free heat for the garage? "green"

Any of the heat recovery systems I've seen that harvest so called "free" energy have been marginally effective in really cold conditions and fairly expensive to set up and maintain.

You did not say what kind of heater you had removed from the building but the rated heating capacity would indicate it was an old furnace of some type.

You say you need around 20,000 BTU to heat the space. For convenient and reasonably efficient short period heating of this nature I'd sure suggest you think about using a ceiling mounted electric shop heater. This would conserve your floor space and be quick and easy to install.

20,000 BTU is not a lot of heat. A little under 6000 watts of resistance heat would do the job. If you use a 220 volt heater that's going to be just under 28 Amps. If you ran this for one hour that would be 6 Kilowatts on your meter. Depending on the going rate of power in your area, here it's around 6 cents per kilowatt hour which would be $.36 per hour of run time, you can figure the cost. I'd guess the heater would cycle on for less than half the time unless the weather is really cold and/or have poor insulation.

This page give a good fuel cost comparison, it's based on coal but a bit of number punching will give you a lot of information.

http://www.readingstove.com/support_chart.html#wood

Mike

the furnace i pulled out was a natural gas furnace just like one out of a house. i had the natural gas pipe to the garage disconnected when they were digging for the city water and sewer. i didn't reconnect it because they twisted that pipe around so much that i'm sure its going to leak. its just a 1/2" copper line buried 6" below ground and then it goes above ground for about 3' before going into the back of the garage. looks fairly corroded back there too.

i'm having second thoughts on that 20k BTU calculation. the garage is insulated with about 2" of cardboard behind the sheet rock and has 4" of real insulation in the attic. so its not a lot of insulation but it was enough to keep it right around freezing through most of last winter without any heater. i think there was about 2 weeks where the water froze in the garage. also its really humid in there during the winter.

i was thinking about making a 4'x8' solar heater and tilting it towards the sun and it would just put out free heat on days when its available. then have another heater of some kind i could run while i'm in there.

something like this would be nice, but i'm sure all those bricks would be spendy.
http://www.youtube.com/watch?v=-jzKKIHhTU0

I'm personally not real fond of that type of heater. This fellow is calling it a "rocket heater" but they go by other names as well. For short term heating that heavy brick construction would require quite a bit of time to heat up and really start putting out some usable heat. The heavy masonry would hold heat and tend to help keep the area warm for a longer period of time after the fire went out however. One of the major drawbacks of this kind of furnace is the inability to control the draft. Since the draft is always open, to allow the insertion of longer pieces of wood such as old boards and fence posts, without cutting them up, the amount of heat is controlled by how much fuel is added. This open draft will draw a large amount of heated room air thru the furnace and up the chimney at all times. Even after the fire has gone out there will be a flow up the chimney due to convection of warmer air moving up. While this kind of furnace works well in some limited applications I would surly not recommend it for your application.

If you are interested in burning wood I'd suggest a good airtight wood stove which can often, in this area at least, be found on CraigsList and other such sources at reasonable prices. The cost of the chimney would be the same, or possibly less, than what would be required for the "rocket stove" and the fuel consumption for usable heat would be much less. I'd opt for a really small stove and avoid as many frills as possible.

Since you have limited insulation and an ongoing moisture problem wood heat would be a good option. The addition of an electric dehumidifier for winter use may be advisable regardless what kind of heat you select. The dehumidifier, I have one from Sears in my gun room, will remove a lot of moisture and add heat to the area as it does so. In your case this would be a double advantage.

If this is an attached garage and has had NG to it previously you may want to consider adding a NG space heater to the area. Natural Gas is usually one of the better and less expensive sources of heat and for your intermittent use would be clean and quick. The chimney required is usually simple to install and made from "B Vent" which is quite a bit less expensive than all fuel or wood burner chimneys. I would avoid the ventless heaters as this would aggravate the moisture problem you already have.

Mike

well NG is sounding more practical. i just have to hook the pipe back up and test it for leaks. its a separate pipe coming from the gas meter straight to the garage. garage is not attached, sits about 20ft from the house.

i do have a dehumidifier, which is a good idea to remove the humidity. but what are the chances of breaking it if it freezes?

i still want to try the solar heater though.

The dehumidifier should be cold weather tolerant. The one I have I used in a service van for a number of years and it was subjected to freezing weather with no ill effects. I did make sure the water collection tank was either empty or very nearly so when I thought it might freeze up. That plastic tank could easily break if allowed to get solid when full. Where the unit is now I have a hose that carries the water to a drain so no longer have to dump the tank. You may be able to do the same or just route the hose outside.

