Frank wrote:
> Just a couple of questions.
A couple of half answers, a freindly offer of personal challenge, a few
recommendations and a vision of the future:
> Second I am thinking of a 12 over 12 pitched metal roof with a gutter system
> for rain water collection.
> Do you know what the angle of such a pitched roof is? is it 45%?
Basic geometry, Frank. A 12:12 pitch means the roof rises 12 inches (or
feet, or whatever unit you want) for every 12 inches (or feet, etc.) of
run. Draw it out once and give it some thought. I'd like to see you
understand it not just take the numbers someone else gives you. This idea
comes from a loving desire to see people realize their own abilities. If
you aren't up to the challenge, let me know and I'll give you the numbers
next time : )
> Like you said it's sometimes hard to "fit" heating and cooling dates for
> optimum performance of both. OK if I choose a date of April 15 for
shading the
> south facing vertical glass what date would I use for the same sun angle in
> the fall... October 15?
I'll answer this question the same way. Please let me know if you hate
this kind of response. I don't know you well enough, but feel this is
ultimately a better way.
Yes, it's hard to compromise on a pair of dates for shading. As I said in
my last message, the pair of dates must be the same number of days from the
summer solstice, so that they will be the same angle.
> Next do I specify a particular time of day to derive that angle for my
> latitude and longitude?
Yes! You must use solar noon, when the sun is at the zenith (at the
highest point in the sky of the day) for all of your calculations.
Longitude, by the way, has little effect on these calculations.
> Ok. This is a metal roof so the overhang can't be too long else I'll have to
> support it won't I?
I assumed you would have rafters so that the roof could stick out beyond
the wall. Otherwise, you won't have much of an overhang to work with. I
don't see how you can avoid having supported overhangs and get it to work
for shading. In our area decent overhangs are important to help protect
the wall from rain. We don't have snow or ice to worry about (ice dams, etc.)
> If you used same angle on East and west eaves and vertical glass would
this be
> an OK solution , or would I be better served to change that angle for better
> control?
The same angle will do something to help, but not as effectively. You
shouldn't be designing in a lot of windows on the west (or east) anyway, as
these will not be very advantageous for solar design. It is a lot easier
to build when all of the roof overhangs are the same, so I would recommend
minimizing the glass on the east and west and not worry too much about the
overhangs there. (The calculations for effective overhangs on the east and
west are quite involved, and so is building them.) It sounds like you are
planning to have a hip roof. Is that true?
> <<I like the way our radiant heating has worked this winter>> Can you
tell me
> a bit more about your system...Brand, cost, sizing...the more details the
> better:) Do you have tubing buried in a slab? Do you have a basement?
I built the system myself, so there is no brand name except on individual
parts. We are heating the floors of our down stairs (880 s.f.) and not
heating the upstairs (so far this seems okay, never getting more than a
couple degrees cooler than down stairs). We are using a domestic 50 gal.
natural gas hot water heater with a heat exchanger to provide the heat. We
were told that it would provide plenty of BTU compared to our heating
needs. This seems correct, as we have had no problems with insufficient
hot water - actually, the system usually only runs at night when we're
asleep adn not using hot water. The tubing is in a thin (1.5 inch) mortar
bed (which could also have been some other kind of cementitious material)
on a raised wood sub floor which is over a crawl space.
Note that your needs will depend on the amount the heat needed to keep your
house comfortable which is based on many things like local outdoor
temperature patterns, tightness of construction, amount of insulation,
amount and efficiency of glass, size of house, shape of house, etc. Our
areas are different enough that the details of my house can only serve as a
take off point for yours. I designed my own system (and house) after doing
much research, but still took my design to a professional radiant heat
company for their advice. Something I would recommend. For $400 I got
their design which varied from mine somewhat, and I made some changes in
my design based on what they said. I did not use their design as is
because I already understood how heating worked in general and knew the
specifics of my house and adjusted things to my satisfaction.
> <<but if I ever
> built again I would keep things very simple, even primitive, because I'd
> like to be able to make all of it and fix any of it myself and not rely on
> factory made parts. >> Huh? Are you unhappy with the RF...or are you more
> concerned with possible future failures?
It's working well, and for many people who want a thermostat controlled,
automatic, no hands on heating system, it is a great choice. It is
probably one of the most efficient and healthy systems. Since I did it
myself, I didn't have to pay specialists to do something that is still
relatively uncommon. The material costs were very reasonable, I imagine
less than doing your own furnace system.
I assume there will be some kind of future failures, eventually, as with
anything, but this is not my main concern. I am looking forward to a time
in the future when people will have to make homes and heat them with local
materials and skills. I don't see distant factories using complicated
systems of machines and energy to make complicted gadgets from matierials
gathered from around the world. Yes, we can just take what is available to
us now and put it to good use, but personally I have taken on the challenge
to look for the ways of the future. My current house does not satisfy me
in this respect. As a modest, effiecient home suited to its site, it is a
great transition for most poeple in our (sub)urban culture, but I am ready
for the next step.
> I had considered these (masonry Stoves) but have found the real world
costs > far higher than I had hoped. In addition it seems that system must
be carefully > built, and
> engineered. Improper installation performed by inexperienced local workmen
> could be a real problem. Too bad they are so costly, and complicatedc to
> install I like the idea, and simple physics.
I would take the time to learn about them, including how to build them
(possible future career?), but that is just my nature. This is much
cheaper than hiring it out, and in the end you're better off. But even if
you hired it out, it's only a one time cost. The simplicity of the system
has many benefits over the life of the system. How long will a circulating
pump or hot water heater work? a gas furnace? A masonry stove, with
minimal attention, will last for generations and can be made and repaired
with simple materials when necessary.
> << I would recommend that you build something small and not so critical in a
> method you think has potential and learn on that project before you build
> you main house>> Normally this makes good sense. problem is I'm under
> enormous time constraints . We can't move until we get the house
finished.And
> we need to move down there as soon as possible. I'm in NY ...so that's a
15 hr
> trip to the farm in Kentucky. We had considered renting locally but it's
not
> really feasible in our circumstances.
I get the impression that you are pushing the limits (time, money, skills,
knowledge, etc.) with this project. That will require some careful
balancing, so that one (or more) of those factors does not over influence
to the detriment of the others. I admire your ambitions, and you certainly
seem to have your heart in the right place. Again I recommend that you
start small. Design the smallest, simplest house you can imagine, and then
take off 10% more. (We moved into a 32' camping trailer for the last two
years.) Build it, move in, and then work out the rest. Don't waste your
money building a larger house compromised by time and finances. By the
time you finish the little house, you'll know a lot more for your main
house. You can be more experimental, and practical if you design that
little house to serve a purpose later on. You have mentioned a rather
large vision for your property; I'm sure a little living structure could
fit into that.
Good Luck and Good Wishes
Eric:
