# Heating Garage with Hot Water



## MoonRiver (Sep 2, 2007)

I've seen several plans for making a solar space heater and plans for making a solar water heater. What I'm wondering is if it would be practical to heat my garage with solar heated water.

What I am thinking is solar heated water that is pumped into the garage and through a radiator with a fan blowing through the radiator. I would want to use a solar panel for the fan and pump. I guess the questions I need answered are:

How much water I would need?
How big a pump I would need?
How much radiator capacity would I need?
How big a fan would I need?
Would it help to store some of the hot water?
I'm at a complete loss as to how to size this to see if it is practical. The garage is about 800 sq ft. My kerosene heater will heat it up to about 55 degrees on really cold days, but it takes an hour or 2 to get it there. The garage is on the north side of the house. I'm also going to work on sealing up leaks as best I can.

The roof on the garage faces east-west, so what I was thinking was to use coiled hose on each slope of the roof filled with water/anti-freeze mixture.


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## Windy in Kansas (Jun 16, 2002)

I highly recommend that you either buy the book at the URL or simply order it in on an Inter-Library Loan.

http://www.alibris.com/booksearch?q...yword=bill+keisling&cm_sp=works*listing*title

The title is "(The homeowner's Handbook of) Solar Water Heating Systems" by Bill Keisling. 

It is an older Rodale book and as with most Rodale publication is very good--at least in my opinion.

A companion book is "(The Complete Handbook of) Solar Air Heating Systems" by Steve Kornher with Andy Zaugg. Again, a Rodale book.

What is presented in both are different kinds of heating units, charts, etc. They give some first rate plans for homemade units that Rodale tested, tweaked to perfection, then published. 

Personally I consider both reference books and purchased used copies a few years ago after getting ILLs of them to see what they were like.


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## agmantoo (May 23, 2003)

In Southern Virginia depending on how warm you want the garage and the amount of insulation plus other things it will take 7 to 8 watts per square feet of floor space. That should give you a starting point. What to do for night heat and non sunny days will also be a consideration.


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## fishhead (Jul 19, 2006)

It's highly dependent on how well your garage is insulated. With enough insulation you should be able to heat the garage.

I know of some commercial sized buildings near here that are nearly 100% heated with solar collectors and lots of storage and we get -30 F and our sun is low in the winter.


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## WisJim (Jan 14, 2004)

The best way to use solar to heat a garage is to circulate the hot water from the solar panels through the floor in tubing, but this requires the tubing be installed when the floor is poured. But this makes use of lower temperature water and uses the concrete floor as heat storage also. And Fishead's advise about insulation is important--insulation is the first thing to do, then figure out how to heat it.


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## Jim-mi (May 15, 2002)

Go reread Windy's post.........
Yes get your self a book or two . . . . . . .then you can see several "options". . .and how they relate to your case.............
Plus there should be charts for tank sizes etc.

No I haven't seen the books that Windy mentioned.....


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## SolarGary (Sep 8, 2005)

MoonRiver said:


> I've seen several plans for making a solar space heater and plans for making a solar water heater. What I'm wondering is if it would be practical to heat my garage with solar heated water.
> 
> What I am thinking is solar heated water that is pumped into the garage and through a radiator with a fan blowing through the radiator. I would want to use a solar panel for the fan and pump. I guess the questions I need answered are:
> 
> ...


Hi,
If you want this for space heating, the coiled hoses on the roof are not going to do much for you in the winter. You need a real solar collector with glazing for winter use.
The east/west exposure is also a problem. You really need a roughly south exposure with a steep collector tilt to be effective with the low winter sun.

So, I'd start by seeing if you can resolve those issues first -- if you can't, than solar heating is not really going to be an answer for you.

Assuming you can get over those issues:

The garage really needs to be well insulated in order to be heated with a practical size solar collector. 
This is my garage/shop, and the collector that heats it:
http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/solarshed.htm
It does a good job on sunny days even down to very cold temperatures, but you can see that the shop is reasonably well insulated, and the collector is large. Your climate may be more mild, and less collector area may be needed.
The other thing to consider is that you will need some kind of backup heat for days when the sun is not shining.


You can get an idea what the heat loss for your garage is using this calculator:
http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm

Once you have the heat loss, you can compare it a typical collector output of about 800 BTU per day per sqft of collector, and see how much collector you might need.

As for performance of radiators, here is an article on using a radiator is a somewhat different application, but there are some performance numbers that may be helpful:
http://www.builditsolar.com/Projects/Sunspace/LowCostHtStorageNathan.pdf

There are lots of solar space heating ideas here:
http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm


Gary


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