NG would be my first choice if it's not too much of a problem to get it hooked back up. With just a 20 or 30 foot run you may want to put in new pipe and be sure of no future problems.

Mike

Can't give you a good answer on the gas pipe. Local codes vary on this, particularly with buried lines. I know in this area you can use black iron, coated black iron and one of the newer flexible metal tubes. What's legal here is not legal in another part of our state.

I'd suggest you contact your local gas company and see if they have a service and install program. Often they do and will run a new line in for free just to get the additional usage. They will at least be able to tell you what kind of pipe to use. Not unusual for them to have special deals for heaters and such as well. A source for good used equipment is often contractors in the area that have taken heaters out of buildings during a remodel.

Good luck with your project, once you get some heat in that shop you'll probably spend most of the winter there.

Mike

For natural gas, the plumbing code calls for "black" steel or galvanized steel. Copper is not suited for NG due to the sulphur content in NG. It will eat the line up especially around the flare fittings (normally seem as black or green areas below the fitting). Do yourself a big favor and use steel or poly pipe (underground only and not disturbed by frequent digging/dig ins). 1" is best suited for a gas furnace to give sufficient flow. PM me if you need more help. Best of luck.

Do you have south facing window in your garage? Or even an east or west facing window?

If so, her is a link to a cheap and easy to build solar heater that I have read great reviews about.

http://www.motherearthnews.com/Renewable-Energy/2006-02-01/Do-It-Yourself-Solar-Heat-Collectors.aspx

I have also read about some people modifying the design to work with a simple wall. I don't see why it couldn't. To me, the possibilities of this solar heater are wide and many.

i still want to make the solar heater but i need to figure out how to make it without spending a fortune. the most expensive piece will be the clear plastic. i was looking at different things at menards and the clear plastic in the window area was over $50. in the roofing area they had the wavy clear plaster for $25 but i don't know if that stuff would work okay or not. its also UV protected and i don't know if that would lower the efficiency.

and then i've been looking at radiatent NG heaters, they doesn't seem to cost a lot. Mr Heater 25k radiant heater
although they don't have any vents, so it'll make the humidity an even bigger problem.

DJ in WV: thanks for the link. unfortunately i don't have any windows in the garage. but thats a neat idea. i wonder if you get more air leaks with the window part way open though.

ancy: how much does a wood burner cost installed? i don't think the rebate will apply to me because i've already maxed out all that stuff with new windows, two new furnaces, and some other things.

I was wondering the same thing about the air leaking in between the window sashes. I would imagine that a nice piece of foam pipe insulation stuffed between the top of the bottom sash and the glass of the top sash would solve it.

I don't have any windows in my shop either, but I was actually thinking of cutting a slot in the siding on the south face to build one of these. The framing wouldn't have to be modified at all in the wall, just build a simple chase to connect the heater box to the open space of the shop.

I haven't insulated yet so I have time, but this is something that I am really chewing on.

tranks said:

DJ in WV: thanks for the link. unfortunately i don't have any windows in the garage. but thats a neat idea. i wonder if you get more air leaks with the window part way open though.

ancy: how much does a wood burner cost installed? i don't think the rebate will apply to me because i've already maxed out all that stuff with new windows, two new furnaces, and some other things.

Click to expand...

TSC was going out of business and picked up a really nice one for $400 then whet to Menards and got piping for around $300 and my buddy put it in for $200. The garage is now like our winter living room. The kids and wife love it.

ancy: thats way out of my budget but sounds like it works great.


heres how i'm thinking about making the solar heater, this way wouldn't use any pop cans and would allow for all the ducting into the garage to be at the top, so i could put a hinge up there and angle it out to get more heat. i'd make it out of 1/4" plywood and insulate it with 1/2" foam on the back and sides. (still working on the design though so any idea would be apperciated)

It will be more difficult to build, but you really need your cold air intake at the bottom to pick up the cold air at the floor. As that cold air is heated, it will rise creating a draft inside your chamber, making it more efficient.

If the intake is at the top, once the air closer to the ceiling of the shop the same height and above the air intake warms, the heater is going to stop working.

I really like the idea of the hinge at the top to follow the sun more though. It make sense. Maybe a flexible, insulated duct would work for the cold air intake at the bottom of the unit. That way, it could still be hinged at the top. What do you think?