GRM Radiator DIY garage heater???

I saw this idea raised on another forum and started thinking... "why wouldn't this work?" stated like this:

"There is a very simple way to heat a garage if you have a hot water source nearby. You buy the largest aluminum automotive heater core you can find. You mount that in a wood box so that only the face of the coil is seen. At the other end of the box install a squirrel cage or even a few computer cooling fans to push air through the hot water pumped through the coil and back into the water heater. To accomplish this you need a tiny recirc pump, a check valve and a line-voltage thermostat to control the pump and fans and you have cheap heat with no fumes."

It sounds simple enough, and something a DIY'er could fab up easy. No fumes. Plumb in a few ball valves and you could fully close/drain the system easy enough when not in use. eh?

Sounds doable to me, the hardests part would be safely tapping into the water heater and running a bunch of pipes through a building.

A cars cooling system runs at 10-15psi, household water pressure is 35-80.

Go big or go home...

http://www.youtube.com/watch?v=PfDr-XXuvmo

They are pretty vague about the 'hot water source', it's not like an endless supply will magically appear from thin air.

edit: you don't want to be tapping into your domestic hot water heater, it's specifically prohibited anyway, at least in some areas, and I doubt that car radiators and hoses are approved for potable water.

That's basically how residential hot water heat works, but I'm skeptical.

Getting past the mechanical issues, efficiency would be my biggest concern.

I think the effect would be to tax the hot water heater by perpetually cooling the tank reservoir without significant btu output to the garage space.

The concept has been used for at least a century with cast iron radiators and a furnace to heat the water.

cast iron radiators are so good because they hold heat so well.. VERY efficient. I wish this place had them

Sounds like the guy invented a cabinet unit heater or a hot water unit heater. If he skipped the fan, it's called a convector, and if you make the box and heat exchanger smaller and drop the fan, it's called fin-tube.

http://www.modinehvac.com/v2portal/page/portal/hvac/hvacGreenhouseDefault/hvac_com/commercial_hvac/level_3_content2_028.htm

If you have a "hot water source" I'm assuming you also have electricity. Why reinvent the wheel....er....heater? Just plug in an electric heater and be done with it. They can be had for under $100 just about anywhere. These are the big ones. Small ones run $30-$40.

This avoids the whole issue of tapping into a hot water line and running you hot shower and drinking water through a questionable radiator or "other finned device."

For the record, the best way to heat a garage is to get an old oil furnace from a house finally upgrading ($free), stick it in the corner, with a 35 or 55 gallon drum of fuel, plumb the chimney, wire it up to a cheap thermostat and go. I suspect it would run well on waste oil if started on kerosene/diesel.

Second best is one of those kerosene torpedo/salamander forced air heaters.

Xceler8x wrote: If you have a "hot water source" I'm assuming you also have electricity. Why reinvent the wheel....er....heater? Just plug in an electric heater and be done with it. They can be had for under $100 just about anywhere. These are the big ones. Small ones run $30-$40. This avoids the whole issue of tapping into a hot water line and running you hot shower and drinking water through a questionable radiator or "other finned device."

I was assuming the water heater was gas-powered here and therefore cheaper, if it's electric, then yeah just cut out the middleman and hook up an electric heater.

Just leave the car running. Problem solved.

Electric resistance heaters are usually a waste of money. They are 100% efficient at converting electricity to heat but you will pay more for that heat than say burning natural gas or propane to heat water and pump it around.

I would rather use the back side of a refrigerator to heat my house and try to cool the outside than to use electric heat. A refrigerator is just a heat pump. Check the coefficient of performance of a heat pump. It can usualy move ~3-4 units of heat for every unit consumed. Example: 1 kw electric resistance heater uses 1 kw of power. You would get 3 kw of heat out the back side of a refrigerator if it was using 1kw of power.

Water heaters are usually around 80% efficient or higher. 1 therm of heat is 100,000 btu and the average therm of NG in my area cost $0.80. We would get 80,000 btu's out of one therm. That's equavalent to heating 800 pounds of water up 100°F. For 80 cents, that's cheap.

Say the average kwh is $0.10. That's equal to 3413 btu's. Spend $0.80 on electricity you get 27,300 btu's.

Of course you have to pay to pump the hot water around so that lessens it's price difference but you get the point...

Contamination of the water source and bursting the radiator/heater core have already been mentioned.

BTU's should be brought up as well. A tiny water pump and a few computer cooling fans will move enough BTU's of heat to warm you up one hand at a time. Ain't gonna be enough heat moving through the unit (water or air) to heat a shop or a garage bay.

Here's a project that doesn't involve woodworking, computer recycling and third degree burns:

1. Get in car.
2. Go to home depot.
3. Buy space heater for $30.
4. Go home.
5. Plug in heater.

for the record I have no intention of actually doing this... just thought it would inspire some good conversation.

Didn't some kid acheive sustained nuclear fusion in his garage? And here we are talking about hot water...

I have a couple electric heaters that warm up my garage pretty quickly. I can also move them around much easier than a hot water setup.

poopshovel wrote: Here's a project that doesn't involve woodworking, computer recycling and third degree burns: 1. Get in car. 2. Go to home depot. 3. Buy space heater for $30. 4. Go home. 5. Plug in heater.

/thread.

That's what I did last year. Got one of those oil-filled radiator-looking ones. Brings the crappily insulated, drafty garage up near 50 degrees in about an hour. On really cold days, I have another smaller fan-blown bench top heater that I get going. With both, I've had the garage up to around 60-65.

That's unless you guys are into weird projects.

xflowgolf wrote: for the record I have no intention of actually doing this... just thought it would inspire some good conversation.

Sorry I pooped on your parade. I just don't understand who has time to do this kind of E36 M3 (as I dick around on the intarwebs when I should be working....)

To turn this around, my brother in law did the opposite to heat his kids swimming pool. Put a car radiator on his house roof, and circulated the water from the pool to the radiator on the roof back to the pool. Seem to work ok.

I could see using a solar collector to heat water and heat the garage with that. I also agree with Mr Poopshovel about the space heater.

Okay, I can see Poopshovel heating his garage with some E36 M3ty 110-volt heater, since he's in Georgia, Landofnowinterstan. But SilverFleet? In freakin' MA? I had a heater I plugged in to the garage, spent over $100 in electricity running it over a few weeks in the dead of the winter, and the garage never got above around 40 degrees. And that was with the heater running non-stop.

Is your garage detached, SilverFleet? How big is it?

I finally just re-plumbed the gas lines to the garage and now have a Reznor heater in the ceiling. A simple twist of the knob and my garage is up to whatever temperature I want a few minutes later. No way would I go back to electric.

dculberson wrote: Okay, I can see Poopshovel heating his garage with some E36 M3ty 110-volt heater, since he's in Georgia, Landofnowinterstan. But SilverFleet? In freakin' MA? I had a heater I plugged in to the garage, spent over $100 in electricity running it over a few weeks in the dead of the winter, and the garage never got above around 40 degrees. And that was with the heater running non-stop. Is your garage detached, SilverFleet? How big is it? I finally just re-plumbed the gas lines to the garage and now have a Reznor heater in the ceiling. A simple twist of the knob and my garage is up to whatever temperature I want a few minutes later. No way would I go back to electric.

Get a 220v heater. It's a WORLD of difference. It can be 0 degrees outside, in an uninsulated garage, and i'll work inside with a short sleeved shirt.

I also have a forced air kerosene heater that will have me sweating at any point in the winter, but i find that thing isn't terribly cheap to operate, and it's loud. What i've been doing is using the kerosene heater to bring up to temp, the 220v electric to maintain.

I have a natural gas heater, it's a lot cheaper to operate than an electric. I was just shocked that someone from Massachusetts would be able to heat their garage with one 110v heater, and have it make any difference in temp.