrainstorming and Development
Water Project 1
Water & Space Heating
Quote:Exhausting all that air to the outside would totally defeat the ideaQuote:.Not necessarily.A lot of homes have CMV, and *THAT* also exhausts air to the outside ! without totally defeating the idea of heating the home...Also, many folks that heat their homes, open a door every so often, to let the cat out, without this defeating the idea of heating...In effect, heating requires VENTILATION also...Warm air holds more water vapor than cold air (I am not telling a Floridian anything new...), and warm air has bad bugs etc. so it needs to be blown out...The 1 CFM per 50 square foot is not my figure - I found it in the article, and it comes from "building code" (whose ?).In any case, it looks pretty modest to me - imagining a 1600 sq.ft home, we are looking at perhaps ? 400 sq.ft of crawlspace (depending on the shape of the home and the number of floors).So that would come out at 8 CFM of extraction.You would have a hard time finding even a PC case fan that would go THAT slow !(I have one that does 19 CFM).I have a bathroom extractor that pulls 57 CFM; the bathroom is "slightly smaller" than the 400 sq.ft of my CS... However, this wild level of extraction is needed to get rid of the excess humidity after the shower is turned off...My fear would be that heating a CS might actually increase the RH.Therefore venting some CS air to the exterior might not be such a bad idea...Also, (particularly if the heating is "free" anyhow (solar)), then it might be a good investment, to vent, in order to maintain a good air environment in the CS.
Otherwise, heating a CS (provided it is insulated and moisture-sealed) (note that I did not say air-sealed...) has got to be a good idea, like Mike said before, the heat has got to go somewhere...If you don't heat your CS, and it is damp to boot, then it certainly will be sucking heat from the house...So I want a conditioned, heated CS.The conditioning will be based on the 1 CFM law, and it requires works (penetration to get the air in from the house); I already have a penetration that will get the air OUT, just have to get the duct into the CS (through a 20-cm solid-block wall loadbearing wall...).The heating will (eventually) be solar hydronic (and a small infrared radiant backup).I am also using the CS to house my whole house fan, which drags house air from upstairs, through the CS (in a duct) then dumps it in the Lobby - this is for stack-effect mitigation, which is my "other" problem.So working on the WHF fan ducts this week !== And so finally, to answer your question, to sort out Terry, I'd suggest that he installs Crawlspace Radiant Heating; this would require first insulating the periphery walls like U said, then insulating the floor (2 inch of XPS) then laying the PEX directly on the floor, then dumping sacks of gravel over the PEX, and if there is any room left, pouring a liquid screed (LIME SLURRY), over the gravel, to form a slab.There ought be be enough room to get that in, even if it means (temporarily) lifting some floor to get into the CS from above.Otherwise, as an ex-spelunker, I would be game for doing it in situ, it would mean getting some GOOD LIGHTING (not to mention VENTILATION...) down there first...Laying the PEX would require an assistant or two - for the uncoiling. It can be softened by dipping in HOT water...).Sorry this was a bit long (Crawlspace stories usually ARE !)G_H
Hi again, Terry,Interesting document !The header theory looks nice on paper, but I am not sure how well the random headers (in particular) would work, from the circulation viewpoint... In my admittedly non-specialist view, the 1st header would take most of the pressure, and the last one would hardly get any... This could result in uneven temps in the floor... Successive headers suffer from (and generate...) all sorts of complex flow phenomena, Gary Resa talks about this elsewhere on here... Updated for link...http://www.simplysolar.supporttopics.com/post/collector-hydraulics-7308100?pid=1286354414#post1286354414The arguments (Item 14) relate to a vertical panel, not to an horizontal floor, but I suspect the problem is analogous...)==========See if Gary or any other specialists respond on this point...========= Otherwise, I had another think about your underfloor: provided you insulate the CS walls (a must...), and also the floor (just as must...), then you *could* put ANY type of heating in your CS, and get the benefit of it...I am thinking in particular of electric storage heater (with bricks or oil etc.) Or just an uninsulated water tank (our main upstairs heating at home in UK, many decades ago !).This might sound like anathema on a "simply solar" site, but it is "simply" suggesting helping out the solar as you would rarely get 100% solar fraction in any case, for heating. (look at it as the equivalent of having solar DHW, but using an immersion tank as backup, for the off days...).(I'd be careful installing infrared radiant under your wood floor...)Maybe a few 100-watt lamps might just do the trick...In any case, without flogging a dead horse, I would highly recommend insulating the CS outer walls, as a first step.read this ! http://homeguides.sfgate.com/install-rigid-foam-board-walls-crawl-space-66641.html
======== Second thing that intrigues me, is why does your kitchen heat feel so poor...Any drafts in the kitchen ? what type of windows, and walls ? Insulation levels ? Ceiling height ? Do you have a ceiling fan in there, if not, perhaps try one... Lack of thermal mass maybe ?Maybe a plan of the house might help - what is the aspect of the kitchen anyhow ? not dead south, I imagine... Maybe you just (simply...) need a CONSERVATORY !(Are you in Tasmania by any chance ?)G_H
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